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authorMatt A. Tobin <mattatobin@localhost.localdomain>2018-02-02 04:16:08 -0500
committerMatt A. Tobin <mattatobin@localhost.localdomain>2018-02-02 04:16:08 -0500
commit5f8de423f190bbb79a62f804151bc24824fa32d8 (patch)
tree10027f336435511475e392454359edea8e25895d /image/DownscalingFilter.h
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Add m-esr52 at 52.6.0
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+/* -*- 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/. */
+
+/**
+ * DownscalingSurfaceFilter is a SurfaceFilter implementation for use with
+ * SurfacePipe which performs Lanczos downscaling.
+ *
+ * It's in this header file, separated from the other SurfaceFilters, because
+ * some preprocessor magic is necessary to ensure that there aren't compilation
+ * issues on platforms where Skia is unavailable.
+ */
+
+#ifndef mozilla_image_DownscalingFilter_h
+#define mozilla_image_DownscalingFilter_h
+
+#include <algorithm>
+#include <ctime>
+#include <stdint.h>
+
+#include "mozilla/Maybe.h"
+#include "mozilla/SSE.h"
+#include "mozilla/mips.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/gfx/2D.h"
+#include "gfxPrefs.h"
+
+#ifdef MOZ_ENABLE_SKIA
+#include "convolver.h"
+#include "image_operations.h"
+#include "skia/include/core/SkTypes.h"
+#endif
+
+#include "SurfacePipe.h"
+
+namespace mozilla {
+namespace image {
+
+//////////////////////////////////////////////////////////////////////////////
+// DownscalingFilter
+//////////////////////////////////////////////////////////////////////////////
+
+template <typename Next> class DownscalingFilter;
+
+/**
+ * A configuration struct for DownscalingConfig.
+ */
+struct DownscalingConfig
+{
+ template <typename Next> using Filter = DownscalingFilter<Next>;
+ gfx::IntSize mInputSize; /// The size of the input image. We'll downscale
+ /// from this size to the input size of the next
+ /// SurfaceFilter in the chain.
+ gfx::SurfaceFormat mFormat; /// The pixel format - BGRA or BGRX. (BGRX has
+ /// slightly better performance.)
+};
+
+#ifndef MOZ_ENABLE_SKIA
+
+/**
+ * DownscalingFilter requires Skia. This is a fallback implementation for
+ * non-Skia builds that fails when Configure() is called (which will prevent
+ * SurfacePipeFactory from returning an instance of it) and crashes if a caller
+ * manually constructs an instance and attempts to actually use it. Callers
+ * should avoid this by ensuring that they do not request downscaling in
+ * non-Skia builds.
+ */
+template <typename Next>
+class DownscalingFilter final : public SurfaceFilter
+{
+public:
+ Maybe<SurfaceInvalidRect> TakeInvalidRect() override { return Nothing(); }
+
+ template <typename... Rest>
+ nsresult Configure(const DownscalingConfig& aConfig, Rest... aRest)
+ {
+ return NS_ERROR_FAILURE;
+ }
+
+protected:
+ uint8_t* DoResetToFirstRow() override { MOZ_CRASH(); return nullptr; }
+ uint8_t* DoAdvanceRow() override { MOZ_CRASH(); return nullptr; }
+};
+
+#else
+
+/**
+ * DownscalingFilter performs Lanczos downscaling, taking image input data at one size
+ * and outputting it rescaled to a different size.
+ *
+ * The 'Next' template parameter specifies the next filter in the chain.
+ */
+template <typename Next>
+class DownscalingFilter final : public SurfaceFilter
+{
+public:
+ DownscalingFilter()
+ : mXFilter(MakeUnique<skia::ConvolutionFilter1D>())
+ , mYFilter(MakeUnique<skia::ConvolutionFilter1D>())
+ , mWindowCapacity(0)
+ , mRowsInWindow(0)
+ , mInputRow(0)
+ , mOutputRow(0)
+ , mHasAlpha(true)
+ {
+ MOZ_ASSERT(gfxPrefs::ImageDownscaleDuringDecodeEnabled(),
+ "Downscaling even though downscale-during-decode is disabled?");
+ }
+
+ ~DownscalingFilter()
+ {
+ ReleaseWindow();
+ }
+
+ template <typename... Rest>
+ nsresult Configure(const DownscalingConfig& aConfig, Rest... aRest)
+ {
+ nsresult rv = mNext.Configure(aRest...);
+ if (NS_FAILED(rv)) {
+ return rv;
+ }
+
+ if (mNext.IsValidPalettedPipe()) {
+ NS_WARNING("Created a downscaler for a paletted surface?");
+ return NS_ERROR_INVALID_ARG;
+ }
+ if (mNext.InputSize() == aConfig.mInputSize) {
+ NS_WARNING("Created a downscaler, but not downscaling?");
+ return NS_ERROR_INVALID_ARG;
+ }
+ if (mNext.InputSize().width > aConfig.mInputSize.width) {
+ NS_WARNING("Created a downscaler, but width is larger");
+ return NS_ERROR_INVALID_ARG;
+ }
+ if (mNext.InputSize().height > aConfig.mInputSize.height) {
+ NS_WARNING("Created a downscaler, but height is larger");
+ return NS_ERROR_INVALID_ARG;
+ }
+ if (aConfig.mInputSize.width <= 0 || aConfig.mInputSize.height <= 0) {
+ NS_WARNING("Invalid input size for DownscalingFilter");
+ return NS_ERROR_INVALID_ARG;
+ }
+
+ mInputSize = aConfig.mInputSize;
+ gfx::IntSize outputSize = mNext.InputSize();
+ mScale = gfxSize(double(mInputSize.width) / outputSize.width,
+ double(mInputSize.height) / outputSize.height);
+ mHasAlpha = aConfig.mFormat == gfx::SurfaceFormat::B8G8R8A8;
+
+ ReleaseWindow();
+
+ auto resizeMethod = skia::ImageOperations::RESIZE_LANCZOS3;
+
+ skia::resize::ComputeFilters(resizeMethod,
+ mInputSize.width, outputSize.width,
+ 0, outputSize.width,
+ mXFilter.get());
+
+ skia::resize::ComputeFilters(resizeMethod,
+ mInputSize.height, outputSize.height,
+ 0, outputSize.height,
+ mYFilter.get());
+
+ // Allocate the buffer, which contains scanlines of the input image.
+ mRowBuffer.reset(new (fallible)
+ uint8_t[PaddedWidthInBytes(mInputSize.width)]);
+ if (MOZ_UNLIKELY(!mRowBuffer)) {
+ return NS_ERROR_OUT_OF_MEMORY;
+ }
+
+ // Clear the buffer to avoid writing uninitialized memory to the output.
+ memset(mRowBuffer.get(), 0, PaddedWidthInBytes(mInputSize.width));
+
+ // Allocate the window, which contains horizontally downscaled scanlines. (We
+ // can store scanlines which are already downscaled because our downscaling
+ // filter is separable.)
+ mWindowCapacity = mYFilter->max_filter();
+ mWindow.reset(new (fallible) uint8_t*[mWindowCapacity]);
+ if (MOZ_UNLIKELY(!mWindow)) {
+ return NS_ERROR_OUT_OF_MEMORY;
+ }
+
+ // Allocate the "window" of recent rows that we keep in memory as input for
+ // the downscaling code. 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.
+ bool anyAllocationFailed = false;
+ const uint32_t windowRowSizeInBytes = PaddedWidthInBytes(outputSize.width);
+ for (int32_t i = 0; i < mWindowCapacity; ++i) {
+ mWindow[i] = new (fallible) uint8_t[windowRowSizeInBytes];
+ anyAllocationFailed = anyAllocationFailed || mWindow[i] == nullptr;
+ }
+
+ if (MOZ_UNLIKELY(anyAllocationFailed)) {
+ return NS_ERROR_OUT_OF_MEMORY;
+ }
+
+ ConfigureFilter(mInputSize, sizeof(uint32_t));
+ return NS_OK;
+ }
+
+ Maybe<SurfaceInvalidRect> TakeInvalidRect() override
+ {
+ Maybe<SurfaceInvalidRect> invalidRect = mNext.TakeInvalidRect();
+
+ if (invalidRect) {
+ // Compute the input space invalid rect by scaling.
+ invalidRect->mInputSpaceRect.ScaleRoundOut(mScale.width, mScale.height);
+ }
+
+ return invalidRect;
+ }
+
+protected:
+ uint8_t* DoResetToFirstRow() override
+ {
+ mNext.ResetToFirstRow();
+
+ mInputRow = 0;
+ mOutputRow = 0;
+ mRowsInWindow = 0;
+
+ return GetRowPointer();
+ }
+
+ uint8_t* DoAdvanceRow() override
+ {
+ if (mInputRow >= mInputSize.height) {
+ NS_WARNING("Advancing DownscalingFilter past the end of the input");
+ return nullptr;
+ }
+
+ if (mOutputRow >= mNext.InputSize().height) {
+ NS_WARNING("Advancing DownscalingFilter past the end of the output");
+ return nullptr;
+ }
+
+ int32_t filterOffset = 0;
+ int32_t filterLength = 0;
+ GetFilterOffsetAndLength(mYFilter, mOutputRow,
+ &filterOffset, &filterLength);
+
+ int32_t inputRowToRead = filterOffset + mRowsInWindow;
+ MOZ_ASSERT(mInputRow <= inputRowToRead, "Reading past end of input");
+ if (mInputRow == inputRowToRead) {
+ skia::ConvolveHorizontally(mRowBuffer.get(), *mXFilter,
+ mWindow[mRowsInWindow++], mHasAlpha,
+ supports_sse2() || supports_mmi());
+ }
+
+ MOZ_ASSERT(mOutputRow < mNext.InputSize().height,
+ "Writing past end of output");
+
+ while (mRowsInWindow == filterLength) {
+ DownscaleInputRow();
+
+ if (mOutputRow == mNext.InputSize().height) {
+ break; // We're done.
+ }
+
+ GetFilterOffsetAndLength(mYFilter, mOutputRow,
+ &filterOffset, &filterLength);
+ }
+
+ mInputRow++;
+
+ return mInputRow < mInputSize.height ? GetRowPointer()
+ : nullptr;
+ }
+
+private:
+ uint8_t* GetRowPointer() const { return mRowBuffer.get(); }
+
+ static uint32_t PaddedWidthInBytes(uint32_t aLogicalWidth)
+ {
+ // Convert from width in BGRA/BGRX pixels to width in bytes, padding by 15
+ // to handle overreads by the SIMD code inside Skia.
+ return aLogicalWidth * sizeof(uint32_t) + 15;
+ }
+
+ static void
+ GetFilterOffsetAndLength(UniquePtr<skia::ConvolutionFilter1D>& aFilter,
+ int32_t aOutputImagePosition,
+ int32_t* aFilterOffsetOut,
+ int32_t* aFilterLengthOut)
+ {
+ MOZ_ASSERT(aOutputImagePosition < aFilter->num_values());
+ aFilter->FilterForValue(aOutputImagePosition,
+ aFilterOffsetOut,
+ aFilterLengthOut);
+ }
+
+ void DownscaleInputRow()
+ {
+ typedef skia::ConvolutionFilter1D::Fixed FilterValue;
+
+ MOZ_ASSERT(mOutputRow < mNext.InputSize().height,
+ "Writing past end of output");
+
+ int32_t filterOffset = 0;
+ int32_t filterLength = 0;
+ MOZ_ASSERT(mOutputRow < mYFilter->num_values());
+ auto filterValues =
+ mYFilter->FilterForValue(mOutputRow, &filterOffset, &filterLength);
+
+ mNext.template WriteUnsafeComputedRow<uint32_t>([&](uint32_t* aRow,
+ uint32_t aLength) {
+ skia::ConvolveVertically(static_cast<const FilterValue*>(filterValues),
+ filterLength, mWindow.get(), mXFilter->num_values(),
+ reinterpret_cast<uint8_t*>(aRow), mHasAlpha,
+ supports_sse2() || supports_mmi());
+ });
+
+ mOutputRow++;
+
+ if (mOutputRow == mNext.InputSize().height) {
+ return; // We're done.
+ }
+
+ int32_t newFilterOffset = 0;
+ int32_t newFilterLength = 0;
+ GetFilterOffsetAndLength(mYFilter, mOutputRow,
+ &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.
+ mRowsInWindow -= diff;
+ mRowsInWindow = std::max(mRowsInWindow, 0);
+ for (int32_t i = 0; i < mRowsInWindow; ++i) {
+ std::swap(mWindow[i], mWindow[filterLength - mRowsInWindow + i]);
+ }
+ }
+
+ void ReleaseWindow()
+ {
+ if (!mWindow) {
+ return;
+ }
+
+ for (int32_t i = 0; i < mWindowCapacity; ++i) {
+ delete[] mWindow[i];
+ }
+
+ mWindow = nullptr;
+ mWindowCapacity = 0;
+ }
+
+ Next mNext; /// The next SurfaceFilter in the chain.
+
+ gfx::IntSize mInputSize; /// The size of the input image.
+ gfxSize mScale; /// The scale factors in each dimension.
+ /// Computed from @mInputSize and
+ /// the next filter's input size.
+
+ UniquePtr<uint8_t[]> mRowBuffer; /// The buffer into which input is written.
+ UniquePtr<uint8_t*[]> mWindow; /// The last few rows which were written.
+
+ UniquePtr<skia::ConvolutionFilter1D> mXFilter; /// The Lanczos filter in X.
+ UniquePtr<skia::ConvolutionFilter1D> mYFilter; /// The Lanczos filter in Y.
+
+ int32_t mWindowCapacity; /// How many rows the window contains.
+
+ int32_t mRowsInWindow; /// How many rows we've buffered in the window.
+ int32_t mInputRow; /// The current row we're reading. (0-indexed)
+ int32_t mOutputRow; /// The current row we're writing. (0-indexed)
+
+ bool mHasAlpha; /// If true, the image has transparency.
+};
+
+#endif
+
+} // namespace image
+} // namespace mozilla
+
+#endif // mozilla_image_DownscalingFilter_h