aboutsummaryrefslogtreecommitdiffhomepage
path: root/tests/WritePixelsTest.cpp
blob: 3fe498508b94bf53edd3340d4ccf845e5e4b82f7 (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
/*
 * 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 "SkColorData.h"
#include "SkImageInfoPriv.h"
#include "SkMathPriv.h"
#include "SkSurface.h"
#include "Test.h"
#include "sk_tool_utils.h"

#include "GrBackendSurface.h"
#include "GrContext.h"
#include "GrContextPriv.h"
#include "GrGpu.h"
#include "GrProxyProvider.h"
#include "GrTest.h"

#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 U8CPU DEV_PAD = 0xee;

static SkPMColor get_canvas_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 = 0x0;
    switch ((x+y) % 5) {
        case 0:
            a = 0xff;
            break;
        case 1:
            a = 0x80;
            break;
        case 2:
            a = 0xCC;
            break;
        case 3:
            a = 0x00;
            break;
        case 4:
            a = 0x01;
            break;
    }
    return SkPremultiplyARGBInline(a, r, g, b);
}

// assumes any premu/.unpremul has been applied
static uint32_t pack_color_type(SkColorType ct, U8CPU a, U8CPU r, U8CPU g, U8CPU b) {
    uint32_t r32;
    uint8_t* result = reinterpret_cast<uint8_t*>(&r32);
    switch (ct) {
        case kBGRA_8888_SkColorType:
            result[0] = b;
            result[1] = g;
            result[2] = r;
            result[3] = a;
            break;
        case kRGBA_8888_SkColorType:  // fallthrough
        case kRGB_888x_SkColorType:
            result[0] = r;
            result[1] = g;
            result[2] = b;
            result[3] = a;
            break;
        default:
            SkASSERT(0);
            return 0;
    }
    return r32;
}

static uint32_t get_bitmap_color(int x, int y, int w, SkColorType ct, SkAlphaType at) {
    int n = y * w + x;
    U8CPU b = n & 0xff;
    U8CPU g = (n >> 8) & 0xff;
    U8CPU r = (n >> 16) & 0xff;
    U8CPU a = 0;
    switch ((x+y) % 5) {
        case 4:
            a = 0xff;
            break;
        case 3:
            a = 0x80;
            break;
        case 2:
            a = 0xCC;
            break;
        case 1:
            a = 0x01;
            break;
        case 0:
            a = 0x00;
            break;
    }
    if (kPremul_SkAlphaType == at) {
        r = SkMulDiv255Ceiling(r, a);
        g = SkMulDiv255Ceiling(g, a);
        b = SkMulDiv255Ceiling(b, a);
    }
    return pack_color_type(ct, a, r, g , b);
}

static void fill_surface(SkSurface* surface) {
    SkBitmap bmp;
    bmp.allocN32Pixels(DEV_W, DEV_H);
    for (int y = 0; y < DEV_H; ++y) {
        for (int x = 0; x < DEV_W; ++x) {
            *bmp.getAddr32(x, y) = get_canvas_color(x, y);
        }
    }
    surface->writePixels(bmp, 0, 0);
}

/**
 *  Lucky for us, alpha is always in the same spot (SK_A32_SHIFT), for both RGBA and BGRA.
 *  Thus this routine doesn't need to know the exact colortype
 */
static uint32_t premul(uint32_t color) {
    unsigned a = SkGetPackedA32(color);
    // these next three are not necessarily r,g,b in that order, but they are r,g,b in some order.
    unsigned c0 = SkGetPackedR32(color);
    unsigned c1 = SkGetPackedG32(color);
    unsigned c2 = SkGetPackedB32(color);
    c0 = SkMulDiv255Ceiling(c0, a);
    c1 = SkMulDiv255Ceiling(c1, a);
    c2 = SkMulDiv255Ceiling(c2, a);
    return SkPackARGB32NoCheck(a, c0, c1, c2);
}

static SkPMColor convert_to_PMColor(SkColorType ct, SkAlphaType at, uint32_t color) {
    if (kUnpremul_SkAlphaType == at) {
        color = premul(color);
    }
    switch (ct) {
        case kRGBA_8888_SkColorType:
        case kRGB_888x_SkColorType:  // fallthrough
            color = SkSwizzle_RGBA_to_PMColor(color);
            break;
        case kBGRA_8888_SkColorType:
            color = SkSwizzle_BGRA_to_PMColor(color);
            break;
        default:
            SkASSERT(0);
            break;
    }
    return color;
}

static bool check_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;
}

bool write_should_succeed(const SkImageInfo& dstInfo, const SkImageInfo& srcInfo, bool isGPU) {
    if (!SkImageInfoValidConversion(dstInfo, srcInfo)) {
        return false;
    }
    if (!isGPU) {
        return true;
    }
    // The GPU backend supports writing unpremul data to a premul dst but not vice versa.
    if (srcInfo.alphaType() == kPremul_SkAlphaType &&
        dstInfo.alphaType() == kUnpremul_SkAlphaType) {
        return false;
    }
    if (!SkColorTypeIsAlwaysOpaque(srcInfo.colorType()) &&
        SkColorTypeIsAlwaysOpaque(dstInfo.colorType())) {
        return false;
    }
    // The source has no alpha value and the dst is only alpha
    if (SkColorTypeIsAlwaysOpaque(srcInfo.colorType()) &&
        SkColorTypeIsAlphaOnly(dstInfo.colorType())) {
        return false;
    }
    return true;
}

static bool check_write(skiatest::Reporter* reporter, SkSurface* surf, SkAlphaType surfaceAlphaType,
                        const SkBitmap& bitmap, int writeX, int writeY) {
    size_t canvasRowBytes;
    const uint32_t* canvasPixels;

    // Can't use canvas->peekPixels(), as we are trying to look at GPU pixels sometimes as well.
    // At some point this will be unsupported, as we won't allow accessBitmap() to magically call
    // readPixels for the client.
    SkBitmap secretDevBitmap;
    secretDevBitmap.allocN32Pixels(surf->width(), surf->height());
    if (!surf->readPixels(secretDevBitmap, 0, 0)) {
        return false;
    }

    canvasRowBytes = secretDevBitmap.rowBytes();
    canvasPixels = static_cast<const uint32_t*>(secretDevBitmap.getPixels());

    if (nullptr == canvasPixels) {
        return false;
    }

    if (surf->width() != DEV_W || surf->height() != DEV_H) {
        return false;
    }

    const SkImageInfo bmInfo = bitmap.info();

    SkIRect writeRect = SkIRect::MakeXYWH(writeX, writeY, bitmap.width(), bitmap.height());
    for (int cy = 0; cy < DEV_H; ++cy) {
        for (int cx = 0; cx < DEV_W; ++cx) {
            SkPMColor canvasPixel = canvasPixels[cx];
            if (writeRect.contains(cx, cy)) {
                int bx = cx - writeX;
                int by = cy - writeY;
                uint32_t bmpColor8888 = get_bitmap_color(bx, by, bitmap.width(),
                                                       bmInfo.colorType(), bmInfo.alphaType());
                bool mul = (kUnpremul_SkAlphaType == bmInfo.alphaType());
                SkPMColor bmpPMColor = convert_to_PMColor(bmInfo.colorType(), bmInfo.alphaType(),
                                                          bmpColor8888);
                if (bmInfo.alphaType() == kOpaque_SkAlphaType ||
                    surfaceAlphaType == kOpaque_SkAlphaType) {
                    bmpPMColor |= 0xFF000000;
                }
                if (!check_pixel(bmpPMColor, canvasPixel, mul)) {
                    ERRORF(reporter, "Expected canvas pixel at %d, %d to be 0x%08x, got 0x%08x. "
                           "Write performed premul: %d", cx, cy, bmpPMColor, canvasPixel, mul);
                    return false;
                }
            } else {
                SkPMColor testColor = get_canvas_color(cx, cy);
                if (canvasPixel != testColor) {
                    ERRORF(reporter, "Canvas pixel outside write rect at %d, %d changed."
                           " Should be 0x%08x, got 0x%08x. ", cx, cy, testColor, canvasPixel);
                    return false;
                }
            }
        }
        if (cy != DEV_H -1) {
            const char* pad = reinterpret_cast<const char*>(canvasPixels + DEV_W);
            for (size_t px = 0; px < canvasRowBytes - 4 * DEV_W; ++px) {
                bool check;
                REPORTER_ASSERT(reporter, check = (pad[px] == static_cast<char>(DEV_PAD)));
                if (!check) {
                    return false;
                }
            }
        }
        canvasPixels += canvasRowBytes/4;
    }

    return true;
}

#include "SkMallocPixelRef.h"

// This is a tricky pattern, because we have to setConfig+rowBytes AND specify
// a custom pixelRef (which also has to specify its rowBytes), so we have to be
// sure that the two rowBytes match (and the infos match).
//
static bool alloc_row_bytes(SkBitmap* bm, const SkImageInfo& info, size_t rowBytes) {
    if (!bm->setInfo(info, rowBytes)) {
        return false;
    }
    sk_sp<SkPixelRef> pr = SkMallocPixelRef::MakeAllocate(info, rowBytes);
    bm->setPixelRef(std::move(pr), 0, 0);
    return true;
}

static void free_pixels(void* pixels, void* ctx) {
    sk_free(pixels);
}

static bool setup_bitmap(SkBitmap* bm, SkColorType ct, SkAlphaType at, int w, int h, int tightRB) {
    size_t rowBytes = tightRB ? 0 : 4 * w + 60;
    SkImageInfo info = SkImageInfo::Make(w, h, ct, at);
    if (!alloc_row_bytes(bm, info, rowBytes)) {
        return false;
    }
    for (int y = 0; y < h; ++y) {
        for (int x = 0; x < w; ++x) {
            *bm->getAddr32(x, y) = get_bitmap_color(x, y, w, ct, at);
        }
    }
    return true;
}

static void call_writepixels(SkSurface* surface) {
    const SkImageInfo info = SkImageInfo::MakeN32Premul(1, 1);
    SkPMColor pixel = 0;
    surface->writePixels({info, &pixel, sizeof(SkPMColor)}, 0, 0);
}

DEF_TEST(WritePixelsSurfaceGenID, reporter) {
    const SkImageInfo info = SkImageInfo::MakeN32Premul(100, 100);
    auto surface(SkSurface::MakeRaster(info));
    uint32_t genID1 = surface->generationID();
    call_writepixels(surface.get());
    uint32_t genID2 = surface->generationID();
    REPORTER_ASSERT(reporter, genID1 != genID2);
}

static void test_write_pixels(skiatest::Reporter* reporter, SkSurface* surface,
                              const SkImageInfo& surfaceInfo) {
    const SkIRect testRects[] = {
        // 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),
    };

    SkCanvas* canvas = surface->getCanvas();

    static const struct {
        SkColorType fColorType;
        SkAlphaType fAlphaType;
    } gSrcConfigs[] = {
            {kRGBA_8888_SkColorType, kPremul_SkAlphaType},
            {kRGBA_8888_SkColorType, kUnpremul_SkAlphaType},
            {kRGB_888x_SkColorType, kOpaque_SkAlphaType},
            {kBGRA_8888_SkColorType, kPremul_SkAlphaType},
            {kBGRA_8888_SkColorType, kUnpremul_SkAlphaType},
    };
    for (size_t r = 0; r < SK_ARRAY_COUNT(testRects); ++r) {
        const SkIRect& rect = testRects[r];
        for (int tightBmp = 0; tightBmp < 2; ++tightBmp) {
            for (size_t c = 0; c < SK_ARRAY_COUNT(gSrcConfigs); ++c) {
                const SkColorType ct = gSrcConfigs[c].fColorType;
                const SkAlphaType at = gSrcConfigs[c].fAlphaType;

                bool isGPU = SkToBool(surface->getCanvas()->getGrContext());
                fill_surface(surface);
                SkBitmap bmp;
                REPORTER_ASSERT(reporter, setup_bitmap(&bmp, ct, at, rect.width(),
                                                       rect.height(), SkToBool(tightBmp)));
                uint32_t idBefore = surface->generationID();

                // sk_tool_utils::write_pixels(&canvas, bmp, rect.fLeft, rect.fTop, ct, at);
                surface->writePixels(bmp, rect.fLeft, rect.fTop);

                uint32_t idAfter = surface->generationID();
                REPORTER_ASSERT(reporter, check_write(reporter, surface, surfaceInfo.alphaType(),
                                                      bmp, rect.fLeft, rect.fTop));

                // we should change the genID iff pixels were actually written.
                SkIRect canvasRect = SkIRect::MakeSize(canvas->getBaseLayerSize());
                SkIRect writeRect = SkIRect::MakeXYWH(rect.fLeft, rect.fTop,
                                                      bmp.width(), bmp.height());
                bool expectSuccess = SkIRect::Intersects(canvasRect, writeRect) &&
                                     write_should_succeed(surfaceInfo, bmp.info(), isGPU);
                REPORTER_ASSERT(reporter, expectSuccess == (idBefore != idAfter));
            }
        }
    }
}

DEF_TEST(WritePixels, reporter) {
    const SkImageInfo info = SkImageInfo::MakeN32Premul(DEV_W, DEV_H);
    for (auto& tightRowBytes : { true, false }) {
        const size_t rowBytes = tightRowBytes ? info.minRowBytes() : 4 * DEV_W + 100;
        const size_t size = info.computeByteSize(rowBytes);
        void* pixels = sk_malloc_throw(size);
        // if rowBytes isn't tight then set the padding to a known value
        if (!tightRowBytes) {
            memset(pixels, DEV_PAD, size);
        }
        auto surface(SkSurface::MakeRasterDirectReleaseProc(info, pixels, rowBytes,
                                                            free_pixels, nullptr));
        test_write_pixels(reporter, surface.get(), info);
    }
}

static void test_write_pixels(skiatest::Reporter* reporter, GrContext* context, int sampleCnt) {
    const SkImageInfo ii = SkImageInfo::MakeN32Premul(DEV_W, DEV_H);
    for (auto& origin : { kTopLeft_GrSurfaceOrigin, kBottomLeft_GrSurfaceOrigin }) {
        sk_sp<SkSurface> surface(SkSurface::MakeRenderTarget(context,
                                                             SkBudgeted::kNo, ii, sampleCnt,
                                                             origin, nullptr));
        if (surface) {
            test_write_pixels(reporter, surface.get(), ii);
        }
    }
}

DEF_GPUTEST_FOR_RENDERING_CONTEXTS(WritePixels_Gpu, reporter, ctxInfo) {
    test_write_pixels(reporter, ctxInfo.grContext(), 1);
}

DEF_GPUTEST_FOR_RENDERING_CONTEXTS(WritePixelsMSAA_Gpu, reporter, ctxInfo) {
    test_write_pixels(reporter, ctxInfo.grContext(), 1);
}

static void test_write_pixels_non_texture(skiatest::Reporter* reporter, GrContext* context,
                                          int sampleCnt) {
    GrGpu* gpu = context->contextPriv().getGpu();

    for (auto& origin : { kTopLeft_GrSurfaceOrigin, kBottomLeft_GrSurfaceOrigin }) {
        GrBackendTexture backendTex = gpu->createTestingOnlyBackendTexture(
                nullptr, DEV_W, DEV_H, kSkia8888_GrPixelConfig, true, GrMipMapped::kNo);
        if (!backendTex.isValid()) {
            continue;
        }
        SkColorType colorType = kN32_SkColorType;
        sk_sp<SkSurface> surface(SkSurface::MakeFromBackendTextureAsRenderTarget(
                context, backendTex, origin, sampleCnt, colorType, nullptr, nullptr));
        if (surface) {
            auto ii = SkImageInfo::MakeN32Premul(DEV_W, DEV_H);
            test_write_pixels(reporter, surface.get(), ii);
        }
        gpu->deleteTestingOnlyBackendTexture(backendTex);
    }
}

DEF_GPUTEST_FOR_RENDERING_CONTEXTS(WritePixelsNonTexture_Gpu, reporter, ctxInfo) {
    test_write_pixels_non_texture(reporter, ctxInfo.grContext(), 1);
}

DEF_GPUTEST_FOR_RENDERING_CONTEXTS(WritePixelsNonTextureMSAA_Gpu, reporter, ctxInfo) {
    test_write_pixels_non_texture(reporter, ctxInfo.grContext(), 4);
}

static sk_sp<SkSurface> create_surf(GrContext* context, int width, int height) {
    const SkImageInfo ii = SkImageInfo::Make(width, height,
                                             kRGBA_8888_SkColorType, kPremul_SkAlphaType);

    sk_sp<SkSurface> surf = SkSurface::MakeRenderTarget(context, SkBudgeted::kYes, ii);
    surf->flush();
    return surf;
}

static sk_sp<SkImage> upload(const sk_sp<SkSurface>& surf, SkColor color) {
    const SkImageInfo smII = SkImageInfo::Make(16, 16, kRGBA_8888_SkColorType, kPremul_SkAlphaType);
    SkBitmap bm;
    bm.allocPixels(smII);
    bm.eraseColor(color);

    surf->writePixels(bm, 0, 0);

    return surf->makeImageSnapshot();
}

// This is tests whether the first writePixels is completed before the
// second writePixels takes effect (i.e., that writePixels correctly flushes
// in between uses of the shared backing resource).
DEF_GPUTEST_FOR_RENDERING_CONTEXTS(WritePixelsPendingIO, reporter, ctxInfo) {
    GrContext* context = ctxInfo.grContext();
    GrProxyProvider* proxyProvider = context->contextPriv().proxyProvider();

    static const int kFullSize = 62;
    static const int kHalfSize = 31;

    static const uint32_t kLeftColor = 0xFF222222;
    static const uint32_t kRightColor = 0xFFAAAAAA;

    const SkImageInfo fullII = SkImageInfo::Make(kFullSize, kFullSize,
                                                 kRGBA_8888_SkColorType, kPremul_SkAlphaType);
    const SkImageInfo halfII = SkImageInfo::Make(kHalfSize, kFullSize,
                                                 kRGBA_8888_SkColorType, kPremul_SkAlphaType);

    sk_sp<SkSurface> dest = SkSurface::MakeRenderTarget(context, SkBudgeted::kYes, fullII);

    {
        // Seed the resource cached with a scratch texture that will be
        // reused by writeSurfacePixels
        GrSurfaceDesc desc;
        desc.fFlags = kNone_GrSurfaceFlags;
        desc.fWidth = 32;
        desc.fHeight = 64;
        desc.fConfig = kRGBA_8888_GrPixelConfig;

        sk_sp<GrTextureProxy> temp = proxyProvider->createProxy(
                desc, kTopLeft_GrSurfaceOrigin, SkBackingFit::kApprox, SkBudgeted::kYes);
        temp->instantiate(context->contextPriv().resourceProvider());
    }

    // Create the surfaces and flush them to ensure there is no lingering pendingIO
    sk_sp<SkSurface> leftSurf = create_surf(context, kHalfSize, kFullSize);
    sk_sp<SkSurface> rightSurf = create_surf(context, kHalfSize, kFullSize);

    sk_sp<SkImage> leftImg = upload(std::move(leftSurf), kLeftColor);
    dest->getCanvas()->drawImage(std::move(leftImg), 0, 0);

    sk_sp<SkImage> rightImg = upload(std::move(rightSurf), kRightColor);
    dest->getCanvas()->drawImage(std::move(rightImg), kHalfSize, 0);

    SkBitmap bm;
    bm.allocPixels(fullII);
    SkAssertResult(dest->readPixels(bm, 0, 0));

    bool isCorrect = true;
    for (int y = 0; isCorrect && y < 16; ++y) {
        const uint32_t* sl = bm.getAddr32(0, y);

        for (int x = 0; x < 16; ++x) {
            if (kLeftColor != sl[x]) {
                isCorrect = false;
                break;
            }
        }
        for (int x = kHalfSize; x < kHalfSize+16; ++x) {
            if (kRightColor != sl[x]) {
                isCorrect = false;
                break;
            }
        }
    }

    REPORTER_ASSERT(reporter, isCorrect);
}