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Mypal/image/Downscaler.cpp

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
*
* 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/. */
#include "Downscaler.h"
#include <algorithm>
#include <ctime>
#include "gfxPrefs.h"
#include "image_operations.h"
#include "mozilla/gfx/2D.h"
#include "mozilla/SSE.h"
#include "mozilla/mips.h"
#include "convolver.h"
#include "skia/include/core/SkTypes.h"
using std::max;
using std::swap;
namespace mozilla {
using gfx::IntRect;
namespace image {
Downscaler::Downscaler(const nsIntSize& aTargetSize)
: mTargetSize(aTargetSize)
, mOutputBuffer(nullptr)
, mXFilter(MakeUnique<skia::ConvolutionFilter1D>())
, mYFilter(MakeUnique<skia::ConvolutionFilter1D>())
, mWindowCapacity(0)
, mHasAlpha(true)
, mFlipVertically(false)
{
MOZ_ASSERT(gfxPrefs::ImageDownscaleDuringDecodeEnabled(),
"Downscaling even though downscale-during-decode is disabled?");
MOZ_ASSERT(mTargetSize.width > 0 && mTargetSize.height > 0,
"Invalid target size");
}
Downscaler::~Downscaler()
{
ReleaseWindow();
}
void
Downscaler::ReleaseWindow()
{
if (!mWindow) {
return;
}
for (int32_t i = 0; i < mWindowCapacity; ++i) {
delete[] mWindow[i];
}
mWindow = nullptr;
mWindowCapacity = 0;
}
nsresult
Downscaler::BeginFrame(const nsIntSize& aOriginalSize,
const Maybe<nsIntRect>& aFrameRect,
uint8_t* aOutputBuffer,
bool aHasAlpha,
bool aFlipVertically /* = false */)
{
MOZ_ASSERT(aOutputBuffer);
MOZ_ASSERT(mTargetSize != aOriginalSize,
"Created a downscaler, but not downscaling?");
MOZ_ASSERT(mTargetSize.width <= aOriginalSize.width,
"Created a downscaler, but width is larger");
MOZ_ASSERT(mTargetSize.height <= aOriginalSize.height,
"Created a downscaler, but height is larger");
MOZ_ASSERT(aOriginalSize.width > 0 && aOriginalSize.height > 0,
"Invalid original size");
// Only downscale from reasonable sizes to avoid using too much memory/cpu
// downscaling and decoding. 1 << 20 == 1,048,576 seems a reasonable limit.
if (aOriginalSize.width > (1 << 20) || aOriginalSize.height > (1 << 20)) {
NS_WARNING("Trying to downscale image frame that is too large");
return NS_ERROR_INVALID_ARG;
}
mFrameRect = aFrameRect.valueOr(nsIntRect(nsIntPoint(), aOriginalSize));
MOZ_ASSERT(mFrameRect.x >= 0 && mFrameRect.y >= 0 &&
mFrameRect.width >= 0 && mFrameRect.height >= 0,
"Frame rect must have non-negative components");
MOZ_ASSERT(nsIntRect(0, 0, aOriginalSize.width, aOriginalSize.height)
.Contains(mFrameRect),
"Frame rect must fit inside image");
MOZ_ASSERT_IF(!nsIntRect(0, 0, aOriginalSize.width, aOriginalSize.height)
.IsEqualEdges(mFrameRect),
aHasAlpha);
mOriginalSize = aOriginalSize;
mScale = gfxSize(double(mOriginalSize.width) / mTargetSize.width,
double(mOriginalSize.height) / mTargetSize.height);
mOutputBuffer = aOutputBuffer;
mHasAlpha = aHasAlpha;
mFlipVertically = aFlipVertically;
ReleaseWindow();
auto resizeMethod = skia::ImageOperations::RESIZE_LANCZOS3;
skia::resize::ComputeFilters(resizeMethod,
mOriginalSize.width, mTargetSize.width,
0, mTargetSize.width,
mXFilter.get());
if (mXFilter->max_filter() <= 0 || mXFilter->num_values() != mTargetSize.width) {
NS_WARNING("Failed to compute filters for image downscaling");
return NS_ERROR_OUT_OF_MEMORY;
}
skia::resize::ComputeFilters(resizeMethod,
mOriginalSize.height, mTargetSize.height,
0, mTargetSize.height,
mYFilter.get());
if (mYFilter->max_filter() <= 0 || mYFilter->num_values() != mTargetSize.height) {
NS_WARNING("Failed to compute filters for image downscaling");
return NS_ERROR_OUT_OF_MEMORY;
}
// Allocate the buffer, which contains scanlines of the original image.
// pad by 15 to handle overreads by the simd code
size_t bufferLen = mOriginalSize.width * sizeof(uint32_t) + 15;
mRowBuffer.reset(new (fallible) uint8_t[bufferLen]);
if (MOZ_UNLIKELY(!mRowBuffer)) {
return NS_ERROR_OUT_OF_MEMORY;
}
// Zero buffer to keep valgrind happy.
memset(mRowBuffer.get(), 0, bufferLen);
// Allocate the window, which contains horizontally downscaled scanlines. (We
// can store scanlines which are already downscale 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;
}
bool anyAllocationFailed = false;
// pad by 15 to handle overreads by the simd code
const int rowSize = mTargetSize.width * sizeof(uint32_t) + 15;
for (int32_t i = 0; i < mWindowCapacity; ++i) {
mWindow[i] = new (fallible) uint8_t[rowSize];
anyAllocationFailed = anyAllocationFailed || mWindow[i] == nullptr;
}
if (MOZ_UNLIKELY(anyAllocationFailed)) {
// 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.
return NS_ERROR_OUT_OF_MEMORY;
}
ResetForNextProgressivePass();
return NS_OK;
}
void
Downscaler::SkipToRow(int32_t aRow)
{
if (mCurrentInLine < aRow) {
ClearRow();
do {
CommitRow();
} while (mCurrentInLine < aRow);
}
}
void
Downscaler::ResetForNextProgressivePass()
{
mPrevInvalidatedLine = 0;
mCurrentOutLine = 0;
mCurrentInLine = 0;
mLinesInBuffer = 0;
if (mFrameRect.IsEmpty()) {
// Our frame rect is zero size; commit rows until the end of the image.
SkipToRow(mOriginalSize.height - 1);
} else {
// If we have a vertical offset, commit rows to shift us past it.
SkipToRow(mFrameRect.y);
}
}
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
Downscaler::ClearRestOfRow(uint32_t aStartingAtCol)
{
MOZ_ASSERT(int64_t(aStartingAtCol) <= int64_t(mOriginalSize.width));
uint32_t bytesToClear = (mOriginalSize.width - aStartingAtCol)
* sizeof(uint32_t);
memset(mRowBuffer.get() + (aStartingAtCol * sizeof(uint32_t)),
0, bytesToClear);
}
void
Downscaler::CommitRow()
{
MOZ_ASSERT(mOutputBuffer, "Should have a current frame");
MOZ_ASSERT(mCurrentInLine < mOriginalSize.height, "Past end of input");
if (mCurrentOutLine < mTargetSize.height) {
int32_t filterOffset = 0;
int32_t filterLength = 0;
GetFilterOffsetAndLength(mYFilter, mCurrentOutLine,
&filterOffset, &filterLength);
int32_t inLineToRead = filterOffset + mLinesInBuffer;
MOZ_ASSERT(mCurrentInLine <= inLineToRead, "Reading past end of input");
if (mCurrentInLine == inLineToRead) {
MOZ_RELEASE_ASSERT(mLinesInBuffer < mWindowCapacity, "Need more rows than capacity!");
skia::ConvolveHorizontally(mRowBuffer.get(), *mXFilter,
mWindow[mLinesInBuffer++], mHasAlpha,
supports_sse2() || supports_mmi());
}
MOZ_ASSERT(mCurrentOutLine < mTargetSize.height,
"Writing past end of output");
while (mLinesInBuffer >= filterLength) {
DownscaleInputLine();
if (mCurrentOutLine == mTargetSize.height) {
break; // We're done.
}
GetFilterOffsetAndLength(mYFilter, mCurrentOutLine,
&filterOffset, &filterLength);
}
}
mCurrentInLine += 1;
// If we're at the end of the part of the original image that has data, commit
// rows to shift us to the end.
if (mCurrentInLine == (mFrameRect.y + mFrameRect.height)) {
SkipToRow(mOriginalSize.height - 1);
}
}
bool
Downscaler::HasInvalidation() const
{
return mCurrentOutLine > mPrevInvalidatedLine;
}
DownscalerInvalidRect
Downscaler::TakeInvalidRect()
{
if (MOZ_UNLIKELY(!HasInvalidation())) {
return DownscalerInvalidRect();
}
DownscalerInvalidRect invalidRect;
// Compute the target size invalid rect.
if (mFlipVertically) {
// We need to flip it. This will implicitly flip the original size invalid
// rect, since we compute it by scaling this rect.
invalidRect.mTargetSizeRect =
IntRect(0, mTargetSize.height - mCurrentOutLine,
mTargetSize.width, mCurrentOutLine - mPrevInvalidatedLine);
} else {
invalidRect.mTargetSizeRect =
IntRect(0, mPrevInvalidatedLine,
mTargetSize.width, mCurrentOutLine - mPrevInvalidatedLine);
}
mPrevInvalidatedLine = mCurrentOutLine;
// Compute the original size invalid rect.
invalidRect.mOriginalSizeRect = invalidRect.mTargetSizeRect;
invalidRect.mOriginalSizeRect.ScaleRoundOut(mScale.width, mScale.height);
return invalidRect;
}
void
Downscaler::DownscaleInputLine()
{
typedef skia::ConvolutionFilter1D::Fixed FilterValue;
MOZ_ASSERT(mOutputBuffer);
MOZ_ASSERT(mCurrentOutLine < mTargetSize.height,
"Writing past end of output");
int32_t filterOffset = 0;
int32_t filterLength = 0;
MOZ_ASSERT(mCurrentOutLine < mYFilter->num_values());
auto filterValues =
mYFilter->FilterForValue(mCurrentOutLine, &filterOffset, &filterLength);
int32_t currentOutLine = mFlipVertically
? mTargetSize.height - (mCurrentOutLine + 1)
: mCurrentOutLine;
MOZ_ASSERT(currentOutLine >= 0);
uint8_t* outputLine =
&mOutputBuffer[currentOutLine * mTargetSize.width * sizeof(uint32_t)];
skia::ConvolveVertically(static_cast<const FilterValue*>(filterValues),
filterLength, mWindow.get(), mXFilter->num_values(),
outputLine, mHasAlpha, supports_sse2() || supports_mmi());
mCurrentOutLine += 1;
if (mCurrentOutLine == mTargetSize.height) {
// We're done.
return;
}
int32_t newFilterOffset = 0;
int32_t newFilterLength = 0;
GetFilterOffsetAndLength(mYFilter, mCurrentOutLine,
&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.
mLinesInBuffer -= diff;
mLinesInBuffer = min(max(mLinesInBuffer, 0), mWindowCapacity);
// If we already have enough rows to satisfy the filter, there is no need
// to swap as we won't be writing more before the next convolution.
if (filterLength > mLinesInBuffer) {
for (int32_t i = 0; i < mLinesInBuffer; ++i) {
swap(mWindow[i], mWindow[filterLength - mLinesInBuffer + i]);
}
}
}
} // namespace image
} // namespace mozilla
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