gecko-dev/dom/base/ImageEncoder.h
Chung-Sheng Fu de8dc32c1d Bug 967895 - Add an option to return a placeholder when extracting image data (Tor 6253). r=jrmuizel
MozReview-Commit-ID: 1zTOUL7CZ1E

--HG--
extra : rebase_source : cf522bc68eddb54ea5d2fa1964de9c45f89d275f
2017-08-22 11:12:49 +08:00

143 lines
5.9 KiB
C++

/* -*- 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/. */
#ifndef ImageEncoder_h
#define ImageEncoder_h
#include "imgIEncoder.h"
#include "nsError.h"
#include "mozilla/dom/File.h"
#include "mozilla/dom/HTMLCanvasElementBinding.h"
#include "mozilla/UniquePtr.h"
#include "nsLayoutUtils.h"
#include "nsSize.h"
class nsICanvasRenderingContextInternal;
class nsIThreadPool;
namespace mozilla {
namespace layers {
class AsyncCanvasRenderer;
class Image;
} // namespace layers
namespace dom {
class EncodeCompleteCallback;
class EncodingRunnable;
class ImageEncoder
{
public:
// Extracts data synchronously and gives you a stream containing the image
// represented by aContext. aType may change to "image/png" if we had to fall
// back to a PNG encoder. A return value of NS_OK implies successful data
// extraction. If there are any unrecognized custom parse options in
// aOptions, NS_ERROR_INVALID_ARG will be returned. When encountering this
// error it is usual to call this function again without any options at all.
static nsresult ExtractData(nsAString& aType,
const nsAString& aOptions,
const nsIntSize aSize,
bool aUsePlaceholder,
nsICanvasRenderingContextInternal* aContext,
layers::AsyncCanvasRenderer* aRenderer,
nsIInputStream** aStream);
// Extracts data asynchronously. aType may change to "image/png" if we had to
// fall back to a PNG encoder. aOptions are the options to be passed to the
// encoder and aUsingCustomOptions specifies whether custom parse options were
// used (i.e. by using -moz-parse-options). If there are any unrecognized
// custom parse options, we fall back to the default values for the encoder
// without any options at all. A return value of NS_OK only implies
// successful dispatching of the extraction step to the encoding thread.
// aEncodeCallback will be called on main thread when encoding process is
// success.
// Note: The callback has to set a valid parent for content for the generated
// Blob object.
static nsresult ExtractDataAsync(nsAString& aType,
const nsAString& aOptions,
bool aUsingCustomOptions,
UniquePtr<uint8_t[]> aImageBuffer,
int32_t aFormat,
const nsIntSize aSize,
bool aUsePlaceholder,
EncodeCompleteCallback* aEncodeCallback);
// Extract an Image asynchronously. Its function is same as ExtractDataAsync
// except for the parameters. aImage is the uncompressed data. aEncodeCallback
// will be called on main thread when encoding process is success.
// Note: The callback has to set a valid parent for content for the generated
// Blob object.
static nsresult ExtractDataFromLayersImageAsync(nsAString& aType,
const nsAString& aOptions,
bool aUsingCustomOptions,
layers::Image* aImage,
bool aUsePlaceholder,
EncodeCompleteCallback* aEncodeCallback);
// Gives you a stream containing the image represented by aImageBuffer.
// The format is given in aFormat, for example
// imgIEncoder::INPUT_FORMAT_HOSTARGB.
static nsresult GetInputStream(int32_t aWidth,
int32_t aHeight,
uint8_t* aImageBuffer,
int32_t aFormat,
imgIEncoder* aEncoder,
const char16_t* aEncoderOptions,
nsIInputStream** aStream);
private:
// When called asynchronously, aContext and aRenderer are null.
static nsresult
ExtractDataInternal(const nsAString& aType,
const nsAString& aOptions,
uint8_t* aImageBuffer,
int32_t aFormat,
const nsIntSize aSize,
bool aUsePlaceholder,
layers::Image* aImage,
nsICanvasRenderingContextInternal* aContext,
layers::AsyncCanvasRenderer* aRenderer,
nsIInputStream** aStream,
imgIEncoder* aEncoder);
// Creates and returns an encoder instance of the type specified in aType.
// aType may change to "image/png" if no instance of the original type could
// be created and we had to fall back to a PNG encoder. A null return value
// should be interpreted as NS_IMAGELIB_ERROR_NO_ENCODER and aType is
// undefined in this case.
static already_AddRefed<imgIEncoder> GetImageEncoder(nsAString& aType);
static nsresult EnsureThreadPool();
// Thread pool for dispatching EncodingRunnable.
static StaticRefPtr<nsIThreadPool> sThreadPool;
friend class EncodingRunnable;
friend class EncoderThreadPoolTerminator;
};
/**
* The callback interface of ExtractDataAsync and ExtractDataFromLayersImageAsync.
* ReceiveBlob() is called on main thread when encoding is complete.
*/
class EncodeCompleteCallback
{
public:
NS_INLINE_DECL_THREADSAFE_REFCOUNTING(EncodeCompleteCallback)
virtual nsresult ReceiveBlob(already_AddRefed<Blob> aBlob) = 0;
protected:
virtual ~EncodeCompleteCallback() {}
};
} // namespace dom
} // namespace mozilla
#endif // ImageEncoder_h