tenfourfox/gfx/layers/ImageDataSerializer.cpp

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2017-04-19 07:56:45 +00:00
/* -*- Mode: C++; tab-width: 20; 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 "ImageDataSerializer.h"
#include "gfx2DGlue.h" // for SurfaceFormatToImageFormat
#include "mozilla/gfx/Point.h" // for IntSize
#include "mozilla/Assertions.h" // for MOZ_ASSERT, etc
#include "mozilla/gfx/2D.h" // for DataSourceSurface, Factory
#include "mozilla/gfx/Logging.h" // for gfxDebug
#include "mozilla/gfx/Tools.h" // for GetAlignedStride, etc
#include "mozilla/mozalloc.h" // for operator delete, etc
namespace mozilla {
namespace layers {
using namespace gfx;
// The Data is layed out as follows:
//
// +-------------------+ -++ --+ <-- ImageDataSerializerBase::mData pointer
// | SurfaceBufferInfo | | |
// +-------------------+ --+ | offset
// | ... | |
// +-------------------+ ------+
// | |
// | data |
// | |
// +-------------------+
// Structure written at the beginning of the data blob containing the image
// (as shown in the figure above). It contains the necessary informations to
// read the image in the blob.
namespace {
struct SurfaceBufferInfo
{
int32_t width;
int32_t height;
SurfaceFormat format;
static int32_t GetOffset()
{
return GetAlignedStride<16>(sizeof(SurfaceBufferInfo));
}
};
} // namespace
static SurfaceBufferInfo*
GetBufferInfo(uint8_t* aData, size_t aDataSize)
{
return aDataSize >= sizeof(SurfaceBufferInfo)
? reinterpret_cast<SurfaceBufferInfo*>(aData)
: nullptr;
}
void
ImageDataSerializer::InitializeBufferInfo(IntSize aSize,
SurfaceFormat aFormat)
{
SurfaceBufferInfo* info = GetBufferInfo(mData, mDataSize);
MOZ_ASSERT(info); // OK to assert here, this method is client-side-only
info->width = aSize.width;
info->height = aSize.height;
info->format = aFormat;
Validate();
}
static inline int32_t
ComputeStride(SurfaceFormat aFormat, int32_t aWidth)
{
CheckedInt<int32_t> size = BytesPerPixel(aFormat);
size *= aWidth;
if (!size.isValid() || size.value() <= 0) {
gfxDebug() << "ComputeStride overflow " << aWidth;
return 0;
}
return GetAlignedStride<4>(size.value());
}
uint32_t
ImageDataSerializerBase::ComputeMinBufferSize(IntSize aSize,
SurfaceFormat aFormat)
{
MOZ_ASSERT(aSize.height >= 0 && aSize.width >= 0);
// This takes care of checking whether there could be overflow
// with enough margin for the metadata.
if (!gfx::Factory::AllowedSurfaceSize(aSize)) {
return 0;
}
int32_t bufsize = GetAlignedStride<16>(ComputeStride(aFormat, aSize.width)
* aSize.height)
+ SurfaceBufferInfo::GetOffset();
if (bufsize < 0) {
// This should not be possible thanks to Factory::AllowedSurfaceSize
return 0;
}
return bufsize;
}
void
ImageDataSerializerBase::Validate()
{
mIsValid = false;
if (!mData) {
return;
}
SurfaceBufferInfo* info = GetBufferInfo(mData, mDataSize);
if (!info) {
return;
}
size_t requiredSize =
ComputeMinBufferSize(IntSize(info->width, info->height), info->format);
mIsValid = !!requiredSize && requiredSize <= mDataSize;
}
uint8_t*
ImageDataSerializerBase::GetData()
{
MOZ_ASSERT(IsValid());
return mData + SurfaceBufferInfo::GetOffset();
}
uint32_t
ImageDataSerializerBase::GetStride() const
{
MOZ_ASSERT(IsValid());
SurfaceBufferInfo* info = GetBufferInfo(mData, mDataSize);
return ComputeStride(GetFormat(), info->width);
}
IntSize
ImageDataSerializerBase::GetSize() const
{
MOZ_ASSERT(IsValid());
SurfaceBufferInfo* info = GetBufferInfo(mData, mDataSize);
return IntSize(info->width, info->height);
}
SurfaceFormat
ImageDataSerializerBase::GetFormat() const
{
MOZ_ASSERT(IsValid());
return GetBufferInfo(mData, mDataSize)->format;
}
already_AddRefed<DrawTarget>
ImageDataSerializerBase::GetAsDrawTarget(gfx::BackendType aBackend)
{
MOZ_ASSERT(IsValid());
RefPtr<DrawTarget> dt = gfx::Factory::CreateDrawTargetForData(aBackend,
GetData(), GetSize(),
GetStride(), GetFormat());
if (!dt) {
gfxCriticalNote << "Failed GetAsDrawTarget " << IsValid() << ", " << hexa(size_t(mData)) << " + " << SurfaceBufferInfo::GetOffset() << ", " << GetSize() << ", " << GetStride() << ", " << (int)GetFormat();
}
return dt.forget();
}
already_AddRefed<gfx::DataSourceSurface>
ImageDataSerializerBase::GetAsSurface()
{
MOZ_ASSERT(IsValid());
return Factory::CreateWrappingDataSourceSurface(GetData(),
GetStride(),
GetSize(),
GetFormat());
}
} // namespace layers
} // namespace mozilla