Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

16 files changed, 3448 insertions, 0 deletions

diff --git a/image/encoders/bmp/moz.build b/image/encoders/bmp/moz.build
new file mode 100644
index 0000000000..783fd37005
--- /dev/null
+++ b/image/encoders/bmp/moz.build
@@ -0,0 +1,15 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+SOURCES += [
+    "nsBMPEncoder.cpp",
+]
+
+LOCAL_INCLUDES += [
+    "/image",
+]
+
+FINAL_LIBRARY = "xul"
diff --git a/image/encoders/bmp/nsBMPEncoder.cpp b/image/encoders/bmp/nsBMPEncoder.cpp
new file mode 100644
index 0000000000..697950d7af
--- /dev/null
+++ b/image/encoders/bmp/nsBMPEncoder.cpp
@@ -0,0 +1,716 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsCRT.h"
+#include "mozilla/EndianUtils.h"
+#include "mozilla/UniquePtrExtensions.h"
+#include "nsBMPEncoder.h"
+#include "nsString.h"
+#include "nsStreamUtils.h"
+#include "nsTArray.h"
+#include "mozilla/CheckedInt.h"
+#include "BMPHeaders.h"
+
+using namespace mozilla;
+using namespace mozilla::image;
+using namespace mozilla::image::bmp;
+
+NS_IMPL_ISUPPORTS(nsBMPEncoder, imgIEncoder, nsIInputStream,
+                  nsIAsyncInputStream)
+
+nsBMPEncoder::nsBMPEncoder()
+    : mBMPInfoHeader{},
+      mImageBufferStart(nullptr),
+      mImageBufferCurr(0),
+      mImageBufferSize(0),
+      mImageBufferReadPoint(0),
+      mFinished(false),
+      mCallback(nullptr),
+      mCallbackTarget(nullptr),
+      mNotifyThreshold(0) {
+  this->mBMPFileHeader.filesize = 0;
+  this->mBMPFileHeader.reserved = 0;
+  this->mBMPFileHeader.dataoffset = 0;
+}
+
+nsBMPEncoder::~nsBMPEncoder() {
+  if (mImageBufferStart) {
+    free(mImageBufferStart);
+    mImageBufferStart = nullptr;
+    mImageBufferCurr = nullptr;
+  }
+}
+
+// nsBMPEncoder::InitFromData
+//
+// One output option is supported: bpp=<bpp_value>
+// bpp specifies the bits per pixel to use where bpp_value can be 24 or 32
+NS_IMETHODIMP
+nsBMPEncoder::InitFromData(const uint8_t* aData,
+                           uint32_t aLength,  // (unused, req'd by JS)
+                           uint32_t aWidth, uint32_t aHeight, uint32_t aStride,
+                           uint32_t aInputFormat,
+                           const nsAString& aOutputOptions) {
+  // validate input format
+  if (aInputFormat != INPUT_FORMAT_RGB && aInputFormat != INPUT_FORMAT_RGBA &&
+      aInputFormat != INPUT_FORMAT_HOSTARGB) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  CheckedInt32 check = CheckedInt32(aWidth) * 4;
+  if (MOZ_UNLIKELY(!check.isValid())) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  // Stride is the padded width of each row, so it better be longer
+  if ((aInputFormat == INPUT_FORMAT_RGB && aStride < aWidth * 3) ||
+      ((aInputFormat == INPUT_FORMAT_RGBA ||
+        aInputFormat == INPUT_FORMAT_HOSTARGB) &&
+       aStride < aWidth * 4)) {
+    NS_WARNING("Invalid stride for InitFromData");
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  nsresult rv;
+  rv = StartImageEncode(aWidth, aHeight, aInputFormat, aOutputOptions);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  rv = AddImageFrame(aData, aLength, aWidth, aHeight, aStride, aInputFormat,
+                     aOutputOptions);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  rv = EndImageEncode();
+  return rv;
+}
+
+// Just a helper method to make it explicit in calculations that we are dealing
+// with bytes and not bits
+static inline uint16_t BytesPerPixel(uint16_t aBPP) { return aBPP / 8; }
+
+// Calculates the number of padding bytes that are needed per row of image data
+static inline uint32_t PaddingBytes(uint16_t aBPP, uint32_t aWidth) {
+  uint32_t rowSize = aWidth * BytesPerPixel(aBPP);
+  uint8_t paddingSize = 0;
+  if (rowSize % 4) {
+    paddingSize = (4 - (rowSize % 4));
+  }
+  return paddingSize;
+}
+
+// See ::InitFromData for other info.
+NS_IMETHODIMP
+nsBMPEncoder::StartImageEncode(uint32_t aWidth, uint32_t aHeight,
+                               uint32_t aInputFormat,
+                               const nsAString& aOutputOptions) {
+  // can't initialize more than once
+  if (mImageBufferStart || mImageBufferCurr) {
+    return NS_ERROR_ALREADY_INITIALIZED;
+  }
+
+  // validate input format
+  if (aInputFormat != INPUT_FORMAT_RGB && aInputFormat != INPUT_FORMAT_RGBA &&
+      aInputFormat != INPUT_FORMAT_HOSTARGB) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  // parse and check any provided output options
+  Version version;
+  uint16_t bpp;
+  nsresult rv = ParseOptions(aOutputOptions, version, bpp);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  MOZ_ASSERT(bpp <= 32);
+
+  rv = InitFileHeader(version, bpp, aWidth, aHeight);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  rv = InitInfoHeader(version, bpp, aWidth, aHeight);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  mImageBufferSize = mBMPFileHeader.filesize;
+  mImageBufferStart = static_cast<uint8_t*>(malloc(mImageBufferSize));
+  if (!mImageBufferStart) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+  mImageBufferCurr = mImageBufferStart;
+
+  EncodeFileHeader();
+  EncodeInfoHeader();
+
+  return NS_OK;
+}
+
+// Returns the number of bytes in the image buffer used.
+// For a BMP file, this is all bytes in the buffer.
+NS_IMETHODIMP
+nsBMPEncoder::GetImageBufferUsed(uint32_t* aOutputSize) {
+  NS_ENSURE_ARG_POINTER(aOutputSize);
+  *aOutputSize = mImageBufferSize;
+  return NS_OK;
+}
+
+// Returns a pointer to the start of the image buffer
+NS_IMETHODIMP
+nsBMPEncoder::GetImageBuffer(char** aOutputBuffer) {
+  NS_ENSURE_ARG_POINTER(aOutputBuffer);
+  *aOutputBuffer = reinterpret_cast<char*>(mImageBufferStart);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsBMPEncoder::AddImageFrame(const uint8_t* aData,
+                            uint32_t aLength,  // (unused, req'd by JS)
+                            uint32_t aWidth, uint32_t aHeight, uint32_t aStride,
+                            uint32_t aInputFormat,
+                            const nsAString& aFrameOptions) {
+  // must be initialized
+  if (!mImageBufferStart || !mImageBufferCurr) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  // validate input format
+  if (aInputFormat != INPUT_FORMAT_RGB && aInputFormat != INPUT_FORMAT_RGBA &&
+      aInputFormat != INPUT_FORMAT_HOSTARGB) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  if (mBMPInfoHeader.width < 0) {
+    return NS_ERROR_ILLEGAL_VALUE;
+  }
+
+  CheckedUint32 size = CheckedUint32(mBMPInfoHeader.width) *
+                       CheckedUint32(BytesPerPixel(mBMPInfoHeader.bpp));
+  if (MOZ_UNLIKELY(!size.isValid())) {
+    return NS_ERROR_FAILURE;
+  }
+
+  auto row = MakeUniqueFallible<uint8_t[]>(size.value());
+  if (!row) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  CheckedUint32 check = CheckedUint32(mBMPInfoHeader.height) * aStride;
+  if (MOZ_UNLIKELY(!check.isValid())) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // write each row: if we add more input formats, we may want to
+  // generalize the conversions
+  if (aInputFormat == INPUT_FORMAT_HOSTARGB) {
+    // BMP requires RGBA with post-multiplied alpha, so we need to convert
+    for (int32_t y = mBMPInfoHeader.height - 1; y >= 0; y--) {
+      ConvertHostARGBRow(&aData[y * aStride], row, mBMPInfoHeader.width);
+      if (mBMPInfoHeader.bpp == 24) {
+        EncodeImageDataRow24(row.get());
+      } else {
+        EncodeImageDataRow32(row.get());
+      }
+    }
+  } else if (aInputFormat == INPUT_FORMAT_RGBA) {
+    // simple RGBA, no conversion needed
+    for (int32_t y = 0; y < mBMPInfoHeader.height; y++) {
+      if (mBMPInfoHeader.bpp == 24) {
+        EncodeImageDataRow24(row.get());
+      } else {
+        EncodeImageDataRow32(row.get());
+      }
+    }
+  } else if (aInputFormat == INPUT_FORMAT_RGB) {
+    // simple RGB, no conversion needed
+    for (int32_t y = 0; y < mBMPInfoHeader.height; y++) {
+      if (mBMPInfoHeader.bpp == 24) {
+        EncodeImageDataRow24(&aData[y * aStride]);
+      } else {
+        EncodeImageDataRow32(&aData[y * aStride]);
+      }
+    }
+  } else {
+    MOZ_ASSERT_UNREACHABLE("Bad format type");
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsBMPEncoder::EndImageEncode() {
+  // must be initialized
+  if (!mImageBufferStart || !mImageBufferCurr) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  mFinished = true;
+  NotifyListener();
+
+  // if output callback can't get enough memory, it will free our buffer
+  if (!mImageBufferStart || !mImageBufferCurr) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  return NS_OK;
+}
+
+// Parses the encoder options and sets the bits per pixel to use
+// See InitFromData for a description of the parse options
+nsresult nsBMPEncoder::ParseOptions(const nsAString& aOptions,
+                                    Version& aVersionOut, uint16_t& aBppOut) {
+  aVersionOut = VERSION_3;
+  aBppOut = 24;
+
+  // Parse the input string into a set of name/value pairs.
+  // From a format like: name=value;bpp=<bpp_value>;name=value
+  // to format: [0] = name=value, [1] = bpp=<bpp_value>, [2] = name=value
+  nsTArray<nsCString> nameValuePairs;
+  ParseString(NS_ConvertUTF16toUTF8(aOptions), ';', nameValuePairs);
+
+  // For each name/value pair in the set
+  for (uint32_t i = 0; i < nameValuePairs.Length(); ++i) {
+    // Split the name value pair [0] = name, [1] = value
+    nsTArray<nsCString> nameValuePair;
+    ParseString(nameValuePairs[i], '=', nameValuePair);
+    if (nameValuePair.Length() != 2) {
+      return NS_ERROR_INVALID_ARG;
+    }
+
+    // Parse the bpp portion of the string name=value;version=<version_value>;
+    // name=value
+    if (nameValuePair[0].Equals("version",
+                                nsCaseInsensitiveCStringComparator)) {
+      if (nameValuePair[1].EqualsLiteral("3")) {
+        aVersionOut = VERSION_3;
+      } else if (nameValuePair[1].EqualsLiteral("5")) {
+        aVersionOut = VERSION_5;
+      } else {
+        return NS_ERROR_INVALID_ARG;
+      }
+    }
+
+    // Parse the bpp portion of the string name=value;bpp=<bpp_value>;name=value
+    if (nameValuePair[0].Equals("bpp", nsCaseInsensitiveCStringComparator)) {
+      if (nameValuePair[1].EqualsLiteral("24")) {
+        aBppOut = 24;
+      } else if (nameValuePair[1].EqualsLiteral("32")) {
+        aBppOut = 32;
+      } else {
+        return NS_ERROR_INVALID_ARG;
+      }
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsBMPEncoder::Close() {
+  if (mImageBufferStart) {
+    free(mImageBufferStart);
+    mImageBufferStart = nullptr;
+    mImageBufferSize = 0;
+    mImageBufferReadPoint = 0;
+    mImageBufferCurr = nullptr;
+  }
+
+  return NS_OK;
+}
+
+// Obtains the available bytes to read
+NS_IMETHODIMP
+nsBMPEncoder::Available(uint64_t* _retval) {
+  if (!mImageBufferStart || !mImageBufferCurr) {
+    return NS_BASE_STREAM_CLOSED;
+  }
+
+  *_retval = GetCurrentImageBufferOffset() - mImageBufferReadPoint;
+  return NS_OK;
+}
+
+// Obtains the stream's status
+NS_IMETHODIMP
+nsBMPEncoder::StreamStatus() {
+  return mImageBufferStart && mImageBufferCurr ? NS_OK : NS_BASE_STREAM_CLOSED;
+}
+
+// [noscript] Reads bytes which are available
+NS_IMETHODIMP
+nsBMPEncoder::Read(char* aBuf, uint32_t aCount, uint32_t* _retval) {
+  return ReadSegments(NS_CopySegmentToBuffer, aBuf, aCount, _retval);
+}
+
+// [noscript] Reads segments
+NS_IMETHODIMP
+nsBMPEncoder::ReadSegments(nsWriteSegmentFun aWriter, void* aClosure,
+                           uint32_t aCount, uint32_t* _retval) {
+  uint32_t maxCount = GetCurrentImageBufferOffset() - mImageBufferReadPoint;
+  if (maxCount == 0) {
+    *_retval = 0;
+    return mFinished ? NS_OK : NS_BASE_STREAM_WOULD_BLOCK;
+  }
+
+  if (aCount > maxCount) {
+    aCount = maxCount;
+  }
+  nsresult rv = aWriter(
+      this, aClosure,
+      reinterpret_cast<const char*>(mImageBufferStart + mImageBufferReadPoint),
+      0, aCount, _retval);
+  if (NS_SUCCEEDED(rv)) {
+    NS_ASSERTION(*_retval <= aCount, "bad write count");
+    mImageBufferReadPoint += *_retval;
+  }
+  // errors returned from the writer end here!
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsBMPEncoder::IsNonBlocking(bool* _retval) {
+  *_retval = true;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsBMPEncoder::AsyncWait(nsIInputStreamCallback* aCallback, uint32_t aFlags,
+                        uint32_t aRequestedCount, nsIEventTarget* aTarget) {
+  if (aFlags != 0) {
+    return NS_ERROR_NOT_IMPLEMENTED;
+  }
+
+  if (mCallback || mCallbackTarget) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  mCallbackTarget = aTarget;
+  // 0 means "any number of bytes except 0"
+  mNotifyThreshold = aRequestedCount;
+  if (!aRequestedCount) {
+    mNotifyThreshold = 1024;  // We don't want to notify incessantly
+  }
+
+  // We set the callback absolutely last, because NotifyListener uses it to
+  // determine if someone needs to be notified.  If we don't set it last,
+  // NotifyListener might try to fire off a notification to a null target
+  // which will generally cause non-threadsafe objects to be used off the
+  // main thread
+  mCallback = aCallback;
+
+  // What we are being asked for may be present already
+  NotifyListener();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsBMPEncoder::CloseWithStatus(nsresult aStatus) { return Close(); }
+
+// nsBMPEncoder::ConvertHostARGBRow
+//
+//    Our colors are stored with premultiplied alphas, but we need
+//    an output with no alpha in machine-independent byte order.
+//
+void nsBMPEncoder::ConvertHostARGBRow(const uint8_t* aSrc,
+                                      const UniquePtr<uint8_t[]>& aDest,
+                                      uint32_t aPixelWidth) {
+  uint16_t bytes = BytesPerPixel(mBMPInfoHeader.bpp);
+
+  if (mBMPInfoHeader.bpp == 32) {
+    for (uint32_t x = 0; x < aPixelWidth; x++) {
+      const uint32_t& pixelIn = ((const uint32_t*)(aSrc))[x];
+      uint8_t* pixelOut = &aDest[x * bytes];
+
+      pixelOut[0] = (pixelIn & 0x00ff0000) >> 16;
+      pixelOut[1] = (pixelIn & 0x0000ff00) >> 8;
+      pixelOut[2] = (pixelIn & 0x000000ff) >> 0;
+      pixelOut[3] = (pixelIn & 0xff000000) >> 24;
+    }
+  } else {
+    for (uint32_t x = 0; x < aPixelWidth; x++) {
+      const uint32_t& pixelIn = ((const uint32_t*)(aSrc))[x];
+      uint8_t* pixelOut = &aDest[x * bytes];
+
+      pixelOut[0] = (pixelIn & 0xff0000) >> 16;
+      pixelOut[1] = (pixelIn & 0x00ff00) >> 8;
+      pixelOut[2] = (pixelIn & 0x0000ff) >> 0;
+    }
+  }
+}
+
+void nsBMPEncoder::NotifyListener() {
+  if (mCallback && (GetCurrentImageBufferOffset() - mImageBufferReadPoint >=
+                        mNotifyThreshold ||
+                    mFinished)) {
+    nsCOMPtr<nsIInputStreamCallback> callback;
+    if (mCallbackTarget) {
+      callback = NS_NewInputStreamReadyEvent("nsBMPEncoder::NotifyListener",
+                                             mCallback, mCallbackTarget);
+    } else {
+      callback = mCallback;
+    }
+
+    NS_ASSERTION(callback, "Shouldn't fail to make the callback");
+    // Null the callback first because OnInputStreamReady could
+    // reenter AsyncWait
+    mCallback = nullptr;
+    mCallbackTarget = nullptr;
+    mNotifyThreshold = 0;
+
+    callback->OnInputStreamReady(this);
+  }
+}
+
+// Initializes the BMP file header mBMPFileHeader to the passed in values
+nsresult nsBMPEncoder::InitFileHeader(Version aVersion, uint16_t aBPP,
+                                      uint32_t aWidth, uint32_t aHeight) {
+  memset(&mBMPFileHeader, 0, sizeof(mBMPFileHeader));
+  mBMPFileHeader.signature[0] = 'B';
+  mBMPFileHeader.signature[1] = 'M';
+
+  if (aVersion == VERSION_3) {
+    mBMPFileHeader.dataoffset = FILE_HEADER_LENGTH + InfoHeaderLength::WIN_V3;
+  } else {  // aVersion == 5
+    mBMPFileHeader.dataoffset = FILE_HEADER_LENGTH + InfoHeaderLength::WIN_V5;
+  }
+
+  // The color table is present only if BPP is <= 8
+  if (aBPP <= 8) {
+    uint32_t numColors = 1 << aBPP;
+    mBMPFileHeader.dataoffset += 4 * numColors;
+    CheckedUint32 filesize = CheckedUint32(mBMPFileHeader.dataoffset) +
+                             CheckedUint32(aWidth) * aHeight;
+    if (MOZ_UNLIKELY(!filesize.isValid())) {
+      return NS_ERROR_INVALID_ARG;
+    }
+    mBMPFileHeader.filesize = filesize.value();
+  } else {
+    CheckedUint32 filesize = CheckedUint32(mBMPFileHeader.dataoffset) +
+                             (CheckedUint32(aWidth) * BytesPerPixel(aBPP) +
+                              PaddingBytes(aBPP, aWidth)) *
+                                 aHeight;
+    if (MOZ_UNLIKELY(!filesize.isValid())) {
+      return NS_ERROR_INVALID_ARG;
+    }
+    mBMPFileHeader.filesize = filesize.value();
+  }
+
+  mBMPFileHeader.reserved = 0;
+
+  return NS_OK;
+}
+
+#define ENCODE(pImageBufferCurr, value)            \
+  memcpy(*pImageBufferCurr, &value, sizeof value); \
+  *pImageBufferCurr += sizeof value;
+
+// Initializes the bitmap info header mBMPInfoHeader to the passed in values
+nsresult nsBMPEncoder::InitInfoHeader(Version aVersion, uint16_t aBPP,
+                                      uint32_t aWidth, uint32_t aHeight) {
+  memset(&mBMPInfoHeader, 0, sizeof(mBMPInfoHeader));
+  if (aVersion == VERSION_3) {
+    mBMPInfoHeader.bihsize = InfoHeaderLength::WIN_V3;
+  } else {
+    MOZ_ASSERT(aVersion == VERSION_5);
+    mBMPInfoHeader.bihsize = InfoHeaderLength::WIN_V5;
+  }
+
+  CheckedInt32 width(aWidth);
+  CheckedInt32 height(aHeight);
+  if (MOZ_UNLIKELY(!width.isValid() || !height.isValid())) {
+    return NS_ERROR_INVALID_ARG;
+  }
+  mBMPInfoHeader.width = width.value();
+  mBMPInfoHeader.height = height.value();
+
+  mBMPInfoHeader.planes = 1;
+  mBMPInfoHeader.bpp = aBPP;
+  mBMPInfoHeader.compression = 0;
+  mBMPInfoHeader.colors = 0;
+  mBMPInfoHeader.important_colors = 0;
+
+  CheckedUint32 check = CheckedUint32(aWidth) * BytesPerPixel(aBPP);
+  if (MOZ_UNLIKELY(!check.isValid())) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  if (aBPP <= 8) {
+    CheckedUint32 imagesize = CheckedUint32(aWidth) * aHeight;
+    if (MOZ_UNLIKELY(!imagesize.isValid())) {
+      return NS_ERROR_INVALID_ARG;
+    }
+    mBMPInfoHeader.image_size = imagesize.value();
+  } else {
+    CheckedUint32 imagesize = (CheckedUint32(aWidth) * BytesPerPixel(aBPP) +
+                               PaddingBytes(aBPP, aWidth)) *
+                              CheckedUint32(aHeight);
+    if (MOZ_UNLIKELY(!imagesize.isValid())) {
+      return NS_ERROR_INVALID_ARG;
+    }
+    mBMPInfoHeader.image_size = imagesize.value();
+  }
+  mBMPInfoHeader.xppm = 0;
+  mBMPInfoHeader.yppm = 0;
+  if (aVersion >= VERSION_5) {
+    mBMPInfoHeader.red_mask = 0x000000FF;
+    mBMPInfoHeader.green_mask = 0x0000FF00;
+    mBMPInfoHeader.blue_mask = 0x00FF0000;
+    mBMPInfoHeader.alpha_mask = 0xFF000000;
+    mBMPInfoHeader.color_space = V5InfoHeader::COLOR_SPACE_LCS_SRGB;
+    mBMPInfoHeader.white_point.r.x = 0;
+    mBMPInfoHeader.white_point.r.y = 0;
+    mBMPInfoHeader.white_point.r.z = 0;
+    mBMPInfoHeader.white_point.g.x = 0;
+    mBMPInfoHeader.white_point.g.y = 0;
+    mBMPInfoHeader.white_point.g.z = 0;
+    mBMPInfoHeader.white_point.b.x = 0;
+    mBMPInfoHeader.white_point.b.y = 0;
+    mBMPInfoHeader.white_point.b.z = 0;
+    mBMPInfoHeader.gamma_red = 0;
+    mBMPInfoHeader.gamma_green = 0;
+    mBMPInfoHeader.gamma_blue = 0;
+    mBMPInfoHeader.intent = 0;
+    mBMPInfoHeader.profile_offset = 0;
+    mBMPInfoHeader.profile_size = 0;
+    mBMPInfoHeader.reserved = 0;
+  }
+
+  return NS_OK;
+}
+
+// Encodes the BMP file header mBMPFileHeader
+void nsBMPEncoder::EncodeFileHeader() {
+  FileHeader littleEndianBFH = mBMPFileHeader;
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianBFH.filesize, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianBFH.reserved, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianBFH.dataoffset, 1);
+
+  ENCODE(&mImageBufferCurr, littleEndianBFH.signature);
+  ENCODE(&mImageBufferCurr, littleEndianBFH.filesize);
+  ENCODE(&mImageBufferCurr, littleEndianBFH.reserved);
+  ENCODE(&mImageBufferCurr, littleEndianBFH.dataoffset);
+}
+
+// Encodes the BMP info header mBMPInfoHeader
+void nsBMPEncoder::EncodeInfoHeader() {
+  V5InfoHeader littleEndianmBIH = mBMPInfoHeader;
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.bihsize, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.width, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.height, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.planes, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.bpp, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.compression, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.image_size, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.xppm, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.yppm, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.colors, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.important_colors,
+                                          1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.red_mask, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.green_mask, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.blue_mask, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.alpha_mask, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.color_space, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.white_point.r.x, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.white_point.r.y, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.white_point.r.z, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.white_point.g.x, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.white_point.g.y, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.white_point.g.z, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.white_point.b.x, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.white_point.b.y, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.white_point.b.z, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.gamma_red, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.gamma_green, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.gamma_blue, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.intent, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.profile_offset, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmBIH.profile_size, 1);
+
+  ENCODE(&mImageBufferCurr, littleEndianmBIH.bihsize);
+  ENCODE(&mImageBufferCurr, littleEndianmBIH.width);
+  ENCODE(&mImageBufferCurr, littleEndianmBIH.height);
+  ENCODE(&mImageBufferCurr, littleEndianmBIH.planes);
+  ENCODE(&mImageBufferCurr, littleEndianmBIH.bpp);
+  ENCODE(&mImageBufferCurr, littleEndianmBIH.compression);
+  ENCODE(&mImageBufferCurr, littleEndianmBIH.image_size);
+  ENCODE(&mImageBufferCurr, littleEndianmBIH.xppm);
+  ENCODE(&mImageBufferCurr, littleEndianmBIH.yppm);
+  ENCODE(&mImageBufferCurr, littleEndianmBIH.colors);
+  ENCODE(&mImageBufferCurr, littleEndianmBIH.important_colors);
+
+  if (mBMPInfoHeader.bihsize > InfoHeaderLength::WIN_V3) {
+    ENCODE(&mImageBufferCurr, littleEndianmBIH.red_mask);
+    ENCODE(&mImageBufferCurr, littleEndianmBIH.green_mask);
+    ENCODE(&mImageBufferCurr, littleEndianmBIH.blue_mask);
+    ENCODE(&mImageBufferCurr, littleEndianmBIH.alpha_mask);
+    ENCODE(&mImageBufferCurr, littleEndianmBIH.color_space);
+    ENCODE(&mImageBufferCurr, littleEndianmBIH.white_point.r.x);
+    ENCODE(&mImageBufferCurr, littleEndianmBIH.white_point.r.y);
+    ENCODE(&mImageBufferCurr, littleEndianmBIH.white_point.r.z);
+    ENCODE(&mImageBufferCurr, littleEndianmBIH.white_point.g.x);
+    ENCODE(&mImageBufferCurr, littleEndianmBIH.white_point.g.y);
+    ENCODE(&mImageBufferCurr, littleEndianmBIH.white_point.g.z);
+    ENCODE(&mImageBufferCurr, littleEndianmBIH.white_point.b.x);
+    ENCODE(&mImageBufferCurr, littleEndianmBIH.white_point.b.y);
+    ENCODE(&mImageBufferCurr, littleEndianmBIH.white_point.b.z);
+    ENCODE(&mImageBufferCurr, littleEndianmBIH.gamma_red);
+    ENCODE(&mImageBufferCurr, littleEndianmBIH.gamma_green);
+    ENCODE(&mImageBufferCurr, littleEndianmBIH.gamma_blue);
+    ENCODE(&mImageBufferCurr, littleEndianmBIH.intent);
+    ENCODE(&mImageBufferCurr, littleEndianmBIH.profile_offset);
+    ENCODE(&mImageBufferCurr, littleEndianmBIH.profile_size);
+    ENCODE(&mImageBufferCurr, littleEndianmBIH.reserved);
+  }
+}
+
+// Sets a pixel in the image buffer that doesn't have alpha data
+static inline void SetPixel24(uint8_t*& imageBufferCurr, uint8_t aRed,
+                              uint8_t aGreen, uint8_t aBlue) {
+  *imageBufferCurr = aBlue;
+  *(imageBufferCurr + 1) = aGreen;
+  *(imageBufferCurr + 2) = aRed;
+}
+
+// Sets a pixel in the image buffer with alpha data
+static inline void SetPixel32(uint8_t*& imageBufferCurr, uint8_t aRed,
+                              uint8_t aGreen, uint8_t aBlue,
+                              uint8_t aAlpha = 0xFF) {
+  *imageBufferCurr = aBlue;
+  *(imageBufferCurr + 1) = aGreen;
+  *(imageBufferCurr + 2) = aRed;
+  *(imageBufferCurr + 3) = aAlpha;
+}
+
+// Encodes a row of image data which does not have alpha data
+void nsBMPEncoder::EncodeImageDataRow24(const uint8_t* aData) {
+  for (int32_t x = 0; x < mBMPInfoHeader.width; x++) {
+    uint32_t pos = x * BytesPerPixel(mBMPInfoHeader.bpp);
+    SetPixel24(mImageBufferCurr, aData[pos], aData[pos + 1], aData[pos + 2]);
+    mImageBufferCurr += BytesPerPixel(mBMPInfoHeader.bpp);
+  }
+
+  for (uint32_t x = 0;
+       x < PaddingBytes(mBMPInfoHeader.bpp, mBMPInfoHeader.width); x++) {
+    *mImageBufferCurr++ = 0;
+  }
+}
+
+// Encodes a row of image data which does have alpha data
+void nsBMPEncoder::EncodeImageDataRow32(const uint8_t* aData) {
+  for (int32_t x = 0; x < mBMPInfoHeader.width; x++) {
+    uint32_t pos = x * BytesPerPixel(mBMPInfoHeader.bpp);
+    SetPixel32(mImageBufferCurr, aData[pos], aData[pos + 1], aData[pos + 2],
+               aData[pos + 3]);
+    mImageBufferCurr += 4;
+  }
+
+  for (uint32_t x = 0;
+       x < PaddingBytes(mBMPInfoHeader.bpp, mBMPInfoHeader.width); x++) {
+    *mImageBufferCurr++ = 0;
+  }
+}
diff --git a/image/encoders/bmp/nsBMPEncoder.h b/image/encoders/bmp/nsBMPEncoder.h
new file mode 100644
index 0000000000..1f40d9df34
--- /dev/null
+++ b/image/encoders/bmp/nsBMPEncoder.h
@@ -0,0 +1,150 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_image_encoders_bmp_nsBMPEncoder_h
+#define mozilla_image_encoders_bmp_nsBMPEncoder_h
+
+#include "mozilla/Attributes.h"
+#include "mozilla/ReentrantMonitor.h"
+#include "mozilla/UniquePtr.h"
+
+#include "imgIEncoder.h"
+
+#include "nsCOMPtr.h"
+
+#define NS_BMPENCODER_CID                            \
+  { /* 13a5320c-4c91-4FA4-bd16-b081a3ba8c0b */       \
+    0x13a5320c, 0x4c91, 0x4fa4, {                    \
+      0xbd, 0x16, 0xb0, 0x81, 0xa3, 0Xba, 0x8c, 0x0b \
+    }                                                \
+  }
+
+namespace mozilla {
+namespace image {
+namespace bmp {
+
+struct FileHeader {
+  char signature[2];    // String "BM".
+  uint32_t filesize;    // File size.
+  int32_t reserved;     // Zero.
+  uint32_t dataoffset;  // Offset to raster data.
+};
+
+struct XYZ {
+  int32_t x, y, z;
+};
+
+struct XYZTriple {
+  XYZ r, g, b;
+};
+
+struct V5InfoHeader {
+  uint32_t bihsize;           // Header size
+  int32_t width;              // Uint16 in OS/2 BMPs
+  int32_t height;             // Uint16 in OS/2 BMPs
+  uint16_t planes;            // =1
+  uint16_t bpp;               // Bits per pixel.
+  uint32_t compression;       // See Compression for valid values
+  uint32_t image_size;        // (compressed) image size. Can be 0 if
+                              // compression==0
+  uint32_t xppm;              // Pixels per meter, horizontal
+  uint32_t yppm;              // Pixels per meter, vertical
+  uint32_t colors;            // Used Colors
+  uint32_t important_colors;  // Number of important colors. 0=all
+  // The rest of the header is not available in WIN_V3 BMP Files
+  uint32_t red_mask;     // Bits used for red component
+  uint32_t green_mask;   // Bits used for green component
+  uint32_t blue_mask;    // Bits used for blue component
+  uint32_t alpha_mask;   // Bits used for alpha component
+  uint32_t color_space;  // 0x73524742=LCS_sRGB ...
+  // These members are unused unless color_space == LCS_CALIBRATED_RGB
+  XYZTriple white_point;  // Logical white point
+  uint32_t gamma_red;     // Red gamma component
+  uint32_t gamma_green;   // Green gamma component
+  uint32_t gamma_blue;    // Blue gamma component
+  uint32_t intent;        // Rendering intent
+  // These members are unused unless color_space == LCS_PROFILE_*
+  uint32_t profile_offset;  // Offset to profile data in bytes
+  uint32_t profile_size;    // Size of profile data in bytes
+  uint32_t reserved;        // =0
+
+  static const uint32_t COLOR_SPACE_LCS_SRGB = 0x73524742;
+};
+
+}  // namespace bmp
+}  // namespace image
+}  // namespace mozilla
+
+// Provides BMP encoding functionality. Use InitFromData() to do the
+// encoding. See that function definition for encoding options.
+
+class nsBMPEncoder final : public imgIEncoder {
+  typedef mozilla::ReentrantMonitor ReentrantMonitor;
+
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_IMGIENCODER
+  NS_DECL_NSIINPUTSTREAM
+  NS_DECL_NSIASYNCINPUTSTREAM
+
+  nsBMPEncoder();
+
+ protected:
+  ~nsBMPEncoder();
+
+  enum Version { VERSION_3 = 3, VERSION_5 = 5 };
+
+  // See InitData in the cpp for valid parse options
+  nsresult ParseOptions(const nsAString& aOptions, Version& aVersionOut,
+                        uint16_t& aBppOut);
+  // Obtains data with no alpha in machine-independent byte order
+  void ConvertHostARGBRow(const uint8_t* aSrc,
+                          const mozilla::UniquePtr<uint8_t[]>& aDest,
+                          uint32_t aPixelWidth);
+  // Thread safe notify listener
+  void NotifyListener();
+
+  // Initializes the bitmap file header member mBMPFileHeader
+  nsresult InitFileHeader(Version aVersion, uint16_t aBPP, uint32_t aWidth,
+                          uint32_t aHeight);
+  // Initializes the bitmap info header member mBMPInfoHeader
+  nsresult InitInfoHeader(Version aVersion, uint16_t aBPP, uint32_t aWidth,
+                          uint32_t aHeight);
+
+  // Encodes the bitmap file header member mBMPFileHeader
+  void EncodeFileHeader();
+  // Encodes the bitmap info header member mBMPInfoHeader
+  void EncodeInfoHeader();
+  // Encodes a row of image data which does not have alpha data
+  void EncodeImageDataRow24(const uint8_t* aData);
+  // Encodes a row of image data which does have alpha data
+  void EncodeImageDataRow32(const uint8_t* aData);
+  // Obtains the current offset filled up to for the image buffer
+  inline int32_t GetCurrentImageBufferOffset() {
+    return static_cast<int32_t>(mImageBufferCurr - mImageBufferStart);
+  }
+
+  // These headers will always contain endian independent stuff
+  // They store the BMP headers which will be encoded
+  mozilla::image::bmp::FileHeader mBMPFileHeader;
+  mozilla::image::bmp::V5InfoHeader mBMPInfoHeader;
+
+  // Keeps track of the start of the image buffer
+  uint8_t* mImageBufferStart;
+  // Keeps track of the current position in the image buffer
+  uint8_t* mImageBufferCurr;
+  // Keeps track of the image buffer size
+  uint32_t mImageBufferSize;
+  // Keeps track of the number of bytes in the image buffer which are read
+  uint32_t mImageBufferReadPoint;
+  // Stores true if the image is done being encoded
+  bool mFinished;
+
+  nsCOMPtr<nsIInputStreamCallback> mCallback;
+  nsCOMPtr<nsIEventTarget> mCallbackTarget;
+  uint32_t mNotifyThreshold;
+};
+
+#endif  // mozilla_image_encoders_bmp_nsBMPEncoder_h
diff --git a/image/encoders/ico/moz.build b/image/encoders/ico/moz.build
new file mode 100644
index 0000000000..27e41489fd
--- /dev/null
+++ b/image/encoders/ico/moz.build
@@ -0,0 +1,20 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+SOURCES += [
+    "nsICOEncoder.cpp",
+]
+
+# Decoders need RasterImage.h
+LOCAL_INCLUDES += [
+    "/image",
+    "/image/encoders/bmp",
+    "/image/encoders/png",
+]
+
+include("/ipc/chromium/chromium-config.mozbuild")
+
+FINAL_LIBRARY = "xul"
diff --git a/image/encoders/ico/nsICOEncoder.cpp b/image/encoders/ico/nsICOEncoder.cpp
new file mode 100644
index 0000000000..518acc9a0b
--- /dev/null
+++ b/image/encoders/ico/nsICOEncoder.cpp
@@ -0,0 +1,499 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsCRT.h"
+#include "mozilla/EndianUtils.h"
+#include "nsBMPEncoder.h"
+#include "BMPHeaders.h"
+#include "nsPNGEncoder.h"
+#include "nsICOEncoder.h"
+#include "nsString.h"
+#include "nsStreamUtils.h"
+#include "nsTArray.h"
+
+using namespace mozilla;
+using namespace mozilla::image;
+
+NS_IMPL_ISUPPORTS(nsICOEncoder, imgIEncoder, nsIInputStream,
+                  nsIAsyncInputStream)
+
+nsICOEncoder::nsICOEncoder()
+    : mICOFileHeader{},
+      mICODirEntry{},
+      mImageBufferStart(nullptr),
+      mImageBufferCurr(0),
+      mImageBufferSize(0),
+      mImageBufferReadPoint(0),
+      mFinished(false),
+      mUsePNG(true),
+      mNotifyThreshold(0) {}
+
+nsICOEncoder::~nsICOEncoder() {
+  if (mImageBufferStart) {
+    free(mImageBufferStart);
+    mImageBufferStart = nullptr;
+    mImageBufferCurr = nullptr;
+  }
+}
+
+// nsICOEncoder::InitFromData
+// Two output options are supported: format=<png|bmp>;bpp=<bpp_value>
+// format specifies whether to use png or bitmap format
+// bpp specifies the bits per pixel to use where bpp_value can be 24 or 32
+NS_IMETHODIMP
+nsICOEncoder::InitFromData(const uint8_t* aData, uint32_t aLength,
+                           uint32_t aWidth, uint32_t aHeight, uint32_t aStride,
+                           uint32_t aInputFormat,
+                           const nsAString& aOutputOptions) {
+  // validate input format
+  if (aInputFormat != INPUT_FORMAT_RGB && aInputFormat != INPUT_FORMAT_RGBA &&
+      aInputFormat != INPUT_FORMAT_HOSTARGB) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  // Stride is the padded width of each row, so it better be longer
+  if ((aInputFormat == INPUT_FORMAT_RGB && aStride < aWidth * 3) ||
+      ((aInputFormat == INPUT_FORMAT_RGBA ||
+        aInputFormat == INPUT_FORMAT_HOSTARGB) &&
+       aStride < aWidth * 4)) {
+    NS_WARNING("Invalid stride for InitFromData");
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  nsresult rv;
+  rv = StartImageEncode(aWidth, aHeight, aInputFormat, aOutputOptions);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  rv = AddImageFrame(aData, aLength, aWidth, aHeight, aStride, aInputFormat,
+                     aOutputOptions);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  rv = EndImageEncode();
+  return rv;
+}
+
+// Returns the number of bytes in the image buffer used
+// For an ICO file, this is all bytes in the buffer.
+NS_IMETHODIMP
+nsICOEncoder::GetImageBufferUsed(uint32_t* aOutputSize) {
+  NS_ENSURE_ARG_POINTER(aOutputSize);
+  *aOutputSize = mImageBufferSize;
+  return NS_OK;
+}
+
+// Returns a pointer to the start of the image buffer
+NS_IMETHODIMP
+nsICOEncoder::GetImageBuffer(char** aOutputBuffer) {
+  NS_ENSURE_ARG_POINTER(aOutputBuffer);
+  *aOutputBuffer = reinterpret_cast<char*>(mImageBufferStart);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsICOEncoder::AddImageFrame(const uint8_t* aData, uint32_t aLength,
+                            uint32_t aWidth, uint32_t aHeight, uint32_t aStride,
+                            uint32_t aInputFormat,
+                            const nsAString& aFrameOptions) {
+  if (mUsePNG) {
+    mContainedEncoder = new nsPNGEncoder();
+    nsresult rv;
+    nsAutoString noParams;
+    rv = mContainedEncoder->InitFromData(aData, aLength, aWidth, aHeight,
+                                         aStride, aInputFormat, noParams);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    uint32_t PNGImageBufferSize;
+    mContainedEncoder->GetImageBufferUsed(&PNGImageBufferSize);
+    mImageBufferSize =
+        ICONFILEHEADERSIZE + ICODIRENTRYSIZE + PNGImageBufferSize;
+    mImageBufferStart = static_cast<uint8_t*>(malloc(mImageBufferSize));
+    if (!mImageBufferStart) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+    mImageBufferCurr = mImageBufferStart;
+    mICODirEntry.mBytesInRes = PNGImageBufferSize;
+
+    EncodeFileHeader();
+    EncodeInfoHeader();
+
+    char* imageBuffer;
+    rv = mContainedEncoder->GetImageBuffer(&imageBuffer);
+    NS_ENSURE_SUCCESS(rv, rv);
+    memcpy(mImageBufferCurr, imageBuffer, PNGImageBufferSize);
+    mImageBufferCurr += PNGImageBufferSize;
+  } else {
+    mContainedEncoder = new nsBMPEncoder();
+    nsresult rv;
+
+    nsAutoString params;
+    params.AppendLiteral("bpp=");
+    params.AppendInt(mICODirEntry.mBitCount);
+
+    rv = mContainedEncoder->InitFromData(aData, aLength, aWidth, aHeight,
+                                         aStride, aInputFormat, params);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    uint32_t andMaskSize = ((GetRealWidth() + 31) / 32) * 4 *  // row AND mask
+                           GetRealHeight();                    // num rows
+
+    uint32_t BMPImageBufferSize;
+    mContainedEncoder->GetImageBufferUsed(&BMPImageBufferSize);
+    mImageBufferSize =
+        ICONFILEHEADERSIZE + ICODIRENTRYSIZE + BMPImageBufferSize + andMaskSize;
+    mImageBufferStart = static_cast<uint8_t*>(malloc(mImageBufferSize));
+    if (!mImageBufferStart) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+    mImageBufferCurr = mImageBufferStart;
+
+    // Icon files that wrap a BMP file must not include the BITMAPFILEHEADER
+    // section at the beginning of the encoded BMP data, so we must skip over
+    // bmp::FILE_HEADER_LENGTH bytes when adding the BMP content to the icon
+    // file.
+    mICODirEntry.mBytesInRes =
+        BMPImageBufferSize - bmp::FILE_HEADER_LENGTH + andMaskSize;
+
+    // Encode the icon headers
+    EncodeFileHeader();
+    EncodeInfoHeader();
+
+    char* imageBuffer;
+    rv = mContainedEncoder->GetImageBuffer(&imageBuffer);
+    NS_ENSURE_SUCCESS(rv, rv);
+    memcpy(mImageBufferCurr, imageBuffer + bmp::FILE_HEADER_LENGTH,
+           BMPImageBufferSize - bmp::FILE_HEADER_LENGTH);
+    // We need to fix the BMP height to be *2 for the AND mask
+    uint32_t fixedHeight = GetRealHeight() * 2;
+    NativeEndian::swapToLittleEndianInPlace(&fixedHeight, 1);
+    // The height is stored at an offset of 8 from the DIB header
+    memcpy(mImageBufferCurr + 8, &fixedHeight, sizeof(fixedHeight));
+    mImageBufferCurr += BMPImageBufferSize - bmp::FILE_HEADER_LENGTH;
+
+    // Calculate rowsize in DWORD's
+    uint32_t rowSize = ((GetRealWidth() + 31) / 32) * 4;  // + 31 to round up
+    int32_t currentLine = GetRealHeight();
+
+    // Write out the AND mask
+    while (currentLine > 0) {
+      currentLine--;
+      uint8_t* encoded = mImageBufferCurr + currentLine * rowSize;
+      uint8_t* encodedEnd = encoded + rowSize;
+      while (encoded != encodedEnd) {
+        *encoded = 0;  // make everything visible
+        encoded++;
+      }
+    }
+
+    mImageBufferCurr += andMaskSize;
+  }
+
+  return NS_OK;
+}
+
+// See ::InitFromData for other info.
+NS_IMETHODIMP
+nsICOEncoder::StartImageEncode(uint32_t aWidth, uint32_t aHeight,
+                               uint32_t aInputFormat,
+                               const nsAString& aOutputOptions) {
+  // can't initialize more than once
+  if (mImageBufferStart || mImageBufferCurr) {
+    return NS_ERROR_ALREADY_INITIALIZED;
+  }
+
+  // validate input format
+  if (aInputFormat != INPUT_FORMAT_RGB && aInputFormat != INPUT_FORMAT_RGBA &&
+      aInputFormat != INPUT_FORMAT_HOSTARGB) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  // Icons are only 1 byte, so make sure our bitmap is in range
+  if (aWidth > 256 || aHeight > 256) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  // parse and check any provided output options
+  uint16_t bpp = 24;
+  bool usePNG = true;
+  nsresult rv = ParseOptions(aOutputOptions, bpp, usePNG);
+  NS_ENSURE_SUCCESS(rv, rv);
+  MOZ_ASSERT(bpp <= 32);
+
+  mUsePNG = usePNG;
+
+  InitFileHeader();
+  // The width and height are stored as 0 when we have a value of 256
+  InitInfoHeader(bpp, aWidth == 256 ? 0 : (uint8_t)aWidth,
+                 aHeight == 256 ? 0 : (uint8_t)aHeight);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsICOEncoder::EndImageEncode() {
+  // must be initialized
+  if (!mImageBufferStart || !mImageBufferCurr) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  mFinished = true;
+  NotifyListener();
+
+  // if output callback can't get enough memory, it will free our buffer
+  if (!mImageBufferStart || !mImageBufferCurr) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  return NS_OK;
+}
+
+// Parses the encoder options and sets the bits per pixel to use and PNG or BMP
+// See InitFromData for a description of the parse options
+nsresult nsICOEncoder::ParseOptions(const nsAString& aOptions,
+                                    uint16_t& aBppOut, bool& aUsePNGOut) {
+  // If no parsing options just use the default of 24BPP and PNG yes
+  if (aOptions.Length() == 0) {
+    aUsePNGOut = true;
+    aBppOut = 24;
+  }
+
+  // Parse the input string into a set of name/value pairs.
+  // From format: format=<png|bmp>;bpp=<bpp_value>
+  // to format: [0] = format=<png|bmp>, [1] = bpp=<bpp_value>
+  nsTArray<nsCString> nameValuePairs;
+  ParseString(NS_ConvertUTF16toUTF8(aOptions), ';', nameValuePairs);
+
+  // For each name/value pair in the set
+  for (unsigned i = 0; i < nameValuePairs.Length(); ++i) {
+    // Split the name value pair [0] = name, [1] = value
+    nsTArray<nsCString> nameValuePair;
+    ParseString(nameValuePairs[i], '=', nameValuePair);
+    if (nameValuePair.Length() != 2) {
+      return NS_ERROR_INVALID_ARG;
+    }
+
+    // Parse the format portion of the string format=<png|bmp>;bpp=<bpp_value>
+    if (nameValuePair[0].Equals("format", nsCaseInsensitiveCStringComparator)) {
+      if (nameValuePair[1].Equals("png", nsCaseInsensitiveCStringComparator)) {
+        aUsePNGOut = true;
+      } else if (nameValuePair[1].Equals("bmp",
+                                         nsCaseInsensitiveCStringComparator)) {
+        aUsePNGOut = false;
+      } else {
+        return NS_ERROR_INVALID_ARG;
+      }
+    }
+
+    // Parse the bpp portion of the string format=<png|bmp>;bpp=<bpp_value>
+    if (nameValuePair[0].Equals("bpp", nsCaseInsensitiveCStringComparator)) {
+      if (nameValuePair[1].EqualsLiteral("24")) {
+        aBppOut = 24;
+      } else if (nameValuePair[1].EqualsLiteral("32")) {
+        aBppOut = 32;
+      } else {
+        return NS_ERROR_INVALID_ARG;
+      }
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsICOEncoder::Close() {
+  if (mImageBufferStart) {
+    free(mImageBufferStart);
+    mImageBufferStart = nullptr;
+    mImageBufferSize = 0;
+    mImageBufferReadPoint = 0;
+    mImageBufferCurr = nullptr;
+  }
+
+  return NS_OK;
+}
+
+// Obtains the available bytes to read
+NS_IMETHODIMP
+nsICOEncoder::Available(uint64_t* _retval) {
+  if (!mImageBufferStart || !mImageBufferCurr) {
+    return NS_BASE_STREAM_CLOSED;
+  }
+
+  *_retval = GetCurrentImageBufferOffset() - mImageBufferReadPoint;
+  return NS_OK;
+}
+
+// Obtains the stream's status
+NS_IMETHODIMP
+nsICOEncoder::StreamStatus() {
+  return mImageBufferStart && mImageBufferCurr ? NS_OK : NS_BASE_STREAM_CLOSED;
+}
+
+// [noscript] Reads bytes which are available
+NS_IMETHODIMP
+nsICOEncoder::Read(char* aBuf, uint32_t aCount, uint32_t* _retval) {
+  return ReadSegments(NS_CopySegmentToBuffer, aBuf, aCount, _retval);
+}
+
+// [noscript] Reads segments
+NS_IMETHODIMP
+nsICOEncoder::ReadSegments(nsWriteSegmentFun aWriter, void* aClosure,
+                           uint32_t aCount, uint32_t* _retval) {
+  uint32_t maxCount = GetCurrentImageBufferOffset() - mImageBufferReadPoint;
+  if (maxCount == 0) {
+    *_retval = 0;
+    return mFinished ? NS_OK : NS_BASE_STREAM_WOULD_BLOCK;
+  }
+
+  if (aCount > maxCount) {
+    aCount = maxCount;
+  }
+
+  nsresult rv = aWriter(
+      this, aClosure,
+      reinterpret_cast<const char*>(mImageBufferStart + mImageBufferReadPoint),
+      0, aCount, _retval);
+  if (NS_SUCCEEDED(rv)) {
+    NS_ASSERTION(*_retval <= aCount, "bad write count");
+    mImageBufferReadPoint += *_retval;
+  }
+  // errors returned from the writer end here!
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsICOEncoder::IsNonBlocking(bool* _retval) {
+  *_retval = true;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsICOEncoder::AsyncWait(nsIInputStreamCallback* aCallback, uint32_t aFlags,
+                        uint32_t aRequestedCount, nsIEventTarget* aTarget) {
+  if (aFlags != 0) {
+    return NS_ERROR_NOT_IMPLEMENTED;
+  }
+
+  if (mCallback || mCallbackTarget) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  mCallbackTarget = aTarget;
+  // 0 means "any number of bytes except 0"
+  mNotifyThreshold = aRequestedCount;
+  if (!aRequestedCount) {
+    mNotifyThreshold = 1024;  // We don't want to notify incessantly
+  }
+
+  // We set the callback absolutely last, because NotifyListener uses it to
+  // determine if someone needs to be notified.  If we don't set it last,
+  // NotifyListener might try to fire off a notification to a null target
+  // which will generally cause non-threadsafe objects to be used off the
+  // main thread
+  mCallback = aCallback;
+
+  // What we are being asked for may be present already
+  NotifyListener();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsICOEncoder::CloseWithStatus(nsresult aStatus) { return Close(); }
+
+void nsICOEncoder::NotifyListener() {
+  if (mCallback && (GetCurrentImageBufferOffset() - mImageBufferReadPoint >=
+                        mNotifyThreshold ||
+                    mFinished)) {
+    nsCOMPtr<nsIInputStreamCallback> callback;
+    if (mCallbackTarget) {
+      callback = NS_NewInputStreamReadyEvent("nsICOEncoder::NotifyListener",
+                                             mCallback, mCallbackTarget);
+    } else {
+      callback = mCallback;
+    }
+
+    NS_ASSERTION(callback, "Shouldn't fail to make the callback");
+    // Null the callback first because OnInputStreamReady could reenter
+    // AsyncWait
+    mCallback = nullptr;
+    mCallbackTarget = nullptr;
+    mNotifyThreshold = 0;
+
+    callback->OnInputStreamReady(this);
+  }
+}
+
+// Initializes the icon file header mICOFileHeader
+void nsICOEncoder::InitFileHeader() {
+  memset(&mICOFileHeader, 0, sizeof(mICOFileHeader));
+  mICOFileHeader.mReserved = 0;
+  mICOFileHeader.mType = 1;
+  mICOFileHeader.mCount = 1;
+}
+
+// Initializes the icon directory info header mICODirEntry
+void nsICOEncoder::InitInfoHeader(uint16_t aBPP, uint8_t aWidth,
+                                  uint8_t aHeight) {
+  memset(&mICODirEntry, 0, sizeof(mICODirEntry));
+  mICODirEntry.mBitCount = aBPP;
+  mICODirEntry.mBytesInRes = 0;
+  mICODirEntry.mColorCount = 0;
+  mICODirEntry.mWidth = aWidth;
+  mICODirEntry.mHeight = aHeight;
+  mICODirEntry.mImageOffset = ICONFILEHEADERSIZE + ICODIRENTRYSIZE;
+  mICODirEntry.mPlanes = 1;
+  mICODirEntry.mReserved = 0;
+}
+
+// Encodes the icon file header mICOFileHeader
+void nsICOEncoder::EncodeFileHeader() {
+  IconFileHeader littleEndianIFH = mICOFileHeader;
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianIFH.mReserved, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianIFH.mType, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianIFH.mCount, 1);
+
+  memcpy(mImageBufferCurr, &littleEndianIFH.mReserved,
+         sizeof(littleEndianIFH.mReserved));
+  mImageBufferCurr += sizeof(littleEndianIFH.mReserved);
+  memcpy(mImageBufferCurr, &littleEndianIFH.mType,
+         sizeof(littleEndianIFH.mType));
+  mImageBufferCurr += sizeof(littleEndianIFH.mType);
+  memcpy(mImageBufferCurr, &littleEndianIFH.mCount,
+         sizeof(littleEndianIFH.mCount));
+  mImageBufferCurr += sizeof(littleEndianIFH.mCount);
+}
+
+// Encodes the icon directory info header mICODirEntry
+void nsICOEncoder::EncodeInfoHeader() {
+  IconDirEntry littleEndianmIDE = mICODirEntry;
+
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmIDE.mPlanes, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmIDE.mBitCount, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmIDE.mBytesInRes, 1);
+  NativeEndian::swapToLittleEndianInPlace(&littleEndianmIDE.mImageOffset, 1);
+
+  memcpy(mImageBufferCurr, &littleEndianmIDE.mWidth,
+         sizeof(littleEndianmIDE.mWidth));
+  mImageBufferCurr += sizeof(littleEndianmIDE.mWidth);
+  memcpy(mImageBufferCurr, &littleEndianmIDE.mHeight,
+         sizeof(littleEndianmIDE.mHeight));
+  mImageBufferCurr += sizeof(littleEndianmIDE.mHeight);
+  memcpy(mImageBufferCurr, &littleEndianmIDE.mColorCount,
+         sizeof(littleEndianmIDE.mColorCount));
+  mImageBufferCurr += sizeof(littleEndianmIDE.mColorCount);
+  memcpy(mImageBufferCurr, &littleEndianmIDE.mReserved,
+         sizeof(littleEndianmIDE.mReserved));
+  mImageBufferCurr += sizeof(littleEndianmIDE.mReserved);
+  memcpy(mImageBufferCurr, &littleEndianmIDE.mPlanes,
+         sizeof(littleEndianmIDE.mPlanes));
+  mImageBufferCurr += sizeof(littleEndianmIDE.mPlanes);
+  memcpy(mImageBufferCurr, &littleEndianmIDE.mBitCount,
+         sizeof(littleEndianmIDE.mBitCount));
+  mImageBufferCurr += sizeof(littleEndianmIDE.mBitCount);
+  memcpy(mImageBufferCurr, &littleEndianmIDE.mBytesInRes,
+         sizeof(littleEndianmIDE.mBytesInRes));
+  mImageBufferCurr += sizeof(littleEndianmIDE.mBytesInRes);
+  memcpy(mImageBufferCurr, &littleEndianmIDE.mImageOffset,
+         sizeof(littleEndianmIDE.mImageOffset));
+  mImageBufferCurr += sizeof(littleEndianmIDE.mImageOffset);
+}
diff --git a/image/encoders/ico/nsICOEncoder.h b/image/encoders/ico/nsICOEncoder.h
new file mode 100644
index 0000000000..ef601ba97e
--- /dev/null
+++ b/image/encoders/ico/nsICOEncoder.h
@@ -0,0 +1,95 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_image_encoders_ico_nsICOEncoder_h
+#define mozilla_image_encoders_ico_nsICOEncoder_h
+
+#include "mozilla/Attributes.h"
+#include "mozilla/ReentrantMonitor.h"
+#include "mozilla/image/ICOFileHeaders.h"
+
+#include "imgIEncoder.h"
+
+#include "nsCOMPtr.h"
+
+#define NS_ICOENCODER_CID                            \
+  { /*92AE3AB2-8968-41B1-8709-B6123BCEAF21 */        \
+    0x92ae3ab2, 0x8968, 0x41b1, {                    \
+      0x87, 0x09, 0xb6, 0x12, 0x3b, 0Xce, 0xaf, 0x21 \
+    }                                                \
+  }
+
+// Provides ICO encoding functionality. Use InitFromData() to do the
+// encoding. See that function definition for encoding options.
+
+class nsICOEncoder final : public imgIEncoder {
+  typedef mozilla::ReentrantMonitor ReentrantMonitor;
+
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_IMGIENCODER
+  NS_DECL_NSIINPUTSTREAM
+  NS_DECL_NSIASYNCINPUTSTREAM
+
+  nsICOEncoder();
+
+  // Obtains the width of the icon directory entry
+  uint32_t GetRealWidth() const {
+    return mICODirEntry.mWidth == 0 ? 256 : mICODirEntry.mWidth;
+  }
+
+  // Obtains the height of the icon directory entry
+  uint32_t GetRealHeight() const {
+    return mICODirEntry.mHeight == 0 ? 256 : mICODirEntry.mHeight;
+  }
+
+ protected:
+  ~nsICOEncoder();
+
+  nsresult ParseOptions(const nsAString& aOptions, uint16_t& aBppOut,
+                        bool& aUsePNGOut);
+  void NotifyListener();
+
+  // Initializes the icon file header mICOFileHeader
+  void InitFileHeader();
+  // Initializes the icon directory info header mICODirEntry
+  void InitInfoHeader(uint16_t aBPP, uint8_t aWidth, uint8_t aHeight);
+  // Encodes the icon file header mICOFileHeader
+  void EncodeFileHeader();
+  // Encodes the icon directory info header mICODirEntry
+  void EncodeInfoHeader();
+  // Obtains the current offset filled up to for the image buffer
+  inline int32_t GetCurrentImageBufferOffset() {
+    return static_cast<int32_t>(mImageBufferCurr - mImageBufferStart);
+  }
+
+  // Holds either a PNG or a BMP depending on the encoding options specified
+  // or if no encoding options specified will use the default (PNG)
+  nsCOMPtr<imgIEncoder> mContainedEncoder;
+
+  // These headers will always contain endian independent stuff.
+  // Don't trust the width and height of mICODirEntry directly,
+  // instead use the accessors GetRealWidth() and GetRealHeight().
+  mozilla::image::IconFileHeader mICOFileHeader;
+  mozilla::image::IconDirEntry mICODirEntry;
+
+  // Keeps track of the start of the image buffer
+  uint8_t* mImageBufferStart;
+  // Keeps track of the current position in the image buffer
+  uint8_t* mImageBufferCurr;
+  // Keeps track of the image buffer size
+  uint32_t mImageBufferSize;
+  // Keeps track of the number of bytes in the image buffer which are read
+  uint32_t mImageBufferReadPoint;
+  // Stores true if the image is done being encoded
+  bool mFinished;
+  // Stores true if the contained image is a PNG
+  bool mUsePNG;
+
+  nsCOMPtr<nsIInputStreamCallback> mCallback;
+  nsCOMPtr<nsIEventTarget> mCallbackTarget;
+  uint32_t mNotifyThreshold;
+};
+
+#endif  // mozilla_image_encoders_ico_nsICOEncoder_h
diff --git a/image/encoders/jpeg/moz.build b/image/encoders/jpeg/moz.build
new file mode 100644
index 0000000000..6952fc1b9f
--- /dev/null
+++ b/image/encoders/jpeg/moz.build
@@ -0,0 +1,11 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+SOURCES += [
+    "nsJPEGEncoder.cpp",
+]
+
+FINAL_LIBRARY = "xul"
diff --git a/image/encoders/jpeg/nsJPEGEncoder.cpp b/image/encoders/jpeg/nsJPEGEncoder.cpp
new file mode 100644
index 0000000000..2975532b58
--- /dev/null
+++ b/image/encoders/jpeg/nsJPEGEncoder.cpp
@@ -0,0 +1,519 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsJPEGEncoder.h"
+#include "prprf.h"
+#include "nsString.h"
+#include "nsStreamUtils.h"
+#include "gfxColor.h"
+#include "mozilla/CheckedInt.h"
+#include "mozilla/UniquePtrExtensions.h"
+
+extern "C" {
+#include "jpeglib.h"
+}
+
+#include <setjmp.h>
+#include "jerror.h"
+
+using namespace mozilla;
+
+NS_IMPL_ISUPPORTS(nsJPEGEncoder, imgIEncoder, nsIInputStream,
+                  nsIAsyncInputStream)
+
+class nsJPEGEncoderInternal {
+  friend class nsJPEGEncoder;
+
+ protected:
+  /**
+   * Initialize destination. This is called by jpeg_start_compress() before
+   * any data is actually written. It must initialize next_output_byte and
+   * free_in_buffer. free_in_buffer must be initialized to a positive value.
+   */
+  static void initDestination(jpeg_compress_struct* cinfo);
+
+  /**
+   * This is called whenever the buffer has filled (free_in_buffer reaches
+   * zero).  In typical applications, it should write out the *entire* buffer
+   * (use the saved start address and buffer length; ignore the current state
+   * of next_output_byte and free_in_buffer).  Then reset the pointer & count
+   * to the start of the buffer, and return TRUE indicating that the buffer
+   * has been dumped.  free_in_buffer must be set to a positive value when
+   * TRUE is returned.  A FALSE return should only be used when I/O suspension
+   * is desired (this operating mode is discussed in the next section).
+   */
+  static boolean emptyOutputBuffer(jpeg_compress_struct* cinfo);
+
+  /**
+   * Terminate destination --- called by jpeg_finish_compress() after all data
+   * has been written.  In most applications, this must flush any data
+   * remaining in the buffer.  Use either next_output_byte or free_in_buffer
+   * to determine how much data is in the buffer.
+   */
+  static void termDestination(jpeg_compress_struct* cinfo);
+
+  /**
+   * Override the standard error method in the IJG JPEG decoder code. This
+   * was mostly copied from nsJPEGDecoder.cpp
+   */
+  static void errorExit(jpeg_common_struct* cinfo);
+};
+
+// used to pass error info through the JPEG library
+struct encoder_error_mgr {
+  jpeg_error_mgr pub;
+  jmp_buf setjmp_buffer;
+};
+
+nsJPEGEncoder::nsJPEGEncoder()
+    : mFinished(false),
+      mImageBuffer(nullptr),
+      mImageBufferSize(0),
+      mImageBufferUsed(0),
+      mImageBufferReadPoint(0),
+      mCallback(nullptr),
+      mCallbackTarget(nullptr),
+      mNotifyThreshold(0),
+      mReentrantMonitor("nsJPEGEncoder.mReentrantMonitor") {}
+
+nsJPEGEncoder::~nsJPEGEncoder() {
+  if (mImageBuffer) {
+    free(mImageBuffer);
+    mImageBuffer = nullptr;
+  }
+}
+
+// nsJPEGEncoder::InitFromData
+//
+//    One output option is supported: "quality=X" where X is an integer in the
+//    range 0-100. Higher values for X give better quality.
+//
+//    Transparency is always discarded.
+
+NS_IMETHODIMP
+nsJPEGEncoder::InitFromData(const uint8_t* aData,
+                            uint32_t aLength,  // (unused, req'd by JS)
+                            uint32_t aWidth, uint32_t aHeight, uint32_t aStride,
+                            uint32_t aInputFormat,
+                            const nsAString& aOutputOptions) {
+  NS_ENSURE_ARG(aData);
+
+  // validate input format
+  if (aInputFormat != INPUT_FORMAT_RGB && aInputFormat != INPUT_FORMAT_RGBA &&
+      aInputFormat != INPUT_FORMAT_HOSTARGB)
+    return NS_ERROR_INVALID_ARG;
+
+  // Stride is the padded width of each row, so it better be longer (I'm afraid
+  // people will not understand what stride means, so check it well)
+  if ((aInputFormat == INPUT_FORMAT_RGB && aStride < aWidth * 3) ||
+      ((aInputFormat == INPUT_FORMAT_RGBA ||
+        aInputFormat == INPUT_FORMAT_HOSTARGB) &&
+       aStride < aWidth * 4)) {
+    NS_WARNING("Invalid stride for InitFromData");
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  // can't initialize more than once
+  if (mImageBuffer != nullptr) {
+    return NS_ERROR_ALREADY_INITIALIZED;
+  }
+
+  // options: we only have one option so this is easy
+  int quality = 92;
+  if (aOutputOptions.Length() > 0) {
+    // have options string
+    const nsString qualityPrefix(u"quality="_ns);
+    if (aOutputOptions.Length() > qualityPrefix.Length() &&
+        StringBeginsWith(aOutputOptions, qualityPrefix)) {
+      // have quality string
+      nsCString value = NS_ConvertUTF16toUTF8(
+          Substring(aOutputOptions, qualityPrefix.Length()));
+      int newquality = -1;
+      if (PR_sscanf(value.get(), "%d", &newquality) == 1) {
+        if (newquality >= 0 && newquality <= 100) {
+          quality = newquality;
+        } else {
+          NS_WARNING(
+              "Quality value out of range, should be 0-100,"
+              " using default");
+        }
+      } else {
+        NS_WARNING(
+            "Quality value invalid, should be integer 0-100,"
+            " using default");
+      }
+    } else {
+      return NS_ERROR_INVALID_ARG;
+    }
+  }
+
+  UniquePtr<uint8_t[]> rowptr;
+  if (aInputFormat == INPUT_FORMAT_RGBA ||
+      aInputFormat == INPUT_FORMAT_HOSTARGB) {
+    rowptr = MakeUniqueFallible<uint8_t[]>(aWidth * 3);
+    if (NS_WARN_IF(!rowptr)) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+  }
+
+  jpeg_compress_struct cinfo;
+
+  // We set up the normal JPEG error routines, then override error_exit.
+  // This must be done before the call to create_compress
+  encoder_error_mgr errmgr;
+  cinfo.err = jpeg_std_error(&errmgr.pub);
+  errmgr.pub.error_exit = nsJPEGEncoderInternal::errorExit;
+  // Establish the setjmp return context for my_error_exit to use.
+  if (setjmp(errmgr.setjmp_buffer)) {
+    // If we get here, the JPEG code has signaled an error.
+    // We need to clean up the JPEG object, close the input file, and return.
+    return NS_ERROR_FAILURE;
+  }
+
+  jpeg_create_compress(&cinfo);
+  cinfo.image_width = aWidth;
+  cinfo.image_height = aHeight;
+  cinfo.input_components = 3;
+  cinfo.in_color_space = JCS_RGB;
+  cinfo.data_precision = 8;
+
+  jpeg_set_defaults(&cinfo);
+  jpeg_set_quality(&cinfo, quality, 1);  // quality here is 0-100
+  if (quality >= 90) {
+    int i;
+    for (i = 0; i < MAX_COMPONENTS; i++) {
+      cinfo.comp_info[i].h_samp_factor = 1;
+      cinfo.comp_info[i].v_samp_factor = 1;
+    }
+  }
+
+  // set up the destination manager
+  jpeg_destination_mgr destmgr;
+  destmgr.init_destination = nsJPEGEncoderInternal::initDestination;
+  destmgr.empty_output_buffer = nsJPEGEncoderInternal::emptyOutputBuffer;
+  destmgr.term_destination = nsJPEGEncoderInternal::termDestination;
+  cinfo.dest = &destmgr;
+  cinfo.client_data = this;
+
+  jpeg_start_compress(&cinfo, 1);
+
+  // feed it the rows
+  if (aInputFormat == INPUT_FORMAT_RGB) {
+    while (cinfo.next_scanline < cinfo.image_height) {
+      const uint8_t* row = &aData[cinfo.next_scanline * aStride];
+      jpeg_write_scanlines(&cinfo, const_cast<uint8_t**>(&row), 1);
+    }
+  } else if (aInputFormat == INPUT_FORMAT_RGBA) {
+    MOZ_ASSERT(rowptr);
+    uint8_t* row = rowptr.get();
+    while (cinfo.next_scanline < cinfo.image_height) {
+      ConvertRGBARow(&aData[cinfo.next_scanline * aStride], row, aWidth);
+      jpeg_write_scanlines(&cinfo, &row, 1);
+    }
+  } else if (aInputFormat == INPUT_FORMAT_HOSTARGB) {
+    MOZ_ASSERT(rowptr);
+    uint8_t* row = rowptr.get();
+    while (cinfo.next_scanline < cinfo.image_height) {
+      ConvertHostARGBRow(&aData[cinfo.next_scanline * aStride], row, aWidth);
+      jpeg_write_scanlines(&cinfo, &row, 1);
+    }
+  }
+
+  jpeg_finish_compress(&cinfo);
+  jpeg_destroy_compress(&cinfo);
+
+  mFinished = true;
+  NotifyListener();
+
+  // if output callback can't get enough memory, it will free our buffer
+  if (!mImageBuffer) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsJPEGEncoder::StartImageEncode(uint32_t aWidth, uint32_t aHeight,
+                                uint32_t aInputFormat,
+                                const nsAString& aOutputOptions) {
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+// Returns the number of bytes in the image buffer used.
+NS_IMETHODIMP
+nsJPEGEncoder::GetImageBufferUsed(uint32_t* aOutputSize) {
+  NS_ENSURE_ARG_POINTER(aOutputSize);
+  *aOutputSize = mImageBufferUsed;
+  return NS_OK;
+}
+
+// Returns a pointer to the start of the image buffer
+NS_IMETHODIMP
+nsJPEGEncoder::GetImageBuffer(char** aOutputBuffer) {
+  NS_ENSURE_ARG_POINTER(aOutputBuffer);
+  *aOutputBuffer = reinterpret_cast<char*>(mImageBuffer);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsJPEGEncoder::AddImageFrame(const uint8_t* aData, uint32_t aLength,
+                             uint32_t aWidth, uint32_t aHeight,
+                             uint32_t aStride, uint32_t aFrameFormat,
+                             const nsAString& aFrameOptions) {
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsJPEGEncoder::EndImageEncode() { return NS_ERROR_NOT_IMPLEMENTED; }
+
+NS_IMETHODIMP
+nsJPEGEncoder::Close() {
+  if (mImageBuffer != nullptr) {
+    free(mImageBuffer);
+    mImageBuffer = nullptr;
+    mImageBufferSize = 0;
+    mImageBufferUsed = 0;
+    mImageBufferReadPoint = 0;
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsJPEGEncoder::Available(uint64_t* _retval) {
+  if (!mImageBuffer) {
+    return NS_BASE_STREAM_CLOSED;
+  }
+
+  *_retval = mImageBufferUsed - mImageBufferReadPoint;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsJPEGEncoder::StreamStatus() {
+  return mImageBuffer ? NS_OK : NS_BASE_STREAM_CLOSED;
+}
+
+NS_IMETHODIMP
+nsJPEGEncoder::Read(char* aBuf, uint32_t aCount, uint32_t* _retval) {
+  return ReadSegments(NS_CopySegmentToBuffer, aBuf, aCount, _retval);
+}
+
+NS_IMETHODIMP
+nsJPEGEncoder::ReadSegments(nsWriteSegmentFun aWriter, void* aClosure,
+                            uint32_t aCount, uint32_t* _retval) {
+  // Avoid another thread reallocing the buffer underneath us
+  ReentrantMonitorAutoEnter autoEnter(mReentrantMonitor);
+
+  uint32_t maxCount = mImageBufferUsed - mImageBufferReadPoint;
+  if (maxCount == 0) {
+    *_retval = 0;
+    return mFinished ? NS_OK : NS_BASE_STREAM_WOULD_BLOCK;
+  }
+
+  if (aCount > maxCount) {
+    aCount = maxCount;
+  }
+  nsresult rv = aWriter(
+      this, aClosure,
+      reinterpret_cast<const char*>(mImageBuffer + mImageBufferReadPoint), 0,
+      aCount, _retval);
+  if (NS_SUCCEEDED(rv)) {
+    NS_ASSERTION(*_retval <= aCount, "bad write count");
+    mImageBufferReadPoint += *_retval;
+  }
+
+  // errors returned from the writer end here!
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsJPEGEncoder::IsNonBlocking(bool* _retval) {
+  *_retval = true;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsJPEGEncoder::AsyncWait(nsIInputStreamCallback* aCallback, uint32_t aFlags,
+                         uint32_t aRequestedCount, nsIEventTarget* aTarget) {
+  if (aFlags != 0) {
+    return NS_ERROR_NOT_IMPLEMENTED;
+  }
+
+  if (mCallback || mCallbackTarget) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  mCallbackTarget = aTarget;
+  // 0 means "any number of bytes except 0"
+  mNotifyThreshold = aRequestedCount;
+  if (!aRequestedCount) {
+    mNotifyThreshold = 1024;  // 1 KB seems good.  We don't want to
+                              // notify incessantly
+  }
+
+  // We set the callback absolutely last, because NotifyListener uses it to
+  // determine if someone needs to be notified.  If we don't set it last,
+  // NotifyListener might try to fire off a notification to a null target
+  // which will generally cause non-threadsafe objects to be used off the
+  // main thread
+  mCallback = aCallback;
+
+  // What we are being asked for may be present already
+  NotifyListener();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsJPEGEncoder::CloseWithStatus(nsresult aStatus) { return Close(); }
+
+// nsJPEGEncoder::ConvertHostARGBRow
+//
+//    Our colors are stored with premultiplied alphas, but we need
+//    an output with no alpha in machine-independent byte order.
+//
+//    See gfx/cairo/cairo/src/cairo-png.c
+void nsJPEGEncoder::ConvertHostARGBRow(const uint8_t* aSrc, uint8_t* aDest,
+                                       uint32_t aPixelWidth) {
+  for (uint32_t x = 0; x < aPixelWidth; x++) {
+    const uint32_t& pixelIn = ((const uint32_t*)(aSrc))[x];
+    uint8_t* pixelOut = &aDest[x * 3];
+
+    pixelOut[0] = (pixelIn & 0xff0000) >> 16;
+    pixelOut[1] = (pixelIn & 0x00ff00) >> 8;
+    pixelOut[2] = (pixelIn & 0x0000ff) >> 0;
+  }
+}
+
+/**
+ * nsJPEGEncoder::ConvertRGBARow
+ *
+ * Input is RGBA, output is RGB, so we should alpha-premultiply.
+ */
+void nsJPEGEncoder::ConvertRGBARow(const uint8_t* aSrc, uint8_t* aDest,
+                                   uint32_t aPixelWidth) {
+  for (uint32_t x = 0; x < aPixelWidth; x++) {
+    const uint8_t* pixelIn = &aSrc[x * 4];
+    uint8_t* pixelOut = &aDest[x * 3];
+
+    uint8_t alpha = pixelIn[3];
+    pixelOut[0] = gfxPreMultiply(pixelIn[0], alpha);
+    pixelOut[1] = gfxPreMultiply(pixelIn[1], alpha);
+    pixelOut[2] = gfxPreMultiply(pixelIn[2], alpha);
+  }
+}
+
+void nsJPEGEncoder::NotifyListener() {
+  // We might call this function on multiple threads (any threads that call
+  // AsyncWait and any that do encoding) so we lock to avoid notifying the
+  // listener twice about the same data (which generally leads to a truncated
+  // image).
+  ReentrantMonitorAutoEnter autoEnter(mReentrantMonitor);
+
+  if (mCallback &&
+      (mImageBufferUsed - mImageBufferReadPoint >= mNotifyThreshold ||
+       mFinished)) {
+    nsCOMPtr<nsIInputStreamCallback> callback;
+    if (mCallbackTarget) {
+      callback = NS_NewInputStreamReadyEvent("nsJPEGEncoder::NotifyListener",
+                                             mCallback, mCallbackTarget);
+    } else {
+      callback = mCallback;
+    }
+
+    NS_ASSERTION(callback, "Shouldn't fail to make the callback");
+    // Null the callback first because OnInputStreamReady could reenter
+    // AsyncWait
+    mCallback = nullptr;
+    mCallbackTarget = nullptr;
+    mNotifyThreshold = 0;
+
+    callback->OnInputStreamReady(this);
+  }
+}
+
+/* static */
+void nsJPEGEncoderInternal::initDestination(jpeg_compress_struct* cinfo) {
+  nsJPEGEncoder* that = static_cast<nsJPEGEncoder*>(cinfo->client_data);
+  NS_ASSERTION(!that->mImageBuffer, "Image buffer already initialized");
+
+  that->mImageBufferSize = 8192;
+  that->mImageBuffer = (uint8_t*)malloc(that->mImageBufferSize);
+  that->mImageBufferUsed = 0;
+
+  cinfo->dest->next_output_byte = that->mImageBuffer;
+  cinfo->dest->free_in_buffer = that->mImageBufferSize;
+}
+
+/* static */
+boolean nsJPEGEncoderInternal::emptyOutputBuffer(jpeg_compress_struct* cinfo) {
+  nsJPEGEncoder* that = static_cast<nsJPEGEncoder*>(cinfo->client_data);
+  NS_ASSERTION(that->mImageBuffer, "No buffer to empty!");
+
+  // When we're reallocing the buffer we need to take the lock to ensure
+  // that nobody is trying to read from the buffer we are destroying
+  ReentrantMonitorAutoEnter autoEnter(that->mReentrantMonitor);
+
+  that->mImageBufferUsed = that->mImageBufferSize;
+
+  // expand buffer, just double size each time
+  uint8_t* newBuf = nullptr;
+  CheckedInt<uint32_t> bufSize =
+      CheckedInt<uint32_t>(that->mImageBufferSize) * 2;
+  if (bufSize.isValid()) {
+    that->mImageBufferSize = bufSize.value();
+    newBuf = (uint8_t*)realloc(that->mImageBuffer, that->mImageBufferSize);
+  }
+
+  if (!newBuf) {
+    // can't resize, just zero (this will keep us from writing more)
+    free(that->mImageBuffer);
+    that->mImageBuffer = nullptr;
+    that->mImageBufferSize = 0;
+    that->mImageBufferUsed = 0;
+
+    // This seems to be the only way to do errors through the JPEG library.  We
+    // pass an nsresult masquerading as an int, which works because the
+    // setjmp() caller casts it back.
+    longjmp(((encoder_error_mgr*)(cinfo->err))->setjmp_buffer,
+            static_cast<int>(NS_ERROR_OUT_OF_MEMORY));
+  }
+  that->mImageBuffer = newBuf;
+
+  cinfo->dest->next_output_byte = &that->mImageBuffer[that->mImageBufferUsed];
+  cinfo->dest->free_in_buffer = that->mImageBufferSize - that->mImageBufferUsed;
+  return 1;
+}
+
+/* static */
+void nsJPEGEncoderInternal::termDestination(jpeg_compress_struct* cinfo) {
+  nsJPEGEncoder* that = static_cast<nsJPEGEncoder*>(cinfo->client_data);
+  if (!that->mImageBuffer) {
+    return;
+  }
+  that->mImageBufferUsed = cinfo->dest->next_output_byte - that->mImageBuffer;
+  NS_ASSERTION(that->mImageBufferUsed < that->mImageBufferSize,
+               "JPEG library busted, got a bad image buffer size");
+  that->NotifyListener();
+}
+
+/* static */
+void nsJPEGEncoderInternal::errorExit(jpeg_common_struct* cinfo) {
+  nsresult error_code;
+  encoder_error_mgr* err = (encoder_error_mgr*)cinfo->err;
+
+  // Convert error to a browser error code
+  switch (cinfo->err->msg_code) {
+    case JERR_OUT_OF_MEMORY:
+      error_code = NS_ERROR_OUT_OF_MEMORY;
+      break;
+    default:
+      error_code = NS_ERROR_FAILURE;
+  }
+
+  // Return control to the setjmp point.  We pass an nsresult masquerading as
+  // an int, which works because the setjmp() caller casts it back.
+  longjmp(err->setjmp_buffer, static_cast<int>(error_code));
+}
diff --git a/image/encoders/jpeg/nsJPEGEncoder.h b/image/encoders/jpeg/nsJPEGEncoder.h
new file mode 100644
index 0000000000..df543d957b
--- /dev/null
+++ b/image/encoders/jpeg/nsJPEGEncoder.h
@@ -0,0 +1,74 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_image_encoders_jpeg_nsJPEGEncoder_h
+#define mozilla_image_encoders_jpeg_nsJPEGEncoder_h
+
+#include "imgIEncoder.h"
+
+#include "mozilla/ReentrantMonitor.h"
+#include "mozilla/Attributes.h"
+
+#include "nsCOMPtr.h"
+
+struct jpeg_compress_struct;
+struct jpeg_common_struct;
+
+#define NS_JPEGENCODER_CID                           \
+  {                                                  \
+    /* ac2bb8fe-eeeb-4572-b40f-be03932b56e0 */       \
+    0xac2bb8fe, 0xeeeb, 0x4572, {                    \
+      0xb4, 0x0f, 0xbe, 0x03, 0x93, 0x2b, 0x56, 0xe0 \
+    }                                                \
+  }
+
+// Provides JPEG encoding functionality. Use InitFromData() to do the
+// encoding. See that function definition for encoding options.
+class nsJPEGEncoderInternal;
+
+class nsJPEGEncoder final : public imgIEncoder {
+  friend class nsJPEGEncoderInternal;
+  typedef mozilla::ReentrantMonitor ReentrantMonitor;
+
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_IMGIENCODER
+  NS_DECL_NSIINPUTSTREAM
+  NS_DECL_NSIASYNCINPUTSTREAM
+
+  nsJPEGEncoder();
+
+ private:
+  ~nsJPEGEncoder();
+
+ protected:
+  void ConvertHostARGBRow(const uint8_t* aSrc, uint8_t* aDest,
+                          uint32_t aPixelWidth);
+  void ConvertRGBARow(const uint8_t* aSrc, uint8_t* aDest,
+                      uint32_t aPixelWidth);
+
+  void NotifyListener();
+
+  bool mFinished;
+
+  // image buffer
+  uint8_t* mImageBuffer;
+  uint32_t mImageBufferSize;
+  uint32_t mImageBufferUsed;
+
+  uint32_t mImageBufferReadPoint;
+
+  nsCOMPtr<nsIInputStreamCallback> mCallback;
+  nsCOMPtr<nsIEventTarget> mCallbackTarget;
+  uint32_t mNotifyThreshold;
+
+  // nsJPEGEncoder is designed to allow one thread to pump data into it while
+  // another reads from it.  We lock to ensure that the buffer remains
+  // append-only while we read from it (that it is not realloced) and to ensure
+  // that only one thread dispatches a callback for each call to AsyncWait.
+  ReentrantMonitor mReentrantMonitor MOZ_UNANNOTATED;
+};
+
+#endif  // mozilla_image_encoders_jpeg_nsJPEGEncoder_h
diff --git a/image/encoders/moz.build b/image/encoders/moz.build
new file mode 100644
index 0000000000..ecb2aa44e0
--- /dev/null
+++ b/image/encoders/moz.build
@@ -0,0 +1,13 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DIRS += [
+    "ico",
+    "png",
+    "jpeg",
+    "bmp",
+    "webp",
+]
diff --git a/image/encoders/png/moz.build b/image/encoders/png/moz.build
new file mode 100644
index 0000000000..fe26a2368e
--- /dev/null
+++ b/image/encoders/png/moz.build
@@ -0,0 +1,17 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+SOURCES += [
+    "nsPNGEncoder.cpp",
+]
+
+LOCAL_INCLUDES += [
+    "/image",
+]
+
+include("/ipc/chromium/chromium-config.mozbuild")
+
+FINAL_LIBRARY = "xul"
diff --git a/image/encoders/png/nsPNGEncoder.cpp b/image/encoders/png/nsPNGEncoder.cpp
new file mode 100644
index 0000000000..f21bab67a6
--- /dev/null
+++ b/image/encoders/png/nsPNGEncoder.cpp
@@ -0,0 +1,820 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ImageLogging.h"
+#include "nsCRT.h"
+#include "nsPNGEncoder.h"
+#include "nsStreamUtils.h"
+#include "nsString.h"
+#include "prprf.h"
+#include "mozilla/CheckedInt.h"
+#include "mozilla/UniquePtrExtensions.h"
+
+using namespace mozilla;
+
+static LazyLogModule sPNGEncoderLog("PNGEncoder");
+
+NS_IMPL_ISUPPORTS(nsPNGEncoder, imgIEncoder, nsIInputStream,
+                  nsIAsyncInputStream)
+
+#define DEFAULT_ZLIB_LEVEL 3
+#define DEFAULT_FILTERS PNG_FILTER_SUB
+
+nsPNGEncoder::nsPNGEncoder()
+    : mPNG(nullptr),
+      mPNGinfo(nullptr),
+      mIsAnimation(false),
+      mFinished(false),
+      mImageBuffer(nullptr),
+      mImageBufferSize(0),
+      mImageBufferUsed(0),
+      mImageBufferReadPoint(0),
+      mCallback(nullptr),
+      mCallbackTarget(nullptr),
+      mNotifyThreshold(0),
+      mReentrantMonitor("nsPNGEncoder.mReentrantMonitor") {}
+
+nsPNGEncoder::~nsPNGEncoder() {
+  if (mImageBuffer) {
+    free(mImageBuffer);
+    mImageBuffer = nullptr;
+  }
+  // don't leak if EndImageEncode wasn't called
+  if (mPNG) {
+    png_destroy_write_struct(&mPNG, &mPNGinfo);
+  }
+}
+
+// nsPNGEncoder::InitFromData
+//
+//    One output option is supported: "transparency=none" means that the
+//    output PNG will not have an alpha channel, even if the input does.
+//
+//    Based partially on gfx/cairo/cairo/src/cairo-png.c
+//    See also media/libpng/libpng-manual.txt
+
+NS_IMETHODIMP
+nsPNGEncoder::InitFromData(const uint8_t* aData,
+                           uint32_t aLength,  // (unused, req'd by JS)
+                           uint32_t aWidth, uint32_t aHeight, uint32_t aStride,
+                           uint32_t aInputFormat,
+                           const nsAString& aOutputOptions) {
+  NS_ENSURE_ARG(aData);
+  nsresult rv;
+
+  rv = StartImageEncode(aWidth, aHeight, aInputFormat, aOutputOptions);
+  if (!NS_SUCCEEDED(rv)) {
+    return rv;
+  }
+
+  rv = AddImageFrame(aData, aLength, aWidth, aHeight, aStride, aInputFormat,
+                     aOutputOptions);
+  if (!NS_SUCCEEDED(rv)) {
+    return rv;
+  }
+
+  rv = EndImageEncode();
+
+  return rv;
+}
+
+// nsPNGEncoder::StartImageEncode
+//
+//
+// See ::InitFromData for other info.
+NS_IMETHODIMP
+nsPNGEncoder::StartImageEncode(uint32_t aWidth, uint32_t aHeight,
+                               uint32_t aInputFormat,
+                               const nsAString& aOutputOptions) {
+  bool useTransparency = true, skipFirstFrame = false;
+  uint32_t numFrames = 1;
+  uint32_t numPlays = 0;  // For animations, 0 == forever
+  int zlibLevel = DEFAULT_ZLIB_LEVEL;
+  int filters = DEFAULT_FILTERS;
+
+  // can't initialize more than once
+  if (mImageBuffer != nullptr) {
+    return NS_ERROR_ALREADY_INITIALIZED;
+  }
+
+  // validate input format
+  if (aInputFormat != INPUT_FORMAT_RGB && aInputFormat != INPUT_FORMAT_RGBA &&
+      aInputFormat != INPUT_FORMAT_HOSTARGB)
+    return NS_ERROR_INVALID_ARG;
+
+  // parse and check any provided output options
+  nsresult rv = ParseOptions(aOutputOptions, &useTransparency, &skipFirstFrame,
+                             &numFrames, &numPlays, &zlibLevel, &filters,
+                             nullptr, nullptr, nullptr, nullptr, nullptr);
+  if (rv != NS_OK) {
+    return rv;
+  }
+
+#ifdef PNG_APNG_SUPPORTED
+  if (numFrames > 1) {
+    mIsAnimation = true;
+  }
+
+#endif
+
+  // initialize
+  mPNG = png_create_write_struct(PNG_LIBPNG_VER_STRING, nullptr, ErrorCallback,
+                                 WarningCallback);
+  if (!mPNG) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  mPNGinfo = png_create_info_struct(mPNG);
+  if (!mPNGinfo) {
+    png_destroy_write_struct(&mPNG, nullptr);
+    return NS_ERROR_FAILURE;
+  }
+
+  // libpng's error handler jumps back here upon an error.
+  // Note: It's important that all png_* callers do this, or errors
+  // will result in a corrupt time-warped stack.
+  if (setjmp(png_jmpbuf(mPNG))) {
+    png_destroy_write_struct(&mPNG, &mPNGinfo);
+    return NS_ERROR_FAILURE;
+  }
+
+#ifdef PNG_WRITE_CUSTOMIZE_COMPRESSION_SUPPORTED
+  png_set_compression_level(mPNG, zlibLevel);
+#endif
+#ifdef PNG_WRITE_FILTER_SUPPORTED
+  png_set_filter(mPNG, PNG_FILTER_TYPE_BASE, filters);
+#endif
+
+  // Set up to read the data into our image buffer, start out with an 8K
+  // estimated size. Note: we don't have to worry about freeing this data
+  // in this function. It will be freed on object destruction.
+  mImageBufferSize = 8192;
+  mImageBuffer = (uint8_t*)malloc(mImageBufferSize);
+  if (!mImageBuffer) {
+    png_destroy_write_struct(&mPNG, &mPNGinfo);
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+  mImageBufferUsed = 0;
+
+  // set our callback for libpng to give us the data
+  png_set_write_fn(mPNG, this, WriteCallback, nullptr);
+
+  // include alpha?
+  int colorType;
+  if ((aInputFormat == INPUT_FORMAT_HOSTARGB ||
+       aInputFormat == INPUT_FORMAT_RGBA) &&
+      useTransparency)
+    colorType = PNG_COLOR_TYPE_RGB_ALPHA;
+  else
+    colorType = PNG_COLOR_TYPE_RGB;
+
+  png_set_IHDR(mPNG, mPNGinfo, aWidth, aHeight, 8, colorType,
+               PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT,
+               PNG_FILTER_TYPE_DEFAULT);
+
+#ifdef PNG_APNG_SUPPORTED
+  if (mIsAnimation) {
+    png_set_first_frame_is_hidden(mPNG, mPNGinfo, skipFirstFrame);
+    png_set_acTL(mPNG, mPNGinfo, numFrames, numPlays);
+  }
+#endif
+
+  // XXX: support PLTE, gAMA, tRNS, bKGD?
+
+  png_write_info(mPNG, mPNGinfo);
+
+  return NS_OK;
+}
+
+// Returns the number of bytes in the image buffer used.
+NS_IMETHODIMP
+nsPNGEncoder::GetImageBufferUsed(uint32_t* aOutputSize) {
+  NS_ENSURE_ARG_POINTER(aOutputSize);
+  *aOutputSize = mImageBufferUsed;
+  return NS_OK;
+}
+
+// Returns a pointer to the start of the image buffer
+NS_IMETHODIMP
+nsPNGEncoder::GetImageBuffer(char** aOutputBuffer) {
+  NS_ENSURE_ARG_POINTER(aOutputBuffer);
+  *aOutputBuffer = reinterpret_cast<char*>(mImageBuffer);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPNGEncoder::AddImageFrame(const uint8_t* aData,
+                            uint32_t aLength,  // (unused, req'd by JS)
+                            uint32_t aWidth, uint32_t aHeight, uint32_t aStride,
+                            uint32_t aInputFormat,
+                            const nsAString& aFrameOptions) {
+  bool useTransparency = true;
+  int filters = DEFAULT_FILTERS;
+  uint32_t delay_ms = 500;
+#ifdef PNG_APNG_SUPPORTED
+  uint32_t dispose_op = PNG_DISPOSE_OP_NONE;
+  uint32_t blend_op = PNG_BLEND_OP_SOURCE;
+#else
+  uint32_t dispose_op;
+  uint32_t blend_op;
+#endif
+  uint32_t x_offset = 0, y_offset = 0;
+
+  // must be initialized
+  if (mImageBuffer == nullptr) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  // EndImageEncode was done, or some error occurred earlier
+  if (!mPNG) {
+    return NS_BASE_STREAM_CLOSED;
+  }
+
+  // validate input format
+  if (aInputFormat != INPUT_FORMAT_RGB && aInputFormat != INPUT_FORMAT_RGBA &&
+      aInputFormat != INPUT_FORMAT_HOSTARGB)
+    return NS_ERROR_INVALID_ARG;
+
+  // libpng's error handler jumps back here upon an error.
+  if (setjmp(png_jmpbuf(mPNG))) {
+    png_destroy_write_struct(&mPNG, &mPNGinfo);
+    return NS_ERROR_FAILURE;
+  }
+
+  // parse and check any provided output options
+  nsresult rv = ParseOptions(aFrameOptions, &useTransparency, nullptr, nullptr,
+                             nullptr, nullptr, &filters, &dispose_op, &blend_op,
+                             &delay_ms, &x_offset, &y_offset);
+  if (rv != NS_OK) {
+    return rv;
+  }
+
+#ifdef PNG_APNG_SUPPORTED
+  if (mIsAnimation) {
+    // XXX the row pointers arg (#3) is unused, can it be removed?
+    png_write_frame_head(mPNG, mPNGinfo, nullptr, aWidth, aHeight, x_offset,
+                         y_offset, delay_ms, 1000, dispose_op, blend_op);
+  }
+#endif
+
+  // Stride is the padded width of each row, so it better be longer
+  // (I'm afraid people will not understand what stride means, so
+  // check it well)
+  if ((aInputFormat == INPUT_FORMAT_RGB && aStride < aWidth * 3) ||
+      ((aInputFormat == INPUT_FORMAT_RGBA ||
+        aInputFormat == INPUT_FORMAT_HOSTARGB) &&
+       aStride < aWidth * 4)) {
+    NS_WARNING("Invalid stride for InitFromData/AddImageFrame");
+    return NS_ERROR_INVALID_ARG;
+  }
+
+#ifdef PNG_WRITE_FILTER_SUPPORTED
+  png_set_filter(mPNG, PNG_FILTER_TYPE_BASE, filters);
+#endif
+
+  // write each row: if we add more input formats, we may want to
+  // generalize the conversions
+  if (aInputFormat == INPUT_FORMAT_HOSTARGB) {
+    // PNG requires RGBA with post-multiplied alpha, so we need to
+    // convert
+    UniquePtr<uint8_t[]> row = MakeUniqueFallible<uint8_t[]>(aWidth * 4);
+    if (NS_WARN_IF(!row)) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+    for (uint32_t y = 0; y < aHeight; y++) {
+      ConvertHostARGBRow(&aData[y * aStride], row.get(), aWidth,
+                         useTransparency);
+      png_write_row(mPNG, row.get());
+    }
+  } else if (aInputFormat == INPUT_FORMAT_RGBA && !useTransparency) {
+    // RBGA, but we need to strip the alpha
+    UniquePtr<uint8_t[]> row = MakeUniqueFallible<uint8_t[]>(aWidth * 4);
+    if (NS_WARN_IF(!row)) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+    for (uint32_t y = 0; y < aHeight; y++) {
+      StripAlpha(&aData[y * aStride], row.get(), aWidth);
+      png_write_row(mPNG, row.get());
+    }
+  } else if (aInputFormat == INPUT_FORMAT_RGB ||
+             aInputFormat == INPUT_FORMAT_RGBA) {
+    // simple RBG(A), no conversion needed
+    for (uint32_t y = 0; y < aHeight; y++) {
+      png_write_row(mPNG, (uint8_t*)&aData[y * aStride]);
+    }
+
+  } else {
+    MOZ_ASSERT_UNREACHABLE("Bad format type");
+    return NS_ERROR_INVALID_ARG;
+  }
+
+#ifdef PNG_APNG_SUPPORTED
+  if (mIsAnimation) {
+    png_write_frame_tail(mPNG, mPNGinfo);
+  }
+#endif
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPNGEncoder::EndImageEncode() {
+  // must be initialized
+  if (mImageBuffer == nullptr) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  // EndImageEncode has already been called, or some error
+  // occurred earlier
+  if (!mPNG) {
+    return NS_BASE_STREAM_CLOSED;
+  }
+
+  // libpng's error handler jumps back here upon an error.
+  if (setjmp(png_jmpbuf(mPNG))) {
+    png_destroy_write_struct(&mPNG, &mPNGinfo);
+    return NS_ERROR_FAILURE;
+  }
+
+  png_write_end(mPNG, mPNGinfo);
+  png_destroy_write_struct(&mPNG, &mPNGinfo);
+
+  mFinished = true;
+  NotifyListener();
+
+  // if output callback can't get enough memory, it will free our buffer
+  if (!mImageBuffer) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  return NS_OK;
+}
+
+nsresult nsPNGEncoder::ParseOptions(const nsAString& aOptions,
+                                    bool* useTransparency, bool* skipFirstFrame,
+                                    uint32_t* numFrames, uint32_t* numPlays,
+                                    int* zlibLevel, int* filters,
+                                    uint32_t* frameDispose,
+                                    uint32_t* frameBlend, uint32_t* frameDelay,
+                                    uint32_t* offsetX, uint32_t* offsetY) {
+#ifdef PNG_APNG_SUPPORTED
+  // Make a copy of aOptions, because strtok() will modify it.
+  nsAutoCString optionsCopy;
+  optionsCopy.Assign(NS_ConvertUTF16toUTF8(aOptions));
+  char* options = optionsCopy.BeginWriting();
+
+  while (char* token = nsCRT::strtok(options, ";", &options)) {
+    // If there's an '=' character, split the token around it.
+    char* equals = token;
+    char* value = nullptr;
+    while (*equals != '=' && *equals) {
+      ++equals;
+    }
+    if (*equals == '=') {
+      value = equals + 1;
+    }
+
+    if (value) {
+      *equals = '\0';  // temporary null
+    }
+
+    // transparency=[yes|no|none]
+    if (nsCRT::strcmp(token, "transparency") == 0 && useTransparency) {
+      if (!value) {
+        return NS_ERROR_INVALID_ARG;
+      }
+
+      if (nsCRT::strcmp(value, "none") == 0 ||
+          nsCRT::strcmp(value, "no") == 0) {
+        *useTransparency = false;
+      } else if (nsCRT::strcmp(value, "yes") == 0) {
+        *useTransparency = true;
+      } else {
+        return NS_ERROR_INVALID_ARG;
+      }
+
+      // skipfirstframe=[yes|no]
+    } else if (nsCRT::strcmp(token, "skipfirstframe") == 0 && skipFirstFrame) {
+      if (!value) {
+        return NS_ERROR_INVALID_ARG;
+      }
+
+      if (nsCRT::strcmp(value, "no") == 0) {
+        *skipFirstFrame = false;
+      } else if (nsCRT::strcmp(value, "yes") == 0) {
+        *skipFirstFrame = true;
+      } else {
+        return NS_ERROR_INVALID_ARG;
+      }
+
+      // frames=#
+    } else if (nsCRT::strcmp(token, "frames") == 0 && numFrames) {
+      if (!value) {
+        return NS_ERROR_INVALID_ARG;
+      }
+
+      if (PR_sscanf(value, "%u", numFrames) != 1) {
+        return NS_ERROR_INVALID_ARG;
+      }
+
+      // frames=0 is nonsense.
+      if (*numFrames == 0) {
+        return NS_ERROR_INVALID_ARG;
+      }
+
+      // plays=#
+    } else if (nsCRT::strcmp(token, "plays") == 0 && numPlays) {
+      if (!value) {
+        return NS_ERROR_INVALID_ARG;
+      }
+
+      // plays=0 to loop forever, otherwise play sequence specified
+      // number of times
+      if (PR_sscanf(value, "%u", numPlays) != 1) {
+        return NS_ERROR_INVALID_ARG;
+      }
+
+      // png-zlib-level=#
+    } else if (nsCRT::strcmp(token, "png-zlib-level") == 0) {
+      if (!value) {
+        return NS_ERROR_INVALID_ARG;
+      }
+
+      int localZlibLevel = DEFAULT_ZLIB_LEVEL;
+      if (PR_sscanf(value, "%d", &localZlibLevel) != 1) {
+        return NS_ERROR_INVALID_ARG;
+      }
+
+      // zlib-level 0-9 are the only valid values
+      if (localZlibLevel < 0 || localZlibLevel > 9) {
+        return NS_ERROR_INVALID_ARG;
+      }
+
+      if (zlibLevel) {
+        *zlibLevel = localZlibLevel;
+      }
+
+      // png-filter=[no_filters|none|sub|up|avg|paeth|fast|all]
+    } else if (nsCRT::strcmp(token, "png-filter") == 0) {
+      if (!value) {
+        return NS_ERROR_INVALID_ARG;
+      }
+
+      if (nsCRT::strcmp(value, "no_filters") == 0) {
+        if (filters) {
+          *filters = PNG_NO_FILTERS;
+        }
+      } else if (nsCRT::strcmp(value, "none") == 0) {
+        if (filters) {
+          *filters = PNG_FILTER_NONE;
+        }
+      } else if (nsCRT::strcmp(value, "sub") == 0) {
+        if (filters) {
+          *filters = PNG_FILTER_SUB;
+        }
+      } else if (nsCRT::strcmp(value, "up") == 0) {
+        if (filters) {
+          *filters = PNG_FILTER_UP;
+        }
+      } else if (nsCRT::strcmp(value, "avg") == 0) {
+        if (filters) {
+          *filters = PNG_FILTER_AVG;
+        }
+      } else if (nsCRT::strcmp(value, "paeth") == 0) {
+        if (filters) {
+          *filters = PNG_FILTER_PAETH;
+        }
+      } else if (nsCRT::strcmp(value, "fast") == 0) {
+        if (filters) {
+          *filters = PNG_FAST_FILTERS;
+        }
+      } else if (nsCRT::strcmp(value, "all") == 0) {
+        if (filters) {
+          *filters = PNG_ALL_FILTERS;
+        }
+      } else {
+        return NS_ERROR_INVALID_ARG;
+      }
+
+      // dispose=[none|background|previous]
+    } else if (nsCRT::strcmp(token, "dispose") == 0 && frameDispose) {
+      if (!value) {
+        return NS_ERROR_INVALID_ARG;
+      }
+
+      if (nsCRT::strcmp(value, "none") == 0) {
+        *frameDispose = PNG_DISPOSE_OP_NONE;
+      } else if (nsCRT::strcmp(value, "background") == 0) {
+        *frameDispose = PNG_DISPOSE_OP_BACKGROUND;
+      } else if (nsCRT::strcmp(value, "previous") == 0) {
+        *frameDispose = PNG_DISPOSE_OP_PREVIOUS;
+      } else {
+        return NS_ERROR_INVALID_ARG;
+      }
+
+      // blend=[source|over]
+    } else if (nsCRT::strcmp(token, "blend") == 0 && frameBlend) {
+      if (!value) {
+        return NS_ERROR_INVALID_ARG;
+      }
+
+      if (nsCRT::strcmp(value, "source") == 0) {
+        *frameBlend = PNG_BLEND_OP_SOURCE;
+      } else if (nsCRT::strcmp(value, "over") == 0) {
+        *frameBlend = PNG_BLEND_OP_OVER;
+      } else {
+        return NS_ERROR_INVALID_ARG;
+      }
+
+      // delay=# (in ms)
+    } else if (nsCRT::strcmp(token, "delay") == 0 && frameDelay) {
+      if (!value) {
+        return NS_ERROR_INVALID_ARG;
+      }
+
+      if (PR_sscanf(value, "%u", frameDelay) != 1) {
+        return NS_ERROR_INVALID_ARG;
+      }
+
+      // xoffset=#
+    } else if (nsCRT::strcmp(token, "xoffset") == 0 && offsetX) {
+      if (!value) {
+        return NS_ERROR_INVALID_ARG;
+      }
+
+      if (PR_sscanf(value, "%u", offsetX) != 1) {
+        return NS_ERROR_INVALID_ARG;
+      }
+
+      // yoffset=#
+    } else if (nsCRT::strcmp(token, "yoffset") == 0 && offsetY) {
+      if (!value) {
+        return NS_ERROR_INVALID_ARG;
+      }
+
+      if (PR_sscanf(value, "%u", offsetY) != 1) {
+        return NS_ERROR_INVALID_ARG;
+      }
+
+      // unknown token name
+    } else
+      return NS_ERROR_INVALID_ARG;
+
+    if (value) {
+      *equals = '=';  // restore '=' so strtok doesn't get lost
+    }
+  }
+
+#endif
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPNGEncoder::Close() {
+  if (mImageBuffer != nullptr) {
+    free(mImageBuffer);
+    mImageBuffer = nullptr;
+    mImageBufferSize = 0;
+    mImageBufferUsed = 0;
+    mImageBufferReadPoint = 0;
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPNGEncoder::Available(uint64_t* _retval) {
+  if (!mImageBuffer) {
+    return NS_BASE_STREAM_CLOSED;
+  }
+
+  *_retval = mImageBufferUsed - mImageBufferReadPoint;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPNGEncoder::StreamStatus() {
+  return mImageBuffer ? NS_OK : NS_BASE_STREAM_CLOSED;
+}
+
+NS_IMETHODIMP
+nsPNGEncoder::Read(char* aBuf, uint32_t aCount, uint32_t* _retval) {
+  return ReadSegments(NS_CopySegmentToBuffer, aBuf, aCount, _retval);
+}
+
+NS_IMETHODIMP
+nsPNGEncoder::ReadSegments(nsWriteSegmentFun aWriter, void* aClosure,
+                           uint32_t aCount, uint32_t* _retval) {
+  // Avoid another thread reallocing the buffer underneath us
+  ReentrantMonitorAutoEnter autoEnter(mReentrantMonitor);
+
+  uint32_t maxCount = mImageBufferUsed - mImageBufferReadPoint;
+  if (maxCount == 0) {
+    *_retval = 0;
+    return mFinished ? NS_OK : NS_BASE_STREAM_WOULD_BLOCK;
+  }
+
+  if (aCount > maxCount) {
+    aCount = maxCount;
+  }
+
+  nsresult rv = aWriter(
+      this, aClosure,
+      reinterpret_cast<const char*>(mImageBuffer + mImageBufferReadPoint), 0,
+      aCount, _retval);
+  if (NS_SUCCEEDED(rv)) {
+    NS_ASSERTION(*_retval <= aCount, "bad write count");
+    mImageBufferReadPoint += *_retval;
+  }
+
+  // errors returned from the writer end here!
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPNGEncoder::IsNonBlocking(bool* _retval) {
+  *_retval = true;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPNGEncoder::AsyncWait(nsIInputStreamCallback* aCallback, uint32_t aFlags,
+                        uint32_t aRequestedCount, nsIEventTarget* aTarget) {
+  if (aFlags != 0) {
+    return NS_ERROR_NOT_IMPLEMENTED;
+  }
+
+  if (mCallback || mCallbackTarget) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  mCallbackTarget = aTarget;
+  // 0 means "any number of bytes except 0"
+  mNotifyThreshold = aRequestedCount;
+  if (!aRequestedCount) {
+    mNotifyThreshold = 1024;  // We don't want to notify incessantly
+  }
+
+  // We set the callback absolutely last, because NotifyListener uses it to
+  // determine if someone needs to be notified.  If we don't set it last,
+  // NotifyListener might try to fire off a notification to a null target
+  // which will generally cause non-threadsafe objects to be used off the main
+  // thread
+  mCallback = aCallback;
+
+  // What we are being asked for may be present already
+  NotifyListener();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsPNGEncoder::CloseWithStatus(nsresult aStatus) { return Close(); }
+
+// nsPNGEncoder::ConvertHostARGBRow
+//
+//    Our colors are stored with premultiplied alphas, but PNGs use
+//    post-multiplied alpha. This swaps to PNG-style alpha.
+//
+//    Copied from gfx/cairo/cairo/src/cairo-png.c
+
+void nsPNGEncoder::ConvertHostARGBRow(const uint8_t* aSrc, uint8_t* aDest,
+                                      uint32_t aPixelWidth,
+                                      bool aUseTransparency) {
+  uint32_t pixelStride = aUseTransparency ? 4 : 3;
+  for (uint32_t x = 0; x < aPixelWidth; x++) {
+    const uint32_t& pixelIn = ((const uint32_t*)(aSrc))[x];
+    uint8_t* pixelOut = &aDest[x * pixelStride];
+
+    uint8_t alpha = (pixelIn & 0xff000000) >> 24;
+    pixelOut[pixelStride - 1] = alpha;  // overwritten below if pixelStride == 3
+    if (alpha == 255) {
+      pixelOut[0] = (pixelIn & 0xff0000) >> 16;
+      pixelOut[1] = (pixelIn & 0x00ff00) >> 8;
+      pixelOut[2] = (pixelIn & 0x0000ff);
+    } else if (alpha == 0) {
+      pixelOut[0] = pixelOut[1] = pixelOut[2] = 0;
+    } else {
+      pixelOut[0] = (((pixelIn & 0xff0000) >> 16) * 255 + alpha / 2) / alpha;
+      pixelOut[1] = (((pixelIn & 0x00ff00) >> 8) * 255 + alpha / 2) / alpha;
+      pixelOut[2] = (((pixelIn & 0x0000ff)) * 255 + alpha / 2) / alpha;
+    }
+  }
+}
+
+// nsPNGEncoder::StripAlpha
+//
+//    Input is RGBA, output is RGB
+
+void nsPNGEncoder::StripAlpha(const uint8_t* aSrc, uint8_t* aDest,
+                              uint32_t aPixelWidth) {
+  for (uint32_t x = 0; x < aPixelWidth; x++) {
+    const uint8_t* pixelIn = &aSrc[x * 4];
+    uint8_t* pixelOut = &aDest[x * 3];
+    pixelOut[0] = pixelIn[0];
+    pixelOut[1] = pixelIn[1];
+    pixelOut[2] = pixelIn[2];
+  }
+}
+
+// nsPNGEncoder::WarningCallback
+
+void nsPNGEncoder::WarningCallback(png_structp png_ptr,
+                                   png_const_charp warning_msg) {
+  MOZ_LOG(sPNGEncoderLog, LogLevel::Warning,
+          ("libpng warning: %s\n", warning_msg));
+}
+
+// nsPNGEncoder::ErrorCallback
+
+void nsPNGEncoder::ErrorCallback(png_structp png_ptr,
+                                 png_const_charp error_msg) {
+  MOZ_LOG(sPNGEncoderLog, LogLevel::Error, ("libpng error: %s\n", error_msg));
+  png_longjmp(png_ptr, 1);
+}
+
+// nsPNGEncoder::WriteCallback
+
+void  // static
+nsPNGEncoder::WriteCallback(png_structp png, png_bytep data, png_size_t size) {
+  nsPNGEncoder* that = static_cast<nsPNGEncoder*>(png_get_io_ptr(png));
+  if (!that->mImageBuffer) {
+    return;
+  }
+
+  CheckedUint32 sizeNeeded = CheckedUint32(that->mImageBufferUsed) + size;
+  if (!sizeNeeded.isValid()) {
+    // Take the lock to ensure that nobody is trying to read from the buffer
+    // we are destroying
+    ReentrantMonitorAutoEnter autoEnter(that->mReentrantMonitor);
+
+    that->NullOutImageBuffer();
+    return;
+  }
+
+  if (sizeNeeded.value() > that->mImageBufferSize) {
+    // When we're reallocing the buffer we need to take the lock to ensure
+    // that nobody is trying to read from the buffer we are destroying
+    ReentrantMonitorAutoEnter autoEnter(that->mReentrantMonitor);
+
+    while (sizeNeeded.value() > that->mImageBufferSize) {
+      // expand buffer, just double each time
+      CheckedUint32 bufferSize = CheckedUint32(that->mImageBufferSize) * 2;
+      if (!bufferSize.isValid()) {
+        that->NullOutImageBuffer();
+        return;
+      }
+      that->mImageBufferSize *= 2;
+      uint8_t* newBuf =
+          (uint8_t*)realloc(that->mImageBuffer, that->mImageBufferSize);
+      if (!newBuf) {
+        // can't resize, just zero (this will keep us from writing more)
+        that->NullOutImageBuffer();
+        return;
+      }
+      that->mImageBuffer = newBuf;
+    }
+  }
+
+  memcpy(&that->mImageBuffer[that->mImageBufferUsed], data, size);
+  that->mImageBufferUsed += size;
+  that->NotifyListener();
+}
+
+void nsPNGEncoder::NullOutImageBuffer() {
+  mReentrantMonitor.AssertCurrentThreadIn();
+
+  free(mImageBuffer);
+  mImageBuffer = nullptr;
+  mImageBufferSize = 0;
+  mImageBufferUsed = 0;
+}
+
+void nsPNGEncoder::NotifyListener() {
+  // We might call this function on multiple threads (any threads that call
+  // AsyncWait and any that do encoding) so we lock to avoid notifying the
+  // listener twice about the same data (which generally leads to a truncated
+  // image).
+  ReentrantMonitorAutoEnter autoEnter(mReentrantMonitor);
+
+  if (mCallback &&
+      (mImageBufferUsed - mImageBufferReadPoint >= mNotifyThreshold ||
+       mFinished)) {
+    nsCOMPtr<nsIInputStreamCallback> callback;
+    if (mCallbackTarget) {
+      callback = NS_NewInputStreamReadyEvent("nsPNGEncoder::NotifyListener",
+                                             mCallback, mCallbackTarget);
+    } else {
+      callback = mCallback;
+    }
+
+    NS_ASSERTION(callback, "Shouldn't fail to make the callback");
+    // Null the callback first because OnInputStreamReady could reenter
+    // AsyncWait
+    mCallback = nullptr;
+    mCallbackTarget = nullptr;
+    mNotifyThreshold = 0;
+
+    callback->OnInputStreamReady(this);
+  }
+}
diff --git a/image/encoders/png/nsPNGEncoder.h b/image/encoders/png/nsPNGEncoder.h
new file mode 100644
index 0000000000..76d695ccfa
--- /dev/null
+++ b/image/encoders/png/nsPNGEncoder.h
@@ -0,0 +1,79 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_image_encoders_png_nsPNGEncoder_h
+#define mozilla_image_encoders_png_nsPNGEncoder_h
+
+#include <png.h>
+
+#include "imgIEncoder.h"
+#include "nsCOMPtr.h"
+
+#include "mozilla/Attributes.h"
+#include "mozilla/ReentrantMonitor.h"
+
+#define NS_PNGENCODER_CID                            \
+  { /* 38d1592e-b81e-432b-86f8-471878bbfe07 */       \
+    0x38d1592e, 0xb81e, 0x432b, {                    \
+      0x86, 0xf8, 0x47, 0x18, 0x78, 0xbb, 0xfe, 0x07 \
+    }                                                \
+  }
+
+// Provides PNG encoding functionality. Use InitFromData() to do the
+// encoding. See that function definition for encoding options.
+
+class nsPNGEncoder final : public imgIEncoder {
+  typedef mozilla::ReentrantMonitor ReentrantMonitor;
+
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_IMGIENCODER
+  NS_DECL_NSIINPUTSTREAM
+  NS_DECL_NSIASYNCINPUTSTREAM
+
+  nsPNGEncoder();
+
+ protected:
+  ~nsPNGEncoder();
+  nsresult ParseOptions(const nsAString& aOptions, bool* useTransparency,
+                        bool* skipFirstFrame, uint32_t* numAnimatedFrames,
+                        uint32_t* numIterations, int* zlibLevel, int* filters,
+                        uint32_t* frameDispose, uint32_t* frameBlend,
+                        uint32_t* frameDelay, uint32_t* offsetX,
+                        uint32_t* offsetY);
+  void ConvertHostARGBRow(const uint8_t* aSrc, uint8_t* aDest,
+                          uint32_t aPixelWidth, bool aUseTransparency);
+  void StripAlpha(const uint8_t* aSrc, uint8_t* aDest, uint32_t aPixelWidth);
+  static void WarningCallback(png_structp png_ptr, png_const_charp warning_msg);
+  static void ErrorCallback(png_structp png_ptr, png_const_charp error_msg);
+  static void WriteCallback(png_structp png, png_bytep data, png_size_t size);
+  void NullOutImageBuffer();
+  void NotifyListener();
+
+  png_struct* mPNG;
+  png_info* mPNGinfo;
+
+  bool mIsAnimation;
+  bool mFinished;
+
+  // image buffer
+  uint8_t* mImageBuffer;
+  uint32_t mImageBufferSize;
+  uint32_t mImageBufferUsed;
+
+  uint32_t mImageBufferReadPoint;
+
+  nsCOMPtr<nsIInputStreamCallback> mCallback;
+  nsCOMPtr<nsIEventTarget> mCallbackTarget;
+  uint32_t mNotifyThreshold;
+
+  // nsPNGEncoder is designed to allow one thread to pump data into it while
+  // another reads from it.  We lock to ensure that the buffer remains
+  // append-only while we read from it (that it is not realloced) and to
+  // ensure that only one thread dispatches a callback for each call to
+  // AsyncWait.
+  ReentrantMonitor mReentrantMonitor MOZ_UNANNOTATED;
+};
+#endif  // mozilla_image_encoders_png_nsPNGEncoder_h
diff --git a/image/encoders/webp/moz.build b/image/encoders/webp/moz.build
new file mode 100644
index 0000000000..4363caa79f
--- /dev/null
+++ b/image/encoders/webp/moz.build
@@ -0,0 +1,15 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+SOURCES += [
+    "nsWebPEncoder.cpp",
+]
+
+LOCAL_INCLUDES += [
+    "/image",
+]
+
+FINAL_LIBRARY = "xul"
diff --git a/image/encoders/webp/nsWebPEncoder.cpp b/image/encoders/webp/nsWebPEncoder.cpp
new file mode 100644
index 0000000000..72ac1388e9
--- /dev/null
+++ b/image/encoders/webp/nsWebPEncoder.cpp
@@ -0,0 +1,342 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// #include "ImageLogging.h"
+#include "nsCRT.h"
+#include "nsWebPEncoder.h"
+#include "nsStreamUtils.h"
+#include "nsString.h"
+#include "prprf.h"
+#include "mozilla/CheckedInt.h"
+#include "mozilla/UniquePtrExtensions.h"
+
+using namespace mozilla;
+
+// static LazyLogModule sWEBPEncoderLog("WEBPEncoder");
+
+NS_IMPL_ISUPPORTS(nsWebPEncoder, imgIEncoder, nsIInputStream,
+                  nsIAsyncInputStream)
+
+nsWebPEncoder::nsWebPEncoder()
+    : mFinished(false),
+      mImageBuffer(nullptr),
+      mImageBufferSize(0),
+      mImageBufferUsed(0),
+      mImageBufferReadPoint(0),
+      mCallback(nullptr),
+      mCallbackTarget(nullptr),
+      mNotifyThreshold(0),
+      mReentrantMonitor("nsWebPEncoder.mReentrantMonitor") {}
+
+nsWebPEncoder::~nsWebPEncoder() {
+  if (mImageBuffer) {
+    WebPFree(mImageBuffer);
+    mImageBuffer = nullptr;
+    mImageBufferSize = 0;
+    mImageBufferUsed = 0;
+    mImageBufferReadPoint = 0;
+  }
+}
+
+// nsWebPEncoder::InitFromData
+//
+//    One output option is supported: "quality=X" where X is an integer in the
+//    range 0-100. Higher values for X give better quality.
+
+NS_IMETHODIMP
+nsWebPEncoder::InitFromData(const uint8_t* aData,
+                            uint32_t aLength,  // (unused, req'd by JS)
+                            uint32_t aWidth, uint32_t aHeight, uint32_t aStride,
+                            uint32_t aInputFormat,
+                            const nsAString& aOutputOptions) {
+  NS_ENSURE_ARG(aData);
+
+  // validate input format
+  if (aInputFormat != INPUT_FORMAT_RGB && aInputFormat != INPUT_FORMAT_RGBA &&
+      aInputFormat != INPUT_FORMAT_HOSTARGB)
+    return NS_ERROR_INVALID_ARG;
+
+  // Stride is the padded width of each row, so it better be longer (I'm afraid
+  // people will not understand what stride means, so check it well)
+  if ((aInputFormat == INPUT_FORMAT_RGB && aStride < aWidth * 3) ||
+      ((aInputFormat == INPUT_FORMAT_RGBA ||
+        aInputFormat == INPUT_FORMAT_HOSTARGB) &&
+       aStride < aWidth * 4)) {
+    NS_WARNING("Invalid stride for InitFromData");
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  // can't initialize more than once
+  if (mImageBuffer != nullptr) {
+    return NS_ERROR_ALREADY_INITIALIZED;
+  }
+
+  // options: we only have one option so this is easy
+  int quality = 92;
+  if (aOutputOptions.Length() > 0) {
+    // have options string
+    const nsString qualityPrefix(u"quality="_ns);
+    if (aOutputOptions.Length() > qualityPrefix.Length() &&
+        StringBeginsWith(aOutputOptions, qualityPrefix)) {
+      // have quality string
+      nsCString value = NS_ConvertUTF16toUTF8(
+          Substring(aOutputOptions, qualityPrefix.Length()));
+      int newquality = -1;
+      if (PR_sscanf(value.get(), "%d", &newquality) == 1) {
+        if (newquality >= 0 && newquality <= 100) {
+          quality = newquality;
+        } else {
+          NS_WARNING(
+              "Quality value out of range, should be 0-100,"
+              " using default");
+        }
+      } else {
+        NS_WARNING(
+            "Quality value invalid, should be integer 0-100,"
+            " using default");
+      }
+    } else {
+      return NS_ERROR_INVALID_ARG;
+    }
+  }
+
+  size_t size = 0;
+
+  CheckedInt32 width = CheckedInt32(aWidth);
+  CheckedInt32 height = CheckedInt32(aHeight);
+  CheckedInt32 stride = CheckedInt32(aStride);
+  if (!width.isValid() || !height.isValid() || !stride.isValid() ||
+      !(CheckedUint32(aStride) * CheckedUint32(aHeight)).isValid()) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  if (aInputFormat == INPUT_FORMAT_RGB) {
+    size = quality == 100
+               ? WebPEncodeLosslessRGB(aData, width.value(), height.value(),
+                                       stride.value(), &mImageBuffer)
+               : WebPEncodeRGB(aData, width.value(), height.value(),
+                               stride.value(), quality, &mImageBuffer);
+  } else if (aInputFormat == INPUT_FORMAT_RGBA) {
+    size = quality == 100
+               ? WebPEncodeLosslessRGBA(aData, width.value(), height.value(),
+                                        stride.value(), &mImageBuffer)
+               : WebPEncodeRGBA(aData, width.value(), height.value(),
+                                stride.value(), quality, &mImageBuffer);
+  } else if (aInputFormat == INPUT_FORMAT_HOSTARGB) {
+    UniquePtr<uint8_t[]> aDest =
+        MakeUniqueFallible<uint8_t[]>(aStride * aHeight);
+    if (NS_WARN_IF(!aDest)) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+
+    for (uint32_t y = 0; y < aHeight; y++) {
+      for (uint32_t x = 0; x < aWidth; x++) {
+        const uint32_t& pixelIn =
+            ((const uint32_t*)(aData))[y * aStride / 4 + x];
+        uint8_t* pixelOut = &aDest[y * aStride + x * 4];
+
+        uint8_t alpha = (pixelIn & 0xff000000) >> 24;
+        pixelOut[3] = alpha;
+        if (alpha == 255) {
+          pixelOut[0] = (pixelIn & 0xff0000) >> 16;
+          pixelOut[1] = (pixelIn & 0x00ff00) >> 8;
+          pixelOut[2] = (pixelIn & 0x0000ff);
+        } else if (alpha == 0) {
+          pixelOut[0] = pixelOut[1] = pixelOut[2] = 0;
+        } else {
+          pixelOut[0] =
+              (((pixelIn & 0xff0000) >> 16) * 255 + alpha / 2) / alpha;
+          pixelOut[1] = (((pixelIn & 0x00ff00) >> 8) * 255 + alpha / 2) / alpha;
+          pixelOut[2] = (((pixelIn & 0x0000ff)) * 255 + alpha / 2) / alpha;
+        }
+      }
+    }
+
+    size =
+        quality == 100
+            ? WebPEncodeLosslessRGBA(aDest.get(), width.value(), height.value(),
+                                     stride.value(), &mImageBuffer)
+            : WebPEncodeRGBA(aDest.get(), width.value(), height.value(),
+                             stride.value(), quality, &mImageBuffer);
+  }
+
+  mFinished = true;
+
+  if (size == 0) {
+    return NS_ERROR_FAILURE;
+  }
+
+  mImageBufferUsed = size;
+
+  return NS_OK;
+}
+
+// nsWebPEncoder::StartImageEncode
+//
+//
+// See ::InitFromData for other info.
+NS_IMETHODIMP
+nsWebPEncoder::StartImageEncode(uint32_t aWidth, uint32_t aHeight,
+                                uint32_t aInputFormat,
+                                const nsAString& aOutputOptions) {
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+// Returns the number of bytes in the image buffer used.
+NS_IMETHODIMP
+nsWebPEncoder::GetImageBufferUsed(uint32_t* aOutputSize) {
+  NS_ENSURE_ARG_POINTER(aOutputSize);
+  *aOutputSize = mImageBufferUsed;
+  return NS_OK;
+}
+
+// Returns a pointer to the start of the image buffer
+NS_IMETHODIMP
+nsWebPEncoder::GetImageBuffer(char** aOutputBuffer) {
+  NS_ENSURE_ARG_POINTER(aOutputBuffer);
+  *aOutputBuffer = reinterpret_cast<char*>(mImageBuffer);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsWebPEncoder::AddImageFrame(const uint8_t* aData,
+                             uint32_t aLength,  // (unused, req'd by JS)
+                             uint32_t aWidth, uint32_t aHeight,
+                             uint32_t aStride, uint32_t aInputFormat,
+                             const nsAString& aFrameOptions) {
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+NS_IMETHODIMP
+nsWebPEncoder::EndImageEncode() { return NS_ERROR_NOT_IMPLEMENTED; }
+
+NS_IMETHODIMP
+nsWebPEncoder::Close() {
+  if (mImageBuffer) {
+    WebPFree(mImageBuffer);
+    mImageBuffer = nullptr;
+    mImageBufferSize = 0;
+    mImageBufferUsed = 0;
+    mImageBufferReadPoint = 0;
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsWebPEncoder::Available(uint64_t* _retval) {
+  if (!mImageBuffer) {
+    return NS_BASE_STREAM_CLOSED;
+  }
+
+  *_retval = mImageBufferUsed - mImageBufferReadPoint;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsWebPEncoder::StreamStatus() {
+  return mImageBuffer ? NS_OK : NS_BASE_STREAM_CLOSED;
+}
+
+NS_IMETHODIMP
+nsWebPEncoder::Read(char* aBuf, uint32_t aCount, uint32_t* _retval) {
+  return ReadSegments(NS_CopySegmentToBuffer, aBuf, aCount, _retval);
+}
+
+NS_IMETHODIMP
+nsWebPEncoder::ReadSegments(nsWriteSegmentFun aWriter, void* aClosure,
+                            uint32_t aCount, uint32_t* _retval) {
+  // Avoid another thread reallocing the buffer underneath us
+  ReentrantMonitorAutoEnter autoEnter(mReentrantMonitor);
+
+  uint32_t maxCount = mImageBufferUsed - mImageBufferReadPoint;
+  if (maxCount == 0) {
+    *_retval = 0;
+    return mFinished ? NS_OK : NS_BASE_STREAM_WOULD_BLOCK;
+  }
+
+  if (aCount > maxCount) {
+    aCount = maxCount;
+  }
+  nsresult rv = aWriter(
+      this, aClosure,
+      reinterpret_cast<const char*>(mImageBuffer + mImageBufferReadPoint), 0,
+      aCount, _retval);
+  if (NS_SUCCEEDED(rv)) {
+    NS_ASSERTION(*_retval <= aCount, "bad write count");
+    mImageBufferReadPoint += *_retval;
+  }
+
+  // errors returned from the writer end here!
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsWebPEncoder::IsNonBlocking(bool* _retval) {
+  *_retval = true;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsWebPEncoder::AsyncWait(nsIInputStreamCallback* aCallback, uint32_t aFlags,
+                         uint32_t aRequestedCount, nsIEventTarget* aTarget) {
+  if (aFlags != 0) {
+    return NS_ERROR_NOT_IMPLEMENTED;
+  }
+
+  if (mCallback || mCallbackTarget) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  mCallbackTarget = aTarget;
+  // 0 means "any number of bytes except 0"
+  mNotifyThreshold = aRequestedCount;
+  if (!aRequestedCount) {
+    mNotifyThreshold = 1024;  // 1 KB seems good.  We don't want to
+                              // notify incessantly
+  }
+
+  // We set the callback absolutely last, because NotifyListener uses it to
+  // determine if someone needs to be notified.  If we don't set it last,
+  // NotifyListener might try to fire off a notification to a null target
+  // which will generally cause non-threadsafe objects to be used off the
+  // main thread
+  mCallback = aCallback;
+
+  // What we are being asked for may be present already
+  NotifyListener();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsWebPEncoder::CloseWithStatus(nsresult aStatus) { return Close(); }
+
+void nsWebPEncoder::NotifyListener() {
+  // We might call this function on multiple threads (any threads that call
+  // AsyncWait and any that do encoding) so we lock to avoid notifying the
+  // listener twice about the same data (which generally leads to a truncated
+  // image).
+  ReentrantMonitorAutoEnter autoEnter(mReentrantMonitor);
+
+  if (mCallback &&
+      (mImageBufferUsed - mImageBufferReadPoint >= mNotifyThreshold ||
+       mFinished)) {
+    nsCOMPtr<nsIInputStreamCallback> callback;
+    if (mCallbackTarget) {
+      callback = NS_NewInputStreamReadyEvent("nsWebPEncoder::NotifyListener",
+                                             mCallback, mCallbackTarget);
+    } else {
+      callback = mCallback;
+    }
+
+    NS_ASSERTION(callback, "Shouldn't fail to make the callback");
+    // Null the callback first because OnInputStreamReady could reenter
+    // AsyncWait
+    mCallback = nullptr;
+    mCallbackTarget = nullptr;
+    mNotifyThreshold = 0;
+
+    callback->OnInputStreamReady(this);
+  }
+}
diff --git a/image/encoders/webp/nsWebPEncoder.h b/image/encoders/webp/nsWebPEncoder.h
new file mode 100644
index 0000000000..8628d12388
--- /dev/null
+++ b/image/encoders/webp/nsWebPEncoder.h
@@ -0,0 +1,63 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_image_encoders_webp_nsWebPEncoder_h
+#define mozilla_image_encoders_webp_nsWebPEncoder_h
+
+#include "webp/encode.h"
+
+#include "imgIEncoder.h"
+#include "nsCOMPtr.h"
+
+#include "mozilla/Attributes.h"
+#include "mozilla/ReentrantMonitor.h"
+
+#define NS_WEBPENCODER_CID                           \
+  { /* a8e5a8e5-bebf-4512-9f50-e41e4748ce28 */       \
+    0xa8e5a8e5, 0xbebf, 0x4512, {                    \
+      0x9f, 0x50, 0xe4, 0x1e, 0x47, 0x48, 0xce, 0x28 \
+    }                                                \
+  }
+
+// Provides WEBP encoding functionality. Use InitFromData() to do the
+// encoding. See that function definition for encoding options.
+
+class nsWebPEncoder final : public imgIEncoder {
+  typedef mozilla::ReentrantMonitor ReentrantMonitor;
+
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_IMGIENCODER
+  NS_DECL_NSIINPUTSTREAM
+  NS_DECL_NSIASYNCINPUTSTREAM
+
+  nsWebPEncoder();
+
+ protected:
+  ~nsWebPEncoder();
+
+  void NotifyListener();
+
+  bool mFinished;
+
+  // image buffer
+  uint8_t* mImageBuffer;
+  uint32_t mImageBufferSize;
+  uint32_t mImageBufferUsed;
+
+  uint32_t mImageBufferReadPoint;
+
+  nsCOMPtr<nsIInputStreamCallback> mCallback;
+  nsCOMPtr<nsIEventTarget> mCallbackTarget;
+  uint32_t mNotifyThreshold;
+
+  // nsWebPEncoder is designed to allow one thread to pump data into it while
+  // another reads from it.  We lock to ensure that the buffer remains
+  // append-only while we read from it (that it is not realloced) and to
+  // ensure that only one thread dispatches a callback for each call to
+  // AsyncWait.
+  ReentrantMonitor mReentrantMonitor MOZ_UNANNOTATED;
+};
+#endif  // mozilla_image_encoders_webp_nsWebPEncoder_h