aboutsummaryrefslogtreecommitdiffhomepage
path: root/src/images/SkDecodingImageGenerator.cpp
blob: cdee7c16764902c31d123d047ce42afa96474cfa (plain)
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
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
/*
 * Copyright 2013 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "SkData.h"
#include "SkDecodingImageGenerator.h"
#include "SkImageDecoder.h"
#include "SkImageInfo.h"
#include "SkImageGenerator.h"
#include "SkImagePriv.h"
#include "SkStream.h"
#include "SkUtils.h"

namespace {
bool equal_modulo_alpha(const SkImageInfo& a, const SkImageInfo& b) {
    return a.width() == b.width() && a.height() == b.height() &&
           a.colorType() == b.colorType();
}

class DecodingImageGenerator : public SkImageGenerator {
public:
    virtual ~DecodingImageGenerator();

    SkData*                fData;
    SkStreamRewindable*    fStream;
    const SkImageInfo      fInfo;
    const int              fSampleSize;
    const bool             fDitherImage;

    DecodingImageGenerator(SkData* data,
                           SkStreamRewindable* stream,
                           const SkImageInfo& info,
                           int sampleSize,
                           bool ditherImage);

protected:
    virtual SkData* onRefEncodedData() SK_OVERRIDE;
    virtual bool onGetInfo(SkImageInfo* info) SK_OVERRIDE {
        *info = fInfo;
        return true;
    }
    virtual bool onGetPixels(const SkImageInfo& info,
                             void* pixels, size_t rowBytes,
                             SkPMColor ctable[], int* ctableCount) SK_OVERRIDE;
    virtual bool onGetYUV8Planes(SkISize sizes[3], void* planes[3], size_t rowBytes[3],
                                 SkYUVColorSpace* colorSpace) SK_OVERRIDE;

private:
    typedef SkImageGenerator INHERITED;
};

/**
 *  Special allocator used by getPixels(). Uses preallocated memory
 *  provided if possible, else fall-back on the default allocator
 */
class TargetAllocator : public SkBitmap::Allocator {
public:
    TargetAllocator(const SkImageInfo& info,
                    void* target,
                    size_t rowBytes)
        : fInfo(info)
        , fTarget(target)
        , fRowBytes(rowBytes)
    {}

    bool isReady() { return (fTarget != NULL); }

    virtual bool allocPixelRef(SkBitmap* bm, SkColorTable* ct) {
        if (NULL == fTarget || !equal_modulo_alpha(fInfo, bm->info())) {
            // Call default allocator.
            return bm->tryAllocPixels(NULL, ct);
        }

        // TODO(halcanary): verify that all callers of this function
        // will respect new RowBytes.  Will be moot once rowbytes belongs
        // to PixelRef.
        bm->installPixels(fInfo, fTarget, fRowBytes, ct, NULL, NULL);

        fTarget = NULL;  // never alloc same pixels twice!
        return true;
    }

private:
    const SkImageInfo fInfo;
    void* fTarget;  // Block of memory to be supplied as pixel memory
                    // in allocPixelRef.  Must be large enough to hold
                    // a bitmap described by fInfo and fRowBytes
    const size_t fRowBytes;  // rowbytes for the destination bitmap

    typedef SkBitmap::Allocator INHERITED;
};

// TODO(halcanary): Give this macro a better name and move it into SkTypes.h
#ifdef SK_DEBUG
    #define SkCheckResult(expr, value)  SkASSERT((value) == (expr))
#else
    #define SkCheckResult(expr, value)  (void)(expr)
#endif

#ifdef SK_DEBUG
inline bool check_alpha(SkAlphaType reported, SkAlphaType actual) {
    return ((reported == actual)
            || ((reported == kPremul_SkAlphaType)
                && (actual == kOpaque_SkAlphaType)));
}
#endif  // SK_DEBUG

////////////////////////////////////////////////////////////////////////////////

DecodingImageGenerator::DecodingImageGenerator(
        SkData* data,
        SkStreamRewindable* stream,
        const SkImageInfo& info,
        int sampleSize,
        bool ditherImage)
    : fData(data)
    , fStream(stream)
    , fInfo(info)
    , fSampleSize(sampleSize)
    , fDitherImage(ditherImage)
{
    SkASSERT(stream != NULL);
    SkSafeRef(fData);  // may be NULL.
}

DecodingImageGenerator::~DecodingImageGenerator() {
    SkSafeUnref(fData);
    fStream->unref();
}

SkData* DecodingImageGenerator::onRefEncodedData() {
    // This functionality is used in `gm --serialize`
    // Does not encode options.
    if (NULL == fData) {
        // TODO(halcanary): SkStreamRewindable needs a refData() function
        // which returns a cheap copy of the underlying data.
        if (!fStream->rewind()) {
            return NULL;
        }
        size_t length = fStream->getLength();
        if (length) {
            fData = SkData::NewFromStream(fStream, length);
        }
    }
    return SkSafeRef(fData);
}

bool DecodingImageGenerator::onGetPixels(const SkImageInfo& info,
                                         void* pixels, size_t rowBytes,
                                         SkPMColor ctableEntries[], int* ctableCount) {
    if (fInfo != info) {
        // The caller has specified a different info.  This is an
        // error for this kind of SkImageGenerator.  Use the Options
        // to change the settings.
        return false;
    }

    SkAssertResult(fStream->rewind());
    SkAutoTDelete<SkImageDecoder> decoder(SkImageDecoder::Factory(fStream));
    if (NULL == decoder.get()) {
        return false;
    }
    decoder->setDitherImage(fDitherImage);
    decoder->setSampleSize(fSampleSize);
    decoder->setRequireUnpremultipliedColors(info.alphaType() == kUnpremul_SkAlphaType);

    SkBitmap bitmap;
    TargetAllocator allocator(fInfo, pixels, rowBytes);
    decoder->setAllocator(&allocator);
    bool success = decoder->decode(fStream, &bitmap, info.colorType(),
                                   SkImageDecoder::kDecodePixels_Mode) != SkImageDecoder::kFailure;
    decoder->setAllocator(NULL);
    if (!success) {
        return false;
    }
    if (allocator.isReady()) {  // Did not use pixels!
        SkBitmap bm;
        SkASSERT(bitmap.canCopyTo(info.colorType()));
        bool copySuccess = bitmap.copyTo(&bm, info.colorType(), &allocator);
        if (!copySuccess || allocator.isReady()) {
            SkDEBUGFAIL("bitmap.copyTo(requestedConfig) failed.");
            // Earlier we checked canCopyto(); we expect consistency.
            return false;
        }
        SkASSERT(check_alpha(info.alphaType(), bm.alphaType()));
    } else {
        SkASSERT(check_alpha(info.alphaType(), bitmap.alphaType()));
    }

    if (kIndex_8_SkColorType == info.colorType()) {
        if (kIndex_8_SkColorType != bitmap.colorType()) {
            return false;   // they asked for Index8, but we didn't receive that from decoder
        }
        SkColorTable* ctable = bitmap.getColorTable();
        if (NULL == ctable) {
            return false;
        }
        const int count = ctable->count();
        memcpy(ctableEntries, ctable->lockColors(), count * sizeof(SkPMColor));
        ctable->unlockColors();
        *ctableCount = count;
    }
    return true;
}

bool DecodingImageGenerator::onGetYUV8Planes(SkISize sizes[3], void* planes[3],
                                             size_t rowBytes[3], SkYUVColorSpace* colorSpace) {
    if (!fStream->rewind()) {
        return false;
    }

    SkAutoTDelete<SkImageDecoder> decoder(SkImageDecoder::Factory(fStream));
    if (NULL == decoder.get()) {
        return false;
    }

    return decoder->decodeYUV8Planes(fStream, sizes, planes, rowBytes, colorSpace);
}

// A contructor-type function that returns NULL on failure.  This
// prevents the returned SkImageGenerator from ever being in a bad
// state.  Called by both Create() functions
SkImageGenerator* CreateDecodingImageGenerator(
        SkData* data,
        SkStreamRewindable* stream,
        const SkDecodingImageGenerator::Options& opts) {
    SkASSERT(stream);
    SkAutoTUnref<SkStreamRewindable> autoStream(stream);  // always unref this.
    SkAssertResult(autoStream->rewind());
    SkAutoTDelete<SkImageDecoder> decoder(SkImageDecoder::Factory(autoStream));
    if (NULL == decoder.get()) {
        return NULL;
    }
    SkBitmap bitmap;
    decoder->setSampleSize(opts.fSampleSize);
    decoder->setRequireUnpremultipliedColors(opts.fRequireUnpremul);
    if (!decoder->decode(stream, &bitmap, SkImageDecoder::kDecodeBounds_Mode)) {
        return NULL;
    }
    if (kUnknown_SkColorType == bitmap.colorType()) {
        return NULL;
    }

    SkImageInfo info = bitmap.info();

    if (opts.fUseRequestedColorType && (opts.fRequestedColorType != info.colorType())) {
        if (!bitmap.canCopyTo(opts.fRequestedColorType)) {
            SkASSERT(bitmap.colorType() != opts.fRequestedColorType);
            return NULL;  // Can not translate to needed config.
        }
        info = info.makeColorType(opts.fRequestedColorType);
    }

    if (opts.fRequireUnpremul && info.alphaType() != kOpaque_SkAlphaType) {
        info = info.makeAlphaType(kUnpremul_SkAlphaType);
    }

    SkAlphaType newAlphaType = info.alphaType();
    if (!SkColorTypeValidateAlphaType(info.colorType(), info.alphaType(), &newAlphaType)) {
        return NULL;
    }

    return SkNEW_ARGS(DecodingImageGenerator,
                      (data, autoStream.detach(), info.makeAlphaType(newAlphaType),
                       opts.fSampleSize, opts.fDitherImage));
}

}  // namespace

////////////////////////////////////////////////////////////////////////////////

SkImageGenerator* SkDecodingImageGenerator::Create(
        SkData* data,
        const SkDecodingImageGenerator::Options& opts) {
    SkASSERT(data != NULL);
    if (NULL == data) {
        return NULL;
    }
    SkStreamRewindable* stream = SkNEW_ARGS(SkMemoryStream, (data));
    SkASSERT(stream != NULL);
    SkASSERT(stream->unique());
    return CreateDecodingImageGenerator(data, stream, opts);
}

SkImageGenerator* SkDecodingImageGenerator::Create(
        SkStreamRewindable* stream,
        const SkDecodingImageGenerator::Options& opts) {
    SkASSERT(stream != NULL);
    SkASSERT(stream->unique());
    if ((stream == NULL) || !stream->unique()) {
        SkSafeUnref(stream);
        return NULL;
    }
    return CreateDecodingImageGenerator(NULL, stream, opts);
}