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      1 /*
      2  * Copyright 2015 Google Inc.
      3  *
      4  * Use of this source code is governed by a BSD-style license that can be
      5  * found in the LICENSE file.
      6  */
      7 
      8 #ifndef SkBitmapRegionDecoder_DEFINED
      9 #define SkBitmapRegionDecoder_DEFINED
     10 
     11 #include "SkBitmap.h"
     12 #include "SkBRDAllocator.h"
     13 #include "SkEncodedFormat.h"
     14 #include "SkStream.h"
     15 
     16 /*
     17  * This class aims to provide an interface to test multiple implementations of
     18  * SkBitmapRegionDecoder.
     19  */
     20 class SkBitmapRegionDecoder {
     21 public:
     22 
     23     enum Strategy {
     24         kCanvas_Strategy,       // Draw to the canvas, uses SkCodec
     25         kAndroidCodec_Strategy, // Uses SkAndroidCodec for scaling and subsetting
     26     };
     27 
     28     /*
     29      * @param data     Refs the data while this object exists, unrefs on destruction
     30      * @param strategy Strategy used for scaling and subsetting
     31      * @return         Tries to create an SkBitmapRegionDecoder, returns NULL on failure
     32      */
     33     static SkBitmapRegionDecoder* Create(
     34             SkData* data, Strategy strategy);
     35 
     36     /*
     37      * @param stream   Takes ownership of the stream
     38      * @param strategy Strategy used for scaling and subsetting
     39      * @return         Tries to create an SkBitmapRegionDecoder, returns NULL on failure
     40      */
     41     static SkBitmapRegionDecoder* Create(
     42             SkStreamRewindable* stream, Strategy strategy);
     43 
     44     /*
     45      * Decode a scaled region of the encoded image stream
     46      *
     47      * @param bitmap          Container for decoded pixels.  It is assumed that the pixels
     48      *                        are initially unallocated and will be allocated by this function.
     49      * @param allocator       Allocator for the pixels.  If this is NULL, the default
     50      *                        allocator (HeapAllocator) will be used.
     51      * @param desiredSubset   Subset of the original image to decode.
     52      * @param sampleSize      An integer downscaling factor for the decode.
     53      * @param colorType       Preferred output colorType.
     54      *                        New implementations should return NULL if they do not support
     55      *                        decoding to this color type.
     56      *                        The old kOriginal_Strategy will decode to a default color type
     57      *                        if this color type is unsupported.
     58      * @param requireUnpremul If the image is not opaque, we will use this to determine the
     59      *                        alpha type to use.
     60      *
     61      */
     62     virtual bool decodeRegion(SkBitmap* bitmap, SkBRDAllocator* allocator,
     63                               const SkIRect& desiredSubset, int sampleSize,
     64                               SkColorType colorType, bool requireUnpremul) = 0;
     65     /*
     66      * @param  Requested destination color type
     67      * @return true if we support the requested color type and false otherwise
     68      */
     69     virtual bool conversionSupported(SkColorType colorType) = 0;
     70 
     71     virtual SkEncodedFormat getEncodedFormat() = 0;
     72 
     73     int width() const { return fWidth; }
     74     int height() const { return fHeight; }
     75 
     76     virtual ~SkBitmapRegionDecoder() {}
     77 
     78 protected:
     79 
     80     SkBitmapRegionDecoder(int width, int height)
     81         : fWidth(width)
     82         , fHeight(height)
     83     {}
     84 
     85 private:
     86     const int fWidth;
     87     const int fHeight;
     88 };
     89 
     90 #endif
     91