summaryrefslogtreecommitdiffstats
path: root/image/Downscaler.cpp
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--image/Downscaler.cpp301
1 files changed, 301 insertions, 0 deletions
diff --git a/image/Downscaler.cpp b/image/Downscaler.cpp
new file mode 100644
index 0000000000..59d2dd0248
--- /dev/null
+++ b/image/Downscaler.cpp
@@ -0,0 +1,301 @@
+/* -*- 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 "Downscaler.h"
+
+#include <algorithm>
+#include <ctime>
+
+#include "mozilla/gfx/2D.h"
+
+using std::swap;
+
+namespace mozilla {
+
+using gfx::IntRect;
+
+namespace image {
+
+Downscaler::Downscaler(const nsIntSize& aTargetSize)
+ : mTargetSize(aTargetSize),
+ mOutputBuffer(nullptr),
+ mWindowCapacity(0),
+ mLinesInBuffer(0),
+ mPrevInvalidatedLine(0),
+ mCurrentOutLine(0),
+ mCurrentInLine(0),
+ mHasAlpha(true),
+ mFlipVertically(false) {
+ MOZ_ASSERT(mTargetSize.width > 0 && mTargetSize.height > 0,
+ "Invalid target size");
+}
+
+Downscaler::~Downscaler() { ReleaseWindow(); }
+
+void Downscaler::ReleaseWindow() {
+ if (!mWindow) {
+ return;
+ }
+
+ for (int32_t i = 0; i < mWindowCapacity; ++i) {
+ delete[] mWindow[i];
+ }
+
+ mWindow = nullptr;
+ mWindowCapacity = 0;
+}
+
+nsresult Downscaler::BeginFrame(const nsIntSize& aOriginalSize,
+ const Maybe<nsIntRect>& aFrameRect,
+ uint8_t* aOutputBuffer, bool aHasAlpha,
+ bool aFlipVertically /* = false */) {
+ MOZ_ASSERT(aOutputBuffer);
+ MOZ_ASSERT(mTargetSize != aOriginalSize,
+ "Created a downscaler, but not downscaling?");
+ MOZ_ASSERT(mTargetSize.width <= aOriginalSize.width,
+ "Created a downscaler, but width is larger");
+ MOZ_ASSERT(mTargetSize.height <= aOriginalSize.height,
+ "Created a downscaler, but height is larger");
+ MOZ_ASSERT(aOriginalSize.width > 0 && aOriginalSize.height > 0,
+ "Invalid original size");
+
+ // Only downscale from reasonable sizes to avoid using too much memory/cpu
+ // downscaling and decoding. 1 << 20 == 1,048,576 seems a reasonable limit.
+ if (aOriginalSize.width > (1 << 20) || aOriginalSize.height > (1 << 20)) {
+ NS_WARNING("Trying to downscale image frame that is too large");
+ return NS_ERROR_INVALID_ARG;
+ }
+
+ mFrameRect = aFrameRect.valueOr(nsIntRect(nsIntPoint(), aOriginalSize));
+ MOZ_ASSERT(mFrameRect.X() >= 0 && mFrameRect.Y() >= 0 &&
+ mFrameRect.Width() >= 0 && mFrameRect.Height() >= 0,
+ "Frame rect must have non-negative components");
+ MOZ_ASSERT(nsIntRect(0, 0, aOriginalSize.width, aOriginalSize.height)
+ .Contains(mFrameRect),
+ "Frame rect must fit inside image");
+ MOZ_ASSERT_IF(!nsIntRect(0, 0, aOriginalSize.width, aOriginalSize.height)
+ .IsEqualEdges(mFrameRect),
+ aHasAlpha);
+
+ mOriginalSize = aOriginalSize;
+ mScale = gfx::MatrixScalesDouble(
+ double(mOriginalSize.width) / mTargetSize.width,
+ double(mOriginalSize.height) / mTargetSize.height);
+ mOutputBuffer = aOutputBuffer;
+ mHasAlpha = aHasAlpha;
+ mFlipVertically = aFlipVertically;
+
+ ReleaseWindow();
+
+ auto resizeMethod = gfx::ConvolutionFilter::ResizeMethod::LANCZOS3;
+ if (!mXFilter.ComputeResizeFilter(resizeMethod, mOriginalSize.width,
+ mTargetSize.width) ||
+ !mYFilter.ComputeResizeFilter(resizeMethod, mOriginalSize.height,
+ mTargetSize.height)) {
+ NS_WARNING("Failed to compute filters for image downscaling");
+ return NS_ERROR_OUT_OF_MEMORY;
+ }
+
+ // Allocate the buffer, which contains scanlines of the original image.
+ // pad to handle overreads by the simd code
+ size_t bufferLen = gfx::ConvolutionFilter::PadBytesForSIMD(
+ mOriginalSize.width * sizeof(uint32_t));
+ mRowBuffer.reset(new (fallible) uint8_t[bufferLen]);
+ if (MOZ_UNLIKELY(!mRowBuffer)) {
+ return NS_ERROR_OUT_OF_MEMORY;
+ }
+
+ // Zero buffer to keep valgrind happy.
+ memset(mRowBuffer.get(), 0, bufferLen);
+
+ // Allocate the window, which contains horizontally downscaled scanlines. (We
+ // can store scanlines which are already downscale because our downscaling
+ // filter is separable.)
+ mWindowCapacity = mYFilter.MaxFilter();
+ mWindow.reset(new (fallible) uint8_t*[mWindowCapacity]);
+ if (MOZ_UNLIKELY(!mWindow)) {
+ return NS_ERROR_OUT_OF_MEMORY;
+ }
+
+ bool anyAllocationFailed = false;
+ // pad to handle overreads by the simd code
+ const size_t rowSize = gfx::ConvolutionFilter::PadBytesForSIMD(
+ mTargetSize.width * sizeof(uint32_t));
+ for (int32_t i = 0; i < mWindowCapacity; ++i) {
+ mWindow[i] = new (fallible) uint8_t[rowSize];
+ anyAllocationFailed = anyAllocationFailed || mWindow[i] == nullptr;
+ }
+
+ if (MOZ_UNLIKELY(anyAllocationFailed)) {
+ // We intentionally iterate through the entire array even if an allocation
+ // fails, to ensure that all the pointers in it are either valid or nullptr.
+ // That in turn ensures that ReleaseWindow() can clean up correctly.
+ return NS_ERROR_OUT_OF_MEMORY;
+ }
+
+ ResetForNextProgressivePass();
+
+ return NS_OK;
+}
+
+void Downscaler::SkipToRow(int32_t aRow) {
+ if (mCurrentInLine < aRow) {
+ ClearRow();
+ do {
+ CommitRow();
+ } while (mCurrentInLine < aRow);
+ }
+}
+
+void Downscaler::ResetForNextProgressivePass() {
+ mPrevInvalidatedLine = 0;
+ mCurrentOutLine = 0;
+ mCurrentInLine = 0;
+ mLinesInBuffer = 0;
+
+ if (mFrameRect.IsEmpty()) {
+ // Our frame rect is zero size; commit rows until the end of the image.
+ SkipToRow(mOriginalSize.height - 1);
+ } else {
+ // If we have a vertical offset, commit rows to shift us past it.
+ SkipToRow(mFrameRect.Y());
+ }
+}
+
+void Downscaler::ClearRestOfRow(uint32_t aStartingAtCol) {
+ MOZ_ASSERT(int64_t(aStartingAtCol) <= int64_t(mOriginalSize.width));
+ uint32_t bytesToClear =
+ (mOriginalSize.width - aStartingAtCol) * sizeof(uint32_t);
+ memset(mRowBuffer.get() + (aStartingAtCol * sizeof(uint32_t)), 0,
+ bytesToClear);
+}
+
+void Downscaler::CommitRow() {
+ MOZ_ASSERT(mOutputBuffer, "Should have a current frame");
+ MOZ_ASSERT(mCurrentInLine < mOriginalSize.height, "Past end of input");
+
+ if (mCurrentOutLine < mTargetSize.height) {
+ int32_t filterOffset = 0;
+ int32_t filterLength = 0;
+ mYFilter.GetFilterOffsetAndLength(mCurrentOutLine, &filterOffset,
+ &filterLength);
+
+ int32_t inLineToRead = filterOffset + mLinesInBuffer;
+ MOZ_ASSERT(mCurrentInLine <= inLineToRead, "Reading past end of input");
+ if (mCurrentInLine == inLineToRead) {
+ MOZ_RELEASE_ASSERT(mLinesInBuffer < mWindowCapacity,
+ "Need more rows than capacity!");
+ mXFilter.ConvolveHorizontally(mRowBuffer.get(), mWindow[mLinesInBuffer++],
+ mHasAlpha);
+ }
+
+ MOZ_ASSERT(mCurrentOutLine < mTargetSize.height,
+ "Writing past end of output");
+
+ while (mLinesInBuffer >= filterLength) {
+ DownscaleInputLine();
+
+ if (mCurrentOutLine == mTargetSize.height) {
+ break; // We're done.
+ }
+
+ mYFilter.GetFilterOffsetAndLength(mCurrentOutLine, &filterOffset,
+ &filterLength);
+ }
+ }
+
+ mCurrentInLine += 1;
+
+ // If we're at the end of the part of the original image that has data, commit
+ // rows to shift us to the end.
+ if (mCurrentInLine == (mFrameRect.Y() + mFrameRect.Height())) {
+ SkipToRow(mOriginalSize.height - 1);
+ }
+}
+
+bool Downscaler::HasInvalidation() const {
+ return mCurrentOutLine > mPrevInvalidatedLine;
+}
+
+DownscalerInvalidRect Downscaler::TakeInvalidRect() {
+ if (MOZ_UNLIKELY(!HasInvalidation())) {
+ return DownscalerInvalidRect();
+ }
+
+ DownscalerInvalidRect invalidRect;
+
+ // Compute the target size invalid rect.
+ if (mFlipVertically) {
+ // We need to flip it. This will implicitly flip the original size invalid
+ // rect, since we compute it by scaling this rect.
+ invalidRect.mTargetSizeRect =
+ IntRect(0, mTargetSize.height - mCurrentOutLine, mTargetSize.width,
+ mCurrentOutLine - mPrevInvalidatedLine);
+ } else {
+ invalidRect.mTargetSizeRect =
+ IntRect(0, mPrevInvalidatedLine, mTargetSize.width,
+ mCurrentOutLine - mPrevInvalidatedLine);
+ }
+
+ mPrevInvalidatedLine = mCurrentOutLine;
+
+ // Compute the original size invalid rect.
+ invalidRect.mOriginalSizeRect = invalidRect.mTargetSizeRect;
+ invalidRect.mOriginalSizeRect.ScaleRoundOut(mScale.xScale, mScale.yScale);
+
+ return invalidRect;
+}
+
+void Downscaler::DownscaleInputLine() {
+ MOZ_ASSERT(mOutputBuffer);
+ MOZ_ASSERT(mCurrentOutLine < mTargetSize.height,
+ "Writing past end of output");
+
+ int32_t filterOffset = 0;
+ int32_t filterLength = 0;
+ mYFilter.GetFilterOffsetAndLength(mCurrentOutLine, &filterOffset,
+ &filterLength);
+
+ int32_t currentOutLine = mFlipVertically
+ ? mTargetSize.height - (mCurrentOutLine + 1)
+ : mCurrentOutLine;
+ MOZ_ASSERT(currentOutLine >= 0);
+
+ uint8_t* outputLine =
+ &mOutputBuffer[currentOutLine * mTargetSize.width * sizeof(uint32_t)];
+ mYFilter.ConvolveVertically(mWindow.get(), outputLine, mCurrentOutLine,
+ mXFilter.NumValues(), mHasAlpha);
+
+ mCurrentOutLine += 1;
+
+ if (mCurrentOutLine == mTargetSize.height) {
+ // We're done.
+ return;
+ }
+
+ int32_t newFilterOffset = 0;
+ int32_t newFilterLength = 0;
+ mYFilter.GetFilterOffsetAndLength(mCurrentOutLine, &newFilterOffset,
+ &newFilterLength);
+
+ int diff = newFilterOffset - filterOffset;
+ MOZ_ASSERT(diff >= 0, "Moving backwards in the filter?");
+
+ // Shift the buffer. We're just moving pointers here, so this is cheap.
+ mLinesInBuffer -= diff;
+ mLinesInBuffer = std::min(std::max(mLinesInBuffer, 0), mWindowCapacity);
+
+ // If we already have enough rows to satisfy the filter, there is no need
+ // to swap as we won't be writing more before the next convolution.
+ if (filterLength > mLinesInBuffer) {
+ for (int32_t i = 0; i < mLinesInBuffer; ++i) {
+ swap(mWindow[i], mWindow[filterLength - mLinesInBuffer + i]);
+ }
+ }
+}
+
+} // namespace image
+} // namespace mozilla