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 Format getFormat() const override {
23 return kPKM_Format;
24 }
25
26 protected:
27 Result onDecode(SkStream* stream, SkBitmap* bm, Mode) override;
28
29 private:
30 typedef SkImageDecoder INHERITED;
31 };
32
33 /////////////////////////////////////////////////////////////////////////////////////////
34
onDecode(SkStream * stream,SkBitmap * bm,Mode mode)35 SkImageDecoder::Result 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 kFailure;
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 // Setup the sampler...
51 SkScaledBitmapSampler sampler(width, height, this->getSampleSize());
52
53 // Set the config...
54 bm->setInfo(SkImageInfo::MakeN32(sampler.scaledWidth(), sampler.scaledHeight(),
55 kOpaque_SkAlphaType));
56 if (SkImageDecoder::kDecodeBounds_Mode == mode) {
57 return kSuccess;
58 }
59
60 if (!this->allocPixelRef(bm, NULL)) {
61 return kFailure;
62 }
63
64 // Lock the pixels, since we're about to write to them...
65 SkAutoLockPixels alp(*bm);
66
67 if (!sampler.begin(bm, SkScaledBitmapSampler::kRGB, *this)) {
68 return kFailure;
69 }
70
71 // Advance buffer past the header
72 buf += ETC_PKM_HEADER_SIZE;
73
74 // ETC1 Data is encoded as RGB pixels, so we should extract it as such
75 int nPixels = width * height;
76 SkAutoMalloc outRGBData(nPixels * 3);
77 uint8_t *outRGBDataPtr = reinterpret_cast<uint8_t *>(outRGBData.get());
78
79 // Decode ETC1
80 if (!SkTextureCompressor::DecompressBufferFromFormat(
81 outRGBDataPtr, width*3, buf, width, height, SkTextureCompressor::kETC1_Format)) {
82 return kFailure;
83 }
84
85 // Set each of the pixels...
86 const int srcRowBytes = width * 3;
87 const int dstHeight = sampler.scaledHeight();
88 const uint8_t *srcRow = reinterpret_cast<uint8_t *>(outRGBDataPtr);
89 srcRow += sampler.srcY0() * srcRowBytes;
90 for (int y = 0; y < dstHeight; ++y) {
91 sampler.next(srcRow);
92 srcRow += sampler.srcDY() * srcRowBytes;
93 }
94
95 return kSuccess;
96 }
97
98 /////////////////////////////////////////////////////////////////////////////////////////
99 DEFINE_DECODER_CREATOR(PKMImageDecoder);
100 /////////////////////////////////////////////////////////////////////////////////////////
101
is_pkm(SkStreamRewindable * stream)102 static bool is_pkm(SkStreamRewindable* stream) {
103 // Read the PKM header and make sure it's valid.
104 unsigned char buf[ETC_PKM_HEADER_SIZE];
105 if (stream->read((void*)buf, ETC_PKM_HEADER_SIZE) != ETC_PKM_HEADER_SIZE) {
106 return false;
107 }
108
109 return SkToBool(etc1_pkm_is_valid(buf));
110 }
111
sk_libpkm_dfactory(SkStreamRewindable * stream)112 static SkImageDecoder* sk_libpkm_dfactory(SkStreamRewindable* stream) {
113 if (is_pkm(stream)) {
114 return SkNEW(SkPKMImageDecoder);
115 }
116 return NULL;
117 }
118
119 static SkImageDecoder_DecodeReg gReg(sk_libpkm_dfactory);
120
get_format_pkm(SkStreamRewindable * stream)121 static SkImageDecoder::Format get_format_pkm(SkStreamRewindable* stream) {
122 if (is_pkm(stream)) {
123 return SkImageDecoder::kPKM_Format;
124 }
125 return SkImageDecoder::kUnknown_Format;
126 }
127
128 static SkImageDecoder_FormatReg gFormatReg(get_format_pkm);
129