diff -r 000000000000 -r 6474c204b198 content/canvas/src/ImageEncoder.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/content/canvas/src/ImageEncoder.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,95 @@
+/* -*- Mode: C++; tab-width: 2; 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/. */
+
+#ifndef ImageEncoder_h
+#define ImageEncoder_h
+
+#include "imgIEncoder.h"
+#include "nsDOMFile.h"
+#include "nsError.h"
+#include "mozilla/dom/HTMLCanvasElementBinding.h"
+#include "nsLayoutUtils.h"
+#include "nsNetUtil.h"
+#include "nsSize.h"
+
+class nsICanvasRenderingContextInternal;
+
+namespace mozilla {
+namespace dom {
+
+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,
+                              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.
+  static nsresult ExtractDataAsync(nsAString& aType,
+                                   const nsAString& aOptions,
+                                   bool aUsingCustomOptions,
+                                   uint8_t* aImageBuffer,
+                                   int32_t aFormat,
+                                   const nsIntSize aSize,
+                                   bool aUsePlaceholder,
+                                   nsICanvasRenderingContextInternal* aContext,
+                                   nsIScriptContext* aScriptContext,
+                                   FileCallback& aCallback);
+
+  // 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 is null.
+  static nsresult
+  ExtractDataInternal(const nsAString& aType,
+                      const nsAString& aOptions,
+                      uint8_t* aImageBuffer,
+                      int32_t aFormat,
+                      const nsIntSize aSize,
+                      bool aUsePlaceholder,
+                      nsICanvasRenderingContextInternal* aContext,
+                      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);
+
+  friend class EncodingRunnable;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // ImageEncoder_h