content/canvas/src/ImageEncoder.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #ifndef ImageEncoder_h
   7 #define ImageEncoder_h
   8
   9 #include "imgIEncoder.h"
  10 #include "nsDOMFile.h"
  11 #include "nsError.h"
  12 #include "mozilla/dom/HTMLCanvasElementBinding.h"
  13 #include "nsLayoutUtils.h"
  14 #include "nsNetUtil.h"
  15 #include "nsSize.h"
  16
  17 class nsICanvasRenderingContextInternal;
  18
  19 namespace mozilla {
  20 namespace dom {
  21
  22 class EncodingRunnable;
  23
  24 class ImageEncoder
  25 {
  26 public:
  27   // Extracts data synchronously and gives you a stream containing the image
  28   // represented by aContext. aType may change to "image/png" if we had to fall
  29   // back to a PNG encoder. A return value of NS_OK implies successful data
  30   // extraction. If there are any unrecognized custom parse options in
  31   // aOptions, NS_ERROR_INVALID_ARG will be returned. When encountering this
  32   // error it is usual to call this function again without any options at all.
  33   static nsresult ExtractData(nsAString& aType,
  34                               const nsAString& aOptions,
  35                               const nsIntSize aSize,
  36                               nsICanvasRenderingContextInternal* aContext,
  37                               nsIInputStream** aStream);
  38
  39   // Extracts data asynchronously. aType may change to "image/png" if we had to
  40   // fall back to a PNG encoder. aOptions are the options to be passed to the
  41   // encoder and aUsingCustomOptions specifies whether custom parse options were
  42   // used (i.e. by using -moz-parse-options). If there are any unrecognized
  43   // custom parse options, we fall back to the default values for the encoder
  44   // without any options at all. A return value of NS_OK only implies
  45   // successful dispatching of the extraction step to the encoding thread.
  46   static nsresult ExtractDataAsync(nsAString& aType,
  47                                    const nsAString& aOptions,
  48                                    bool aUsingCustomOptions,
  49                                    uint8_t* aImageBuffer,
  50                                    int32_t aFormat,
  51                                    const nsIntSize aSize,
  52                                    nsICanvasRenderingContextInternal* aContext,
  53                                    nsIScriptContext* aScriptContext,
  54                                    FileCallback& aCallback);
  55
  56   // Gives you a stream containing the image represented by aImageBuffer.
  57   // The format is given in aFormat, for example
  58   // imgIEncoder::INPUT_FORMAT_HOSTARGB.
  59   static nsresult GetInputStream(int32_t aWidth,
  60                                  int32_t aHeight,
  61                                  uint8_t* aImageBuffer,
  62                                  int32_t aFormat,
  63                                  imgIEncoder* aEncoder,
  64                                  const PRUnichar* aEncoderOptions,
  65                                  nsIInputStream** aStream);
  66
  67 private:
  68   // When called asynchronously, aContext is null.
  69   static nsresult
  70   ExtractDataInternal(const nsAString& aType,
  71                       const nsAString& aOptions,
  72                       uint8_t* aImageBuffer,
  73                       int32_t aFormat,
  74                       const nsIntSize aSize,
  75                       nsICanvasRenderingContextInternal* aContext,
  76                       nsIInputStream** aStream,
  77                       imgIEncoder* aEncoder);
  78
  79   // Creates and returns an encoder instance of the type specified in aType.
  80   // aType may change to "image/png" if no instance of the original type could
  81   // be created and we had to fall back to a PNG encoder. A null return value
  82   // should be interpreted as NS_IMAGELIB_ERROR_NO_ENCODER and aType is
  83   // undefined in this case.
  84   static already_AddRefed<imgIEncoder> GetImageEncoder(nsAString& aType);
  85
  86   friend class EncodingRunnable;
  87 };
  88
  89 } // namespace dom
  90 } // namespace mozilla
  91
  92 #endif // ImageEncoder_h