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:
getFormat() const27 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
read_byte(SkStream * stream,uint8_t * data)36 static bool read_byte(SkStream* stream, uint8_t* data)
37 {
38 return stream->read(data, 1) == 1;
39 }
40
read_mbf(SkStream * stream,int * value)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
initwbmp_head60 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
expand_bits_to_bytes(uint8_t dst[],const uint8_t src[],int bits)80 static void expand_bits_to_bytes(uint8_t dst[], const uint8_t src[], int bits)
81 {
82 int bytes = bits >> 3;
83
84 for (int i = 0; i < bytes; i++) {
85 unsigned mask = *src++;
86 dst[0] = (mask >> 7) & 1;
87 dst[1] = (mask >> 6) & 1;
88 dst[2] = (mask >> 5) & 1;
89 dst[3] = (mask >> 4) & 1;
90 dst[4] = (mask >> 3) & 1;
91 dst[5] = (mask >> 2) & 1;
92 dst[6] = (mask >> 1) & 1;
93 dst[7] = (mask >> 0) & 1;
94 dst += 8;
95 }
96
97 bits &= 7;
98 if (bits > 0) {
99 unsigned mask = *src;
100 do {
101 *dst++ = (mask >> 7) & 1;;
102 mask <<= 1;
103 } while (--bits != 0);
104 }
105 }
106
107 #define SkAlign8(x) (((x) + 7) & ~7)
108
onDecode(SkStream * stream,SkBitmap * decodedBitmap,SkBitmap::Config prefConfig,Mode mode)109 bool SkWBMPImageDecoder::onDecode(SkStream* stream, SkBitmap* decodedBitmap,
110 SkBitmap::Config prefConfig, Mode mode)
111 {
112 wbmp_head head;
113
114 if (!head.init(stream)) {
115 return false;
116 }
117
118 int width = head.fWidth;
119 int height = head.fHeight;
120
121 // assign these directly, in case we return kDimensions_Result
122 decodedBitmap->setConfig(SkBitmap::kIndex8_Config, width, height);
123 decodedBitmap->setIsOpaque(true);
124
125 if (SkImageDecoder::kDecodeBounds_Mode == mode)
126 return true;
127
128 const SkPMColor colors[] = { SK_ColorBLACK, SK_ColorWHITE };
129 SkColorTable* ct = SkNEW_ARGS(SkColorTable, (colors, 2));
130 SkAutoUnref aur(ct);
131
132 if (!this->allocPixelRef(decodedBitmap, ct)) {
133 return false;
134 }
135
136 SkAutoLockPixels alp(*decodedBitmap);
137
138 uint8_t* dst = decodedBitmap->getAddr8(0, 0);
139 // store the 1-bit valuess at the end of our pixels, so we won't stomp
140 // on them before we're read them. Just trying to avoid a temp allocation
141 size_t srcRB = SkAlign8(width) >> 3;
142 size_t srcSize = height * srcRB;
143 uint8_t* src = dst + decodedBitmap->getSize() - srcSize;
144 if (stream->read(src, srcSize) != srcSize) {
145 return false;
146 }
147
148 for (int y = 0; y < height; y++)
149 {
150 expand_bits_to_bytes(dst, src, width);
151 dst += decodedBitmap->rowBytes();
152 src += srcRB;
153 }
154
155 return true;
156 }
157
158 ///////////////////////////////////////////////////////////////////////////////
159
160 #include "SkTRegistry.h"
161
Factory(SkStream * stream)162 static SkImageDecoder* Factory(SkStream* stream) {
163 wbmp_head head;
164
165 if (head.init(stream)) {
166 return SkNEW(SkWBMPImageDecoder);
167 }
168 return NULL;
169 }
170
171 static SkTRegistry<SkImageDecoder*, SkStream*> gReg(Factory);
172
173