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302 lines
10 KiB
C++
302 lines
10 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "Downscaler.h"
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#include <algorithm>
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#include <ctime>
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#include "mozilla/gfx/2D.h"
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using std::swap;
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namespace mozilla {
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using gfx::IntRect;
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namespace image {
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Downscaler::Downscaler(const nsIntSize& aTargetSize)
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: mTargetSize(aTargetSize),
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mOutputBuffer(nullptr),
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mWindowCapacity(0),
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mLinesInBuffer(0),
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mPrevInvalidatedLine(0),
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mCurrentOutLine(0),
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mCurrentInLine(0),
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mHasAlpha(true),
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mFlipVertically(false) {
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MOZ_ASSERT(mTargetSize.width > 0 && mTargetSize.height > 0,
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"Invalid target size");
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}
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Downscaler::~Downscaler() { ReleaseWindow(); }
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void Downscaler::ReleaseWindow() {
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if (!mWindow) {
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return;
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}
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for (int32_t i = 0; i < mWindowCapacity; ++i) {
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delete[] mWindow[i];
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}
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mWindow = nullptr;
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mWindowCapacity = 0;
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}
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nsresult Downscaler::BeginFrame(const nsIntSize& aOriginalSize,
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const Maybe<nsIntRect>& aFrameRect,
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uint8_t* aOutputBuffer, bool aHasAlpha,
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bool aFlipVertically /* = false */) {
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MOZ_ASSERT(aOutputBuffer);
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MOZ_ASSERT(mTargetSize != aOriginalSize,
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"Created a downscaler, but not downscaling?");
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MOZ_ASSERT(mTargetSize.width <= aOriginalSize.width,
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"Created a downscaler, but width is larger");
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MOZ_ASSERT(mTargetSize.height <= aOriginalSize.height,
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"Created a downscaler, but height is larger");
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MOZ_ASSERT(aOriginalSize.width > 0 && aOriginalSize.height > 0,
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"Invalid original size");
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// Only downscale from reasonable sizes to avoid using too much memory/cpu
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// downscaling and decoding. 1 << 20 == 1,048,576 seems a reasonable limit.
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if (aOriginalSize.width > (1 << 20) || aOriginalSize.height > (1 << 20)) {
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NS_WARNING("Trying to downscale image frame that is too large");
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return NS_ERROR_INVALID_ARG;
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}
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mFrameRect = aFrameRect.valueOr(nsIntRect(nsIntPoint(), aOriginalSize));
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MOZ_ASSERT(mFrameRect.X() >= 0 && mFrameRect.Y() >= 0 &&
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mFrameRect.Width() >= 0 && mFrameRect.Height() >= 0,
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"Frame rect must have non-negative components");
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MOZ_ASSERT(nsIntRect(0, 0, aOriginalSize.width, aOriginalSize.height)
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.Contains(mFrameRect),
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"Frame rect must fit inside image");
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MOZ_ASSERT_IF(!nsIntRect(0, 0, aOriginalSize.width, aOriginalSize.height)
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.IsEqualEdges(mFrameRect),
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aHasAlpha);
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mOriginalSize = aOriginalSize;
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mScale = gfx::MatrixScalesDouble(
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double(mOriginalSize.width) / mTargetSize.width,
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double(mOriginalSize.height) / mTargetSize.height);
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mOutputBuffer = aOutputBuffer;
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mHasAlpha = aHasAlpha;
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mFlipVertically = aFlipVertically;
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ReleaseWindow();
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auto resizeMethod = gfx::ConvolutionFilter::ResizeMethod::LANCZOS3;
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if (!mXFilter.ComputeResizeFilter(resizeMethod, mOriginalSize.width,
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mTargetSize.width) ||
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!mYFilter.ComputeResizeFilter(resizeMethod, mOriginalSize.height,
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mTargetSize.height)) {
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NS_WARNING("Failed to compute filters for image downscaling");
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return NS_ERROR_OUT_OF_MEMORY;
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}
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// Allocate the buffer, which contains scanlines of the original image.
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// pad to handle overreads by the simd code
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size_t bufferLen = gfx::ConvolutionFilter::PadBytesForSIMD(
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mOriginalSize.width * sizeof(uint32_t));
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mRowBuffer.reset(new (fallible) uint8_t[bufferLen]);
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if (MOZ_UNLIKELY(!mRowBuffer)) {
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return NS_ERROR_OUT_OF_MEMORY;
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}
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// Zero buffer to keep valgrind happy.
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memset(mRowBuffer.get(), 0, bufferLen);
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// Allocate the window, which contains horizontally downscaled scanlines. (We
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// can store scanlines which are already downscale because our downscaling
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// filter is separable.)
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mWindowCapacity = mYFilter.MaxFilter();
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mWindow.reset(new (fallible) uint8_t*[mWindowCapacity]);
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if (MOZ_UNLIKELY(!mWindow)) {
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return NS_ERROR_OUT_OF_MEMORY;
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}
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bool anyAllocationFailed = false;
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// pad to handle overreads by the simd code
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const size_t rowSize = gfx::ConvolutionFilter::PadBytesForSIMD(
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mTargetSize.width * sizeof(uint32_t));
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for (int32_t i = 0; i < mWindowCapacity; ++i) {
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mWindow[i] = new (fallible) uint8_t[rowSize];
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anyAllocationFailed = anyAllocationFailed || mWindow[i] == nullptr;
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}
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if (MOZ_UNLIKELY(anyAllocationFailed)) {
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// We intentionally iterate through the entire array even if an allocation
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// fails, to ensure that all the pointers in it are either valid or nullptr.
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// That in turn ensures that ReleaseWindow() can clean up correctly.
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return NS_ERROR_OUT_OF_MEMORY;
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}
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ResetForNextProgressivePass();
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return NS_OK;
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}
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void Downscaler::SkipToRow(int32_t aRow) {
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if (mCurrentInLine < aRow) {
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ClearRow();
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do {
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CommitRow();
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} while (mCurrentInLine < aRow);
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}
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}
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void Downscaler::ResetForNextProgressivePass() {
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mPrevInvalidatedLine = 0;
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mCurrentOutLine = 0;
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mCurrentInLine = 0;
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mLinesInBuffer = 0;
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if (mFrameRect.IsEmpty()) {
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// Our frame rect is zero size; commit rows until the end of the image.
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SkipToRow(mOriginalSize.height - 1);
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} else {
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// If we have a vertical offset, commit rows to shift us past it.
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SkipToRow(mFrameRect.Y());
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}
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}
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void Downscaler::ClearRestOfRow(uint32_t aStartingAtCol) {
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MOZ_ASSERT(int64_t(aStartingAtCol) <= int64_t(mOriginalSize.width));
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uint32_t bytesToClear =
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(mOriginalSize.width - aStartingAtCol) * sizeof(uint32_t);
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memset(mRowBuffer.get() + (aStartingAtCol * sizeof(uint32_t)), 0,
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bytesToClear);
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}
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void Downscaler::CommitRow() {
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MOZ_ASSERT(mOutputBuffer, "Should have a current frame");
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MOZ_ASSERT(mCurrentInLine < mOriginalSize.height, "Past end of input");
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if (mCurrentOutLine < mTargetSize.height) {
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int32_t filterOffset = 0;
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int32_t filterLength = 0;
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mYFilter.GetFilterOffsetAndLength(mCurrentOutLine, &filterOffset,
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&filterLength);
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int32_t inLineToRead = filterOffset + mLinesInBuffer;
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MOZ_ASSERT(mCurrentInLine <= inLineToRead, "Reading past end of input");
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if (mCurrentInLine == inLineToRead) {
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MOZ_RELEASE_ASSERT(mLinesInBuffer < mWindowCapacity,
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"Need more rows than capacity!");
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mXFilter.ConvolveHorizontally(mRowBuffer.get(), mWindow[mLinesInBuffer++],
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mHasAlpha);
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}
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MOZ_ASSERT(mCurrentOutLine < mTargetSize.height,
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"Writing past end of output");
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while (mLinesInBuffer >= filterLength) {
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DownscaleInputLine();
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if (mCurrentOutLine == mTargetSize.height) {
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break; // We're done.
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}
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mYFilter.GetFilterOffsetAndLength(mCurrentOutLine, &filterOffset,
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&filterLength);
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}
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}
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mCurrentInLine += 1;
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// If we're at the end of the part of the original image that has data, commit
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// rows to shift us to the end.
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if (mCurrentInLine == (mFrameRect.Y() + mFrameRect.Height())) {
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SkipToRow(mOriginalSize.height - 1);
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}
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}
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bool Downscaler::HasInvalidation() const {
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return mCurrentOutLine > mPrevInvalidatedLine;
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}
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DownscalerInvalidRect Downscaler::TakeInvalidRect() {
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if (MOZ_UNLIKELY(!HasInvalidation())) {
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return DownscalerInvalidRect();
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}
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DownscalerInvalidRect invalidRect;
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// Compute the target size invalid rect.
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if (mFlipVertically) {
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// We need to flip it. This will implicitly flip the original size invalid
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// rect, since we compute it by scaling this rect.
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invalidRect.mTargetSizeRect =
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IntRect(0, mTargetSize.height - mCurrentOutLine, mTargetSize.width,
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mCurrentOutLine - mPrevInvalidatedLine);
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} else {
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invalidRect.mTargetSizeRect =
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IntRect(0, mPrevInvalidatedLine, mTargetSize.width,
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mCurrentOutLine - mPrevInvalidatedLine);
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}
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mPrevInvalidatedLine = mCurrentOutLine;
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// Compute the original size invalid rect.
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invalidRect.mOriginalSizeRect = invalidRect.mTargetSizeRect;
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invalidRect.mOriginalSizeRect.ScaleRoundOut(mScale.xScale, mScale.yScale);
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return invalidRect;
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}
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void Downscaler::DownscaleInputLine() {
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MOZ_ASSERT(mOutputBuffer);
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MOZ_ASSERT(mCurrentOutLine < mTargetSize.height,
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"Writing past end of output");
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int32_t filterOffset = 0;
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int32_t filterLength = 0;
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mYFilter.GetFilterOffsetAndLength(mCurrentOutLine, &filterOffset,
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&filterLength);
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int32_t currentOutLine = mFlipVertically
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? mTargetSize.height - (mCurrentOutLine + 1)
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: mCurrentOutLine;
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MOZ_ASSERT(currentOutLine >= 0);
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uint8_t* outputLine =
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&mOutputBuffer[currentOutLine * mTargetSize.width * sizeof(uint32_t)];
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mYFilter.ConvolveVertically(mWindow.get(), outputLine, mCurrentOutLine,
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mXFilter.NumValues(), mHasAlpha);
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mCurrentOutLine += 1;
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if (mCurrentOutLine == mTargetSize.height) {
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// We're done.
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return;
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}
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int32_t newFilterOffset = 0;
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int32_t newFilterLength = 0;
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mYFilter.GetFilterOffsetAndLength(mCurrentOutLine, &newFilterOffset,
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&newFilterLength);
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int diff = newFilterOffset - filterOffset;
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MOZ_ASSERT(diff >= 0, "Moving backwards in the filter?");
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// Shift the buffer. We're just moving pointers here, so this is cheap.
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mLinesInBuffer -= diff;
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mLinesInBuffer = std::min(std::max(mLinesInBuffer, 0), mWindowCapacity);
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// If we already have enough rows to satisfy the filter, there is no need
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// to swap as we won't be writing more before the next convolution.
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if (filterLength > mLinesInBuffer) {
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for (int32_t i = 0; i < mLinesInBuffer; ++i) {
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swap(mWindow[i], mWindow[filterLength - mLinesInBuffer + i]);
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}
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}
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}
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} // namespace image
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} // namespace mozilla
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