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gecko-dev/image/SurfaceFilters.h

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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/. */
/**
* This header contains various SurfaceFilter implementations that apply
* transformations to image data, for usage with SurfacePipe.
*/
#ifndef mozilla_image_SurfaceFilters_h
#define mozilla_image_SurfaceFilters_h
#include <algorithm>
#include <stdint.h>
#include <string.h>
#include "mozilla/Likely.h"
#include "mozilla/Maybe.h"
#include "mozilla/UniquePtr.h"
#include "mozilla/gfx/2D.h"
#include "mozilla/gfx/Swizzle.h"
#include "skia/src/core/SkBlitRow.h"
#include "DownscalingFilter.h"
#include "SurfaceCache.h"
#include "SurfacePipe.h"
namespace mozilla {
namespace image {
//////////////////////////////////////////////////////////////////////////////
// SwizzleFilter
//////////////////////////////////////////////////////////////////////////////
template <typename Next>
class SwizzleFilter;
/**
* A configuration struct for SwizzleFilter.
*/
struct SwizzleConfig {
template <typename Next>
using Filter = SwizzleFilter<Next>;
gfx::SurfaceFormat mInFormat;
gfx::SurfaceFormat mOutFormat;
bool mPremultiplyAlpha;
};
/**
* SwizzleFilter performs premultiplication, swizzling and unpacking on
* rows written to it. It can use accelerated methods to perform these
* operations if supported on the platform.
*
* The 'Next' template parameter specifies the next filter in the chain.
*/
template <typename Next>
class SwizzleFilter final : public SurfaceFilter {
public:
SwizzleFilter() : mSwizzleFn(nullptr) {}
template <typename... Rest>
nsresult Configure(const SwizzleConfig& aConfig, const Rest&... aRest) {
nsresult rv = mNext.Configure(aRest...);
if (NS_FAILED(rv)) {
return rv;
}
if (aConfig.mPremultiplyAlpha) {
mSwizzleFn = gfx::PremultiplyRow(aConfig.mInFormat, aConfig.mOutFormat);
} else {
mSwizzleFn = gfx::SwizzleRow(aConfig.mInFormat, aConfig.mOutFormat);
}
if (!mSwizzleFn) {
return NS_ERROR_INVALID_ARG;
}
ConfigureFilter(mNext.InputSize(), sizeof(uint32_t));
return NS_OK;
}
Maybe<SurfaceInvalidRect> TakeInvalidRect() override {
return mNext.TakeInvalidRect();
}
protected:
uint8_t* DoResetToFirstRow() override { return mNext.ResetToFirstRow(); }
uint8_t* DoAdvanceRowFromBuffer(const uint8_t* aInputRow) override {
uint8_t* rowPtr = mNext.CurrentRowPointer();
if (!rowPtr) {
return nullptr; // We already got all the input rows we expect.
}
mSwizzleFn(aInputRow, rowPtr, mNext.InputSize().width);
return mNext.AdvanceRow();
}
uint8_t* DoAdvanceRow() override {
return DoAdvanceRowFromBuffer(mNext.CurrentRowPointer());
}
Next mNext; /// The next SurfaceFilter in the chain.
gfx::SwizzleRowFn mSwizzleFn;
};
//////////////////////////////////////////////////////////////////////////////
// ColorManagementFilter
//////////////////////////////////////////////////////////////////////////////
template <typename Next>
class ColorManagementFilter;
/**
* A configuration struct for ColorManagementFilter.
*/
struct ColorManagementConfig {
template <typename Next>
using Filter = ColorManagementFilter<Next>;
qcms_transform* mTransform;
};
/**
* ColorManagementFilter performs color transforms with qcms on rows written
* to it.
*
* The 'Next' template parameter specifies the next filter in the chain.
*/
template <typename Next>
class ColorManagementFilter final : public SurfaceFilter {
public:
ColorManagementFilter() : mTransform(nullptr) {}
template <typename... Rest>
nsresult Configure(const ColorManagementConfig& aConfig,
const Rest&... aRest) {
nsresult rv = mNext.Configure(aRest...);
if (NS_FAILED(rv)) {
return rv;
}
if (!aConfig.mTransform) {
return NS_ERROR_INVALID_ARG;
}
mTransform = aConfig.mTransform;
ConfigureFilter(mNext.InputSize(), sizeof(uint32_t));
return NS_OK;
}
Maybe<SurfaceInvalidRect> TakeInvalidRect() override {
return mNext.TakeInvalidRect();
}
protected:
uint8_t* DoResetToFirstRow() override { return mNext.ResetToFirstRow(); }
uint8_t* DoAdvanceRowFromBuffer(const uint8_t* aInputRow) override {
qcms_transform_data(mTransform, aInputRow, mNext.CurrentRowPointer(),
mNext.InputSize().width);
return mNext.AdvanceRow();
}
uint8_t* DoAdvanceRow() override {
return DoAdvanceRowFromBuffer(mNext.CurrentRowPointer());
}
Next mNext; /// The next SurfaceFilter in the chain.
qcms_transform* mTransform;
};
//////////////////////////////////////////////////////////////////////////////
// DeinterlacingFilter
//////////////////////////////////////////////////////////////////////////////
template <typename PixelType, typename Next>
class DeinterlacingFilter;
/**
* A configuration struct for DeinterlacingFilter.
*
* The 'PixelType' template parameter should be either uint32_t (for output to a
* SurfaceSink) or uint8_t (for output to a PalettedSurfaceSink).
*/
template <typename PixelType>
struct DeinterlacingConfig {
template <typename Next>
using Filter = DeinterlacingFilter<PixelType, Next>;
bool mProgressiveDisplay; /// If true, duplicate rows during deinterlacing
/// to make progressive display look better, at
/// the cost of some performance.
};
/**
* DeinterlacingFilter performs deinterlacing by reordering the rows that are
* written to it.
*
* The 'PixelType' template parameter should be either uint32_t (for output to a
* SurfaceSink) or uint8_t (for output to a PalettedSurfaceSink).
*
* The 'Next' template parameter specifies the next filter in the chain.
*/
template <typename PixelType, typename Next>
class DeinterlacingFilter final : public SurfaceFilter {
public:
DeinterlacingFilter()
: mInputRow(0), mOutputRow(0), mPass(0), mProgressiveDisplay(true) {}
template <typename... Rest>
nsresult Configure(const DeinterlacingConfig<PixelType>& aConfig,
const Rest&... aRest) {
nsresult rv = mNext.Configure(aRest...);
if (NS_FAILED(rv)) {
return rv;
}
gfx::IntSize outputSize = mNext.InputSize();
mProgressiveDisplay = aConfig.mProgressiveDisplay;
const CheckedUint32 bufferSize = CheckedUint32(outputSize.width) *
CheckedUint32(outputSize.height) *
CheckedUint32(sizeof(PixelType));
// Use the size of the SurfaceCache as a heuristic to avoid gigantic
// allocations. Even if DownscalingFilter allowed us to allocate space for
// the output image, the deinterlacing buffer may still be too big, and
// fallible allocation won't always save us in the presence of overcommit.
if (!bufferSize.isValid() || !SurfaceCache::CanHold(bufferSize.value())) {
return NS_ERROR_OUT_OF_MEMORY;
}
// Allocate the buffer, which contains deinterlaced scanlines of the image.
// The buffer is necessary so that we can output rows which have already
// been deinterlaced again on subsequent passes. Since a later stage in the
// pipeline may be transforming the rows it receives (for example, by
// downscaling them), the rows may no longer exist in their original form on
// the surface itself.
mBuffer.reset(new (fallible) uint8_t[bufferSize.value()]);
if (MOZ_UNLIKELY(!mBuffer)) {
return NS_ERROR_OUT_OF_MEMORY;
}
// Clear the buffer to avoid writing uninitialized memory to the output.
memset(mBuffer.get(), 0, bufferSize.value());
ConfigureFilter(outputSize, sizeof(PixelType));
return NS_OK;
}
Maybe<SurfaceInvalidRect> TakeInvalidRect() override {
return mNext.TakeInvalidRect();
}
protected:
uint8_t* DoResetToFirstRow() override {
mNext.ResetToFirstRow();
mPass = 0;
mInputRow = 0;
mOutputRow = InterlaceOffset(mPass);
return GetRowPointer(mOutputRow);
}
uint8_t* DoAdvanceRowFromBuffer(const uint8_t* aInputRow) override {
CopyInputRow(aInputRow);
return DoAdvanceRow();
}
uint8_t* DoAdvanceRow() override {
if (mPass >= 4) {
return nullptr; // We already finished all passes.
}
if (mInputRow >= InputSize().height) {
return nullptr; // We already got all the input rows we expect.
}
// Duplicate from the first Haeberli row to the remaining Haeberli rows
// within the buffer.
DuplicateRows(
HaeberliOutputStartRow(mPass, mProgressiveDisplay, mOutputRow),
HaeberliOutputUntilRow(mPass, mProgressiveDisplay, InputSize(),
mOutputRow));
// Write the current set of Haeberli rows (which contains the current row)
// to the next stage in the pipeline.
OutputRows(HaeberliOutputStartRow(mPass, mProgressiveDisplay, mOutputRow),
HaeberliOutputUntilRow(mPass, mProgressiveDisplay, InputSize(),
mOutputRow));
// Determine which output row the next input row corresponds to.
bool advancedPass = false;
uint32_t stride = InterlaceStride(mPass);
int32_t nextOutputRow = mOutputRow + stride;
while (nextOutputRow >= InputSize().height) {
// Copy any remaining rows from the buffer.
if (!advancedPass) {
OutputRows(HaeberliOutputUntilRow(mPass, mProgressiveDisplay,
InputSize(), mOutputRow),
InputSize().height);
}
// We finished the current pass; advance to the next one.
mPass++;
if (mPass >= 4) {
return nullptr; // Finished all passes.
}
// Tell the next pipeline stage that we're starting the next pass.
mNext.ResetToFirstRow();
// Update our state to reflect the pass change.
advancedPass = true;
stride = InterlaceStride(mPass);
nextOutputRow = InterlaceOffset(mPass);
}
MOZ_ASSERT(nextOutputRow >= 0);
MOZ_ASSERT(nextOutputRow < InputSize().height);
MOZ_ASSERT(
HaeberliOutputStartRow(mPass, mProgressiveDisplay, nextOutputRow) >= 0);
MOZ_ASSERT(HaeberliOutputStartRow(mPass, mProgressiveDisplay,
nextOutputRow) < InputSize().height);
MOZ_ASSERT(HaeberliOutputStartRow(mPass, mProgressiveDisplay,
nextOutputRow) <= nextOutputRow);
MOZ_ASSERT(HaeberliOutputUntilRow(mPass, mProgressiveDisplay, InputSize(),
nextOutputRow) >= 0);
MOZ_ASSERT(HaeberliOutputUntilRow(mPass, mProgressiveDisplay, InputSize(),
nextOutputRow) <= InputSize().height);
MOZ_ASSERT(HaeberliOutputUntilRow(mPass, mProgressiveDisplay, InputSize(),
nextOutputRow) > nextOutputRow);
int32_t nextHaeberliOutputRow =
HaeberliOutputStartRow(mPass, mProgressiveDisplay, nextOutputRow);
// Copy rows from the buffer until we reach the desired output row.
if (advancedPass) {
OutputRows(0, nextHaeberliOutputRow);
} else {
OutputRows(HaeberliOutputUntilRow(mPass, mProgressiveDisplay, InputSize(),
mOutputRow),
nextHaeberliOutputRow);
}
// Update our position within the buffer.
mInputRow++;
mOutputRow = nextOutputRow;
// We'll actually write to the first Haeberli output row, then copy it until
// we reach the last Haeberli output row. The assertions above make sure
// this always includes mOutputRow.
return GetRowPointer(nextHaeberliOutputRow);
}
private:
static uint32_t InterlaceOffset(uint32_t aPass) {
MOZ_ASSERT(aPass < 4, "Invalid pass");
static const uint8_t offset[] = {0, 4, 2, 1};
return offset[aPass];
}
static uint32_t InterlaceStride(uint32_t aPass) {
MOZ_ASSERT(aPass < 4, "Invalid pass");
static const uint8_t stride[] = {8, 8, 4, 2};
return stride[aPass];
}
static int32_t HaeberliOutputStartRow(uint32_t aPass,
bool aProgressiveDisplay,
int32_t aOutputRow) {
MOZ_ASSERT(aPass < 4, "Invalid pass");
static const uint8_t firstRowOffset[] = {3, 1, 0, 0};
if (aProgressiveDisplay) {
return std::max(aOutputRow - firstRowOffset[aPass], 0);
} else {
return aOutputRow;
}
}
static int32_t HaeberliOutputUntilRow(uint32_t aPass,
bool aProgressiveDisplay,
const gfx::IntSize& aInputSize,
int32_t aOutputRow) {
MOZ_ASSERT(aPass < 4, "Invalid pass");
static const uint8_t lastRowOffset[] = {4, 2, 1, 0};
if (aProgressiveDisplay) {
return std::min(aOutputRow + lastRowOffset[aPass],
aInputSize.height - 1) +
1; // Add one because this is an open interval on the right.
} else {
return aOutputRow + 1;
}
}
void DuplicateRows(int32_t aStart, int32_t aUntil) {
MOZ_ASSERT(aStart >= 0);
MOZ_ASSERT(aUntil >= 0);
if (aUntil <= aStart || aStart >= InputSize().height) {
return;
}
// The source row is the first row in the range.
const uint8_t* sourceRowPointer = GetRowPointer(aStart);
// We duplicate the source row into each subsequent row in the range.
for (int32_t destRow = aStart + 1; destRow < aUntil; ++destRow) {
uint8_t* destRowPointer = GetRowPointer(destRow);
memcpy(destRowPointer, sourceRowPointer,
InputSize().width * sizeof(PixelType));
}
}
void OutputRows(int32_t aStart, int32_t aUntil) {
MOZ_ASSERT(aStart >= 0);
MOZ_ASSERT(aUntil >= 0);
if (aUntil <= aStart || aStart >= InputSize().height) {
return;
}
for (int32_t rowToOutput = aStart; rowToOutput < aUntil; ++rowToOutput) {
mNext.WriteBuffer(
reinterpret_cast<PixelType*>(GetRowPointer(rowToOutput)));
}
}
uint8_t* GetRowPointer(uint32_t aRow) const {
#ifdef DEBUG
uint64_t offset64 = uint64_t(aRow) * uint64_t(InputSize().width) *
uint64_t(sizeof(PixelType));
uint64_t bufferLength = uint64_t(InputSize().width) *
uint64_t(InputSize().height) *
uint64_t(sizeof(PixelType));
MOZ_ASSERT(offset64 < bufferLength, "Start of row is outside of image");
MOZ_ASSERT(
offset64 + uint64_t(InputSize().width) * uint64_t(sizeof(PixelType)) <=
bufferLength,
"End of row is outside of image");
#endif
uint32_t offset = aRow * InputSize().width * sizeof(PixelType);
return mBuffer.get() + offset;
}
Next mNext; /// The next SurfaceFilter in the chain.
UniquePtr<uint8_t[]> mBuffer; /// The buffer used to store reordered rows.
int32_t mInputRow; /// The current row we're reading. (0-indexed)
int32_t mOutputRow; /// The current row we're writing. (0-indexed)
uint8_t mPass; /// Which pass we're on. (0-indexed)
bool mProgressiveDisplay; /// If true, duplicate rows to optimize for
/// progressive display.
};
//////////////////////////////////////////////////////////////////////////////
// BlendAnimationFilter
//////////////////////////////////////////////////////////////////////////////
template <typename Next>
class BlendAnimationFilter;
/**
* A configuration struct for BlendAnimationFilter.
*/
struct BlendAnimationConfig {
template <typename Next>
using Filter = BlendAnimationFilter<Next>;
Decoder* mDecoder; /// The decoder producing the animation.
};
/**
* BlendAnimationFilter turns a partial image as part of an animation into a
* complete frame given its frame rect, blend method, and the base frame's
* data buffer, frame rect and disposal method. Any excess data caused by a
* frame rect not being contained by the output size will be discarded.
*
* The base frame is an already produced complete frame from the animation.
* It may be any previous frame depending on the disposal method, although
* most often it will be the immediate previous frame to the current we are
* generating.
*
* The 'Next' template parameter specifies the next filter in the chain.
*/
template <typename Next>
class BlendAnimationFilter final : public SurfaceFilter {
public:
BlendAnimationFilter()
: mRow(0),
mRowLength(0),
mRecycleRow(0),
mRecycleRowMost(0),
mRecycleRowOffset(0),
mRecycleRowLength(0),
mClearRow(0),
mClearRowMost(0),
mClearPrefixLength(0),
mClearInfixOffset(0),
mClearInfixLength(0),
mClearPostfixOffset(0),
mClearPostfixLength(0),
mOverProc(nullptr),
mBaseFrameStartPtr(nullptr),
mBaseFrameRowPtr(nullptr) {}
template <typename... Rest>
nsresult Configure(const BlendAnimationConfig& aConfig,
const Rest&... aRest) {
nsresult rv = mNext.Configure(aRest...);
if (NS_FAILED(rv)) {
return rv;
}
imgFrame* currentFrame = aConfig.mDecoder->GetCurrentFrame();
if (!currentFrame) {
MOZ_ASSERT_UNREACHABLE("Decoder must have current frame!");
return NS_ERROR_FAILURE;
}
mFrameRect = mUnclampedFrameRect = currentFrame->GetBlendRect();
gfx::IntSize outputSize = mNext.InputSize();
mRowLength = outputSize.width * sizeof(uint32_t);
// Forbid frame rects with negative size.
if (mUnclampedFrameRect.width < 0 || mUnclampedFrameRect.height < 0) {
return NS_ERROR_FAILURE;
}
// Clamp mFrameRect to the output size.
gfx::IntRect outputRect(0, 0, outputSize.width, outputSize.height);
mFrameRect = mFrameRect.Intersect(outputRect);
bool fullFrame = outputRect.IsEqualEdges(mFrameRect);
// If there's no intersection, |mFrameRect| will be an empty rect positioned
// at the maximum of |inputRect|'s and |aFrameRect|'s coordinates, which is
// not what we want. Force it to (0, 0) sized 0 x 0 in that case.
if (mFrameRect.IsEmpty()) {
mFrameRect.SetRect(0, 0, 0, 0);
}
BlendMethod blendMethod = currentFrame->GetBlendMethod();
switch (blendMethod) {
default:
blendMethod = BlendMethod::SOURCE;
MOZ_FALLTHROUGH_ASSERT("Unexpected blend method!");
case BlendMethod::SOURCE:
// Default, overwrites base frame data (if any) with new.
break;
case BlendMethod::OVER:
// OVER only has an impact on the output if we have new data to blend
// with.
if (mFrameRect.IsEmpty()) {
blendMethod = BlendMethod::SOURCE;
}
break;
}
// Determine what we need to clear and what we need to copy. If this frame
// is a full frame and uses source blending, there is no need to consider
// the disposal method of the previous frame.
gfx::IntRect dirtyRect(outputRect);
gfx::IntRect clearRect;
if (!fullFrame || blendMethod != BlendMethod::SOURCE) {
const RawAccessFrameRef& restoreFrame =
aConfig.mDecoder->GetRestoreFrameRef();
if (restoreFrame) {
MOZ_ASSERT(restoreFrame->GetSize() == outputSize);
MOZ_ASSERT(restoreFrame->IsFinished());
// We can safely use this pointer without holding a RawAccessFrameRef
// because the decoder will keep it alive for us.
mBaseFrameStartPtr = restoreFrame.Data();
MOZ_ASSERT(mBaseFrameStartPtr);
gfx::IntRect restoreBlendRect = restoreFrame->GetBoundedBlendRect();
gfx::IntRect restoreDirtyRect = aConfig.mDecoder->GetRestoreDirtyRect();
switch (restoreFrame->GetDisposalMethod()) {
default:
case DisposalMethod::RESTORE_PREVIOUS:
MOZ_FALLTHROUGH_ASSERT("Unexpected DisposalMethod");
case DisposalMethod::NOT_SPECIFIED:
case DisposalMethod::KEEP:
dirtyRect = mFrameRect.Union(restoreDirtyRect);
break;
case DisposalMethod::CLEAR:
// We only need to clear if the rect is outside the frame rect (i.e.
// overwrites a non-overlapping area) or the blend method may cause
// us to combine old data and new.
if (!mFrameRect.Contains(restoreBlendRect) ||
blendMethod == BlendMethod::OVER) {
clearRect = restoreBlendRect;
}
// If we are clearing the whole frame, we do not need to retain a
// reference to the base frame buffer.
if (outputRect.IsEqualEdges(clearRect)) {
mBaseFrameStartPtr = nullptr;
} else {
dirtyRect = mFrameRect.Union(restoreDirtyRect).Union(clearRect);
}
break;
}
} else if (!fullFrame) {
// This must be the first frame, clear everything.
clearRect = outputRect;
}
}
// We may be able to reuse parts of our underlying buffer that we are
// writing the new frame to. The recycle rect gives us the invalidation
// region which needs to be copied from the restore frame.
const gfx::IntRect& recycleRect = aConfig.mDecoder->GetRecycleRect();
mRecycleRow = recycleRect.y;
mRecycleRowMost = recycleRect.YMost();
mRecycleRowOffset = recycleRect.x * sizeof(uint32_t);
mRecycleRowLength = recycleRect.width * sizeof(uint32_t);
if (!clearRect.IsEmpty()) {
// The clear rect interacts with the recycle rect because we need to copy
// the prefix and postfix data from the base frame. The one thing we do
// know is that the infix area is always cleared explicitly.
mClearRow = clearRect.y;
mClearRowMost = clearRect.YMost();
mClearInfixOffset = clearRect.x * sizeof(uint32_t);
mClearInfixLength = clearRect.width * sizeof(uint32_t);
// The recycle row offset is where we need to begin copying base frame
// data for a row. If this offset begins after or at the clear infix
// offset, then there is no prefix data at all.
if (mClearInfixOffset > mRecycleRowOffset) {
mClearPrefixLength = mClearInfixOffset - mRecycleRowOffset;
}
// Similar to the prefix, if the postfix offset begins outside the recycle
// rect, then we know we already have all the data we need.
mClearPostfixOffset = mClearInfixOffset + mClearInfixLength;
size_t recycleRowEndOffset = mRecycleRowOffset + mRecycleRowLength;
if (mClearPostfixOffset < recycleRowEndOffset) {
mClearPostfixLength = recycleRowEndOffset - mClearPostfixOffset;
}
}
// The dirty rect, or delta between the current frame and the previous frame
// (chronologically, not necessarily the restore frame) is the last
// animation parameter we need to initialize the new frame with.
currentFrame->SetDirtyRect(dirtyRect);
if (!mBaseFrameStartPtr) {
// Switch to SOURCE if no base frame to ensure we don't allocate an
// intermediate buffer below. OVER does nothing without the base frame
// data.
blendMethod = BlendMethod::SOURCE;
}
// Skia provides arch-specific accelerated methods to perform blending.
// Note that this is an internal Skia API and may be prone to change,
// but we avoid the overhead of setting up Skia objects.
if (blendMethod == BlendMethod::OVER) {
mOverProc = SkBlitRow::Factory32(SkBlitRow::kSrcPixelAlpha_Flag32);
MOZ_ASSERT(mOverProc);
}
// We don't need an intermediate buffer unless the unclamped frame rect
// width is larger than the clamped frame rect width. In that case, the
// caller will end up writing data that won't end up in the final image at
// all, and we'll need a buffer to give that data a place to go.
if (mFrameRect.width < mUnclampedFrameRect.width || mOverProc) {
mBuffer.reset(new (fallible)
uint8_t[mUnclampedFrameRect.width * sizeof(uint32_t)]);
if (MOZ_UNLIKELY(!mBuffer)) {
return NS_ERROR_OUT_OF_MEMORY;
}
memset(mBuffer.get(), 0, mUnclampedFrameRect.width * sizeof(uint32_t));
}
ConfigureFilter(mUnclampedFrameRect.Size(), sizeof(uint32_t));
return NS_OK;
}
Maybe<SurfaceInvalidRect> TakeInvalidRect() override {
return mNext.TakeInvalidRect();
}
protected:
uint8_t* DoResetToFirstRow() override {
uint8_t* rowPtr = mNext.ResetToFirstRow();
if (rowPtr == nullptr) {
mRow = mFrameRect.YMost();
return nullptr;
}
mRow = 0;
mBaseFrameRowPtr = mBaseFrameStartPtr;
while (mRow < mFrameRect.y) {
WriteBaseFrameRow();
AdvanceRowOutsideFrameRect();
}
// We're at the beginning of the frame rect now, so return if we're either
// ready for input or we're already done.
rowPtr = mBuffer ? mBuffer.get() : mNext.CurrentRowPointer();
if (!mFrameRect.IsEmpty() || rowPtr == nullptr) {
// Note that the pointer we're returning is for the next row we're
// actually going to write to, but we may discard writes before that point
// if mRow < mFrameRect.y.
mRow = mUnclampedFrameRect.y;
WriteBaseFrameRow();
return AdjustRowPointer(rowPtr);
}
// We've finished the region specified by the frame rect, but the frame rect
// is empty, so we need to output the rest of the image immediately. Advance
// to the end of the next pipeline stage's buffer, outputting rows that are
// copied from the base frame and/or cleared.
WriteBaseFrameRowsUntilComplete();
mRow = mFrameRect.YMost();
return nullptr; // We're done.
}
uint8_t* DoAdvanceRowFromBuffer(const uint8_t* aInputRow) override {
CopyInputRow(aInputRow);
return DoAdvanceRow();
}
uint8_t* DoAdvanceRow() override {
uint8_t* rowPtr = nullptr;
const int32_t currentRow = mRow;
mRow++;
// The unclamped frame rect has a negative offset which means -y rows from
// the decoder need to be discarded before we advance properly.
if (currentRow >= 0 && mBaseFrameRowPtr) {
mBaseFrameRowPtr += mRowLength;
}
if (currentRow < mFrameRect.y) {
// This row is outside of the frame rect, so just drop it on the floor.
rowPtr = mBuffer ? mBuffer.get() : mNext.CurrentRowPointer();
return AdjustRowPointer(rowPtr);
} else if (NS_WARN_IF(currentRow >= mFrameRect.YMost())) {
return nullptr;
}
// If we had to buffer, merge the data into the row. Otherwise we had the
// decoder write directly to the next stage's buffer.
if (mBuffer) {
int32_t width = mFrameRect.width;
uint32_t* dst = reinterpret_cast<uint32_t*>(mNext.CurrentRowPointer());
uint32_t* src = reinterpret_cast<uint32_t*>(mBuffer.get()) -
std::min(mUnclampedFrameRect.x, 0);
dst += mFrameRect.x;
if (mOverProc) {
mOverProc(dst, src, width, 0xFF);
} else {
memcpy(dst, src, width * sizeof(uint32_t));
}
rowPtr = mNext.AdvanceRow() ? mBuffer.get() : nullptr;
} else {
MOZ_ASSERT(!mOverProc);
rowPtr = mNext.AdvanceRow();
}
// If there's still more data coming or we're already done, just adjust the
// pointer and return.
if (mRow < mFrameRect.YMost() || rowPtr == nullptr) {
WriteBaseFrameRow();
return AdjustRowPointer(rowPtr);
}
// We've finished the region specified by the frame rect. Advance to the end
// of the next pipeline stage's buffer, outputting rows that are copied from
// the base frame and/or cleared.
WriteBaseFrameRowsUntilComplete();
return nullptr; // We're done.
}
private:
void WriteBaseFrameRowsUntilComplete() {
do {
WriteBaseFrameRow();
} while (AdvanceRowOutsideFrameRect());
}
void WriteBaseFrameRow() {
uint8_t* dest = mNext.CurrentRowPointer();
if (!dest) {
return;
}
// No need to copy pixels from the base frame for rows that will not change
// between the recycled frame and the new frame.
bool needBaseFrame = mRow >= mRecycleRow && mRow < mRecycleRowMost;
if (!mBaseFrameRowPtr) {
// No base frame, so we are clearing everything.
if (needBaseFrame) {
memset(dest + mRecycleRowOffset, 0, mRecycleRowLength);
}
} else if (mClearRow <= mRow && mClearRowMost > mRow) {
// We have a base frame, but we are inside the area to be cleared.
// Only copy the data we need from the source.
if (needBaseFrame) {
memcpy(dest + mRecycleRowOffset, mBaseFrameRowPtr + mRecycleRowOffset,
mClearPrefixLength);
memcpy(dest + mClearPostfixOffset,
mBaseFrameRowPtr + mClearPostfixOffset, mClearPostfixLength);
}
memset(dest + mClearInfixOffset, 0, mClearInfixLength);
} else if (needBaseFrame) {
memcpy(dest + mRecycleRowOffset, mBaseFrameRowPtr + mRecycleRowOffset,
mRecycleRowLength);
}
}
bool AdvanceRowOutsideFrameRect() {
// The unclamped frame rect may have a negative offset however we should
// never be advancing the row via this path (otherwise mBaseFrameRowPtr
// will be wrong.
MOZ_ASSERT(mRow >= 0);
MOZ_ASSERT(mRow < mFrameRect.y || mRow >= mFrameRect.YMost());
mRow++;
if (mBaseFrameRowPtr) {
mBaseFrameRowPtr += mRowLength;
}
return mNext.AdvanceRow() != nullptr;
}
uint8_t* AdjustRowPointer(uint8_t* aNextRowPointer) const {
if (mBuffer) {
MOZ_ASSERT(aNextRowPointer == mBuffer.get() ||
aNextRowPointer == nullptr);
return aNextRowPointer; // No adjustment needed for an intermediate
// buffer.
}
if (mFrameRect.IsEmpty() || mRow >= mFrameRect.YMost() ||
aNextRowPointer == nullptr) {
return nullptr; // Nothing left to write.
}
MOZ_ASSERT(!mOverProc);
return aNextRowPointer + mFrameRect.x * sizeof(uint32_t);
}
Next mNext; /// The next SurfaceFilter in the chain.
gfx::IntRect mFrameRect; /// The surface subrect which contains data,
/// clamped to the image size.
gfx::IntRect mUnclampedFrameRect; /// The frame rect before clamping.
UniquePtr<uint8_t[]> mBuffer; /// The intermediate buffer, if one is
/// necessary because the frame rect width
/// is larger than the image's logical width.
int32_t mRow; /// The row in unclamped frame rect space
/// that we're currently writing.
size_t mRowLength; /// Length in bytes of a row that is the input
/// for the next filter.
int32_t mRecycleRow; /// The starting row of the recycle rect.
int32_t mRecycleRowMost; /// The ending row of the recycle rect.
size_t mRecycleRowOffset; /// Row offset in bytes of the recycle rect.
size_t mRecycleRowLength; /// Row length in bytes of the recycle rect.
/// The frame area to clear before blending the current frame.
int32_t mClearRow; /// The starting row of the clear rect.
int32_t mClearRowMost; /// The ending row of the clear rect.
size_t mClearPrefixLength; /// Row length in bytes of clear prefix.
size_t mClearInfixOffset; /// Row offset in bytes of clear area.
size_t mClearInfixLength; /// Row length in bytes of clear area.
size_t mClearPostfixOffset; /// Row offset in bytes of clear postfix.
size_t mClearPostfixLength; /// Row length in bytes of clear postfix.
SkBlitRow::Proc32 mOverProc; /// Function pointer to perform over blending.
const uint8_t*
mBaseFrameStartPtr; /// Starting row pointer to the base frame
/// data from which we copy pixel data from.
const uint8_t* mBaseFrameRowPtr; /// Current row pointer to the base frame
/// data.
};
//////////////////////////////////////////////////////////////////////////////
// RemoveFrameRectFilter
//////////////////////////////////////////////////////////////////////////////
template <typename Next>
class RemoveFrameRectFilter;
/**
* A configuration struct for RemoveFrameRectFilter.
*/
struct RemoveFrameRectConfig {
template <typename Next>
using Filter = RemoveFrameRectFilter<Next>;
gfx::IntRect mFrameRect; /// The surface subrect which contains data.
};
/**
* RemoveFrameRectFilter turns an image with a frame rect that does not match
* its logical size into an image with no frame rect. It does this by writing
* transparent pixels into any padding regions and throwing away excess data.
*
* The 'Next' template parameter specifies the next filter in the chain.
*/
template <typename Next>
class RemoveFrameRectFilter final : public SurfaceFilter {
public:
RemoveFrameRectFilter() : mRow(0) {}
template <typename... Rest>
nsresult Configure(const RemoveFrameRectConfig& aConfig,
const Rest&... aRest) {
nsresult rv = mNext.Configure(aRest...);
if (NS_FAILED(rv)) {
return rv;
}
mFrameRect = mUnclampedFrameRect = aConfig.mFrameRect;
gfx::IntSize outputSize = mNext.InputSize();
// Forbid frame rects with negative size.
if (aConfig.mFrameRect.Width() < 0 || aConfig.mFrameRect.Height() < 0) {
return NS_ERROR_INVALID_ARG;
}
// Clamp mFrameRect to the output size.
gfx::IntRect outputRect(0, 0, outputSize.width, outputSize.height);
mFrameRect = mFrameRect.Intersect(outputRect);
// If there's no intersection, |mFrameRect| will be an empty rect positioned
// at the maximum of |inputRect|'s and |aFrameRect|'s coordinates, which is
// not what we want. Force it to (0, 0) in that case.
if (mFrameRect.IsEmpty()) {
mFrameRect.MoveTo(0, 0);
}
// We don't need an intermediate buffer unless the unclamped frame rect
// width is larger than the clamped frame rect width. In that case, the
// caller will end up writing data that won't end up in the final image at
// all, and we'll need a buffer to give that data a place to go.
if (mFrameRect.Width() < mUnclampedFrameRect.Width()) {
mBuffer.reset(new (
fallible) uint8_t[mUnclampedFrameRect.Width() * sizeof(uint32_t)]);
if (MOZ_UNLIKELY(!mBuffer)) {
return NS_ERROR_OUT_OF_MEMORY;
}
memset(mBuffer.get(), 0, mUnclampedFrameRect.Width() * sizeof(uint32_t));
}
ConfigureFilter(mUnclampedFrameRect.Size(), sizeof(uint32_t));
return NS_OK;
}
Maybe<SurfaceInvalidRect> TakeInvalidRect() override {
return mNext.TakeInvalidRect();
}
protected:
uint8_t* DoResetToFirstRow() override {
uint8_t* rowPtr = mNext.ResetToFirstRow();
if (rowPtr == nullptr) {
mRow = mFrameRect.YMost();
return nullptr;
}
mRow = mUnclampedFrameRect.Y();
// Advance the next pipeline stage to the beginning of the frame rect,
// outputting blank rows.
if (mFrameRect.Y() > 0) {
for (int32_t rowToOutput = 0; rowToOutput < mFrameRect.Y();
++rowToOutput) {
mNext.WriteEmptyRow();
}
}
// We're at the beginning of the frame rect now, so return if we're either
// ready for input or we're already done.
rowPtr = mBuffer ? mBuffer.get() : mNext.CurrentRowPointer();
if (!mFrameRect.IsEmpty() || rowPtr == nullptr) {
// Note that the pointer we're returning is for the next row we're
// actually going to write to, but we may discard writes before that point
// if mRow < mFrameRect.y.
return AdjustRowPointer(rowPtr);
}
// We've finished the region specified by the frame rect, but the frame rect
// is empty, so we need to output the rest of the image immediately. Advance
// to the end of the next pipeline stage's buffer, outputting blank rows.
while (mNext.WriteEmptyRow() == WriteState::NEED_MORE_DATA) {
}
mRow = mFrameRect.YMost();
return nullptr; // We're done.
}
uint8_t* DoAdvanceRowFromBuffer(const uint8_t* aInputRow) override {
CopyInputRow(aInputRow);
return DoAdvanceRow();
}
uint8_t* DoAdvanceRow() override {
uint8_t* rowPtr = nullptr;
const int32_t currentRow = mRow;
mRow++;
if (currentRow < mFrameRect.Y()) {
// This row is outside of the frame rect, so just drop it on the floor.
rowPtr = mBuffer ? mBuffer.get() : mNext.CurrentRowPointer();
return AdjustRowPointer(rowPtr);
} else if (currentRow >= mFrameRect.YMost()) {
NS_WARNING("RemoveFrameRectFilter: Advancing past end of frame rect");
return nullptr;
}
// If we had to buffer, copy the data. Otherwise, just advance the row.
if (mBuffer) {
// We write from the beginning of the buffer unless
// |mUnclampedFrameRect.x| is negative; if that's the case, we have to
// skip the portion of the unclamped frame rect that's outside the row.
uint32_t* source = reinterpret_cast<uint32_t*>(mBuffer.get()) -
std::min(mUnclampedFrameRect.X(), 0);
// We write |mFrameRect.width| columns starting at |mFrameRect.x|; we've
// already clamped these values to the size of the output, so we don't
// have to worry about bounds checking here (though WriteBuffer() will do
// it for us in any case).
WriteState state =
mNext.WriteBuffer(source, mFrameRect.X(), mFrameRect.Width());
rowPtr = state == WriteState::NEED_MORE_DATA ? mBuffer.get() : nullptr;
} else {
rowPtr = mNext.AdvanceRow();
}
// If there's still more data coming or we're already done, just adjust the
// pointer and return.
if (mRow < mFrameRect.YMost() || rowPtr == nullptr) {
return AdjustRowPointer(rowPtr);
}
// We've finished the region specified by the frame rect. Advance to the end
// of the next pipeline stage's buffer, outputting blank rows.
while (mNext.WriteEmptyRow() == WriteState::NEED_MORE_DATA) {
}
mRow = mFrameRect.YMost();
return nullptr; // We're done.
}
private:
uint8_t* AdjustRowPointer(uint8_t* aNextRowPointer) const {
if (mBuffer) {
MOZ_ASSERT(aNextRowPointer == mBuffer.get() ||
aNextRowPointer == nullptr);
return aNextRowPointer; // No adjustment needed for an intermediate
// buffer.
}
if (mFrameRect.IsEmpty() || mRow >= mFrameRect.YMost() ||
aNextRowPointer == nullptr) {
return nullptr; // Nothing left to write.
}
return aNextRowPointer + mFrameRect.X() * sizeof(uint32_t);
}
Next mNext; /// The next SurfaceFilter in the chain.
gfx::IntRect mFrameRect; /// The surface subrect which contains data,
/// clamped to the image size.
gfx::IntRect mUnclampedFrameRect; /// The frame rect before clamping.
UniquePtr<uint8_t[]> mBuffer; /// The intermediate buffer, if one is
/// necessary because the frame rect width
/// is larger than the image's logical width.
int32_t mRow; /// The row in unclamped frame rect space
/// that we're currently writing.
};
//////////////////////////////////////////////////////////////////////////////
// ADAM7InterpolatingFilter
//////////////////////////////////////////////////////////////////////////////
template <typename Next>
class ADAM7InterpolatingFilter;
/**
* A configuration struct for ADAM7InterpolatingFilter.
*/
struct ADAM7InterpolatingConfig {
template <typename Next>
using Filter = ADAM7InterpolatingFilter<Next>;
};
/**
* ADAM7InterpolatingFilter performs bilinear interpolation over an ADAM7
* interlaced image.
*
* ADAM7 breaks up the image into 8x8 blocks. On each of the 7 passes, a new set
* of pixels in each block receives their final values, according to the
* following pattern:
*
* 1 6 4 6 2 6 4 6
* 7 7 7 7 7 7 7 7
* 5 6 5 6 5 6 5 6
* 7 7 7 7 7 7 7 7
* 3 6 4 6 3 6 4 6
* 7 7 7 7 7 7 7 7
* 5 6 5 6 5 6 5 6
* 7 7 7 7 7 7 7 7
*
* When rendering the pixels that have not yet received their final values, we
* can get much better intermediate results if we interpolate between
* the pixels we *have* gotten so far. This filter performs bilinear
* interpolation by first performing linear interpolation horizontally for each
* "important" row (which we'll define as a row that has received any pixels
* with final values at all) and then performing linear interpolation vertically
* to produce pixel values for rows which aren't important on the current pass.
*
* Note that this filter totally ignores the data which is written to rows which
* aren't important on the current pass! It's fine to write nothing at all for
* these rows, although doing so won't cause any harm.
*
* XXX(seth): In bug 1280552 we'll add a SIMD implementation for this filter.
*
* The 'Next' template parameter specifies the next filter in the chain.
*/
template <typename Next>
class ADAM7InterpolatingFilter final : public SurfaceFilter {
public:
ADAM7InterpolatingFilter()
: mPass(0) // The current pass, in the range 1..7. Starts at 0 so that
// DoResetToFirstRow() doesn't have to special case the first
// pass.
,
mRow(0) {}
template <typename... Rest>
nsresult Configure(const ADAM7InterpolatingConfig& aConfig,
const Rest&... aRest) {
nsresult rv = mNext.Configure(aRest...);
if (NS_FAILED(rv)) {
return rv;
}
// We have two intermediate buffers, one for the previous row with final
// pixel values and one for the row that the previous filter in the chain is
// currently writing to.
size_t inputWidthInBytes = mNext.InputSize().width * sizeof(uint32_t);
mPreviousRow.reset(new (fallible) uint8_t[inputWidthInBytes]);
if (MOZ_UNLIKELY(!mPreviousRow)) {
return NS_ERROR_OUT_OF_MEMORY;
}
mCurrentRow.reset(new (fallible) uint8_t[inputWidthInBytes]);
if (MOZ_UNLIKELY(!mCurrentRow)) {
return NS_ERROR_OUT_OF_MEMORY;
}
memset(mPreviousRow.get(), 0, inputWidthInBytes);
memset(mCurrentRow.get(), 0, inputWidthInBytes);
ConfigureFilter(mNext.InputSize(), sizeof(uint32_t));
return NS_OK;
}
Maybe<SurfaceInvalidRect> TakeInvalidRect() override {
return mNext.TakeInvalidRect();
}
protected:
uint8_t* DoResetToFirstRow() override {
mRow = 0;
mPass = std::min(mPass + 1, 7);
uint8_t* rowPtr = mNext.ResetToFirstRow();
if (mPass == 7) {
// Short circuit this filter on the final pass, since all pixels have
// their final values at that point.
return rowPtr;
}
return mCurrentRow.get();
}
uint8_t* DoAdvanceRowFromBuffer(const uint8_t* aInputRow) override {
CopyInputRow(aInputRow);
return DoAdvanceRow();
}
uint8_t* DoAdvanceRow() override {
MOZ_ASSERT(0 < mPass && mPass <= 7, "Invalid pass");
int32_t currentRow = mRow;
++mRow;
if (mPass == 7) {
// On the final pass we short circuit this filter totally.
return mNext.AdvanceRow();
}
const int32_t lastImportantRow =
LastImportantRow(InputSize().height, mPass);
if (currentRow > lastImportantRow) {
return nullptr; // This pass is already complete.
}
if (!IsImportantRow(currentRow, mPass)) {
// We just ignore whatever the caller gives us for these rows. We'll
// interpolate them in later.
return mCurrentRow.get();
}
// This is an important row. We need to perform horizontal interpolation for
// these rows.
InterpolateHorizontally(mCurrentRow.get(), InputSize().width, mPass);
// Interpolate vertically between the previous important row and the current
// important row. We skip this if the current row is 0 (which is always an
// important row), because in that case there is no previous important row
// to interpolate with.
if (currentRow != 0) {
InterpolateVertically(mPreviousRow.get(), mCurrentRow.get(), mPass,
mNext);
}
// Write out the current row itself, which, being an important row, does not
// need vertical interpolation.
uint32_t* currentRowAsPixels =
reinterpret_cast<uint32_t*>(mCurrentRow.get());
mNext.WriteBuffer(currentRowAsPixels);
if (currentRow == lastImportantRow) {
// This is the last important row, which completes this pass. Note that
// for very small images, this may be the first row! Since there won't be
// another important row, there's nothing to interpolate with vertically,
// so we just duplicate this row until the end of the image.
while (mNext.WriteBuffer(currentRowAsPixels) ==
WriteState::NEED_MORE_DATA) {
}
// All of the remaining rows in the image were determined above, so we're
// done.
return nullptr;
}
// The current row is now the previous important row; save it.
std::swap(mPreviousRow, mCurrentRow);
MOZ_ASSERT(mRow < InputSize().height,
"Reached the end of the surface without "
"hitting the last important row?");
return mCurrentRow.get();
}
private:
static void InterpolateVertically(uint8_t* aPreviousRow, uint8_t* aCurrentRow,
uint8_t aPass, SurfaceFilter& aNext) {
const float* weights = InterpolationWeights(ImportantRowStride(aPass));
// We need to interpolate vertically to generate the rows between the
// previous important row and the next one. Recall that important rows are
// rows which contain at least some final pixels; see
// InterpolateHorizontally() for some additional explanation as to what that
// means. Note that we've already written out the previous important row, so
// we start the iteration at 1.
for (int32_t outRow = 1; outRow < ImportantRowStride(aPass); ++outRow) {
const float weight = weights[outRow];
// We iterate through the previous and current important row every time we
// write out an interpolated row, so we need to copy the pointers.
uint8_t* prevRowBytes = aPreviousRow;
uint8_t* currRowBytes = aCurrentRow;
// Write out the interpolated pixels. Interpolation is componentwise.
aNext.template WritePixelsToRow<uint32_t>([&] {
uint32_t pixel = 0;
auto* component = reinterpret_cast<uint8_t*>(&pixel);
*component++ =
InterpolateByte(*prevRowBytes++, *currRowBytes++, weight);
*component++ =
InterpolateByte(*prevRowBytes++, *currRowBytes++, weight);
*component++ =
InterpolateByte(*prevRowBytes++, *currRowBytes++, weight);
*component++ =
InterpolateByte(*prevRowBytes++, *currRowBytes++, weight);
return AsVariant(pixel);
});
}
}
static void InterpolateHorizontally(uint8_t* aRow, int32_t aWidth,
uint8_t aPass) {
// Collect the data we'll need to perform horizontal interpolation. The
// terminology here bears some explanation: a "final pixel" is a pixel which
// has received its final value. On each pass, a new set of pixels receives
// their final value; see the diagram above of the 8x8 pattern that ADAM7
// uses. Any pixel which hasn't received its final value on this pass
// derives its value from either horizontal or vertical interpolation
// instead.
const size_t finalPixelStride = FinalPixelStride(aPass);
const size_t finalPixelStrideBytes = finalPixelStride * sizeof(uint32_t);
const size_t lastFinalPixel = LastFinalPixel(aWidth, aPass);
const size_t lastFinalPixelBytes = lastFinalPixel * sizeof(uint32_t);
const float* weights = InterpolationWeights(finalPixelStride);
// Interpolate blocks of pixels which lie between two final pixels.
// Horizontal interpolation is done in place, as we'll need the results
// later when we vertically interpolate.
for (size_t blockBytes = 0; blockBytes < lastFinalPixelBytes;
blockBytes += finalPixelStrideBytes) {
uint8_t* finalPixelA = aRow + blockBytes;
uint8_t* finalPixelB = aRow + blockBytes + finalPixelStrideBytes;
MOZ_ASSERT(finalPixelA < aRow + aWidth * sizeof(uint32_t),
"Running off end of buffer");
MOZ_ASSERT(finalPixelB < aRow + aWidth * sizeof(uint32_t),
"Running off end of buffer");
// Interpolate the individual pixels componentwise. Note that we start
// iteration at 1 since we don't need to apply any interpolation to the
// first pixel in the block, which has its final value.
for (size_t pixelIndex = 1; pixelIndex < finalPixelStride; ++pixelIndex) {
const float weight = weights[pixelIndex];
uint8_t* pixel = aRow + blockBytes + pixelIndex * sizeof(uint32_t);
MOZ_ASSERT(pixel < aRow + aWidth * sizeof(uint32_t),
"Running off end of buffer");
for (size_t component = 0; component < sizeof(uint32_t); ++component) {
pixel[component] = InterpolateByte(finalPixelA[component],
finalPixelB[component], weight);
}
}
}
// For the pixels after the last final pixel in the row, there isn't a
// second final pixel to interpolate with, so just duplicate.
uint32_t* rowPixels = reinterpret_cast<uint32_t*>(aRow);
uint32_t pixelToDuplicate = rowPixels[lastFinalPixel];
for (int32_t pixelIndex = lastFinalPixel + 1; pixelIndex < aWidth;
++pixelIndex) {
MOZ_ASSERT(pixelIndex < aWidth, "Running off end of buffer");
rowPixels[pixelIndex] = pixelToDuplicate;
}
}
static uint8_t InterpolateByte(uint8_t aByteA, uint8_t aByteB,
float aWeight) {
return uint8_t(aByteA * aWeight + aByteB * (1.0f - aWeight));
}
static int32_t ImportantRowStride(uint8_t aPass) {
MOZ_ASSERT(0 < aPass && aPass <= 7, "Invalid pass");
// The stride between important rows for each pass, with a dummy value for
// the nonexistent pass 0.
static int32_t strides[] = {1, 8, 8, 4, 4, 2, 2, 1};
return strides[aPass];
}
static bool IsImportantRow(int32_t aRow, uint8_t aPass) {
MOZ_ASSERT(aRow >= 0);
// Whether the row is important comes down to divisibility by the stride for
// this pass, which is always a power of 2, so we can check using a mask.
int32_t mask = ImportantRowStride(aPass) - 1;
return (aRow & mask) == 0;
}
static int32_t LastImportantRow(int32_t aHeight, uint8_t aPass) {
MOZ_ASSERT(aHeight > 0);
// We can find the last important row using the same mask trick as above.
int32_t lastRow = aHeight - 1;
int32_t mask = ImportantRowStride(aPass) - 1;
return lastRow - (lastRow & mask);
}
static size_t FinalPixelStride(uint8_t aPass) {
MOZ_ASSERT(0 < aPass && aPass <= 7, "Invalid pass");
// The stride between the final pixels in important rows for each pass, with
// a dummy value for the nonexistent pass 0.
static size_t strides[] = {1, 8, 4, 4, 2, 2, 1, 1};
return strides[aPass];
}
static size_t LastFinalPixel(int32_t aWidth, uint8_t aPass) {
MOZ_ASSERT(aWidth >= 0);
// Again, we can use the mask trick above to find the last important pixel.
int32_t lastColumn = aWidth - 1;
size_t mask = FinalPixelStride(aPass) - 1;
return lastColumn - (lastColumn & mask);
}
static const float* InterpolationWeights(int32_t aStride) {
// Precalculated interpolation weights. These are used to interpolate
// between final pixels or between important rows. Although no interpolation
// is actually applied to the previous final pixel or important row value,
// the arrays still start with 1.0f, which is always skipped, primarily
// because otherwise |stride1Weights| would have zero elements.
static float stride8Weights[] = {1.0f, 7 / 8.0f, 6 / 8.0f, 5 / 8.0f,
4 / 8.0f, 3 / 8.0f, 2 / 8.0f, 1 / 8.0f};
static float stride4Weights[] = {1.0f, 3 / 4.0f, 2 / 4.0f, 1 / 4.0f};
static float stride2Weights[] = {1.0f, 1 / 2.0f};
static float stride1Weights[] = {1.0f};
switch (aStride) {
case 8:
return stride8Weights;
case 4:
return stride4Weights;
case 2:
return stride2Weights;
case 1:
return stride1Weights;
default:
MOZ_CRASH();
}
}
Next mNext; /// The next SurfaceFilter in the chain.
UniquePtr<uint8_t[]>
mPreviousRow; /// The last important row (i.e., row with
/// final pixel values) that got written to.
UniquePtr<uint8_t[]> mCurrentRow; /// The row that's being written to right
/// now.
uint8_t mPass; /// Which ADAM7 pass we're on. Valid passes
/// are 1..7 during processing and 0 prior
/// to configuration.
int32_t mRow; /// The row we're currently reading.
};
} // namespace image
} // namespace mozilla
#endif // mozilla_image_SurfaceFilters_h
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