Adding upstream version 110.0.1.upstream/110.0.1upstream

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

1 files changed, 850 insertions, 0 deletions

diff --git a/image/SurfacePipe.h b/image/SurfacePipe.h
new file mode 100644
index 0000000000..0c3533c9f9
--- /dev/null
+++ b/image/SurfacePipe.h
@@ -0,0 +1,850 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+/**
+ * A SurfacePipe is a pipeline that consists of a series of SurfaceFilters
+ * terminating in a SurfaceSink. Each SurfaceFilter transforms the image data in
+ * some way before the SurfaceSink ultimately writes it to the surface. This
+ * design allows for each transformation to be tested independently, for the
+ * transformations to be combined as needed to meet the needs of different
+ * situations, and for all image decoders to share the same code for these
+ * transformations.
+ *
+ * Writing to the SurfacePipe is done using lambdas that act as generator
+ * functions. Because the SurfacePipe machinery controls where the writes take
+ * place, a bug in an image decoder cannot cause a buffer overflow of the
+ * underlying surface.
+ */
+
+#ifndef mozilla_image_SurfacePipe_h
+#define mozilla_image_SurfacePipe_h
+
+#include <stdint.h>
+
+#include <utility>
+
+#include "AnimationParams.h"
+#include "mozilla/Likely.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/Tuple.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/Unused.h"
+#include "mozilla/Variant.h"
+#include "mozilla/gfx/2D.h"
+#include "mozilla/gfx/Swizzle.h"
+#include "nsDebug.h"
+#include "Orientation.h"
+
+namespace mozilla {
+namespace image {
+
+class Decoder;
+
+/**
+ * An invalid rect for a surface. Results are given both in the space of the
+ * input image (i.e., before any SurfaceFilters are applied) and in the space
+ * of the output surface (after all SurfaceFilters).
+ */
+struct SurfaceInvalidRect {
+  OrientedIntRect
+      mInputSpaceRect;  /// The invalid rect in pre-SurfacePipe space.
+  OrientedIntRect
+      mOutputSpaceRect;  /// The invalid rect in post-SurfacePipe space.
+};
+
+/**
+ * An enum used to allow the lambdas passed to WritePixels() to communicate
+ * their state to the caller.
+ */
+enum class WriteState : uint8_t {
+  NEED_MORE_DATA,  /// The lambda ran out of data.
+
+  FINISHED,  /// The lambda is done writing to the surface; future writes
+             /// will fail.
+
+  FAILURE  /// The lambda encountered an error. The caller may recover
+           /// if possible and continue to write. (This never indicates
+           /// an error in the SurfacePipe machinery itself; it's only
+           /// generated by the lambdas.)
+};
+
+/**
+ * A template alias used to make the return value of WritePixels() lambdas
+ * (which may return either a pixel value or a WriteState) easier to specify.
+ */
+template <typename PixelType>
+using NextPixel = Variant<PixelType, WriteState>;
+
+/**
+ * SurfaceFilter is the abstract superclass of SurfacePipe pipeline stages.  It
+ * implements the the code that actually writes to the surface - WritePixels()
+ * and the other Write*() methods - which are non-virtual for efficiency.
+ *
+ * SurfaceFilter's API is nonpublic; only SurfacePipe and other SurfaceFilters
+ * should use it. Non-SurfacePipe code should use the methods on SurfacePipe.
+ *
+ * To implement a SurfaceFilter, it's necessary to subclass SurfaceFilter and
+ * implement, at a minimum, the pure virtual methods. It's also necessary to
+ * define a Config struct with a Filter typedef member that identifies the
+ * matching SurfaceFilter class, and a Configure() template method. See an
+ * existing SurfaceFilter subclass, such as RemoveFrameRectFilter, for an
+ * example of how the Configure() method must be implemented. It takes a list of
+ * Config structs, passes the tail of the list to the next filter in the chain's
+ * Configure() method, and then uses the head of the list to configure itself. A
+ * SurfaceFilter's Configure() method must also call
+ * SurfaceFilter::ConfigureFilter() to provide the Write*() methods with the
+ * information they need to do their jobs.
+ */
+class SurfaceFilter {
+ public:
+  SurfaceFilter() : mRowPointer(nullptr), mCol(0), mPixelSize(0) {}
+
+  virtual ~SurfaceFilter() {}
+
+  /**
+   * Reset this surface to the first row. It's legal for this filter to throw
+   * away any previously written data at this point, as all rows must be written
+   * to on every pass.
+   *
+   * @return a pointer to the buffer for the first row.
+   */
+  uint8_t* ResetToFirstRow() {
+    mCol = 0;
+    mRowPointer = DoResetToFirstRow();
+    return mRowPointer;
+  }
+
+  /**
+   * Called by WritePixels() to advance this filter to the next row.
+   *
+   * @return a pointer to the buffer for the next row, or nullptr to indicate
+   *         that we've finished the entire surface.
+   */
+  uint8_t* AdvanceRow() {
+    mCol = 0;
+    mRowPointer = DoAdvanceRow();
+    return mRowPointer;
+  }
+
+  /**
+   * Called by WriteBuffer() to advance this filter to the next row, if the
+   * supplied row is a full row.
+   *
+   * @return a pointer to the buffer for the next row, or nullptr to indicate
+   *         that we've finished the entire surface.
+   */
+  uint8_t* AdvanceRow(const uint8_t* aInputRow) {
+    mCol = 0;
+    mRowPointer = DoAdvanceRowFromBuffer(aInputRow);
+    return mRowPointer;
+  }
+
+  /// @return a pointer to the buffer for the current row.
+  uint8_t* CurrentRowPointer() const { return mRowPointer; }
+
+  /// @return true if we've finished writing to the surface.
+  bool IsSurfaceFinished() const { return mRowPointer == nullptr; }
+
+  /// @return the input size this filter expects.
+  gfx::IntSize InputSize() const { return mInputSize; }
+
+  /**
+   * Write pixels to the surface one at a time by repeatedly calling a lambda
+   * that yields pixels. WritePixels() is completely memory safe.
+   *
+   * Writing continues until every pixel in the surface has been written to
+   * (i.e., IsSurfaceFinished() returns true) or the lambda returns a WriteState
+   * which WritePixels() will return to the caller.
+   *
+   * The template parameter PixelType must be uint8_t (for paletted surfaces) or
+   * uint32_t (for BGRA/BGRX surfaces) and must be in agreement with the pixel
+   * size passed to ConfigureFilter().
+   *
+   * XXX(seth): We'll remove all support for paletted surfaces in bug 1247520,
+   * which means we can remove the PixelType template parameter from this
+   * method.
+   *
+   * @param aFunc A lambda that functions as a generator, yielding the next
+   *              pixel in the surface each time it's called. The lambda must
+   *              return a NextPixel<PixelType> value.
+   *
+   * @return A WriteState value indicating the lambda generator's state.
+   *         WritePixels() itself will return WriteState::FINISHED if writing
+   *         has finished, regardless of the lambda's internal state.
+   */
+  template <typename PixelType, typename Func>
+  WriteState WritePixels(Func aFunc) {
+    Maybe<WriteState> result;
+    while (
+        !(result = DoWritePixelsToRow<PixelType>(std::forward<Func>(aFunc)))) {
+    }
+
+    return *result;
+  }
+
+  /**
+   * Write pixels to the surface by calling a lambda which may write as many
+   * pixels as there is remaining to complete the row. It is not completely
+   * memory safe as it trusts the underlying decoder not to overrun the given
+   * buffer, however it is an acceptable tradeoff for performance.
+   *
+   * Writing continues until every pixel in the surface has been written to
+   * (i.e., IsSurfaceFinished() returns true) or the lambda returns a WriteState
+   * which WritePixelBlocks() will return to the caller.
+   *
+   * The template parameter PixelType must be uint8_t (for paletted surfaces) or
+   * uint32_t (for BGRA/BGRX surfaces) and must be in agreement with the pixel
+   * size passed to ConfigureFilter().
+   *
+   * XXX(seth): We'll remove all support for paletted surfaces in bug 1247520,
+   * which means we can remove the PixelType template parameter from this
+   * method.
+   *
+   * @param aFunc A lambda that functions as a generator, yielding at most the
+   *              maximum number of pixels requested. The lambda must accept a
+   *              pointer argument to the first pixel to write, a maximum
+   *              number of pixels to write as part of the block, and return a
+   *              NextPixel<PixelType> value.
+   *
+   * @return A WriteState value indicating the lambda generator's state.
+   *         WritePixelBlocks() itself will return WriteState::FINISHED if
+   *         writing has finished, regardless of the lambda's internal state.
+   */
+  template <typename PixelType, typename Func>
+  WriteState WritePixelBlocks(Func aFunc) {
+    Maybe<WriteState> result;
+    while (!(result = DoWritePixelBlockToRow<PixelType>(
+                 std::forward<Func>(aFunc)))) {
+    }
+
+    return *result;
+  }
+
+  /**
+   * A variant of WritePixels() that writes a single row of pixels to the
+   * surface one at a time by repeatedly calling a lambda that yields pixels.
+   * WritePixelsToRow() is completely memory safe.
+   *
+   * Writing continues until every pixel in the row has been written to. If the
+   * surface is complete at that pointer, WriteState::FINISHED is returned;
+   * otherwise, WritePixelsToRow() returns WriteState::NEED_MORE_DATA. The
+   * lambda can terminate writing early by returning a WriteState itself, which
+   * WritePixelsToRow() will return to the caller.
+   *
+   * The template parameter PixelType must be uint8_t (for paletted surfaces) or
+   * uint32_t (for BGRA/BGRX surfaces) and must be in agreement with the pixel
+   * size passed to ConfigureFilter().
+   *
+   * XXX(seth): We'll remove all support for paletted surfaces in bug 1247520,
+   * which means we can remove the PixelType template parameter from this
+   * method.
+   *
+   * @param aFunc A lambda that functions as a generator, yielding the next
+   *              pixel in the surface each time it's called. The lambda must
+   *              return a NextPixel<PixelType> value.
+   *
+   * @return A WriteState value indicating the lambda generator's state.
+   *         WritePixels() itself will return WriteState::FINISHED if writing
+   *         the entire surface has finished, or WriteState::NEED_MORE_DATA if
+   *         writing the row has finished, regardless of the lambda's internal
+   *         state.
+   */
+  template <typename PixelType, typename Func>
+  WriteState WritePixelsToRow(Func aFunc) {
+    return DoWritePixelsToRow<PixelType>(std::forward<Func>(aFunc))
+        .valueOr(WriteState::NEED_MORE_DATA);
+  }
+
+  /**
+   * Write a row to the surface by copying from a buffer. This is bounds checked
+   * and memory safe with respect to the surface, but care must still be taken
+   * by the caller not to overread the source buffer. This variant of
+   * WriteBuffer() requires a source buffer which contains |mInputSize.width|
+   * pixels.
+   *
+   * The template parameter PixelType must be uint8_t (for paletted surfaces) or
+   * uint32_t (for BGRA/BGRX surfaces) and must be in agreement with the pixel
+   * size passed to ConfigureFilter().
+   *
+   * XXX(seth): We'll remove all support for paletted surfaces in bug 1247520,
+   * which means we can remove the PixelType template parameter from this
+   * method.
+   *
+   * @param aSource A buffer to copy from. This buffer must be
+   *                |mInputSize.width| pixels wide,  which means
+   *                |mInputSize.width * sizeof(PixelType)| bytes. May not be
+   *                null.
+   *
+   * @return WriteState::FINISHED if the entire surface has been written to.
+   *         Otherwise, returns WriteState::NEED_MORE_DATA. If a null |aSource|
+   *         value is passed, returns WriteState::FAILURE.
+   */
+  template <typename PixelType>
+  WriteState WriteBuffer(const PixelType* aSource) {
+    MOZ_ASSERT(mPixelSize == 1 || mPixelSize == 4);
+    MOZ_ASSERT_IF(mPixelSize == 1, sizeof(PixelType) == sizeof(uint8_t));
+    MOZ_ASSERT_IF(mPixelSize == 4, sizeof(PixelType) == sizeof(uint32_t));
+
+    if (IsSurfaceFinished()) {
+      return WriteState::FINISHED;  // Already done.
+    }
+
+    if (MOZ_UNLIKELY(!aSource)) {
+      NS_WARNING("Passed a null pointer to WriteBuffer");
+      return WriteState::FAILURE;
+    }
+
+    AdvanceRow(reinterpret_cast<const uint8_t*>(aSource));
+    return IsSurfaceFinished() ? WriteState::FINISHED
+                               : WriteState::NEED_MORE_DATA;
+  }
+
+  /**
+   * Write a row to the surface by copying from a buffer. This is bounds checked
+   * and memory safe with respect to the surface, but care must still be taken
+   * by the caller not to overread the source buffer. This variant of
+   * WriteBuffer() reads at most @aLength pixels from the buffer and writes them
+   * to the row starting at @aStartColumn. Any pixels in columns before
+   * @aStartColumn or after the pixels copied from the buffer are cleared.
+   *
+   * Bounds checking failures produce warnings in debug builds because although
+   * the bounds checking maintains safety, this kind of failure could indicate a
+   * bug in the calling code.
+   *
+   * The template parameter PixelType must be uint8_t (for paletted surfaces) or
+   * uint32_t (for BGRA/BGRX surfaces) and must be in agreement with the pixel
+   * size passed to ConfigureFilter().
+   *
+   * XXX(seth): We'll remove all support for paletted surfaces in bug 1247520,
+   * which means we can remove the PixelType template parameter from this
+   * method.
+   *
+   * @param aSource A buffer to copy from. This buffer must be @aLength pixels
+   *                wide, which means |aLength * sizeof(PixelType)| bytes. May
+   *                not be null.
+   * @param aStartColumn The column to start writing to in the row. Columns
+   *                     before this are cleared.
+   * @param aLength The number of bytes, at most, which may be copied from
+   *                @aSource. Fewer bytes may be copied in practice due to
+   *                bounds checking.
+   *
+   * @return WriteState::FINISHED if the entire surface has been written to.
+   *         Otherwise, returns WriteState::NEED_MORE_DATA. If a null |aSource|
+   *         value is passed, returns WriteState::FAILURE.
+   */
+  template <typename PixelType>
+  WriteState WriteBuffer(const PixelType* aSource, const size_t aStartColumn,
+                         const size_t aLength) {
+    MOZ_ASSERT(mPixelSize == 1 || mPixelSize == 4);
+    MOZ_ASSERT_IF(mPixelSize == 1, sizeof(PixelType) == sizeof(uint8_t));
+    MOZ_ASSERT_IF(mPixelSize == 4, sizeof(PixelType) == sizeof(uint32_t));
+
+    if (IsSurfaceFinished()) {
+      return WriteState::FINISHED;  // Already done.
+    }
+
+    if (MOZ_UNLIKELY(!aSource)) {
+      NS_WARNING("Passed a null pointer to WriteBuffer");
+      return WriteState::FAILURE;
+    }
+
+    PixelType* dest = reinterpret_cast<PixelType*>(mRowPointer);
+
+    // Clear the area before |aStartColumn|.
+    const size_t prefixLength =
+        std::min<size_t>(mInputSize.width, aStartColumn);
+    if (MOZ_UNLIKELY(prefixLength != aStartColumn)) {
+      NS_WARNING("Provided starting column is out-of-bounds in WriteBuffer");
+    }
+
+    memset(dest, 0, mInputSize.width * sizeof(PixelType));
+    dest += prefixLength;
+
+    // Write |aLength| pixels from |aSource| into the row, with bounds checking.
+    const size_t bufferLength =
+        std::min<size_t>(mInputSize.width - prefixLength, aLength);
+    if (MOZ_UNLIKELY(bufferLength != aLength)) {
+      NS_WARNING("Provided buffer length is out-of-bounds in WriteBuffer");
+    }
+
+    memcpy(dest, aSource, bufferLength * sizeof(PixelType));
+    dest += bufferLength;
+
+    // Clear the rest of the row.
+    const size_t suffixLength =
+        mInputSize.width - (prefixLength + bufferLength);
+    memset(dest, 0, suffixLength * sizeof(PixelType));
+
+    AdvanceRow();
+
+    return IsSurfaceFinished() ? WriteState::FINISHED
+                               : WriteState::NEED_MORE_DATA;
+  }
+
+  /**
+   * Write an empty row to the surface. If some pixels have already been written
+   * to this row, they'll be discarded.
+   *
+   * @return WriteState::FINISHED if the entire surface has been written to.
+   *         Otherwise, returns WriteState::NEED_MORE_DATA.
+   */
+  WriteState WriteEmptyRow() {
+    if (IsSurfaceFinished()) {
+      return WriteState::FINISHED;  // Already done.
+    }
+
+    memset(mRowPointer, 0, mInputSize.width * mPixelSize);
+    AdvanceRow();
+
+    return IsSurfaceFinished() ? WriteState::FINISHED
+                               : WriteState::NEED_MORE_DATA;
+  }
+
+  /**
+   * Write a row to the surface by calling a lambda that uses a pointer to
+   * directly write to the row. This is unsafe because SurfaceFilter can't
+   * provide any bounds checking; that's up to the lambda itself. For this
+   * reason, the other Write*() methods should be preferred whenever it's
+   * possible to use them; WriteUnsafeComputedRow() should be used only when
+   * it's absolutely necessary to avoid extra copies or other performance
+   * penalties.
+   *
+   * This method should never be exposed to SurfacePipe consumers; it's strictly
+   * for use in SurfaceFilters. If external code needs this method, it should
+   * probably be turned into a SurfaceFilter.
+   *
+   * The template parameter PixelType must be uint8_t (for paletted surfaces) or
+   * uint32_t (for BGRA/BGRX surfaces) and must be in agreement with the pixel
+   * size passed to ConfigureFilter().
+   *
+   * XXX(seth): We'll remove all support for paletted surfaces in bug 1247520,
+   * which means we can remove the PixelType template parameter from this
+   * method.
+   *
+   * @param aFunc A lambda that writes directly to the row.
+   *
+   * @return WriteState::FINISHED if the entire surface has been written to.
+   *         Otherwise, returns WriteState::NEED_MORE_DATA.
+   */
+  template <typename PixelType, typename Func>
+  WriteState WriteUnsafeComputedRow(Func aFunc) {
+    MOZ_ASSERT(mPixelSize == 1 || mPixelSize == 4);
+    MOZ_ASSERT_IF(mPixelSize == 1, sizeof(PixelType) == sizeof(uint8_t));
+    MOZ_ASSERT_IF(mPixelSize == 4, sizeof(PixelType) == sizeof(uint32_t));
+
+    if (IsSurfaceFinished()) {
+      return WriteState::FINISHED;  // Already done.
+    }
+
+    // Call the provided lambda with a pointer to the buffer for the current
+    // row. This is unsafe because we can't do any bounds checking; the lambda
+    // itself has to be responsible for that.
+    PixelType* rowPtr = reinterpret_cast<PixelType*>(mRowPointer);
+    aFunc(rowPtr, mInputSize.width);
+    AdvanceRow();
+
+    return IsSurfaceFinished() ? WriteState::FINISHED
+                               : WriteState::NEED_MORE_DATA;
+  }
+
+  //////////////////////////////////////////////////////////////////////////////
+  // Methods Subclasses Should Override
+  //////////////////////////////////////////////////////////////////////////////
+
+  /**
+   * @return a SurfaceInvalidRect representing the region of the surface that
+   *         has been written to since the last time TakeInvalidRect() was
+   *         called, or Nothing() if the region is empty (i.e. nothing has been
+   *         written).
+   */
+  virtual Maybe<SurfaceInvalidRect> TakeInvalidRect() = 0;
+
+ protected:
+  /**
+   * Called by ResetToFirstRow() to actually perform the reset. It's legal to
+   * throw away any previously written data at this point, as all rows must be
+   * written to on every pass.
+   */
+  virtual uint8_t* DoResetToFirstRow() = 0;
+
+  /**
+   * Called by AdvanceRow() to actually advance this filter to the next row.
+   *
+   * @param aInputRow The input row supplied by the decoder.
+   *
+   * @return a pointer to the buffer for the next row, or nullptr to indicate
+   *         that we've finished the entire surface.
+   */
+  virtual uint8_t* DoAdvanceRowFromBuffer(const uint8_t* aInputRow) = 0;
+
+  /**
+   * Called by AdvanceRow() to actually advance this filter to the next row.
+   *
+   * @return a pointer to the buffer for the next row, or nullptr to indicate
+   *         that we've finished the entire surface.
+   */
+  virtual uint8_t* DoAdvanceRow() = 0;
+
+  //////////////////////////////////////////////////////////////////////////////
+  // Methods For Internal Use By Subclasses
+  //////////////////////////////////////////////////////////////////////////////
+
+  /**
+   * Called by subclasses' Configure() methods to initialize the configuration
+   * of this filter. After the filter is configured, calls ResetToFirstRow().
+   *
+   * @param aInputSize The input size of this filter, in pixels. The previous
+   *                   filter in the chain will expect to write into rows
+   *                   |aInputSize.width| pixels wide.
+   * @param aPixelSize How large, in bytes, each pixel in the surface is. This
+   *                   should be either 1 for paletted images or 4 for BGRA/BGRX
+   *                   images.
+   */
+  void ConfigureFilter(gfx::IntSize aInputSize, uint8_t aPixelSize) {
+    mInputSize = aInputSize;
+    mPixelSize = aPixelSize;
+
+    ResetToFirstRow();
+  }
+
+  /**
+   * Called by subclasses' DoAdvanceRowFromBuffer() methods to copy a decoder
+   * supplied row buffer into its internal row pointer. Ideally filters at the
+   * top of the filter pipeline are able to consume the decoder row buffer
+   * directly without the extra copy prior to performing its transformation.
+   *
+   * @param aInputRow The input row supplied by the decoder.
+   */
+  void CopyInputRow(const uint8_t* aInputRow) {
+    MOZ_ASSERT(aInputRow);
+    MOZ_ASSERT(mCol == 0);
+    memcpy(mRowPointer, aInputRow, mPixelSize * mInputSize.width);
+  }
+
+ private:
+  /**
+   * An internal method used to implement WritePixelBlocks. This method writes
+   * up to the number of pixels necessary to complete the row and returns Some()
+   * if we either finished the entire surface or the lambda returned a
+   * WriteState indicating that we should return to the caller. If the row was
+   * successfully written without either of those things happening, it returns
+   * Nothing(), allowing WritePixelBlocks() to iterate to fill as many rows as
+   * possible.
+   */
+  template <typename PixelType, typename Func>
+  Maybe<WriteState> DoWritePixelBlockToRow(Func aFunc) {
+    MOZ_ASSERT(mPixelSize == 1 || mPixelSize == 4);
+    MOZ_ASSERT_IF(mPixelSize == 1, sizeof(PixelType) == sizeof(uint8_t));
+    MOZ_ASSERT_IF(mPixelSize == 4, sizeof(PixelType) == sizeof(uint32_t));
+
+    if (IsSurfaceFinished()) {
+      return Some(WriteState::FINISHED);  // We're already done.
+    }
+
+    PixelType* rowPtr = reinterpret_cast<PixelType*>(mRowPointer);
+    int32_t remainder = mInputSize.width - mCol;
+    int32_t written;
+    Maybe<WriteState> result;
+    Tie(written, result) = aFunc(&rowPtr[mCol], remainder);
+    if (written == remainder) {
+      MOZ_ASSERT(result.isNothing());
+      mCol = mInputSize.width;
+      AdvanceRow();  // We've finished the row.
+      return IsSurfaceFinished() ? Some(WriteState::FINISHED) : Nothing();
+    }
+
+    MOZ_ASSERT(written >= 0 && written < remainder);
+    MOZ_ASSERT(result.isSome());
+
+    mCol += written;
+    if (*result == WriteState::FINISHED) {
+      ZeroOutRestOfSurface<PixelType>();
+    }
+
+    return result;
+  }
+
+  /**
+   * An internal method used to implement both WritePixels() and
+   * WritePixelsToRow(). Those methods differ only in their behavior after a row
+   * is successfully written - WritePixels() continues to write another row,
+   * while WritePixelsToRow() returns to the caller. This method writes a single
+   * row and returns Some() if we either finished the entire surface or the
+   * lambda returned a WriteState indicating that we should return to the
+   * caller. If the row was successfully written without either of those things
+   * happening, it returns Nothing(), allowing WritePixels() and
+   * WritePixelsToRow() to implement their respective behaviors.
+   */
+  template <typename PixelType, typename Func>
+  Maybe<WriteState> DoWritePixelsToRow(Func aFunc) {
+    MOZ_ASSERT(mPixelSize == 1 || mPixelSize == 4);
+    MOZ_ASSERT_IF(mPixelSize == 1, sizeof(PixelType) == sizeof(uint8_t));
+    MOZ_ASSERT_IF(mPixelSize == 4, sizeof(PixelType) == sizeof(uint32_t));
+
+    if (IsSurfaceFinished()) {
+      return Some(WriteState::FINISHED);  // We're already done.
+    }
+
+    PixelType* rowPtr = reinterpret_cast<PixelType*>(mRowPointer);
+
+    for (; mCol < mInputSize.width; ++mCol) {
+      NextPixel<PixelType> result = aFunc();
+      if (result.template is<PixelType>()) {
+        rowPtr[mCol] = result.template as<PixelType>();
+        continue;
+      }
+
+      switch (result.template as<WriteState>()) {
+        case WriteState::NEED_MORE_DATA:
+          return Some(WriteState::NEED_MORE_DATA);
+
+        case WriteState::FINISHED:
+          ZeroOutRestOfSurface<PixelType>();
+          return Some(WriteState::FINISHED);
+
+        case WriteState::FAILURE:
+          // Note that we don't need to record this anywhere, because this
+          // indicates an error in aFunc, and there's nothing wrong with our
+          // machinery. The caller can recover as needed and continue writing to
+          // the row.
+          return Some(WriteState::FAILURE);
+      }
+    }
+
+    AdvanceRow();  // We've finished the row.
+
+    return IsSurfaceFinished() ? Some(WriteState::FINISHED) : Nothing();
+  }
+
+  template <typename PixelType>
+  void ZeroOutRestOfSurface() {
+    WritePixels<PixelType>([] { return AsVariant(PixelType(0)); });
+  }
+
+  gfx::IntSize mInputSize;  /// The size of the input this filter expects.
+  uint8_t* mRowPointer;     /// Pointer to the current row or null if finished.
+  int32_t mCol;             /// The current column we're writing to. (0-indexed)
+  uint8_t mPixelSize;  /// How large each pixel in the surface is, in bytes.
+};
+
+/**
+ * SurfacePipe is the public API that decoders should use to interact with a
+ * SurfaceFilter pipeline.
+ */
+class SurfacePipe {
+ public:
+  SurfacePipe() {}
+
+  SurfacePipe(SurfacePipe&& aOther) : mHead(std::move(aOther.mHead)) {}
+
+  ~SurfacePipe() {}
+
+  SurfacePipe& operator=(SurfacePipe&& aOther) {
+    MOZ_ASSERT(this != &aOther);
+    mHead = std::move(aOther.mHead);
+    return *this;
+  }
+
+  /// Begins a new pass, seeking to the first row of the surface.
+  void ResetToFirstRow() {
+    MOZ_ASSERT(mHead, "Use before configured!");
+    mHead->ResetToFirstRow();
+  }
+
+  /**
+   * Write pixels to the surface one at a time by repeatedly calling a lambda
+   * that yields pixels. WritePixels() is completely memory safe.
+   *
+   * @see SurfaceFilter::WritePixels() for the canonical documentation.
+   */
+  template <typename PixelType, typename Func>
+  WriteState WritePixels(Func aFunc) {
+    MOZ_ASSERT(mHead, "Use before configured!");
+    return mHead->WritePixels<PixelType>(std::forward<Func>(aFunc));
+  }
+
+  /**
+   * A variant of WritePixels() that writes up to a single row of pixels to the
+   * surface in blocks by repeatedly calling a lambda that yields up to the
+   * requested number of pixels.
+   *
+   * @see SurfaceFilter::WritePixelBlocks() for the canonical documentation.
+   */
+  template <typename PixelType, typename Func>
+  WriteState WritePixelBlocks(Func aFunc) {
+    MOZ_ASSERT(mHead, "Use before configured!");
+    return mHead->WritePixelBlocks<PixelType>(std::forward<Func>(aFunc));
+  }
+
+  /**
+   * A variant of WritePixels() that writes a single row of pixels to the
+   * surface one at a time by repeatedly calling a lambda that yields pixels.
+   * WritePixelsToRow() is completely memory safe.
+   *
+   * @see SurfaceFilter::WritePixelsToRow() for the canonical documentation.
+   */
+  template <typename PixelType, typename Func>
+  WriteState WritePixelsToRow(Func aFunc) {
+    MOZ_ASSERT(mHead, "Use before configured!");
+    return mHead->WritePixelsToRow<PixelType>(std::forward<Func>(aFunc));
+  }
+
+  /**
+   * Write a row to the surface by copying from a buffer. This is bounds checked
+   * and memory safe with respect to the surface, but care must still be taken
+   * by the caller not to overread the source buffer. This variant of
+   * WriteBuffer() requires a source buffer which contains |mInputSize.width|
+   * pixels.
+   *
+   * @see SurfaceFilter::WriteBuffer() for the canonical documentation.
+   */
+  template <typename PixelType>
+  WriteState WriteBuffer(const PixelType* aSource) {
+    MOZ_ASSERT(mHead, "Use before configured!");
+    return mHead->WriteBuffer<PixelType>(aSource);
+  }
+
+  /**
+   * Write a row to the surface by copying from a buffer. This is bounds checked
+   * and memory safe with respect to the surface, but care must still be taken
+   * by the caller not to overread the source buffer. This variant of
+   * WriteBuffer() reads at most @aLength pixels from the buffer and writes them
+   * to the row starting at @aStartColumn. Any pixels in columns before
+   * @aStartColumn or after the pixels copied from the buffer are cleared.
+   *
+   * @see SurfaceFilter::WriteBuffer() for the canonical documentation.
+   */
+  template <typename PixelType>
+  WriteState WriteBuffer(const PixelType* aSource, const size_t aStartColumn,
+                         const size_t aLength) {
+    MOZ_ASSERT(mHead, "Use before configured!");
+    return mHead->WriteBuffer<PixelType>(aSource, aStartColumn, aLength);
+  }
+
+  /**
+   * Write an empty row to the surface. If some pixels have already been written
+   * to this row, they'll be discarded.
+   *
+   * @see SurfaceFilter::WriteEmptyRow() for the canonical documentation.
+   */
+  WriteState WriteEmptyRow() {
+    MOZ_ASSERT(mHead, "Use before configured!");
+    return mHead->WriteEmptyRow();
+  }
+
+  /// @return true if we've finished writing to the surface.
+  bool IsSurfaceFinished() const { return mHead->IsSurfaceFinished(); }
+
+  /// @see SurfaceFilter::TakeInvalidRect() for the canonical documentation.
+  Maybe<SurfaceInvalidRect> TakeInvalidRect() const {
+    MOZ_ASSERT(mHead, "Use before configured!");
+    return mHead->TakeInvalidRect();
+  }
+
+ private:
+  friend class SurfacePipeFactory;
+  friend class TestSurfacePipeFactory;
+
+  explicit SurfacePipe(UniquePtr<SurfaceFilter>&& aHead)
+      : mHead(std::move(aHead)) {}
+
+  SurfacePipe(const SurfacePipe&) = delete;
+  SurfacePipe& operator=(const SurfacePipe&) = delete;
+
+  UniquePtr<SurfaceFilter> mHead;  /// The first filter in the chain.
+};
+
+/**
+ * AbstractSurfaceSink contains shared implementation for both SurfaceSink and
+ * ReorientSurfaceSink.
+ */
+class AbstractSurfaceSink : public SurfaceFilter {
+ public:
+  AbstractSurfaceSink()
+      : mImageData(nullptr),
+        mImageDataLength(0),
+        mRow(0),
+        mFlipVertically(false) {}
+
+  Maybe<SurfaceInvalidRect> TakeInvalidRect() final;
+
+ protected:
+  uint8_t* DoResetToFirstRow() final;
+  virtual uint8_t* GetRowPointer() const = 0;
+
+  OrientedIntRect
+      mInvalidRect;     /// The region of the surface that has been written
+                        /// to since the last call to TakeInvalidRect().
+  uint8_t* mImageData;  /// A pointer to the beginning of the surface data.
+  uint32_t mImageDataLength;  /// The length of the surface data.
+  uint32_t mRow;              /// The row to which we're writing. (0-indexed)
+  bool mFlipVertically;       /// If true, write the rows from top to bottom.
+};
+
+class SurfaceSink;
+
+/// A configuration struct for SurfaceSink.
+struct SurfaceConfig {
+  using Filter = SurfaceSink;
+  Decoder* mDecoder;           /// Which Decoder to use to allocate the surface.
+  gfx::IntSize mOutputSize;    /// The size of the surface.
+  gfx::SurfaceFormat mFormat;  /// The surface format (BGRA or BGRX).
+  bool mFlipVertically;        /// If true, write the rows from bottom to top.
+  Maybe<AnimationParams> mAnimParams;  /// Given for animated images.
+};
+
+/**
+ * A sink for surfaces. It handles the allocation of the surface and protects
+ * against buffer overflow. This sink should be used for most images.
+ *
+ * Sinks must always be at the end of the SurfaceFilter chain.
+ */
+class SurfaceSink final : public AbstractSurfaceSink {
+ public:
+  nsresult Configure(const SurfaceConfig& aConfig);
+
+ protected:
+  uint8_t* DoAdvanceRowFromBuffer(const uint8_t* aInputRow) final;
+  uint8_t* DoAdvanceRow() final;
+  uint8_t* GetRowPointer() const final;
+};
+
+class ReorientSurfaceSink;
+
+/// A configuration struct for ReorientSurfaceSink.
+struct ReorientSurfaceConfig {
+  using Filter = ReorientSurfaceSink;
+  Decoder* mDecoder;  /// Which Decoder to use to allocate the surface.
+  OrientedIntSize mOutputSize;  /// The size of the surface.
+  gfx::SurfaceFormat mFormat;   /// The surface format (BGRA or BGRX).
+  Orientation mOrientation;     /// The desired orientation of the surface data.
+};
+
+/**
+ * A sink for surfaces. It handles the allocation of the surface and protects
+ * against buffer overflow. This sink should be used for images which have a
+ * non-identity orientation which we want to apply during decoding.
+ *
+ * Sinks must always be at the end of the SurfaceFilter chain.
+ */
+class ReorientSurfaceSink final : public AbstractSurfaceSink {
+ public:
+  nsresult Configure(const ReorientSurfaceConfig& aConfig);
+
+ protected:
+  uint8_t* DoAdvanceRowFromBuffer(const uint8_t* aInputRow) final;
+  uint8_t* DoAdvanceRow() final;
+  uint8_t* GetRowPointer() const final;
+
+  UniquePtr<uint8_t[]> mBuffer;
+  gfx::ReorientRowFn mReorientFn;
+  gfx::IntSize mSurfaceSize;
+};
+
+}  // namespace image
+}  // namespace mozilla
+
+#endif  // mozilla_image_SurfacePipe_h