1
2 /*
3 * Copyright 2007 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 "bmpdecoderhelper.h"
11 #include "SkColorPriv.h"
12 #include "SkImageDecoder.h"
13 #include "SkScaledBitmapSampler.h"
14 #include "SkStream.h"
15 #include "SkStreamPriv.h"
16 #include "SkTDArray.h"
17
18 class SkBMPImageDecoder : public SkImageDecoder {
19 public:
SkBMPImageDecoder()20 SkBMPImageDecoder() {}
21
getFormat() const22 virtual Format getFormat() const SK_OVERRIDE {
23 return kBMP_Format;
24 }
25
26 protected:
27 virtual bool onDecode(SkStream* stream, SkBitmap* bm, Mode mode) SK_OVERRIDE;
28
29 private:
30 typedef SkImageDecoder INHERITED;
31 };
32
33 ///////////////////////////////////////////////////////////////////////////////
34 DEFINE_DECODER_CREATOR(BMPImageDecoder);
35 ///////////////////////////////////////////////////////////////////////////////
36
is_bmp(SkStreamRewindable * stream)37 static bool is_bmp(SkStreamRewindable* stream) {
38 static const char kBmpMagic[] = { 'B', 'M' };
39
40
41 char buffer[sizeof(kBmpMagic)];
42
43 return stream->read(buffer, sizeof(kBmpMagic)) == sizeof(kBmpMagic) &&
44 !memcmp(buffer, kBmpMagic, sizeof(kBmpMagic));
45 }
46
sk_libbmp_dfactory(SkStreamRewindable * stream)47 static SkImageDecoder* sk_libbmp_dfactory(SkStreamRewindable* stream) {
48 if (is_bmp(stream)) {
49 return SkNEW(SkBMPImageDecoder);
50 }
51 return NULL;
52 }
53
54 static SkImageDecoder_DecodeReg gReg(sk_libbmp_dfactory);
55
get_format_bmp(SkStreamRewindable * stream)56 static SkImageDecoder::Format get_format_bmp(SkStreamRewindable* stream) {
57 if (is_bmp(stream)) {
58 return SkImageDecoder::kBMP_Format;
59 }
60 return SkImageDecoder::kUnknown_Format;
61 }
62
63 static SkImageDecoder_FormatReg gFormatReg(get_format_bmp);
64
65 ///////////////////////////////////////////////////////////////////////////////
66
67 class SkBmpDecoderCallback : public image_codec::BmpDecoderCallback {
68 public:
69 // we don't copy the bitmap, just remember the pointer
SkBmpDecoderCallback(bool justBounds)70 SkBmpDecoderCallback(bool justBounds) : fJustBounds(justBounds) {}
71
72 // override from BmpDecoderCallback
SetSize(int width,int height)73 virtual uint8* SetSize(int width, int height) {
74 fWidth = width;
75 fHeight = height;
76 if (fJustBounds) {
77 return NULL;
78 }
79
80 fRGB.setCount(width * height * 3); // 3 == r, g, b
81 return fRGB.begin();
82 }
83
width() const84 int width() const { return fWidth; }
height() const85 int height() const { return fHeight; }
rgb() const86 const uint8_t* rgb() const { return fRGB.begin(); }
87
88 private:
89 SkTDArray<uint8_t> fRGB;
90 int fWidth;
91 int fHeight;
92 bool fJustBounds;
93 };
94
onDecode(SkStream * stream,SkBitmap * bm,Mode mode)95 bool SkBMPImageDecoder::onDecode(SkStream* stream, SkBitmap* bm, Mode mode) {
96 // First read the entire stream, so that all of the data can be passed to
97 // the BmpDecoderHelper.
98
99 // Allocated space used to hold the data.
100 SkAutoMalloc storage;
101 // Byte length of all of the data.
102 const size_t length = SkCopyStreamToStorage(&storage, stream);
103 if (0 == length) {
104 return 0;
105 }
106
107 const bool justBounds = SkImageDecoder::kDecodeBounds_Mode == mode;
108 SkBmpDecoderCallback callback(justBounds);
109
110 // Now decode the BMP into callback's rgb() array [r,g,b, r,g,b, ...]
111 {
112 image_codec::BmpDecoderHelper helper;
113 const int max_pixels = 16383*16383; // max width*height
114 if (!helper.DecodeImage((const char*)storage.get(), length,
115 max_pixels, &callback)) {
116 return false;
117 }
118 }
119
120 // we don't need this anymore, so free it now (before we try to allocate
121 // the bitmap's pixels) rather than waiting for its destructor
122 storage.free();
123
124 int width = callback.width();
125 int height = callback.height();
126 SkColorType colorType = this->getPrefColorType(k32Bit_SrcDepth, false);
127
128 // only accept prefConfig if it makes sense for us
129 if (kARGB_4444_SkColorType != colorType && kRGB_565_SkColorType != colorType) {
130 colorType = kN32_SkColorType;
131 }
132
133 SkScaledBitmapSampler sampler(width, height, getSampleSize());
134
135 bm->setInfo(SkImageInfo::Make(sampler.scaledWidth(), sampler.scaledHeight(),
136 colorType, kOpaque_SkAlphaType));
137
138 if (justBounds) {
139 return true;
140 }
141
142 if (!this->allocPixelRef(bm, NULL)) {
143 return false;
144 }
145
146 SkAutoLockPixels alp(*bm);
147
148 if (!sampler.begin(bm, SkScaledBitmapSampler::kRGB, *this)) {
149 return false;
150 }
151
152 const int srcRowBytes = width * 3;
153 const int dstHeight = sampler.scaledHeight();
154 const uint8_t* srcRow = callback.rgb();
155
156 srcRow += sampler.srcY0() * srcRowBytes;
157 for (int y = 0; y < dstHeight; y++) {
158 sampler.next(srcRow);
159 srcRow += sampler.srcDY() * srcRowBytes;
160 }
161 return true;
162 }
163