gecko-dev/gfx/2d/SourceSurfaceSkia.cpp

/* -*- 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 SkImage::MakeRasterData(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 = SkImage::MakeRasterData(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());
    mStride = pixmap.rowBytes();
  } else if (aFormat != SurfaceFormat::UNKNOWN) {
    mFormat = aFormat;
    SkImageInfo info = MakeSkiaImageInfo(mSize, mFormat);
    mStride = GetAlignedStride<4>(info.width(), info.bytesPerPixel());
    if (!mStride) {
      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