aboutsummaryrefslogtreecommitdiffhomepage
path: root/tests/ReadPixelsTest.cpp
blob: 87e51163da6bde89c6eb94981ae611a562b47dca (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
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
/*
 * Copyright 2011 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "SkCanvas.h"
#include "SkColorPriv.h"
#include "SkMathPriv.h"
#include "SkRegion.h"
#include "SkSurface.h"
#include "Test.h"

#if SK_SUPPORT_GPU
#include "GrContext.h"
#include "SkGr.h"
#endif

#include <initializer_list>

static const int DEV_W = 100, DEV_H = 100;
static const SkIRect DEV_RECT = SkIRect::MakeWH(DEV_W, DEV_H);
static const SkRect DEV_RECT_S = SkRect::MakeWH(DEV_W * SK_Scalar1,
                                                DEV_H * SK_Scalar1);

static SkPMColor get_src_color(int x, int y) {
    SkASSERT(x >= 0 && x < DEV_W);
    SkASSERT(y >= 0 && y < DEV_H);

    U8CPU r = x;
    U8CPU g = y;
    U8CPU b = 0xc;

    U8CPU a = 0xff;
    switch ((x+y) % 5) {
        case 0:
            a = 0xff;
            break;
        case 1:
            a = 0x80;
            break;
        case 2:
            a = 0xCC;
            break;
        case 4:
            a = 0x01;
            break;
        case 3:
            a = 0x00;
            break;
    }
    return SkPremultiplyARGBInline(a, r, g, b);
}
    
static SkPMColor get_dst_bmp_init_color(int x, int y, int w) {
    int n = y * w + x;

    U8CPU b = n & 0xff;
    U8CPU g = (n >> 8) & 0xff;
    U8CPU r = (n >> 16) & 0xff;
    return SkPackARGB32(0xff, r, g , b);
}

static SkPMColor convert_to_pmcolor(SkColorType ct, SkAlphaType at, const uint32_t* addr,
                                    bool* doUnpremul) {
    *doUnpremul = (kUnpremul_SkAlphaType == at);

    const uint8_t* c = reinterpret_cast<const uint8_t*>(addr);
    U8CPU a,r,g,b;
    switch (ct) {
        case kBGRA_8888_SkColorType:
            b = static_cast<U8CPU>(c[0]);
            g = static_cast<U8CPU>(c[1]);
            r = static_cast<U8CPU>(c[2]);
            a = static_cast<U8CPU>(c[3]);
            break;
        case kRGBA_8888_SkColorType:
            r = static_cast<U8CPU>(c[0]);
            g = static_cast<U8CPU>(c[1]);
            b = static_cast<U8CPU>(c[2]);
            a = static_cast<U8CPU>(c[3]);
            break;
        default:
            SkDEBUGFAIL("Unexpected colortype");
            return 0;
    }

    if (*doUnpremul) {
        r = SkMulDiv255Ceiling(r, a);
        g = SkMulDiv255Ceiling(g, a);
        b = SkMulDiv255Ceiling(b, a);
    }
    return SkPackARGB32(a, r, g, b);
}

static SkBitmap make_src_bitmap() {
    static SkBitmap bmp;
    if (bmp.isNull()) {
        bmp.allocN32Pixels(DEV_W, DEV_H);
        intptr_t pixels = reinterpret_cast<intptr_t>(bmp.getPixels());
        for (int y = 0; y < DEV_H; ++y) {
            for (int x = 0; x < DEV_W; ++x) {
                SkPMColor* pixel = reinterpret_cast<SkPMColor*>(pixels + y * bmp.rowBytes() + x * bmp.bytesPerPixel());
                *pixel = get_src_color(x, y);
            }
        }
    }
    return bmp;
}

static void fill_src_canvas(SkCanvas* canvas) {
    canvas->save();
    canvas->setMatrix(SkMatrix::I());
    canvas->clipRect(DEV_RECT_S, SkRegion::kReplace_Op);
    SkPaint paint;
    paint.setXfermodeMode(SkXfermode::kSrc_Mode);
    canvas->drawBitmap(make_src_bitmap(), 0, 0, &paint);
    canvas->restore();
}

#if SK_SUPPORT_GPU
static void fill_src_texture(GrTexture* texture) {
    SkBitmap bmp = make_src_bitmap();
    bmp.lockPixels();
    texture->writePixels(0, 0, DEV_W, DEV_H, kSkia8888_GrPixelConfig, bmp.getPixels(),
                         bmp.rowBytes());
    bmp.unlockPixels();
}
#endif

static void fill_dst_bmp_with_init_data(SkBitmap* bitmap) {
    SkASSERT(bitmap->lockPixelsAreWritable());
    SkAutoLockPixels alp(*bitmap);
    int w = bitmap->width();
    int h = bitmap->height();
    intptr_t pixels = reinterpret_cast<intptr_t>(bitmap->getPixels());
    for (int y = 0; y < h; ++y) {
        for (int x = 0; x < w; ++x) {
            SkPMColor* pixel = reinterpret_cast<SkPMColor*>(pixels + y * bitmap->rowBytes() + x * bitmap->bytesPerPixel());
            *pixel = get_dst_bmp_init_color(x, y, w);
        }
    }
}

static bool check_read_pixel(SkPMColor a, SkPMColor b, bool didPremulConversion) {
    if (!didPremulConversion) {
        return a == b;
    }
    int32_t aA = static_cast<int32_t>(SkGetPackedA32(a));
    int32_t aR = static_cast<int32_t>(SkGetPackedR32(a));
    int32_t aG = static_cast<int32_t>(SkGetPackedG32(a));
    int32_t aB = SkGetPackedB32(a);

    int32_t bA = static_cast<int32_t>(SkGetPackedA32(b));
    int32_t bR = static_cast<int32_t>(SkGetPackedR32(b));
    int32_t bG = static_cast<int32_t>(SkGetPackedG32(b));
    int32_t bB = static_cast<int32_t>(SkGetPackedB32(b));

    return aA == bA &&
           SkAbs32(aR - bR) <= 1 &&
           SkAbs32(aG - bG) <= 1 &&
           SkAbs32(aB - bB) <= 1;
}

// checks the bitmap contains correct pixels after the readPixels
// if the bitmap was prefilled with pixels it checks that these weren't
// overwritten in the area outside the readPixels.
static bool check_read(skiatest::Reporter* reporter,
                       const SkBitmap& bitmap,
                       int x, int y,
                       bool checkCanvasPixels,
                       bool checkBitmapPixels) {
    SkASSERT(4 == bitmap.bytesPerPixel());
    SkASSERT(!bitmap.isNull());
    SkASSERT(checkCanvasPixels || checkBitmapPixels);

    const SkColorType ct = bitmap.colorType();
    const SkAlphaType at = bitmap.alphaType();

    int bw = bitmap.width();
    int bh = bitmap.height();

    SkIRect srcRect = SkIRect::MakeXYWH(x, y, bw, bh);
    SkIRect clippedSrcRect = DEV_RECT;
    if (!clippedSrcRect.intersect(srcRect)) {
        clippedSrcRect.setEmpty();
    }
    SkAutoLockPixels alp(bitmap);
    for (int by = 0; by < bh; ++by) {
        for (int bx = 0; bx < bw; ++bx) {
            int devx = bx + srcRect.fLeft;
            int devy = by + srcRect.fTop;

            const uint32_t* pixel = bitmap.getAddr32(bx, by);

            if (clippedSrcRect.contains(devx, devy)) {
                if (checkCanvasPixels) {
                    SkPMColor canvasPixel = get_src_color(devx, devy);
                    bool didPremul;
                    SkPMColor pmPixel = convert_to_pmcolor(ct, at, pixel, &didPremul);
                    if (!check_read_pixel(pmPixel, canvasPixel, didPremul)) {
                        ERRORF(reporter, "Expected readback pixel value 0x%08x, got 0x%08x. "
                               "Readback was unpremul: %d", canvasPixel, pmPixel, didPremul);
                        return false;
                    }
                }
            } else if (checkBitmapPixels) {
                uint32_t origDstPixel = get_dst_bmp_init_color(bx, by, bw);
                if (origDstPixel != *pixel) {
                    ERRORF(reporter, "Expected clipped out area of readback to be unchanged. "
                           "Expected 0x%08x, got 0x%08x", origDstPixel, *pixel);
                    return false;
                }
            }
        }
    }
    return true;
}

enum BitmapInit {
    kFirstBitmapInit = 0,

    kNoPixels_BitmapInit = kFirstBitmapInit,
    kTight_BitmapInit,
    kRowBytes_BitmapInit,
    kRowBytesOdd_BitmapInit,

    kLastAligned_BitmapInit = kRowBytes_BitmapInit,

#if 0  // THIS CAUSES ERRORS ON WINDOWS AND SOME ANDROID DEVICES
    kLast_BitmapInit = kRowBytesOdd_BitmapInit
#else
    kLast_BitmapInit = kLastAligned_BitmapInit
#endif
};

static BitmapInit nextBMI(BitmapInit bmi) {
    int x = bmi;
    return static_cast<BitmapInit>(++x);
}

static void init_bitmap(SkBitmap* bitmap, const SkIRect& rect, BitmapInit init, SkColorType ct,
                        SkAlphaType at) {
    SkImageInfo info = SkImageInfo::Make(rect.width(), rect.height(), ct, at);
    size_t rowBytes = 0;
    bool alloc = true;
    switch (init) {
        case kNoPixels_BitmapInit:
            alloc = false;
        case kTight_BitmapInit:
            break;
        case kRowBytes_BitmapInit:
            rowBytes = (info.width() + 16) * sizeof(SkPMColor);
            break;
        case kRowBytesOdd_BitmapInit:
            rowBytes = (info.width() * sizeof(SkPMColor)) + 3;
            break;
        default:
            SkASSERT(0);
            break;
    }

    if (alloc) {
        bitmap->allocPixels(info, rowBytes);
    } else {
        bitmap->setInfo(info, rowBytes);
    }
}

static const struct {
    SkColorType fColorType;
    SkAlphaType fAlphaType;
} gReadPixelsConfigs[] = {
    { kRGBA_8888_SkColorType,   kPremul_SkAlphaType },
    { kRGBA_8888_SkColorType,   kUnpremul_SkAlphaType },
    { kBGRA_8888_SkColorType,   kPremul_SkAlphaType },
    { kBGRA_8888_SkColorType,   kUnpremul_SkAlphaType },
};
const SkIRect gReadPixelsTestRects[] = {
    // entire thing
    DEV_RECT,
    // larger on all sides
    SkIRect::MakeLTRB(-10, -10, DEV_W + 10, DEV_H + 10),
    // fully contained
    SkIRect::MakeLTRB(DEV_W / 4, DEV_H / 4, 3 * DEV_W / 4, 3 * DEV_H / 4),
    // outside top left
    SkIRect::MakeLTRB(-10, -10, -1, -1),
    // touching top left corner
    SkIRect::MakeLTRB(-10, -10, 0, 0),
    // overlapping top left corner
    SkIRect::MakeLTRB(-10, -10, DEV_W / 4, DEV_H / 4),
    // overlapping top left and top right corners
    SkIRect::MakeLTRB(-10, -10, DEV_W  + 10, DEV_H / 4),
    // touching entire top edge
    SkIRect::MakeLTRB(-10, -10, DEV_W  + 10, 0),
    // overlapping top right corner
    SkIRect::MakeLTRB(3 * DEV_W / 4, -10, DEV_W  + 10, DEV_H / 4),
    // contained in x, overlapping top edge
    SkIRect::MakeLTRB(DEV_W / 4, -10, 3 * DEV_W  / 4, DEV_H / 4),
    // outside top right corner
    SkIRect::MakeLTRB(DEV_W + 1, -10, DEV_W + 10, -1),
    // touching top right corner
    SkIRect::MakeLTRB(DEV_W, -10, DEV_W + 10, 0),
    // overlapping top left and bottom left corners
    SkIRect::MakeLTRB(-10, -10, DEV_W / 4, DEV_H + 10),
    // touching entire left edge
    SkIRect::MakeLTRB(-10, -10, 0, DEV_H + 10),
    // overlapping bottom left corner
    SkIRect::MakeLTRB(-10, 3 * DEV_H / 4, DEV_W / 4, DEV_H + 10),
    // contained in y, overlapping left edge
    SkIRect::MakeLTRB(-10, DEV_H / 4, DEV_W / 4, 3 * DEV_H / 4),
    // outside bottom left corner
    SkIRect::MakeLTRB(-10, DEV_H + 1, -1, DEV_H + 10),
    // touching bottom left corner
    SkIRect::MakeLTRB(-10, DEV_H, 0, DEV_H + 10),
    // overlapping bottom left and bottom right corners
    SkIRect::MakeLTRB(-10, 3 * DEV_H / 4, DEV_W + 10, DEV_H + 10),
    // touching entire left edge
    SkIRect::MakeLTRB(0, DEV_H, DEV_W, DEV_H + 10),
    // overlapping bottom right corner
    SkIRect::MakeLTRB(3 * DEV_W / 4, 3 * DEV_H / 4, DEV_W + 10, DEV_H + 10),
    // overlapping top right and bottom right corners
    SkIRect::MakeLTRB(3 * DEV_W / 4, -10, DEV_W + 10, DEV_H + 10),
};

static void test_readpixels(skiatest::Reporter* reporter, SkSurface* surface,
                            BitmapInit lastBitmapInit) {
    SkCanvas* canvas = surface->getCanvas();
    fill_src_canvas(canvas);
    for (size_t rect = 0; rect < SK_ARRAY_COUNT(gReadPixelsTestRects); ++rect) {
        const SkIRect& srcRect = gReadPixelsTestRects[rect];
        for (BitmapInit bmi = kFirstBitmapInit; bmi <= lastBitmapInit; bmi = nextBMI(bmi)) {
            for (size_t c = 0; c < SK_ARRAY_COUNT(gReadPixelsConfigs); ++c) {
                SkBitmap bmp;
                init_bitmap(&bmp, srcRect, bmi,
                            gReadPixelsConfigs[c].fColorType, gReadPixelsConfigs[c].fAlphaType);

                // if the bitmap has pixels allocated before the readPixels,
                // note that and fill them with pattern
                bool startsWithPixels = !bmp.isNull();
                if (startsWithPixels) {
                    fill_dst_bmp_with_init_data(&bmp);
                }
                uint32_t idBefore = surface->generationID();
                bool success = canvas->readPixels(&bmp, srcRect.fLeft, srcRect.fTop);
                uint32_t idAfter = surface->generationID();

                // we expect to succeed when the read isn't fully clipped
                // out.
                bool expectSuccess = SkIRect::Intersects(srcRect, DEV_RECT);
                // determine whether we expected the read to succeed.
                REPORTER_ASSERT(reporter, success == expectSuccess);
                // read pixels should never change the gen id
                REPORTER_ASSERT(reporter, idBefore == idAfter);

                if (success || startsWithPixels) {
                    check_read(reporter, bmp, srcRect.fLeft, srcRect.fTop,
                               success, startsWithPixels);
                } else {
                    // if we had no pixels beforehand and the readPixels
                    // failed then our bitmap should still not have pixels
                    REPORTER_ASSERT(reporter, bmp.isNull());
                }
            }
            // check the old webkit version of readPixels that clips the
            // bitmap size
            SkBitmap wkbmp;
            bool success = canvas->readPixels(srcRect, &wkbmp);
            SkIRect clippedRect = DEV_RECT;
            if (clippedRect.intersect(srcRect)) {
                REPORTER_ASSERT(reporter, success);
                REPORTER_ASSERT(reporter, kN32_SkColorType == wkbmp.colorType());
                REPORTER_ASSERT(reporter, kPremul_SkAlphaType == wkbmp.alphaType());
                check_read(reporter, wkbmp, clippedRect.fLeft,
                           clippedRect.fTop, true, false);
            } else {
                REPORTER_ASSERT(reporter, !success);
            }
        }
    }
}
DEF_TEST(ReadPixels, reporter) {
    const SkImageInfo info = SkImageInfo::MakeN32Premul(DEV_W, DEV_H);
    SkAutoTUnref<SkSurface> surface(SkSurface::NewRaster(info));
    // SW readback fails a premul check when reading back to an unaligned rowbytes.
    test_readpixels(reporter, surface, kLastAligned_BitmapInit);
}
#if SK_SUPPORT_GPU
DEF_GPUTEST_FOR_RENDERING_CONTEXTS(ReadPixels_Gpu, reporter, context) {
    for (auto& origin : {kBottomLeft_GrSurfaceOrigin, kTopLeft_GrSurfaceOrigin}) {
        GrSurfaceDesc desc;
        desc.fFlags = kRenderTarget_GrSurfaceFlag;
        desc.fWidth = DEV_W;
        desc.fHeight = DEV_H;
        desc.fConfig = kSkia8888_GrPixelConfig;
        desc.fOrigin = origin;
        SkAutoTUnref<GrTexture> surfaceTexture(
            context->textureProvider()->createTexture(desc, SkBudgeted::kNo));
        SkAutoTUnref<SkSurface> surface(SkSurface::NewRenderTargetDirect(surfaceTexture->asRenderTarget()));
        desc.fFlags = kNone_GrSurfaceFlags;
        test_readpixels(reporter, surface, kLast_BitmapInit);
    }
}
#endif

#if SK_SUPPORT_GPU
static void test_readpixels_texture(skiatest::Reporter* reporter, GrTexture* texture) {
    fill_src_texture(texture);
    for (size_t rect = 0; rect < SK_ARRAY_COUNT(gReadPixelsTestRects); ++rect) {
        const SkIRect& srcRect = gReadPixelsTestRects[rect];
        for (BitmapInit bmi = kFirstBitmapInit; bmi <= kLast_BitmapInit; bmi = nextBMI(bmi)) {
            for (size_t c = 0; c < SK_ARRAY_COUNT(gReadPixelsConfigs); ++c) {
                SkBitmap bmp;
                init_bitmap(&bmp, srcRect, bmi,
                            gReadPixelsConfigs[c].fColorType, gReadPixelsConfigs[c].fAlphaType);

                // if the bitmap has pixels allocated before the readPixels,
                // note that and fill them with pattern
                bool startsWithPixels = !bmp.isNull();
                // Try doing the read directly from a non-renderable texture
                if (startsWithPixels) {
                    fill_dst_bmp_with_init_data(&bmp);
                    GrPixelConfig dstConfig =
                            SkImageInfo2GrPixelConfig(gReadPixelsConfigs[c].fColorType,
                                                      gReadPixelsConfigs[c].fAlphaType,
                                                      kLinear_SkColorProfileType,
                                                      *texture->getContext()->caps());
                    uint32_t flags = 0;
                    if (gReadPixelsConfigs[c].fAlphaType == kUnpremul_SkAlphaType) {
                        flags = GrContext::kUnpremul_PixelOpsFlag;
                    }
                    bmp.lockPixels();
                    bool success = texture->readPixels(srcRect.fLeft, srcRect.fTop, bmp.width(),
                                                       bmp.height(), dstConfig, bmp.getPixels(),
                                                       bmp.rowBytes(), flags);
                    bmp.unlockPixels();
                    check_read(reporter, bmp, srcRect.fLeft, srcRect.fTop,
                               success, true);
                }
            }
        }
    }
}
DEF_GPUTEST_FOR_RENDERING_CONTEXTS(ReadPixels_Texture, reporter, context) {
    // On the GPU we will also try reading back from a non-renderable texture.
    for (auto& origin : {kBottomLeft_GrSurfaceOrigin, kTopLeft_GrSurfaceOrigin}) {
        SkAutoTUnref<GrTexture> texture;
        GrSurfaceDesc desc;
        desc.fFlags = kRenderTarget_GrSurfaceFlag;
        desc.fWidth = DEV_W;
        desc.fHeight = DEV_H;
        desc.fConfig = kSkia8888_GrPixelConfig;
        desc.fOrigin = origin;
        desc.fFlags = kNone_GrSurfaceFlags;
        texture.reset(context->textureProvider()->createTexture(desc, SkBudgeted::kNo));
        test_readpixels_texture(reporter, texture);
    }
}
#endif
/////////////////////
#if SK_SUPPORT_GPU

// make_ringed_bitmap was lifted from gm/bleed.cpp, as that GM was what showed the following
// bug when a change was made to SkImage_Raster.cpp. It is possible that other test bitmaps
// would also tickle https://bug.skia.org/4351 but this one is know to do it, so I've pasted the code
// here so we have a dependable repro case.

// Create a black&white checked texture with 2 1-pixel rings
// around the outside edge. The inner ring is red and the outer ring is blue.
static void make_ringed_bitmap(SkBitmap* result, int width, int height) {
    SkASSERT(0 == width % 2 && 0 == height % 2);

    static const SkPMColor kRed = SkPreMultiplyColor(SK_ColorRED);
    static const SkPMColor kBlue = SkPreMultiplyColor(SK_ColorBLUE);
    static const SkPMColor kBlack = SkPreMultiplyColor(SK_ColorBLACK);
    static const SkPMColor kWhite = SkPreMultiplyColor(SK_ColorWHITE);

    result->allocN32Pixels(width, height, true);

    SkPMColor* scanline = result->getAddr32(0, 0);
    for (int x = 0; x < width; ++x) {
        scanline[x] = kBlue;
    }
    scanline = result->getAddr32(0, 1);
    scanline[0] = kBlue;
    for (int x = 1; x < width - 1; ++x) {
        scanline[x] = kRed;
    }
    scanline[width-1] = kBlue;

    for (int y = 2; y < height/2; ++y) {
        scanline = result->getAddr32(0, y);
        scanline[0] = kBlue;
        scanline[1] = kRed;
        for (int x = 2; x < width/2; ++x) {
            scanline[x] = kBlack;
        }
        for (int x = width/2; x < width-2; ++x) {
            scanline[x] = kWhite;
        }
        scanline[width-2] = kRed;
        scanline[width-1] = kBlue;
    }

    for (int y = height/2; y < height-2; ++y) {
        scanline = result->getAddr32(0, y);
        scanline[0] = kBlue;
        scanline[1] = kRed;
        for (int x = 2; x < width/2; ++x) {
            scanline[x] = kWhite;
        }
        for (int x = width/2; x < width-2; ++x) {
            scanline[x] = kBlack;
        }
        scanline[width-2] = kRed;
        scanline[width-1] = kBlue;
    }

    scanline = result->getAddr32(0, height-2);
    scanline[0] = kBlue;
    for (int x = 1; x < width - 1; ++x) {
        scanline[x] = kRed;
    }
    scanline[width-1] = kBlue;

    scanline = result->getAddr32(0, height-1);
    for (int x = 0; x < width; ++x) {
        scanline[x] = kBlue;
    }
    result->setImmutable();
}

static void compare_textures(skiatest::Reporter* reporter, GrTexture* txa, GrTexture* txb) {
    REPORTER_ASSERT(reporter, txa->width() == 2);
    REPORTER_ASSERT(reporter, txa->height() == 2);
    REPORTER_ASSERT(reporter, txb->width() == 2);
    REPORTER_ASSERT(reporter, txb->height() == 2);
    REPORTER_ASSERT(reporter, txa->config() == txb->config());

    SkPMColor pixelsA[4], pixelsB[4];
    REPORTER_ASSERT(reporter, txa->readPixels(0, 0, 2, 2, txa->config(), pixelsA));
    REPORTER_ASSERT(reporter, txb->readPixels(0, 0, 2, 2, txa->config(), pixelsB));
    REPORTER_ASSERT(reporter, 0 == memcmp(pixelsA, pixelsB, sizeof(pixelsA)));
}

static SkData* draw_into_surface(SkSurface* surf, const SkBitmap& bm, SkFilterQuality quality) {
    SkCanvas* canvas = surf->getCanvas();
    canvas->clear(SK_ColorBLUE);

    SkPaint paint;
    paint.setFilterQuality(quality);

    canvas->translate(40, 100);
    canvas->rotate(30);
    canvas->scale(20, 30);
    canvas->translate(-SkScalarHalf(bm.width()), -SkScalarHalf(bm.height()));
    canvas->drawBitmap(bm, 0, 0, &paint);

    return surf->makeImageSnapshot()->encode();
}

#include "SkStream.h"
static void dump_to_file(const char name[], SkData* data) {
    SkFILEWStream file(name);
    file.write(data->data(), data->size());
}

/*
 *  Test two different ways to turn a subset of a bitmap into a texture
 *  - subset and then upload to a texture
 *  - upload to a texture and then subset
 *
 *  These two techniques result in the same pixels (ala readPixels)
 *  but when we draw them (rotated+scaled) we don't always get the same results.
 *
 *  https://bug.skia.org/4351
 */
DEF_GPUTEST_FOR_NATIVE_CONTEXT(ReadPixels_Subset_Gpu, reporter, context) {
    SkBitmap bitmap;
    make_ringed_bitmap(&bitmap, 6, 6);
    const SkIRect subset = SkIRect::MakeLTRB(2, 2, 4, 4);

    // make two textures...
    SkBitmap bm_subset, tx_subset;

    // ... one from a texture-subset
    SkAutoTUnref<GrTexture> fullTx(GrRefCachedBitmapTexture(context, bitmap,
                                                            GrTextureParams::ClampNoFilter()));
    SkBitmap tx_full;
    GrWrapTextureInBitmap(fullTx, bitmap.width(), bitmap.height(), true, &tx_full);
    tx_full.extractSubset(&tx_subset, subset);

    // ... one from a bitmap-subset
    SkBitmap tmp_subset;
    bitmap.extractSubset(&tmp_subset, subset);
    SkAutoTUnref<GrTexture> subsetTx(GrRefCachedBitmapTexture(context, tmp_subset,
                                                              GrTextureParams::ClampNoFilter()));
    GrWrapTextureInBitmap(subsetTx, tmp_subset.width(), tmp_subset.height(), true, &bm_subset);

    // did we get the same subset?
    compare_textures(reporter, bm_subset.getTexture(), tx_subset.getTexture());

    // do they draw the same?
    const SkImageInfo info = SkImageInfo::MakeN32Premul(128, 128);
    SkAutoTUnref<SkSurface> surfA(SkSurface::NewRenderTarget(context, SkBudgeted::kNo, info, 0));
    SkAutoTUnref<SkSurface> surfB(SkSurface::NewRenderTarget(context, SkBudgeted::kNo, info, 0));

    if (false) {
        //
        //  BUG: depending on the driver, if we calls this with various quality settings, it
        //       may fail.
        //
        SkFilterQuality quality = kLow_SkFilterQuality;

        SkAutoTUnref<SkData> dataA(draw_into_surface(surfA, bm_subset, quality));
        SkAutoTUnref<SkData> dataB(draw_into_surface(surfB, tx_subset, quality));

        REPORTER_ASSERT(reporter, dataA->equals(dataB));
        if (false) {
            dump_to_file("test_image_A.png", dataA);
            dump_to_file("test_image_B.png", dataB);
        }
    }
}
#endif