1/*
2 * Copyright 2014 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 SkTextureCompressor_DEFINED
9#define SkTextureCompressor_DEFINED
10
11#include "SkBitmapProcShader.h"
12#include "SkImageInfo.h"
13
14class SkBitmap;
15class SkBlitter;
16class SkData;
17
18namespace SkTextureCompressor {
19    // Various texture compression formats that we support.
20    enum Format {
21        // Alpha only formats.
22        kLATC_Format,       // 4x4 blocks, (de)compresses A8
23        kR11_EAC_Format,    // 4x4 blocks, (de)compresses A8
24
25        // RGB only formats
26        kETC1_Format,       // 4x4 blocks, compresses RGB 565, decompresses 8-bit RGB
27                            //    NOTE: ETC1 supports 8-bit RGB compression, but we
28                            //    currently don't have any RGB8 SkColorTypes. We could
29                            //    support 8-bit RGBA but we would have to preprocess the
30                            //    bitmap to insert alphas.
31
32        // Multi-purpose formats
33        kASTC_4x4_Format,   // 4x4 blocks, no compression, decompresses RGBA
34        kASTC_5x4_Format,   // 5x4 blocks, no compression, decompresses RGBA
35        kASTC_5x5_Format,   // 5x5 blocks, no compression, decompresses RGBA
36        kASTC_6x5_Format,   // 6x5 blocks, no compression, decompresses RGBA
37        kASTC_6x6_Format,   // 6x6 blocks, no compression, decompresses RGBA
38        kASTC_8x5_Format,   // 8x5 blocks, no compression, decompresses RGBA
39        kASTC_8x6_Format,   // 8x6 blocks, no compression, decompresses RGBA
40        kASTC_8x8_Format,   // 8x8 blocks, no compression, decompresses RGBA
41        kASTC_10x5_Format,  // 10x5 blocks, no compression, decompresses RGBA
42        kASTC_10x6_Format,  // 10x6 blocks, no compression, decompresses RGBA
43        kASTC_10x8_Format,  // 10x8 blocks, no compression, decompresses RGBA
44        kASTC_10x10_Format, // 10x10 blocks, no compression, decompresses RGBA
45        kASTC_12x10_Format, // 12x10 blocks, no compression, decompresses RGBA
46        kASTC_12x12_Format, // 12x12 blocks, compresses A8, decompresses RGBA
47
48        kLast_Format = kASTC_12x12_Format
49    };
50    static const int kFormatCnt = kLast_Format + 1;
51
52    // Returns the size of the compressed data given the width, height, and
53    // desired compression format. If the width and height are not an appropriate
54    // multiple of the block size, then this function returns an error (-1).
55    int GetCompressedDataSize(Format fmt, int width, int height);
56
57    // Returns an SkData holding a blob of compressed data that corresponds
58    // to the bitmap. If the bitmap colorType cannot be compressed using the
59    // associated format, then we return NULL. The caller is responsible for
60    // calling unref() on the returned data.
61    SkData* CompressBitmapToFormat(const SkBitmap& bitmap, Format format);
62
63    // Compresses the given src data into dst. The src data is assumed to be
64    // large enough to hold width*height pixels. The dst data is expected to
65    // be large enough to hold the compressed data according to the format.
66    bool CompressBufferToFormat(uint8_t* dst, const uint8_t* src, SkColorType srcColorType,
67                                int width, int height, int rowBytes, Format format,
68                                bool opt = true /* Use optimization if available */);
69
70    // Decompresses the given src data from the format specified into the
71    // destination buffer. The width and height of the data passed corresponds
72    // to the width and height of the uncompressed image. The destination buffer (dst)
73    // is assumed to be large enough to hold the entire decompressed image. The
74    // decompressed image colors are determined based on the passed format.
75    //
76    // Note, CompressBufferToFormat compresses A8 data into ASTC. However,
77    // general ASTC data encodes RGBA data, so that is what the decompressor
78    // operates on.
79    //
80    // Returns true if successfully decompresses the src data.
81    bool DecompressBufferFromFormat(uint8_t* dst, int dstRowBytes, const uint8_t* src,
82                                    int width, int height, Format format);
83
84    // This typedef defines what the nominal aspects of a compression function
85    // are. The typedef is not meant to be used by clients of the API, but rather
86    // allows SIMD optimized compression functions to be implemented.
87    typedef bool (*CompressionProc)(uint8_t* dst, const uint8_t* src,
88                                    int width, int height, int rowBytes);
89
90    // Returns true if there exists a blitter for the specified format.
91    inline bool ExistsBlitterForFormat(Format format) {
92        switch (format) {
93            case kLATC_Format:
94            case kR11_EAC_Format:
95            case kASTC_12x12_Format:
96                return true;
97
98            default:
99                return false;
100        }
101    }
102
103    // Returns the blitter for the given compression format. Note, the blitter
104    // is intended to be used with the proper input. I.e. if you try to blit
105    // RGB source data into an R11 EAC texture, you're gonna have a bad time.
106    SkBlitter* CreateBlitterForFormat(int width, int height, void* compressedBuffer,
107                                      SkTBlitterAllocator *allocator, Format format);
108
109    // Returns the desired dimensions of the block size for the given format. These dimensions
110    // don't necessarily correspond to the specification's dimensions, since there may
111    // be specialized algorithms that operate on multiple blocks at once. If the
112    // flag 'matchSpec' is true, then the actual dimensions from the specification are
113    // returned. If the flag is false, then these dimensions reflect the appropriate operable
114    // dimensions of the compression functions.
115    void GetBlockDimensions(Format format, int* dimX, int* dimY, bool matchSpec = false);
116}
117
118#endif
119