1
2 /*
3 * Copyright 2006 The Android Open Source Project
4 *
5 * Use of this source code is governed by a BSD-style license that can be
6 * found in the LICENSE file.
7 */
8
9
10 #include "SkImageDecoder.h"
11 #include "SkColor.h"
12 #include "SkColorPriv.h"
13 #include "SkMath.h"
14 #include "SkStream.h"
15 #include "SkTemplates.h"
16 #include "SkUtils.h"
17
18 class SkWBMPImageDecoder : public SkImageDecoder {
19 public:
getFormat() const20 Format getFormat() const override {
21 return kWBMP_Format;
22 }
23
24 protected:
25 Result onDecode(SkStream* stream, SkBitmap* bm, Mode) override;
26
27 private:
28 typedef SkImageDecoder INHERITED;
29 };
30
read_byte(SkStream * stream,uint8_t * data)31 static bool read_byte(SkStream* stream, uint8_t* data)
32 {
33 return stream->read(data, 1) == 1;
34 }
35
read_mbf(SkStream * stream,int * value)36 static bool read_mbf(SkStream* stream, int* value)
37 {
38 int n = 0;
39 uint8_t data;
40 do {
41 if (!read_byte(stream, &data)) {
42 return false;
43 }
44 n = (n << 7) | (data & 0x7F);
45 } while (data & 0x80);
46
47 *value = n;
48 return true;
49 }
50
51 struct wbmp_head {
52 int fWidth;
53 int fHeight;
54
initwbmp_head55 bool init(SkStream* stream)
56 {
57 uint8_t data;
58
59 if (!read_byte(stream, &data) || data != 0) { // unknown type
60 return false;
61 }
62 if (!read_byte(stream, &data) || (data & 0x9F)) { // skip fixed header
63 return false;
64 }
65 if (!read_mbf(stream, &fWidth) || (unsigned)fWidth > 0xFFFF) {
66 return false;
67 }
68 if (!read_mbf(stream, &fHeight) || (unsigned)fHeight > 0xFFFF) {
69 return false;
70 }
71 return fWidth != 0 && fHeight != 0;
72 }
73 };
74
expand_bits_to_bytes(uint8_t dst[],const uint8_t src[],int bits)75 static void expand_bits_to_bytes(uint8_t dst[], const uint8_t src[], int bits)
76 {
77 int bytes = bits >> 3;
78
79 for (int i = 0; i < bytes; i++) {
80 unsigned mask = *src++;
81 dst[0] = (mask >> 7) & 1;
82 dst[1] = (mask >> 6) & 1;
83 dst[2] = (mask >> 5) & 1;
84 dst[3] = (mask >> 4) & 1;
85 dst[4] = (mask >> 3) & 1;
86 dst[5] = (mask >> 2) & 1;
87 dst[6] = (mask >> 1) & 1;
88 dst[7] = (mask >> 0) & 1;
89 dst += 8;
90 }
91
92 bits &= 7;
93 if (bits > 0) {
94 unsigned mask = *src;
95 do {
96 *dst++ = (mask >> 7) & 1;
97 mask <<= 1;
98 } while (--bits != 0);
99 }
100 }
101
onDecode(SkStream * stream,SkBitmap * decodedBitmap,Mode mode)102 SkImageDecoder::Result SkWBMPImageDecoder::onDecode(SkStream* stream, SkBitmap* decodedBitmap,
103 Mode mode)
104 {
105 wbmp_head head;
106
107 if (!head.init(stream)) {
108 return kFailure;
109 }
110
111 int width = head.fWidth;
112 int height = head.fHeight;
113
114 decodedBitmap->setInfo(SkImageInfo::Make(width, height,
115 kIndex_8_SkColorType, kOpaque_SkAlphaType));
116
117 if (SkImageDecoder::kDecodeBounds_Mode == mode) {
118 return kSuccess;
119 }
120
121 const SkPMColor colors[] = { SK_ColorBLACK, SK_ColorWHITE };
122 SkColorTable* ct = SkNEW_ARGS(SkColorTable, (colors, 2));
123 SkAutoUnref aur(ct);
124
125 if (!this->allocPixelRef(decodedBitmap, ct)) {
126 return kFailure;
127 }
128
129 SkAutoLockPixels alp(*decodedBitmap);
130
131 uint8_t* dst = decodedBitmap->getAddr8(0, 0);
132 // store the 1-bit valuess at the end of our pixels, so we won't stomp
133 // on them before we're read them. Just trying to avoid a temp allocation
134 size_t srcRB = SkAlign8(width) >> 3;
135 size_t srcSize = height * srcRB;
136 uint8_t* src = dst + decodedBitmap->getSize() - srcSize;
137 if (stream->read(src, srcSize) != srcSize) {
138 return kFailure;
139 }
140
141 for (int y = 0; y < height; y++)
142 {
143 expand_bits_to_bytes(dst, src, width);
144 dst += decodedBitmap->rowBytes();
145 src += srcRB;
146 }
147
148 return kSuccess;
149 }
150
151 ///////////////////////////////////////////////////////////////////////////////
152 DEFINE_DECODER_CREATOR(WBMPImageDecoder);
153 ///////////////////////////////////////////////////////////////////////////////
154
sk_wbmp_dfactory(SkStreamRewindable * stream)155 static SkImageDecoder* sk_wbmp_dfactory(SkStreamRewindable* stream) {
156 wbmp_head head;
157
158 if (head.init(stream)) {
159 return SkNEW(SkWBMPImageDecoder);
160 }
161 return NULL;
162 }
163
get_format_wbmp(SkStreamRewindable * stream)164 static SkImageDecoder::Format get_format_wbmp(SkStreamRewindable* stream) {
165 wbmp_head head;
166 if (head.init(stream)) {
167 return SkImageDecoder::kWBMP_Format;
168 }
169 return SkImageDecoder::kUnknown_Format;
170 }
171
172 static SkImageDecoder_DecodeReg gDReg(sk_wbmp_dfactory);
173 static SkImageDecoder_FormatReg gFormatReg(get_format_wbmp);
174