gecko-dev/dom/canvas/ImageUtils.h
Kaku Kuo c4341b59cc Bug 1141979 - part7 - implement ImageUtils; r=jrmuizel
MozReview-Commit-ID: INrfdqBr4m4

--HG--
extra : transplant_source : %A2%9B%B0%C3%DEX%5B%DCW%7D%94%C1Ao%04A2%E6i%FD
2016-03-21 14:33:10 +08:00

74 lines
2.2 KiB
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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* 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/. */
#ifndef mozilla_dom_ImageBitmapFormatUtils_h
#define mozilla_dom_ImageBitmapFormatUtils_h
#include "mozilla/UniquePtr.h"
#include "nsTArrayForwardDeclare.h"
namespace mozilla {
namespace layers {
class Image;
}
class ErrorResult;
namespace dom {
struct ChannelPixelLayout;
enum class ImageBitmapFormat : uint32_t;
typedef nsTArray<ChannelPixelLayout> ImagePixelLayout;
/*
* ImageUtils is a wrapper around layers::Image. It provides three unified
* methods to all sub-classes of layers::Image, which are:
*
* (1) GetFormat() converts the image's format into ImageBitmapFormat enum.
* (2) GetBufferLength() returns the number of bytes that are used to store
* the image's underlying raw data.
* (3) MapDataInto() writes the image's underlying raw data into a given
* ArrayBuffer in the given format. (If the given format is different from
* the existing format, the ImageUtils uses the ImageBitmapFormatUtils to
* performa color conversion.)
*
* In theory, the functionalities of this class could be merged into the
* interface of layers::Image. However, this is designed as a isolated wrapper
* because we don't want to pollute the layers::Image's interface with methods
* that are only meaningful to the ImageBitmap.
*/
class ImageUtils
{
public:
class Impl;
ImageUtils() = delete;
ImageUtils(const ImageUtils&) = delete;
ImageUtils(ImageUtils&&) = delete;
ImageUtils& operator=(const ImageUtils&) = delete;
ImageUtils& operator=(ImageUtils&&) = delete;
explicit ImageUtils(layers::Image* aImage);
~ImageUtils();
ImageBitmapFormat GetFormat() const;
uint32_t GetBufferLength() const;
UniquePtr<ImagePixelLayout>
MapDataInto(uint8_t* aBuffer, uint32_t aOffset, uint32_t aBufferLength,
ImageBitmapFormat aFormat, ErrorResult& aRv) const;
protected:
Impl* mImpl;
};
} // namespace dom
} // namespace mozilla
#endif /* mozilla_dom_ImageBitmapFormatUtils_h */