1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
|
/*
* Copyright 2015 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkCodec.h"
#include "SkCodecPriv.h"
#include "SkColorPriv.h"
#include "SkColorTable.h"
#include "SkData.h"
#include "SkStream.h"
#include "SkWbmpCodec.h"
// Each bit represents a pixel, so width is actually a number of bits.
// A row will always be stored in bytes, so we round width up to the
// nearest multiple of 8 to get the number of bits actually in the row.
// We then divide by 8 to convert to bytes.
static inline size_t get_src_row_bytes(int width) {
return SkAlign8(width) >> 3;
}
static inline void setup_color_table(SkColorType colorType,
SkPMColor* colorPtr, int* colorCount) {
if (kIndex_8_SkColorType == colorType) {
colorPtr[0] = SK_ColorBLACK;
colorPtr[1] = SK_ColorWHITE;
*colorCount = 2;
}
}
static inline bool valid_color_type(SkColorType colorType) {
switch (colorType) {
case kRGBA_8888_SkColorType:
case kBGRA_8888_SkColorType:
case kIndex_8_SkColorType:
case kGray_8_SkColorType:
case kRGB_565_SkColorType:
return true;
default:
return false;
}
}
static bool read_byte(SkStream* stream, uint8_t* data)
{
return stream->read(data, 1) == 1;
}
// http://en.wikipedia.org/wiki/Variable-length_quantity
static bool read_mbf(SkStream* stream, uint64_t* value) {
uint64_t n = 0;
uint8_t data;
const uint64_t kLimit = 0xFE00000000000000;
SkASSERT(kLimit == ~((~static_cast<uint64_t>(0)) >> 7));
do {
if (n & kLimit) { // Will overflow on shift by 7.
return false;
}
if (stream->read(&data, 1) != 1) {
return false;
}
n = (n << 7) | (data & 0x7F);
} while (data & 0x80);
*value = n;
return true;
}
static bool read_header(SkStream* stream, SkISize* size) {
{
uint8_t data;
if (!read_byte(stream, &data) || data != 0) { // unknown type
return false;
}
if (!read_byte(stream, &data) || (data & 0x9F)) { // skip fixed header
return false;
}
}
uint64_t width, height;
if (!read_mbf(stream, &width) || width > 0xFFFF || !width) {
return false;
}
if (!read_mbf(stream, &height) || height > 0xFFFF || !height) {
return false;
}
if (size) {
*size = SkISize::Make(SkToS32(width), SkToS32(height));
}
return true;
}
bool SkWbmpCodec::onRewind() {
return read_header(this->stream(), nullptr);
}
SkSwizzler* SkWbmpCodec::initializeSwizzler(const SkImageInfo& info, const SkPMColor* ctable,
const Options& opts) {
return SkSwizzler::CreateSwizzler(this->getEncodedInfo(), ctable, info, opts);
}
bool SkWbmpCodec::readRow(uint8_t* row) {
return this->stream()->read(row, fSrcRowBytes) == fSrcRowBytes;
}
SkWbmpCodec::SkWbmpCodec(int width, int height, const SkEncodedInfo& info, SkStream* stream)
: INHERITED(width, height, info, stream)
, fSrcRowBytes(get_src_row_bytes(this->getInfo().width()))
, fSwizzler(nullptr)
, fColorTable(nullptr)
{}
SkEncodedFormat SkWbmpCodec::onGetEncodedFormat() const {
return kWBMP_SkEncodedFormat;
}
SkCodec::Result SkWbmpCodec::onGetPixels(const SkImageInfo& info,
void* dst,
size_t rowBytes,
const Options& options,
SkPMColor ctable[],
int* ctableCount,
int* rowsDecoded) {
if (options.fSubset) {
// Subsets are not supported.
return kUnimplemented;
}
if (!valid_color_type(info.colorType()) ||
!valid_alpha(info.alphaType(), this->getInfo().alphaType())) {
return kInvalidConversion;
}
// Prepare a color table if necessary
setup_color_table(info.colorType(), ctable, ctableCount);
// Initialize the swizzler
SkAutoTDelete<SkSwizzler> swizzler(this->initializeSwizzler(info, ctable, options));
SkASSERT(swizzler);
// Perform the decode
SkISize size = info.dimensions();
SkAutoTMalloc<uint8_t> src(fSrcRowBytes);
void* dstRow = dst;
for (int y = 0; y < size.height(); ++y) {
if (!this->readRow(src.get())) {
*rowsDecoded = y;
return kIncompleteInput;
}
swizzler->swizzle(dstRow, src.get());
dstRow = SkTAddOffset<void>(dstRow, rowBytes);
}
return kSuccess;
}
bool SkWbmpCodec::IsWbmp(const void* buffer, size_t bytesRead) {
SkMemoryStream stream(buffer, bytesRead, false);
return read_header(&stream, nullptr);
}
SkCodec* SkWbmpCodec::NewFromStream(SkStream* stream) {
SkAutoTDelete<SkStream> streamDeleter(stream);
SkISize size;
if (!read_header(stream, &size)) {
return nullptr;
}
SkEncodedInfo info = SkEncodedInfo::Make(SkEncodedInfo::kGray_Color,
SkEncodedInfo::kOpaque_Alpha, 1);
return new SkWbmpCodec(size.width(), size.height(), info, streamDeleter.release());
}
int SkWbmpCodec::onGetScanlines(void* dst, int count, size_t dstRowBytes) {
void* dstRow = dst;
for (int y = 0; y < count; ++y) {
if (!this->readRow(fSrcBuffer.get())) {
return y;
}
fSwizzler->swizzle(dstRow, fSrcBuffer.get());
dstRow = SkTAddOffset<void>(dstRow, dstRowBytes);
}
return count;
}
bool SkWbmpCodec::onSkipScanlines(int count) {
const size_t bytesToSkip = count * fSrcRowBytes;
return this->stream()->skip(bytesToSkip) == bytesToSkip;
}
SkCodec::Result SkWbmpCodec::onStartScanlineDecode(const SkImageInfo& dstInfo,
const Options& options, SkPMColor inputColorTable[], int* inputColorCount) {
if (options.fSubset) {
// Subsets are not supported.
return kUnimplemented;
}
if (!valid_color_type(dstInfo.colorType()) ||
!valid_alpha(dstInfo.alphaType(), this->getInfo().alphaType())) {
return kInvalidConversion;
}
// Fill in the color table
setup_color_table(dstInfo.colorType(), inputColorTable, inputColorCount);
// Copy the color table to a pointer that can be owned by the scanline decoder
if (kIndex_8_SkColorType == dstInfo.colorType()) {
fColorTable.reset(new SkColorTable(inputColorTable, 2));
}
// Initialize the swizzler
fSwizzler.reset(this->initializeSwizzler(dstInfo, get_color_ptr(fColorTable.get()), options));
SkASSERT(fSwizzler);
fSrcBuffer.reset(fSrcRowBytes);
return kSuccess;
}
|
