diff -r 000000000000 -r 6474c204b198 image/encoders/png/nsPNGEncoder.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/image/encoders/png/nsPNGEncoder.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,82 @@
+/* -*- 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/. */
+
+#include "mozilla/Attributes.h"
+#include "mozilla/ReentrantMonitor.h"
+
+#include "imgIEncoder.h"
+
+#include "nsCOMPtr.h"
+
+#include <png.h>
+
+#define NS_PNGENCODER_CID \
+{ /* 38d1592e-b81e-432b-86f8-471878bbfe07 */         \
+     0x38d1592e,                                     \
+     0xb81e,                                         \
+     0x432b,                                         \
+    {0x86, 0xf8, 0x47, 0x18, 0x78, 0xbb, 0xfe, 0x07} \
+}
+
+// Provides PNG encoding functionality. Use InitFromData() to do the
+// encoding. See that function definition for encoding options.
+
+class nsPNGEncoder MOZ_FINAL : public imgIEncoder
+{
+  typedef mozilla::ReentrantMonitor ReentrantMonitor;
+public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_IMGIENCODER
+  NS_DECL_NSIINPUTSTREAM
+  NS_DECL_NSIASYNCINPUTSTREAM
+
+  nsPNGEncoder();
+  ~nsPNGEncoder();
+
+protected:
+  nsresult ParseOptions(const nsAString& aOptions,
+                        bool* useTransparency,
+                        bool* skipFirstFrame,
+                        uint32_t* numAnimatedFrames,
+                        uint32_t* numIterations,
+                        uint32_t* frameDispose,
+                        uint32_t* frameBlend,
+                        uint32_t* frameDelay,
+                        uint32_t* offsetX,
+                        uint32_t* offsetY);
+  void ConvertHostARGBRow(const uint8_t* aSrc, uint8_t* aDest,
+                          uint32_t aPixelWidth, bool aUseTransparency);
+  void StripAlpha(const uint8_t* aSrc, uint8_t* aDest,
+                  uint32_t aPixelWidth);
+  static void WarningCallback(png_structp png_ptr, png_const_charp warning_msg);
+  static void ErrorCallback(png_structp png_ptr, png_const_charp error_msg);
+  static void WriteCallback(png_structp png, png_bytep data, png_size_t size);
+  void NotifyListener();
+
+  png_struct* mPNG;
+  png_info* mPNGinfo;
+
+  bool mIsAnimation;
+  bool mFinished;
+
+  // image buffer
+  uint8_t* mImageBuffer;
+  uint32_t mImageBufferSize;
+  uint32_t mImageBufferUsed;
+
+  uint32_t mImageBufferReadPoint;
+
+  nsCOMPtr<nsIInputStreamCallback> mCallback;
+  nsCOMPtr<nsIEventTarget> mCallbackTarget;
+  uint32_t mNotifyThreshold;
+
+  /*
+    nsPNGEncoder is designed to allow one thread to pump data into it while another
+    reads from it.  We lock to ensure that the buffer remains append-only while
+    we read from it (that it is not realloced) and to ensure that only one thread
+    dispatches a callback for each call to AsyncWait.
+   */
+  ReentrantMonitor mReentrantMonitor;
+};