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 "SkStreamHelpers.h"
16#include "SkTDArray.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 Result 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(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
47static SkImageDecoder* sk_libbmp_dfactory(SkStreamRewindable* stream) {
48    if (is_bmp(stream)) {
49        return SkNEW(SkBMPImageDecoder);
50    }
51    return NULL;
52}
53
54static SkImageDecoder_DecodeReg gReg(sk_libbmp_dfactory);
55
56static 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
63static SkImageDecoder_FormatReg 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
95SkImageDecoder::Result 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 = CopyStreamToStorage(&storage, stream);
103    if (0 == length) {
104        return kFailure;
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 kFailure;
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 kSuccess;
140    }
141
142    if (!this->allocPixelRef(bm, NULL)) {
143        return kFailure;
144    }
145
146    SkAutoLockPixels alp(*bm);
147
148    if (!sampler.begin(bm, SkScaledBitmapSampler::kRGB, *this)) {
149        return kFailure;
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 kSuccess;
162}
163