dom/canvas/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 class nsIGlobalObject;
  19
  20 namespace mozilla {
  21 namespace dom {
  22
  23 class EncodingRunnable;
  24
  25 class ImageEncoder
  26 {
  27 public:
  28   // Extracts data synchronously and gives you a stream containing the image
  29   // represented by aContext. aType may change to "image/png" if we had to fall
  30   // back to a PNG encoder. A return value of NS_OK implies successful data
  31   // extraction. If there are any unrecognized custom parse options in
  32   // aOptions, NS_ERROR_INVALID_ARG will be returned. When encountering this
  33   // error it is usual to call this function again without any options at all.
  34   static nsresult ExtractData(nsAString& aType,
  35                               const nsAString& aOptions,
  36                               const nsIntSize aSize,
  37                               nsICanvasRenderingContextInternal* aContext,
  38                               nsIInputStream** aStream);
  39
  40   // Extracts data asynchronously. aType may change to "image/png" if we had to
  41   // fall back to a PNG encoder. aOptions are the options to be passed to the
  42   // encoder and aUsingCustomOptions specifies whether custom parse options were
  43   // used (i.e. by using -moz-parse-options). If there are any unrecognized
  44   // custom parse options, we fall back to the default values for the encoder
  45   // without any options at all. A return value of NS_OK only implies
  46   // successful dispatching of the extraction step to the encoding thread.
  47   static nsresult ExtractDataAsync(nsAString& aType,
  48                                    const nsAString& aOptions,
  49                                    bool aUsingCustomOptions,
  50                                    uint8_t* aImageBuffer,
  51                                    int32_t aFormat,
  52                                    const nsIntSize aSize,
  53                                    nsICanvasRenderingContextInternal* aContext,
  54                                    nsIGlobalObject* aGlobal,
  55                                    FileCallback& aCallback);
  56
  57   // Gives you a stream containing the image represented by aImageBuffer.
  58   // The format is given in aFormat, for example
  59   // imgIEncoder::INPUT_FORMAT_HOSTARGB.
  60   static nsresult GetInputStream(int32_t aWidth,
  61                                  int32_t aHeight,
  62                                  uint8_t* aImageBuffer,
  63                                  int32_t aFormat,
  64                                  imgIEncoder* aEncoder,
  65                                  const char16_t* aEncoderOptions,
  66                                  nsIInputStream** aStream);
  67
  68 private:
  69   // When called asynchronously, aContext is null.
  70   static nsresult
  71   ExtractDataInternal(const nsAString& aType,
  72                       const nsAString& aOptions,
  73                       uint8_t* aImageBuffer,
  74                       int32_t aFormat,
  75                       const nsIntSize aSize,
  76                       nsICanvasRenderingContextInternal* aContext,
  77                       nsIInputStream** aStream,
  78                       imgIEncoder* aEncoder);
  79
  80   // Creates and returns an encoder instance of the type specified in aType.
  81   // aType may change to "image/png" if no instance of the original type could
  82   // be created and we had to fall back to a PNG encoder. A null return value
  83   // should be interpreted as NS_IMAGELIB_ERROR_NO_ENCODER and aType is
  84   // undefined in this case.
  85   static already_AddRefed<imgIEncoder> GetImageEncoder(nsAString& aType);
  86
  87   friend class EncodingRunnable;
  88 };
  89
  90 } // namespace dom
  91 } // namespace mozilla
  92
  93 #endif // ImageEncoder_h