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 /*

  * 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