tor-browser

SourceSurfaceSkia.cpp (7482B)

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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/. */

#include "Logging.h"
#include "SourceSurfaceSkia.h"
#include "HelpersSkia.h"
#include "DrawTargetSkia.h"
#include "skia/include/core/SkData.h"
#include "skia/include/core/SkImage.h"
#include "skia/include/core/SkSurface.h"
#include "skia/include/private/base/SkMalloc.h"
#include "mozilla/CheckedInt.h"

namespace mozilla::gfx {

SourceSurfaceSkia::SourceSurfaceSkia()
   : mFormat(SurfaceFormat::UNKNOWN),
     mStride(0),
     mDrawTarget(nullptr),
     mChangeMutex("SourceSurfaceSkia::mChangeMutex"),
     mIsMapped(false) {}

SourceSurfaceSkia::~SourceSurfaceSkia() {
 // if mIsMapped is true then mChangeMutex will be locked
 // which will cause problems during destruction.
 MOZ_RELEASE_ASSERT(!mIsMapped);
}

IntSize SourceSurfaceSkia::GetSize() const { return mSize; }

SurfaceFormat SourceSurfaceSkia::GetFormat() const { return mFormat; }

// This is only ever called by the DT destructor, which can only ever happen
// from one place at a time. Therefore it doesn't need to hold the ChangeMutex
// as mSurface is never read to directly and is just there to keep the object
// alive, which itself is refcounted in a thread-safe manner.
void SourceSurfaceSkia::GiveSurface(SkSurface* aSurface) {
 mSurface.reset(aSurface);
 mDrawTarget = nullptr;
}

sk_sp<SkImage> SourceSurfaceSkia::GetImage(Maybe<MutexAutoLock>* aLock) {
 // If we were provided a lock object, we can let the caller access
 // a shared SkImage and we know it won't go away while the lock is held.
 // Otherwise we need to call DrawTargetWillChange to ensure we have our
 // own SkImage.
 if (aLock) {
   MOZ_ASSERT(aLock->isNothing());
   aLock->emplace(mChangeMutex);

   // Now that we are locked, we can check mDrawTarget. If it's null, then
   // we're not shared and we can unlock eagerly.
   if (!mDrawTarget) {
     aLock->reset();
   }
 } else {
   DrawTargetWillChange();
 }
 sk_sp<SkImage> image = mImage;
 return image;
}

static sk_sp<SkData> MakeSkData(void* aData, int32_t aHeight, size_t aStride) {
 CheckedInt<size_t> size = aStride;
 size *= aHeight;
 if (size.isValid()) {
   void* mem = sk_malloc_flags(size.value(), 0);
   if (mem) {
     if (aData) {
       memcpy(mem, aData, size.value());
     }
     return SkData::MakeFromMalloc(mem, size.value());
   }
 }
 return nullptr;
}

static sk_sp<SkImage> ReadSkImage(const sk_sp<SkImage>& aImage,
                                 const SkImageInfo& aInfo, size_t aStride,
                                 int aX = 0, int aY = 0) {
 if (sk_sp<SkData> data = MakeSkData(nullptr, aInfo.height(), aStride)) {
   if (aImage->readPixels(aInfo, data->writable_data(), aStride, aX, aY,
                          SkImage::kDisallow_CachingHint)) {
     return SkImages::RasterFromData(aInfo, data, aStride);
   }
 }
 return nullptr;
}

bool SourceSurfaceSkia::InitFromData(unsigned char* aData, const IntSize& aSize,
                                    int32_t aStride, SurfaceFormat aFormat) {
 sk_sp<SkData> data = MakeSkData(aData, aSize.height, aStride);
 if (!data) {
   return false;
 }

 SkImageInfo info = MakeSkiaImageInfo(aSize, aFormat);
 mImage = SkImages::RasterFromData(info, data, aStride);
 if (!mImage) {
   return false;
 }

 mSize = aSize;
 mFormat = aFormat;
 mStride = aStride;
 return true;
}

bool SourceSurfaceSkia::InitFromImage(const sk_sp<SkImage>& aImage,
                                     SurfaceFormat aFormat,
                                     DrawTargetSkia* aOwner) {
 if (!aImage) {
   return false;
 }

 mSize = IntSize(aImage->width(), aImage->height());

 // For the raster image case, we want to use the format and stride
 // information that the underlying raster image is using, which is
 // reliable.
 // For the GPU case (for which peekPixels is false), we can't easily
 // figure this information out. It is better to report the originally
 // intended format and stride that we will convert to if this GPU
 // image is ever read back into a raster image.
 SkPixmap pixmap;
 if (aImage->peekPixels(&pixmap)) {
   mFormat =
       aFormat != SurfaceFormat::UNKNOWN
           ? aFormat
           : SkiaColorTypeToGfxFormat(pixmap.colorType(), pixmap.alphaType());
   if (pixmap.info().bytesPerPixel() != BytesPerPixel(mFormat)) {
     return false;
   }
   mStride = pixmap.rowBytes();
 } else if (aFormat != SurfaceFormat::UNKNOWN) {
   mFormat = aFormat;
   const SkImageInfo& info = aImage->imageInfo();
   if (info.bytesPerPixel() != BytesPerPixel(mFormat)) {
     return false;
   }
   mStride = GetAlignedStride<4>(info.width(), info.bytesPerPixel());
   if (mStride <= 0 || size_t(mStride) < info.minRowBytes64()) {
     return false;
   }
 } else {
   return false;
 }

 mImage = aImage;

 if (aOwner) {
   mDrawTarget = aOwner;
 }

 return true;
}

already_AddRefed<SourceSurface> SourceSurfaceSkia::ExtractSubrect(
   const IntRect& aRect) {
 if (!mImage || aRect.IsEmpty() || !GetRect().Contains(aRect)) {
   return nullptr;
 }
 SkImageInfo info = MakeSkiaImageInfo(aRect.Size(), mFormat);
 size_t stride = GetAlignedStride<4>(info.width(), info.bytesPerPixel());
 if (!stride) {
   return nullptr;
 }
 sk_sp<SkImage> subImage = ReadSkImage(mImage, info, stride, aRect.x, aRect.y);
 if (!subImage) {
   return nullptr;
 }
 RefPtr<SourceSurfaceSkia> surface = new SourceSurfaceSkia;
 if (!surface->InitFromImage(subImage)) {
   return nullptr;
 }
 return surface.forget().downcast<SourceSurface>();
}

uint8_t* SourceSurfaceSkia::GetData() {
 if (!mImage) {
   return nullptr;
 }
 SkPixmap pixmap;
 if (!mImage->peekPixels(&pixmap)) {
   gfxCriticalError() << "Failed accessing pixels for Skia raster image";
 }
 return reinterpret_cast<uint8_t*>(pixmap.writable_addr());
}

bool SourceSurfaceSkia::Map(MapType, MappedSurface* aMappedSurface)
   MOZ_NO_THREAD_SAFETY_ANALYSIS {
 mChangeMutex.Lock();
 aMappedSurface->mData = GetData();
 aMappedSurface->mStride = Stride();
 mIsMapped = !!aMappedSurface->mData;
 bool isMapped = mIsMapped;
 if (!mIsMapped) {
   mChangeMutex.Unlock();
 }
 // Static analysis will warn due to a conditional Unlock
 MOZ_PUSH_IGNORE_THREAD_SAFETY
 return isMapped;
 MOZ_POP_THREAD_SAFETY
}

void SourceSurfaceSkia::Unmap() MOZ_NO_THREAD_SAFETY_ANALYSIS {
 mChangeMutex.AssertCurrentThreadOwns();
 MOZ_ASSERT(mIsMapped);
 mIsMapped = false;
 mChangeMutex.Unlock();
}

void SourceSurfaceSkia::DrawTargetWillChange() {
 MutexAutoLock lock(mChangeMutex);
 if (mDrawTarget.exchange(nullptr)) {
   // Raster snapshots do not use Skia's internal copy-on-write mechanism,
   // so we need to do an explicit copy here.
   // GPU snapshots, for which peekPixels is false, will already be dealt
   // with automatically via the internal copy-on-write mechanism, so we
   // don't need to do anything for them here.
   SkPixmap pixmap;
   if (mImage->peekPixels(&pixmap)) {
     mImage = ReadSkImage(mImage, pixmap.info(), pixmap.rowBytes());
     if (!mImage) {
       gfxCriticalError() << "Failed copying Skia raster snapshot";
     }
   }
 }
}

}  // namespace mozilla::gfx