386 lines
13 KiB
C++
386 lines
13 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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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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/**
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* DownscalingSurfaceFilter is a SurfaceFilter implementation for use with
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* SurfacePipe which performs Lanczos downscaling.
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*
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* It's in this header file, separated from the other SurfaceFilters, because
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* some preprocessor magic is necessary to ensure that there aren't compilation
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* issues on platforms where Skia is unavailable.
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*/
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#ifndef mozilla_image_DownscalingFilter_h
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#define mozilla_image_DownscalingFilter_h
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#include <algorithm>
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#include <ctime>
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#include <stdint.h>
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#include "mozilla/Maybe.h"
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#include "mozilla/SSE.h"
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#include "mozilla/mips.h"
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#include "mozilla/UniquePtr.h"
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#include "mozilla/gfx/2D.h"
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#include "gfxPrefs.h"
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#ifdef MOZ_ENABLE_SKIA
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#include "convolver.h"
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#include "image_operations.h"
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#include "skia/include/core/SkTypes.h"
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#endif
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#include "SurfacePipe.h"
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namespace mozilla {
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namespace image {
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//////////////////////////////////////////////////////////////////////////////
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// DownscalingFilter
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//////////////////////////////////////////////////////////////////////////////
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template <typename Next> class DownscalingFilter;
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/**
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* A configuration struct for DownscalingConfig.
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*/
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struct DownscalingConfig
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{
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template <typename Next> using Filter = DownscalingFilter<Next>;
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gfx::IntSize mInputSize; /// The size of the input image. We'll downscale
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/// from this size to the input size of the next
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/// SurfaceFilter in the chain.
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gfx::SurfaceFormat mFormat; /// The pixel format - BGRA or BGRX. (BGRX has
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/// slightly better performance.)
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};
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#ifndef MOZ_ENABLE_SKIA
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/**
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* DownscalingFilter requires Skia. This is a fallback implementation for
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* non-Skia builds that fails when Configure() is called (which will prevent
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* SurfacePipeFactory from returning an instance of it) and crashes if a caller
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* manually constructs an instance and attempts to actually use it. Callers
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* should avoid this by ensuring that they do not request downscaling in
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* non-Skia builds.
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*/
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template <typename Next>
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class DownscalingFilter final : public SurfaceFilter
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{
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public:
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Maybe<SurfaceInvalidRect> TakeInvalidRect() override { return Nothing(); }
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template <typename... Rest>
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nsresult Configure(const DownscalingConfig& aConfig, const Rest&... aRest)
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{
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return NS_ERROR_FAILURE;
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}
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protected:
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uint8_t* DoResetToFirstRow() override { MOZ_CRASH(); return nullptr; }
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uint8_t* DoAdvanceRow() override { MOZ_CRASH(); return nullptr; }
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};
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#else
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/**
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* DownscalingFilter performs Lanczos downscaling, taking image input data at one size
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* and outputting it rescaled to a different size.
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*
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* The 'Next' template parameter specifies the next filter in the chain.
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*/
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template <typename Next>
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class DownscalingFilter final : public SurfaceFilter
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{
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public:
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DownscalingFilter()
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: mXFilter(MakeUnique<skia::ConvolutionFilter1D>())
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, mYFilter(MakeUnique<skia::ConvolutionFilter1D>())
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, mWindowCapacity(0)
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, mRowsInWindow(0)
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, mInputRow(0)
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, mOutputRow(0)
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, mHasAlpha(true)
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{
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MOZ_ASSERT(gfxPrefs::ImageDownscaleDuringDecodeEnabled(),
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"Downscaling even though downscale-during-decode is disabled?");
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}
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~DownscalingFilter()
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{
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ReleaseWindow();
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}
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template <typename... Rest>
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nsresult Configure(const DownscalingConfig& aConfig, const Rest&... aRest)
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{
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nsresult rv = mNext.Configure(aRest...);
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if (NS_FAILED(rv)) {
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return rv;
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}
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if (mNext.IsValidPalettedPipe()) {
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NS_WARNING("Created a downscaler for a paletted surface?");
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return NS_ERROR_INVALID_ARG;
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}
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if (mNext.InputSize() == aConfig.mInputSize) {
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NS_WARNING("Created a downscaler, but not downscaling?");
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return NS_ERROR_INVALID_ARG;
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}
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if (mNext.InputSize().width > aConfig.mInputSize.width) {
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NS_WARNING("Created a downscaler, but width is larger");
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return NS_ERROR_INVALID_ARG;
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}
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if (mNext.InputSize().height > aConfig.mInputSize.height) {
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NS_WARNING("Created a downscaler, but height is larger");
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return NS_ERROR_INVALID_ARG;
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}
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if (aConfig.mInputSize.width <= 0 || aConfig.mInputSize.height <= 0) {
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NS_WARNING("Invalid input size for DownscalingFilter");
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return NS_ERROR_INVALID_ARG;
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}
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mInputSize = aConfig.mInputSize;
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gfx::IntSize outputSize = mNext.InputSize();
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mScale = gfxSize(double(mInputSize.width) / outputSize.width,
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double(mInputSize.height) / outputSize.height);
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mHasAlpha = aConfig.mFormat == gfx::SurfaceFormat::B8G8R8A8;
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ReleaseWindow();
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auto resizeMethod = skia::ImageOperations::RESIZE_LANCZOS3;
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skia::resize::ComputeFilters(resizeMethod,
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mInputSize.width, outputSize.width,
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0, outputSize.width,
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mXFilter.get());
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skia::resize::ComputeFilters(resizeMethod,
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mInputSize.height, outputSize.height,
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0, outputSize.height,
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mYFilter.get());
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// Allocate the buffer, which contains scanlines of the input image.
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mRowBuffer.reset(new (fallible)
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uint8_t[PaddedWidthInBytes(mInputSize.width)]);
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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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// Clear the buffer to avoid writing uninitialized memory to the output.
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memset(mRowBuffer.get(), 0, PaddedWidthInBytes(mInputSize.width));
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// Allocate the window, which contains horizontally downscaled scanlines. (We
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// can store scanlines which are already downscaled because our downscaling
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// filter is separable.)
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mWindowCapacity = mYFilter->max_filter();
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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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// Allocate the "window" of recent rows that we keep in memory as input for
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// the downscaling code. We intentionally iterate through the entire array
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// even if an allocation fails, to ensure that all the pointers in it are
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// either valid or nullptr. That in turn ensures that ReleaseWindow() can
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// clean up correctly.
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bool anyAllocationFailed = false;
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const uint32_t windowRowSizeInBytes = PaddedWidthInBytes(outputSize.width);
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for (int32_t i = 0; i < mWindowCapacity; ++i) {
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mWindow[i] = new (fallible) uint8_t[windowRowSizeInBytes];
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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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return NS_ERROR_OUT_OF_MEMORY;
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}
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ConfigureFilter(mInputSize, sizeof(uint32_t));
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return NS_OK;
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}
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Maybe<SurfaceInvalidRect> TakeInvalidRect() override
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{
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Maybe<SurfaceInvalidRect> invalidRect = mNext.TakeInvalidRect();
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if (invalidRect) {
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// Compute the input space invalid rect by scaling.
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invalidRect->mInputSpaceRect.ScaleRoundOut(mScale.width, mScale.height);
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}
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return invalidRect;
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}
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protected:
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uint8_t* DoResetToFirstRow() override
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{
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mNext.ResetToFirstRow();
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mInputRow = 0;
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mOutputRow = 0;
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mRowsInWindow = 0;
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return GetRowPointer();
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}
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uint8_t* DoAdvanceRow() override
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{
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if (mInputRow >= mInputSize.height) {
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NS_WARNING("Advancing DownscalingFilter past the end of the input");
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return nullptr;
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}
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if (mOutputRow >= mNext.InputSize().height) {
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NS_WARNING("Advancing DownscalingFilter past the end of the output");
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return nullptr;
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}
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int32_t filterOffset = 0;
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int32_t filterLength = 0;
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GetFilterOffsetAndLength(mYFilter, mOutputRow,
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&filterOffset, &filterLength);
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int32_t inputRowToRead = filterOffset + mRowsInWindow;
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MOZ_ASSERT(mInputRow <= inputRowToRead, "Reading past end of input");
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if (mInputRow == inputRowToRead) {
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MOZ_RELEASE_ASSERT(mRowsInWindow < mWindowCapacity, "Need more rows than capacity!");
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skia::ConvolveHorizontally(mRowBuffer.get(), *mXFilter,
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mWindow[mRowsInWindow++], mHasAlpha,
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supports_sse2() || supports_mmi());
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}
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MOZ_ASSERT(mOutputRow < mNext.InputSize().height,
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"Writing past end of output");
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while (mRowsInWindow >= filterLength) {
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DownscaleInputRow();
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if (mOutputRow == mNext.InputSize().height) {
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break; // We're done.
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}
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GetFilterOffsetAndLength(mYFilter, mOutputRow,
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&filterOffset, &filterLength);
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}
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mInputRow++;
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return mInputRow < mInputSize.height ? GetRowPointer()
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: nullptr;
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}
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private:
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uint8_t* GetRowPointer() const { return mRowBuffer.get(); }
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static uint32_t PaddedWidthInBytes(uint32_t aLogicalWidth)
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{
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// Convert from width in BGRA/BGRX pixels to width in bytes, padding by 15
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// to handle overreads by the SIMD code inside Skia.
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return aLogicalWidth * sizeof(uint32_t) + 15;
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}
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static void
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GetFilterOffsetAndLength(UniquePtr<skia::ConvolutionFilter1D>& aFilter,
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int32_t aOutputImagePosition,
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int32_t* aFilterOffsetOut,
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int32_t* aFilterLengthOut)
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{
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MOZ_ASSERT(aOutputImagePosition < aFilter->num_values());
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aFilter->FilterForValue(aOutputImagePosition,
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aFilterOffsetOut,
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aFilterLengthOut);
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}
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void DownscaleInputRow()
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{
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typedef skia::ConvolutionFilter1D::Fixed FilterValue;
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MOZ_ASSERT(mOutputRow < mNext.InputSize().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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MOZ_ASSERT(mOutputRow < mYFilter->num_values());
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auto filterValues =
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mYFilter->FilterForValue(mOutputRow, &filterOffset, &filterLength);
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mNext.template WriteUnsafeComputedRow<uint32_t>([&](uint32_t* aRow,
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uint32_t aLength) {
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skia::ConvolveVertically(static_cast<const FilterValue*>(filterValues),
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filterLength, mWindow.get(), mXFilter->num_values(),
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reinterpret_cast<uint8_t*>(aRow), mHasAlpha,
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supports_sse2() || supports_mmi());
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});
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mOutputRow++;
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if (mOutputRow == mNext.InputSize().height) {
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return; // We're done.
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}
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int32_t newFilterOffset = 0;
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int32_t newFilterLength = 0;
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GetFilterOffsetAndLength(mYFilter, mOutputRow,
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&newFilterOffset, &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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mRowsInWindow -= diff;
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mRowsInWindow = std::min(std::max(mRowsInWindow, 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 > mRowsInWindow) {
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for (int32_t i = 0; i < mRowsInWindow; ++i) {
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std::swap(mWindow[i], mWindow[filterLength - mRowsInWindow + i]);
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}
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}
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}
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void ReleaseWindow()
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{
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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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Next mNext; /// The next SurfaceFilter in the chain.
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gfx::IntSize mInputSize; /// The size of the input image.
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gfxSize mScale; /// The scale factors in each dimension.
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/// Computed from @mInputSize and
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/// the next filter's input size.
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UniquePtr<uint8_t[]> mRowBuffer; /// The buffer into which input is written.
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UniquePtr<uint8_t*[]> mWindow; /// The last few rows which were written.
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UniquePtr<skia::ConvolutionFilter1D> mXFilter; /// The Lanczos filter in X.
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UniquePtr<skia::ConvolutionFilter1D> mYFilter; /// The Lanczos filter in Y.
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int32_t mWindowCapacity; /// How many rows the window contains.
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int32_t mRowsInWindow; /// How many rows we've buffered in the window.
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int32_t mInputRow; /// The current row we're reading. (0-indexed)
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int32_t mOutputRow; /// The current row we're writing. (0-indexed)
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bool mHasAlpha; /// If true, the image has transparency.
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};
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#endif
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} // namespace image
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} // namespace mozilla
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#endif // mozilla_image_DownscalingFilter_h
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