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 "SkImageDecoder.h"
12#include "SkScaledBitmapSampler.h"
13#include "SkStream.h"
14#include "SkColorPriv.h"
15#include "SkTDArray.h"
16#include "SkTRegistry.h"
17
18class SkBMPImageDecoder : public SkImageDecoder {
19public:
20    SkBMPImageDecoder() {}
21
22    virtual Format getFormat() const SK_OVERRIDE {
23        return kBMP_Format;
24    }
25
26protected:
27    virtual bool onDecode(SkStream* stream, SkBitmap* bm, Mode mode) SK_OVERRIDE;
28
29private:
30    typedef SkImageDecoder INHERITED;
31};
32
33///////////////////////////////////////////////////////////////////////////////
34DEFINE_DECODER_CREATOR(BMPImageDecoder);
35///////////////////////////////////////////////////////////////////////////////
36
37static bool is_bmp(SkStream* 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
47static SkImageDecoder* sk_libbmp_dfactory(SkStream* stream) {
48    if (is_bmp(stream)) {
49        return SkNEW(SkBMPImageDecoder);
50    }
51    return NULL;
52}
53
54static SkTRegistry<SkImageDecoder*, SkStream*> gReg(sk_libbmp_dfactory);
55
56static SkImageDecoder::Format get_format_bmp(SkStream* stream) {
57    if (is_bmp(stream)) {
58        return SkImageDecoder::kBMP_Format;
59    }
60    return SkImageDecoder::kUnknown_Format;
61}
62
63static SkTRegistry<SkImageDecoder::Format, SkStream*> gFormatReg(get_format_bmp);
64
65///////////////////////////////////////////////////////////////////////////////
66
67class SkBmpDecoderCallback : public image_codec::BmpDecoderCallback {
68public:
69    // we don't copy the bitmap, just remember the pointer
70    SkBmpDecoderCallback(bool justBounds) : fJustBounds(justBounds) {}
71
72    // override from BmpDecoderCallback
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
84    int width() const { return fWidth; }
85    int height() const { return fHeight; }
86    const uint8_t* rgb() const { return fRGB.begin(); }
87
88private:
89    SkTDArray<uint8_t> fRGB;
90    int fWidth;
91    int fHeight;
92    bool fJustBounds;
93};
94
95bool SkBMPImageDecoder::onDecode(SkStream* stream, SkBitmap* bm, Mode mode) {
96
97    size_t length = stream->getLength();
98    SkAutoMalloc storage(length);
99
100    if (stream->read(storage.get(), length) != length) {
101        return false;
102    }
103
104    const bool justBounds = SkImageDecoder::kDecodeBounds_Mode == mode;
105    SkBmpDecoderCallback callback(justBounds);
106
107    // Now decode the BMP into callback's rgb() array [r,g,b, r,g,b, ...]
108    {
109        image_codec::BmpDecoderHelper helper;
110        const int max_pixels = 16383*16383; // max width*height
111        if (!helper.DecodeImage((const char*)storage.get(), length,
112                                max_pixels, &callback)) {
113            return false;
114        }
115    }
116
117    // we don't need this anymore, so free it now (before we try to allocate
118    // the bitmap's pixels) rather than waiting for its destructor
119    storage.free();
120
121    int width = callback.width();
122    int height = callback.height();
123    SkBitmap::Config config = this->getPrefConfig(k32Bit_SrcDepth, false);
124
125    // only accept prefConfig if it makes sense for us
126    if (SkBitmap::kARGB_4444_Config != config &&
127            SkBitmap::kRGB_565_Config != config) {
128        config = SkBitmap::kARGB_8888_Config;
129    }
130
131    SkScaledBitmapSampler sampler(width, height, getSampleSize());
132
133    bm->setConfig(config, sampler.scaledWidth(), sampler.scaledHeight());
134    bm->setIsOpaque(true);
135
136    if (justBounds) {
137        return true;
138    }
139
140    if (!this->allocPixelRef(bm, NULL)) {
141        return false;
142    }
143
144    SkAutoLockPixels alp(*bm);
145
146    if (!sampler.begin(bm, SkScaledBitmapSampler::kRGB, getDitherImage())) {
147        return false;
148    }
149
150    const int srcRowBytes = width * 3;
151    const int dstHeight = sampler.scaledHeight();
152    const uint8_t* srcRow = callback.rgb();
153
154    srcRow += sampler.srcY0() * srcRowBytes;
155    for (int y = 0; y < dstHeight; y++) {
156        sampler.next(srcRow);
157        srcRow += sampler.srcDY() * srcRowBytes;
158    }
159    return true;
160}
161