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
18 class SkPKMImageDecoder : public SkImageDecoder {
19 public:
SkPKMImageDecoder()20 SkPKMImageDecoder() { }
21
getFormat() const22 virtual Format getFormat() const SK_OVERRIDE {
23 return kPKM_Format;
24 }
25
26 protected:
27 virtual bool onDecode(SkStream* stream, SkBitmap* bm, Mode) SK_OVERRIDE;
28
29 private:
30 typedef SkImageDecoder INHERITED;
31 };
32
33 /////////////////////////////////////////////////////////////////////////////////////////
34
onDecode(SkStream * stream,SkBitmap * bm,Mode mode)35 bool 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 /////////////////////////////////////////////////////////////////////////////////////////
106 DEFINE_DECODER_CREATOR(PKMImageDecoder);
107 /////////////////////////////////////////////////////////////////////////////////////////
108
is_pkm(SkStreamRewindable * stream)109 static 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
sk_libpkm_dfactory(SkStreamRewindable * stream)119 static SkImageDecoder* sk_libpkm_dfactory(SkStreamRewindable* stream) {
120 if (is_pkm(stream)) {
121 return SkNEW(SkPKMImageDecoder);
122 }
123 return NULL;
124 }
125
126 static SkImageDecoder_DecodeReg gReg(sk_libpkm_dfactory);
127
get_format_pkm(SkStreamRewindable * stream)128 static 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
135 static SkImageDecoder_FormatReg gFormatReg(get_format_pkm);
136