diff -r 000000000000 -r 6474c204b198 gfx/skia/trunk/src/images/SkDecodingImageGenerator.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gfx/skia/trunk/src/images/SkDecodingImageGenerator.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,140 @@
+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkDecodingImageGenerator_DEFINED
+#define SkDecodingImageGenerator_DEFINED
+
+#include "SkBitmap.h"
+#include "SkImageGenerator.h"
+
+class SkData;
+class SkStreamRewindable;
+
+/**
+ *  An implementation of SkImageGenerator that calls into
+ *  SkImageDecoder.
+ */
+class SkDecodingImageGenerator : public SkImageGenerator {
+public:
+    virtual ~SkDecodingImageGenerator();
+    virtual SkData* refEncodedData() SK_OVERRIDE;
+    // This implementaion of getInfo() always returns true.
+    virtual bool getInfo(SkImageInfo* info) SK_OVERRIDE;
+    virtual bool getPixels(const SkImageInfo& info,
+                           void* pixels,
+                           size_t rowBytes) SK_OVERRIDE;
+    /**
+     *  These options will be passed on to the image decoder.  The
+     *  defaults are sensible.
+     *
+     *  @param fSampleSize If set to > 1, tells the decoder to return a
+     *         smaller than original bitmap, sampling 1 pixel for
+     *         every size pixels. e.g. if sample size is set to 3,
+     *         then the returned bitmap will be 1/3 as wide and high,
+     *         and will contain 1/9 as many pixels as the original.
+     *         Note: this is a hint, and the codec may choose to
+     *         ignore this, or only approximate the sample size.
+     *
+     *  @param fDitherImage Set to true if the the decoder should try to
+     *         dither the resulting image when decoding to a smaller
+     *         color-space.  The default is true.
+     *
+     *  @param fRequestedColorType If not given, then use whichever
+     *         config the decoder wants.  Else try to use this color
+     *         type.  If the decoder won't support this color type,
+     *         SkDecodingImageGenerator::Create will return
+     *         NULL. kIndex_8_SkColorType is not supported.
+     */
+    struct Options {
+        Options()
+            : fSampleSize(1)
+            , fDitherImage(true)
+            , fUseRequestedColorType(false)
+            , fRequestedColorType() { }
+        Options(int sampleSize, bool dither)
+            : fSampleSize(sampleSize)
+            , fDitherImage(dither)
+            , fUseRequestedColorType(false)
+            , fRequestedColorType() { }
+        Options(int sampleSize, bool dither, SkColorType colorType)
+            : fSampleSize(sampleSize)
+            , fDitherImage(dither)
+            , fUseRequestedColorType(true)
+            , fRequestedColorType(colorType) { }
+        const int         fSampleSize;
+        const bool        fDitherImage;
+        const bool        fUseRequestedColorType;
+        const SkColorType fRequestedColorType;
+    };
+
+    /**
+     *  These two functions return a SkImageGenerator that calls into
+     *  SkImageDecoder.  They return NULL on failure.
+     *
+     *  The SkData version of this function is preferred.  If the stream
+     *  has an underlying SkData (such as a SkMemoryStream) pass that in.
+     *
+     *  This object will unref the stream when done or on failure.  Since
+     *  streams have internal state (position), the caller should not pass
+     *  a shared stream in.  Pass either a new duplicated stream in or
+     *  transfer ownership of the stream.  This factory asserts
+     *  stream->unique().
+     *
+     *  For example:
+     *    SkStreamRewindable* stream;
+     *    ...
+     *    SkImageGenerator* gen
+     *        = SkDecodingImageGenerator::Create(
+     *            stream->duplicate(), SkDecodingImageGenerator::Options());
+     *    ...
+     *    SkDELETE(gen);
+     *
+     *  @param Options (see above)
+     *
+     *  @return NULL on failure, a new SkImageGenerator on success.
+     */
+    static SkImageGenerator* Create(SkStreamRewindable* stream,
+                                    const Options& opt);
+
+    /**
+     *  @param data Contains the encoded image data that will be used by
+     *         the SkDecodingImageGenerator.  Will be ref()ed by the
+     *         SkImageGenerator constructor and and unref()ed on deletion.
+     */
+    static SkImageGenerator* Create(SkData* data, const Options& opt);
+
+private:
+    SkData*                fData;
+    SkStreamRewindable*    fStream;
+    const SkImageInfo      fInfo;
+    const int              fSampleSize;
+    const bool             fDitherImage;
+
+    SkDecodingImageGenerator(SkData* data,
+                             SkStreamRewindable* stream,
+                             const SkImageInfo& info,
+                             int sampleSize,
+                             bool ditherImage);
+    static SkImageGenerator* Create(SkData*, SkStreamRewindable*,
+                                    const Options&);
+    typedef SkImageGenerator INHERITED;
+};
+
+//  // Example of most basic use case:
+//
+//  bool install_data(SkData* data, SkBitmap* dst) {
+//     return SkInstallDiscardablePixelRef(
+//         SkDecodingImageGenerator::Create(
+//             data, SkDecodingImageGenerator::Options()), dst, NULL);
+//  }
+//  bool install_stream(SkStreamRewindable* stream, SkBitmap* dst) {
+//     return SkInstallDiscardablePixelRef(
+//         SkDecodingImageGenerator::Create(
+//             stream, SkDecodingImageGenerator::Options()), dst, NULL);
+//  }
+
+#endif  // SkDecodingImageGenerator_DEFINED