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 "SkEncodedImageFormat.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         kAndroidCodec_Strategy, // Uses SkAndroidCodec for scaling and subsetting
25     };
26 
27     /*
28      * @param data     Refs the data while this object exists, unrefs on destruction
29      * @param strategy Strategy used for scaling and subsetting
30      * @return         Tries to create an SkBitmapRegionDecoder, returns NULL on failure
31      */
32     static SkBitmapRegionDecoder* Create(sk_sp<SkData>, Strategy strategy);
33 
34     /*
35      * @param stream   Takes ownership of the stream
36      * @param strategy Strategy used for scaling and subsetting
37      * @return         Tries to create an SkBitmapRegionDecoder, returns NULL on failure
38      */
39     static SkBitmapRegionDecoder* Create(
40             SkStreamRewindable* stream, Strategy strategy);
41 
42     /*
43      * Decode a scaled region of the encoded image stream
44      *
45      * @param bitmap          Container for decoded pixels.  It is assumed that the pixels
46      *                        are initially unallocated and will be allocated by this function.
47      * @param allocator       Allocator for the pixels.  If this is NULL, the default
48      *                        allocator (HeapAllocator) will be used.
49      * @param desiredSubset   Subset of the original image to decode.
50      * @param sampleSize      An integer downscaling factor for the decode.
51      * @param colorType       Preferred output colorType.
52      *                        New implementations should return NULL if they do not support
53      *                        decoding to this color type.
54      *                        The old kOriginal_Strategy will decode to a default color type
55      *                        if this color type is unsupported.
56      * @param requireUnpremul If the image is not opaque, we will use this to determine the
57      *                        alpha type to use.
58      * @param prefColorSpace  If non-null and supported, this is the color space that we will
59      *                        decode into.  Otherwise, we will choose a default.
60      *
61      */
62     virtual bool decodeRegion(SkBitmap* bitmap, SkBRDAllocator* allocator,
63                               const SkIRect& desiredSubset, int sampleSize,
64                               SkColorType colorType, bool requireUnpremul,
65                               sk_sp<SkColorSpace> prefColorSpace = nullptr) = 0;
66     /*
67      * @param  Requested destination color type
68      * @return true if we support the requested color type and false otherwise
69      */
70     virtual bool conversionSupported(SkColorType colorType) = 0;
71 
72     virtual SkEncodedImageFormat getEncodedFormat() = 0;
73 
74     virtual SkColorType computeOutputColorType(SkColorType requestedColorType) = 0;
75 
76     virtual sk_sp<SkColorSpace> computeOutputColorSpace(SkColorType outputColorType,
77             sk_sp<SkColorSpace> prefColorSpace = nullptr) = 0;
78 
79 
width()80     int width() const { return fWidth; }
height()81     int height() const { return fHeight; }
82 
~SkBitmapRegionDecoder()83     virtual ~SkBitmapRegionDecoder() {}
84 
85 protected:
86 
SkBitmapRegionDecoder(int width,int height)87     SkBitmapRegionDecoder(int width, int height)
88         : fWidth(width)
89         , fHeight(height)
90     {}
91 
92 private:
93     const int fWidth;
94     const int fHeight;
95 };
96 
97 #endif
98