/* -*- 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