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1 /** | |
2 ** Copyright 2006, The Android Open Source Project | |
3 ** | |
4 ** Licensed under the Apache License, Version 2.0 (the "License"); | |
5 ** you may not use this file except in compliance with the License. | |
6 ** You may obtain a copy of the License at | |
7 ** | |
8 ** http://www.apache.org/licenses/LICENSE-2.0 | |
9 ** | |
10 ** Unless required by applicable law or agreed to in writing, software | |
11 ** distributed under the License is distributed on an "AS IS" BASIS, | |
12 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
13 ** See the License for the specific language governing permissions and | |
14 ** limitations under the License. | |
15 */ | |
16 | |
17 #include "SkImageDecoder.h" | |
18 #include "SkColor.h" | |
19 #include "SkColorPriv.h" | |
20 #include "SkMath.h" | |
21 #include "SkStream.h" | |
22 #include "SkTemplates.h" | |
23 #include "SkUtils.h" | |
24 | |
25 class SkWBMPImageDecoder : public SkImageDecoder { | |
26 public: | |
27 virtual Format getFormat() const { | |
28 return kWBMP_Format; | |
29 } | |
30 | |
31 protected: | |
32 virtual bool onDecode(SkStream* stream, SkBitmap* bm, | |
33 SkBitmap::Config pref, Mode); | |
34 }; | |
35 | |
36 static bool read_byte(SkStream* stream, uint8_t* data) | |
37 { | |
38 return stream->read(data, 1) == 1; | |
39 } | |
40 | |
41 static bool read_mbf(SkStream* stream, int* value) | |
42 { | |
43 int n = 0; | |
44 uint8_t data; | |
45 do { | |
46 if (!read_byte(stream, &data)) { | |
47 return false; | |
48 } | |
49 n = (n << 7) | (data & 0x7F); | |
50 } while (data & 0x80); | |
51 | |
52 *value = n; | |
53 return true; | |
54 } | |
55 | |
56 struct wbmp_head { | |
57 int fWidth; | |
58 int fHeight; | |
59 | |
60 bool init(SkStream* stream) | |
61 { | |
62 uint8_t data; | |
63 | |
64 if (!read_byte(stream, &data) || data != 0) { // unknown type | |
65 return false; | |
66 } | |
67 if (!read_byte(stream, &data) || (data & 0x9F)) { // skip fixed header | |
68 return false; | |
69 } | |
70 if (!read_mbf(stream, &fWidth) || (unsigned)fWidth > 0xFFFF) { | |
71 return false; | |
72 } | |
73 if (!read_mbf(stream, &fHeight) || (unsigned)fHeight > 0xFFFF) { | |
74 return false; | |
75 } | |
76 return fWidth != 0 && fHeight != 0; | |
77 } | |
78 }; | |
79 | |
80 SkImageDecoder* SkImageDecoder_WBMP_Factory(SkStream* stream) | |
81 { | |
82 wbmp_head head; | |
83 | |
84 if (head.init(stream)) { | |
85 return SkNEW(SkWBMPImageDecoder); | |
86 } | |
87 return NULL; | |
88 } | |
89 | |
90 static void expand_bits_to_bytes(uint8_t dst[], const uint8_t src[], int bits) | |
91 { | |
92 int bytes = bits >> 3; | |
93 | |
94 for (int i = 0; i < bytes; i++) { | |
95 unsigned mask = *src++; | |
96 dst[0] = (mask >> 7) & 1; | |
97 dst[1] = (mask >> 6) & 1; | |
98 dst[2] = (mask >> 5) & 1; | |
99 dst[3] = (mask >> 4) & 1; | |
100 dst[4] = (mask >> 3) & 1; | |
101 dst[5] = (mask >> 2) & 1; | |
102 dst[6] = (mask >> 1) & 1; | |
103 dst[7] = (mask >> 0) & 1; | |
104 dst += 8; | |
105 } | |
106 | |
107 bits &= 7; | |
108 if (bits > 0) { | |
109 unsigned mask = *src; | |
110 do { | |
111 *dst++ = (mask >> 7) & 1;; | |
112 mask <<= 1; | |
113 } while (--bits != 0); | |
114 } | |
115 } | |
116 | |
117 #define SkAlign8(x) (((x) + 7) & ~7) | |
118 | |
119 bool SkWBMPImageDecoder::onDecode(SkStream* stream, SkBitmap* decodedBitmap, | |
120 SkBitmap::Config prefConfig, Mode mode) | |
121 { | |
122 wbmp_head head; | |
123 | |
124 if (!head.init(stream)) { | |
125 return false; | |
126 } | |
127 | |
128 int width = head.fWidth; | |
129 int height = head.fHeight; | |
130 | |
131 // assign these directly, in case we return kDimensions_Result | |
132 decodedBitmap->setConfig(SkBitmap::kIndex8_Config, width, height); | |
133 decodedBitmap->setIsOpaque(true); | |
134 | |
135 if (SkImageDecoder::kDecodeBounds_Mode == mode) | |
136 return true; | |
137 | |
138 const SkPMColor colors[] = { SK_ColorBLACK, SK_ColorWHITE }; | |
139 SkColorTable* ct = SkNEW_ARGS(SkColorTable, (colors, 2)); | |
140 SkAutoUnref aur(ct); | |
141 | |
142 if (!this->allocPixelRef(decodedBitmap, ct)) { | |
143 return false; | |
144 } | |
145 | |
146 SkAutoLockPixels alp(*decodedBitmap); | |
147 | |
148 uint8_t* dst = decodedBitmap->getAddr8(0, 0); | |
149 // store the 1-bit valuess at the end of our pixels, so we won't stomp | |
150 // on them before we're read them. Just trying to avoid a temp allocation | |
151 size_t srcRB = SkAlign8(width) >> 3; | |
152 size_t srcSize = height * srcRB; | |
153 uint8_t* src = dst + decodedBitmap->getSize() - srcSize; | |
154 if (stream->read(src, srcSize) != srcSize) { | |
155 return false; | |
156 } | |
157 | |
158 for (int y = 0; y < height; y++) | |
159 { | |
160 expand_bits_to_bytes(dst, src, width); | |
161 dst += decodedBitmap->rowBytes(); | |
162 src += srcRB; | |
163 } | |
164 | |
165 return true; | |
166 } | |
167 | |
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