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#include "SkColorPriv.h"
9#include "SkImageDecoder.h"
10#include "SkScaledBitmapSampler.h"
11#include "SkStream.h"
12#include "SkStreamPriv.h"
13#include "SkTextureCompressor.h"
14#include "SkTypes.h"
15
16#include "etc1.h"
17
18class SkPKMImageDecoder : public SkImageDecoder {
19public:
20    SkPKMImageDecoder() { }
21
22    virtual Format getFormat() const SK_OVERRIDE {
23        return kPKM_Format;
24    }
25
26protected:
27    virtual bool onDecode(SkStream* stream, SkBitmap* bm, Mode) SK_OVERRIDE;
28
29private:
30    typedef SkImageDecoder INHERITED;
31};
32
33/////////////////////////////////////////////////////////////////////////////////////////
34
35bool SkPKMImageDecoder::onDecode(SkStream* stream, SkBitmap* bm, Mode mode) {
36    SkAutoMalloc autoMal;
37    const size_t length = SkCopyStreamToStorage(&autoMal, stream);
38    if (0 == length) {
39        return false;
40    }
41
42    unsigned char* buf = (unsigned char*)autoMal.get();
43
44    // Make sure original PKM header is there...
45    SkASSERT(etc1_pkm_is_valid(buf));
46
47    const unsigned short width = etc1_pkm_get_width(buf);
48    const unsigned short height = etc1_pkm_get_height(buf);
49
50#ifdef SK_SUPPORT_LEGACY_IMAGEDECODER_CHOOSER
51    // should we allow the Chooser (if present) to pick a config for us???
52    if (!this->chooseFromOneChoice(kN32_SkColorType, width, height)) {
53        return false;
54    }
55#endif
56
57    // Setup the sampler...
58    SkScaledBitmapSampler sampler(width, height, this->getSampleSize());
59
60    // Set the config...
61    bm->setInfo(SkImageInfo::MakeN32(sampler.scaledWidth(), sampler.scaledHeight(),
62                                     kOpaque_SkAlphaType));
63    if (SkImageDecoder::kDecodeBounds_Mode == mode) {
64        return true;
65    }
66
67    if (!this->allocPixelRef(bm, NULL)) {
68        return false;
69    }
70
71    // Lock the pixels, since we're about to write to them...
72    SkAutoLockPixels alp(*bm);
73
74    if (!sampler.begin(bm, SkScaledBitmapSampler::kRGB, *this)) {
75        return false;
76    }
77
78    // Advance buffer past the header
79    buf += ETC_PKM_HEADER_SIZE;
80
81    // ETC1 Data is encoded as RGB pixels, so we should extract it as such
82    int nPixels = width * height;
83    SkAutoMalloc outRGBData(nPixels * 3);
84    uint8_t *outRGBDataPtr = reinterpret_cast<uint8_t *>(outRGBData.get());
85
86    // Decode ETC1
87    if (!SkTextureCompressor::DecompressBufferFromFormat(
88            outRGBDataPtr, width*3, buf, width, height, SkTextureCompressor::kETC1_Format)) {
89        return false;
90    }
91
92    // Set each of the pixels...
93    const int srcRowBytes = width * 3;
94    const int dstHeight = sampler.scaledHeight();
95    const uint8_t *srcRow = reinterpret_cast<uint8_t *>(outRGBDataPtr);
96    srcRow += sampler.srcY0() * srcRowBytes;
97    for (int y = 0; y < dstHeight; ++y) {
98        sampler.next(srcRow);
99        srcRow += sampler.srcDY() * srcRowBytes;
100    }
101
102    return true;
103}
104
105/////////////////////////////////////////////////////////////////////////////////////////
106DEFINE_DECODER_CREATOR(PKMImageDecoder);
107/////////////////////////////////////////////////////////////////////////////////////////
108
109static bool is_pkm(SkStreamRewindable* stream) {
110    // Read the PKM header and make sure it's valid.
111    unsigned char buf[ETC_PKM_HEADER_SIZE];
112    if (stream->read((void*)buf, ETC_PKM_HEADER_SIZE) != ETC_PKM_HEADER_SIZE) {
113        return false;
114    }
115
116    return SkToBool(etc1_pkm_is_valid(buf));
117}
118
119static SkImageDecoder* sk_libpkm_dfactory(SkStreamRewindable* stream) {
120    if (is_pkm(stream)) {
121        return SkNEW(SkPKMImageDecoder);
122    }
123    return NULL;
124}
125
126static SkImageDecoder_DecodeReg gReg(sk_libpkm_dfactory);
127
128static SkImageDecoder::Format get_format_pkm(SkStreamRewindable* stream) {
129    if (is_pkm(stream)) {
130        return SkImageDecoder::kPKM_Format;
131    }
132    return SkImageDecoder::kUnknown_Format;
133}
134
135static SkImageDecoder_FormatReg gFormatReg(get_format_pkm);
136