aboutsummaryrefslogtreecommitdiffhomepage
path: root/src/core/SkBlitter.cpp
blob: d8553f16a2c9f40b831699075646c17182f8bf83 (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
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
/*
 * Copyright 2006 The Android Open Source Project
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "SkBlitter.h"
#include "SkAntiRun.h"
#include "SkColor.h"
#include "SkColorFilter.h"
#include "SkCoreBlitters.h"
#include "SkFilterShader.h"
#include "SkReadBuffer.h"
#include "SkWriteBuffer.h"
#include "SkMask.h"
#include "SkMaskFilter.h"
#include "SkString.h"
#include "SkTLazy.h"
#include "SkUtils.h"
#include "SkXfermode.h"

SkBlitter::~SkBlitter() {}

bool SkBlitter::isNullBlitter() const { return false; }

bool SkBlitter::resetShaderContext(const SkShader::ContextRec&) {
    return true;
}

SkShader::Context* SkBlitter::getShaderContext() const {
    return NULL;
}

const SkBitmap* SkBlitter::justAnOpaqueColor(uint32_t* value) {
    return NULL;
}

void SkBlitter::blitH(int x, int y, int width) {
    SkDEBUGFAIL("unimplemented");
}

void SkBlitter::blitAntiH(int x, int y, const SkAlpha antialias[],
                          const int16_t runs[]) {
    SkDEBUGFAIL("unimplemented");
}

void SkBlitter::blitV(int x, int y, int height, SkAlpha alpha) {
    if (alpha == 255) {
        this->blitRect(x, y, 1, height);
    } else {
        int16_t runs[2];
        runs[0] = 1;
        runs[1] = 0;

        while (--height >= 0) {
            this->blitAntiH(x, y++, &alpha, runs);
        }
    }
}

void SkBlitter::blitRect(int x, int y, int width, int height) {
    SkASSERT(width > 0);
    while (--height >= 0) {
        this->blitH(x, y++, width);
    }
}

/// Default implementation doesn't check for any easy optimizations
/// such as alpha == 0 or 255; also uses blitV(), which some subclasses
/// may not support.
void SkBlitter::blitAntiRect(int x, int y, int width, int height,
                             SkAlpha leftAlpha, SkAlpha rightAlpha) {
    this->blitV(x++, y, height, leftAlpha);
    if (width > 0) {
        this->blitRect(x, y, width, height);
        x += width;
    }
    this->blitV(x, y, height, rightAlpha);
}

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

static inline void bits_to_runs(SkBlitter* blitter, int x, int y,
                                const uint8_t bits[],
                                U8CPU left_mask, int rowBytes,
                                U8CPU right_mask) {
    int inFill = 0;
    int pos = 0;

    while (--rowBytes >= 0) {
        unsigned b = *bits++ & left_mask;
        if (rowBytes == 0) {
            b &= right_mask;
        }

        for (unsigned test = 0x80; test != 0; test >>= 1) {
            if (b & test) {
                if (!inFill) {
                    pos = x;
                    inFill = true;
                }
            } else {
                if (inFill) {
                    blitter->blitH(pos, y, x - pos);
                    inFill = false;
                }
            }
            x += 1;
        }
        left_mask = 0xFF;
    }

    // final cleanup
    if (inFill) {
        blitter->blitH(pos, y, x - pos);
    }
}

void SkBlitter::blitMask(const SkMask& mask, const SkIRect& clip) {
    SkASSERT(mask.fBounds.contains(clip));

    if (mask.fFormat == SkMask::kBW_Format) {
        int cx = clip.fLeft;
        int cy = clip.fTop;
        int maskLeft = mask.fBounds.fLeft;
        int mask_rowBytes = mask.fRowBytes;
        int height = clip.height();

        const uint8_t* bits = mask.getAddr1(cx, cy);

        if (cx == maskLeft && clip.fRight == mask.fBounds.fRight) {
            while (--height >= 0) {
                bits_to_runs(this, cx, cy, bits, 0xFF, mask_rowBytes, 0xFF);
                bits += mask_rowBytes;
                cy += 1;
            }
        } else {
            int left_edge = cx - maskLeft;
            SkASSERT(left_edge >= 0);
            int rite_edge = clip.fRight - maskLeft;
            SkASSERT(rite_edge > left_edge);

            int left_mask = 0xFF >> (left_edge & 7);
            int rite_mask = 0xFF << (8 - (rite_edge & 7));
            int full_runs = (rite_edge >> 3) - ((left_edge + 7) >> 3);

            // check for empty right mask, so we don't read off the end (or go slower than we need to)
            if (rite_mask == 0) {
                SkASSERT(full_runs >= 0);
                full_runs -= 1;
                rite_mask = 0xFF;
            }
            if (left_mask == 0xFF) {
                full_runs -= 1;
            }

            // back up manually so we can keep in sync with our byte-aligned src
            // have cx reflect our actual starting x-coord
            cx -= left_edge & 7;

            if (full_runs < 0) {
                SkASSERT((left_mask & rite_mask) != 0);
                while (--height >= 0) {
                    bits_to_runs(this, cx, cy, bits, left_mask, 1, rite_mask);
                    bits += mask_rowBytes;
                    cy += 1;
                }
            } else {
                while (--height >= 0) {
                    bits_to_runs(this, cx, cy, bits, left_mask, full_runs + 2, rite_mask);
                    bits += mask_rowBytes;
                    cy += 1;
                }
            }
        }
    } else {
        int                         width = clip.width();
        SkAutoSTMalloc<64, int16_t> runStorage(width + 1);
        int16_t*                    runs = runStorage.get();
        const uint8_t*              aa = mask.getAddr8(clip.fLeft, clip.fTop);

        sk_memset16((uint16_t*)runs, 1, width);
        runs[width] = 0;

        int height = clip.height();
        int y = clip.fTop;
        while (--height >= 0) {
            this->blitAntiH(clip.fLeft, y, aa, runs);
            aa += mask.fRowBytes;
            y += 1;
        }
    }
}

/////////////////////// these guys are not virtual, just a helpers

void SkBlitter::blitMaskRegion(const SkMask& mask, const SkRegion& clip) {
    if (clip.quickReject(mask.fBounds)) {
        return;
    }

    SkRegion::Cliperator clipper(clip, mask.fBounds);

    while (!clipper.done()) {
        const SkIRect& cr = clipper.rect();
        this->blitMask(mask, cr);
        clipper.next();
    }
}

void SkBlitter::blitRectRegion(const SkIRect& rect, const SkRegion& clip) {
    SkRegion::Cliperator clipper(clip, rect);

    while (!clipper.done()) {
        const SkIRect& cr = clipper.rect();
        this->blitRect(cr.fLeft, cr.fTop, cr.width(), cr.height());
        clipper.next();
    }
}

void SkBlitter::blitRegion(const SkRegion& clip) {
    SkRegion::Iterator iter(clip);

    while (!iter.done()) {
        const SkIRect& cr = iter.rect();
        this->blitRect(cr.fLeft, cr.fTop, cr.width(), cr.height());
        iter.next();
    }
}

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

void SkNullBlitter::blitH(int x, int y, int width) {}

void SkNullBlitter::blitAntiH(int x, int y, const SkAlpha antialias[],
                              const int16_t runs[]) {}

void SkNullBlitter::blitV(int x, int y, int height, SkAlpha alpha) {}

void SkNullBlitter::blitRect(int x, int y, int width, int height) {}

void SkNullBlitter::blitMask(const SkMask& mask, const SkIRect& clip) {}

const SkBitmap* SkNullBlitter::justAnOpaqueColor(uint32_t* value) {
    return NULL;
}

bool SkNullBlitter::isNullBlitter() const { return true; }

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

static int compute_anti_width(const int16_t runs[]) {
    int width = 0;

    for (;;) {
        int count = runs[0];

        SkASSERT(count >= 0);
        if (count == 0) {
            break;
        }
        width += count;
        runs += count;
    }
    return width;
}

static inline bool y_in_rect(int y, const SkIRect& rect) {
    return (unsigned)(y - rect.fTop) < (unsigned)rect.height();
}

static inline bool x_in_rect(int x, const SkIRect& rect) {
    return (unsigned)(x - rect.fLeft) < (unsigned)rect.width();
}

void SkRectClipBlitter::blitH(int left, int y, int width) {
    SkASSERT(width > 0);

    if (!y_in_rect(y, fClipRect)) {
        return;
    }

    int right = left + width;

    if (left < fClipRect.fLeft) {
        left = fClipRect.fLeft;
    }
    if (right > fClipRect.fRight) {
        right = fClipRect.fRight;
    }

    width = right - left;
    if (width > 0) {
        fBlitter->blitH(left, y, width);
    }
}

void SkRectClipBlitter::blitAntiH(int left, int y, const SkAlpha aa[],
                                  const int16_t runs[]) {
    if (!y_in_rect(y, fClipRect) || left >= fClipRect.fRight) {
        return;
    }

    int x0 = left;
    int x1 = left + compute_anti_width(runs);

    if (x1 <= fClipRect.fLeft) {
        return;
    }

    SkASSERT(x0 < x1);
    if (x0 < fClipRect.fLeft) {
        int dx = fClipRect.fLeft - x0;
        SkAlphaRuns::BreakAt((int16_t*)runs, (uint8_t*)aa, dx);
        runs += dx;
        aa += dx;
        x0 = fClipRect.fLeft;
    }

    SkASSERT(x0 < x1 && runs[x1 - x0] == 0);
    if (x1 > fClipRect.fRight) {
        x1 = fClipRect.fRight;
        SkAlphaRuns::BreakAt((int16_t*)runs, (uint8_t*)aa, x1 - x0);
        ((int16_t*)runs)[x1 - x0] = 0;
    }

    SkASSERT(x0 < x1 && runs[x1 - x0] == 0);
    SkASSERT(compute_anti_width(runs) == x1 - x0);

    fBlitter->blitAntiH(x0, y, aa, runs);
}

void SkRectClipBlitter::blitV(int x, int y, int height, SkAlpha alpha) {
    SkASSERT(height > 0);

    if (!x_in_rect(x, fClipRect)) {
        return;
    }

    int y0 = y;
    int y1 = y + height;

    if (y0 < fClipRect.fTop) {
        y0 = fClipRect.fTop;
    }
    if (y1 > fClipRect.fBottom) {
        y1 = fClipRect.fBottom;
    }

    if (y0 < y1) {
        fBlitter->blitV(x, y0, y1 - y0, alpha);
    }
}

void SkRectClipBlitter::blitRect(int left, int y, int width, int height) {
    SkIRect    r;

    r.set(left, y, left + width, y + height);
    if (r.intersect(fClipRect)) {
        fBlitter->blitRect(r.fLeft, r.fTop, r.width(), r.height());
    }
}

void SkRectClipBlitter::blitAntiRect(int left, int y, int width, int height,
                                     SkAlpha leftAlpha, SkAlpha rightAlpha) {
    SkIRect    r;

    // The *true* width of the rectangle blitted is width+2:
    r.set(left, y, left + width + 2, y + height);
    if (r.intersect(fClipRect)) {
        if (r.fLeft != left) {
            SkASSERT(r.fLeft > left);
            leftAlpha = 255;
        }
        if (r.fRight != left + width + 2) {
            SkASSERT(r.fRight < left + width + 2);
            rightAlpha = 255;
        }
        if (255 == leftAlpha && 255 == rightAlpha) {
            fBlitter->blitRect(r.fLeft, r.fTop, r.width(), r.height());
        } else if (1 == r.width()) {
            if (r.fLeft == left) {
                fBlitter->blitV(r.fLeft, r.fTop, r.height(), leftAlpha);
            } else {
                SkASSERT(r.fLeft == left + width + 1);
                fBlitter->blitV(r.fLeft, r.fTop, r.height(), rightAlpha);
            }
        } else {
            fBlitter->blitAntiRect(r.fLeft, r.fTop, r.width() - 2, r.height(),
                                   leftAlpha, rightAlpha);
        }
    }
}

void SkRectClipBlitter::blitMask(const SkMask& mask, const SkIRect& clip) {
    SkASSERT(mask.fBounds.contains(clip));

    SkIRect    r = clip;

    if (r.intersect(fClipRect)) {
        fBlitter->blitMask(mask, r);
    }
}

const SkBitmap* SkRectClipBlitter::justAnOpaqueColor(uint32_t* value) {
    return fBlitter->justAnOpaqueColor(value);
}

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

void SkRgnClipBlitter::blitH(int x, int y, int width) {
    SkRegion::Spanerator span(*fRgn, y, x, x + width);
    int left, right;

    while (span.next(&left, &right)) {
        SkASSERT(left < right);
        fBlitter->blitH(left, y, right - left);
    }
}

void SkRgnClipBlitter::blitAntiH(int x, int y, const SkAlpha aa[],
                                 const int16_t runs[]) {
    int width = compute_anti_width(runs);
    SkRegion::Spanerator span(*fRgn, y, x, x + width);
    int left, right;
    SkDEBUGCODE(const SkIRect& bounds = fRgn->getBounds();)

    int prevRite = x;
    while (span.next(&left, &right)) {
        SkASSERT(x <= left);
        SkASSERT(left < right);
        SkASSERT(left >= bounds.fLeft && right <= bounds.fRight);

        SkAlphaRuns::Break((int16_t*)runs, (uint8_t*)aa, left - x, right - left);

        // now zero before left
        if (left > prevRite) {
            int index = prevRite - x;
            ((uint8_t*)aa)[index] = 0;   // skip runs after right
            ((int16_t*)runs)[index] = SkToS16(left - prevRite);
        }

        prevRite = right;
    }

    if (prevRite > x) {
        ((int16_t*)runs)[prevRite - x] = 0;

        if (x < 0) {
            int skip = runs[0];
            SkASSERT(skip >= -x);
            aa += skip;
            runs += skip;
            x += skip;
        }
        fBlitter->blitAntiH(x, y, aa, runs);
    }
}

void SkRgnClipBlitter::blitV(int x, int y, int height, SkAlpha alpha) {
    SkIRect    bounds;
    bounds.set(x, y, x + 1, y + height);

    SkRegion::Cliperator    iter(*fRgn, bounds);

    while (!iter.done()) {
        const SkIRect& r = iter.rect();
        SkASSERT(bounds.contains(r));

        fBlitter->blitV(x, r.fTop, r.height(), alpha);
        iter.next();
    }
}

void SkRgnClipBlitter::blitRect(int x, int y, int width, int height) {
    SkIRect    bounds;
    bounds.set(x, y, x + width, y + height);

    SkRegion::Cliperator    iter(*fRgn, bounds);

    while (!iter.done()) {
        const SkIRect& r = iter.rect();
        SkASSERT(bounds.contains(r));

        fBlitter->blitRect(r.fLeft, r.fTop, r.width(), r.height());
        iter.next();
    }
}

void SkRgnClipBlitter::blitAntiRect(int x, int y, int width, int height,
                                    SkAlpha leftAlpha, SkAlpha rightAlpha) {
    // The *true* width of the rectangle to blit is width + 2
    SkIRect    bounds;
    bounds.set(x, y, x + width + 2, y + height);

    SkRegion::Cliperator    iter(*fRgn, bounds);

    while (!iter.done()) {
        const SkIRect& r = iter.rect();
        SkASSERT(bounds.contains(r));
        SkASSERT(r.fLeft >= x);
        SkASSERT(r.fRight <= x + width + 2);

        SkAlpha effectiveLeftAlpha = (r.fLeft == x) ? leftAlpha : 255;
        SkAlpha effectiveRightAlpha = (r.fRight == x + width + 2) ?
                                      rightAlpha : 255;

        if (255 == effectiveLeftAlpha && 255 == effectiveRightAlpha) {
            fBlitter->blitRect(r.fLeft, r.fTop, r.width(), r.height());
        } else if (1 == r.width()) {
            if (r.fLeft == x) {
                fBlitter->blitV(r.fLeft, r.fTop, r.height(),
                                effectiveLeftAlpha);
            } else {
                SkASSERT(r.fLeft == x + width + 1);
                fBlitter->blitV(r.fLeft, r.fTop, r.height(),
                                effectiveRightAlpha);
            }
        } else {
            fBlitter->blitAntiRect(r.fLeft, r.fTop, r.width() - 2, r.height(),
                                   effectiveLeftAlpha, effectiveRightAlpha);
        }
        iter.next();
    }
}


void SkRgnClipBlitter::blitMask(const SkMask& mask, const SkIRect& clip) {
    SkASSERT(mask.fBounds.contains(clip));

    SkRegion::Cliperator iter(*fRgn, clip);
    const SkIRect&       r = iter.rect();
    SkBlitter*           blitter = fBlitter;

    while (!iter.done()) {
        blitter->blitMask(mask, r);
        iter.next();
    }
}

const SkBitmap* SkRgnClipBlitter::justAnOpaqueColor(uint32_t* value) {
    return fBlitter->justAnOpaqueColor(value);
}

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

SkBlitter* SkBlitterClipper::apply(SkBlitter* blitter, const SkRegion* clip,
                                   const SkIRect* ir) {
    if (clip) {
        const SkIRect& clipR = clip->getBounds();

        if (clip->isEmpty() || (ir && !SkIRect::Intersects(clipR, *ir))) {
            blitter = &fNullBlitter;
        } else if (clip->isRect()) {
            if (ir == NULL || !clipR.contains(*ir)) {
                fRectBlitter.init(blitter, clipR);
                blitter = &fRectBlitter;
            }
        } else {
            fRgnBlitter.init(blitter, clip);
            blitter = &fRgnBlitter;
        }
    }
    return blitter;
}

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

#include "SkColorShader.h"
#include "SkColorPriv.h"

class Sk3DShader : public SkShader {
public:
    Sk3DShader(SkShader* proxy) : fProxy(proxy) {
        SkSafeRef(proxy);
    }

    virtual ~Sk3DShader() {
        SkSafeUnref(fProxy);
    }

    size_t contextSize() const override {
        size_t size = sizeof(Sk3DShaderContext);
        if (fProxy) {
            size += fProxy->contextSize();
        }
        return size;
    }

    Context* onCreateContext(const ContextRec& rec, void* storage) const override {
        SkShader::Context* proxyContext = NULL;
        if (fProxy) {
            char* proxyContextStorage = (char*) storage + sizeof(Sk3DShaderContext);
            proxyContext = fProxy->createContext(rec, proxyContextStorage);
            if (!proxyContext) {
                return NULL;
            }
        }
        return SkNEW_PLACEMENT_ARGS(storage, Sk3DShaderContext, (*this, rec, proxyContext));
    }

    class Sk3DShaderContext : public SkShader::Context {
    public:
        // Calls proxyContext's destructor but will NOT free its memory.
        Sk3DShaderContext(const Sk3DShader& shader, const ContextRec& rec,
                          SkShader::Context* proxyContext)
            : INHERITED(shader, rec)
            , fMask(NULL)
            , fProxyContext(proxyContext)
        {
            if (!fProxyContext) {
                fPMColor = SkPreMultiplyColor(rec.fPaint->getColor());
            }
        }

        virtual ~Sk3DShaderContext() {
            if (fProxyContext) {
                fProxyContext->~Context();
            }
        }

        void set3DMask(const SkMask* mask) override { fMask = mask; }

        void shadeSpan(int x, int y, SkPMColor span[], int count) override {
            if (fProxyContext) {
                fProxyContext->shadeSpan(x, y, span, count);
            }

            if (fMask == NULL) {
                if (fProxyContext == NULL) {
                    sk_memset32(span, fPMColor, count);
                }
                return;
            }

            SkASSERT(fMask->fBounds.contains(x, y));
            SkASSERT(fMask->fBounds.contains(x + count - 1, y));

            size_t          size = fMask->computeImageSize();
            const uint8_t*  alpha = fMask->getAddr8(x, y);
            const uint8_t*  mulp = alpha + size;
            const uint8_t*  addp = mulp + size;

            if (fProxyContext) {
                for (int i = 0; i < count; i++) {
                    if (alpha[i]) {
                        SkPMColor c = span[i];
                        if (c) {
                            unsigned a = SkGetPackedA32(c);
                            unsigned r = SkGetPackedR32(c);
                            unsigned g = SkGetPackedG32(c);
                            unsigned b = SkGetPackedB32(c);

                            unsigned mul = SkAlpha255To256(mulp[i]);
                            unsigned add = addp[i];

                            r = SkFastMin32(SkAlphaMul(r, mul) + add, a);
                            g = SkFastMin32(SkAlphaMul(g, mul) + add, a);
                            b = SkFastMin32(SkAlphaMul(b, mul) + add, a);

                            span[i] = SkPackARGB32(a, r, g, b);
                        }
                    } else {
                        span[i] = 0;
                    }
                }
            } else {    // color
                unsigned a = SkGetPackedA32(fPMColor);
                unsigned r = SkGetPackedR32(fPMColor);
                unsigned g = SkGetPackedG32(fPMColor);
                unsigned b = SkGetPackedB32(fPMColor);
                for (int i = 0; i < count; i++) {
                    if (alpha[i]) {
                        unsigned mul = SkAlpha255To256(mulp[i]);
                        unsigned add = addp[i];

                        span[i] = SkPackARGB32( a,
                                        SkFastMin32(SkAlphaMul(r, mul) + add, a),
                                        SkFastMin32(SkAlphaMul(g, mul) + add, a),
                                        SkFastMin32(SkAlphaMul(b, mul) + add, a));
                    } else {
                        span[i] = 0;
                    }
                }
            }
        }

    private:
        // Unowned.
        const SkMask*       fMask;
        // Memory is unowned, but we need to call the destructor.
        SkShader::Context*  fProxyContext;
        SkPMColor           fPMColor;

        typedef SkShader::Context INHERITED;
    };

#ifndef SK_IGNORE_TO_STRING
    void toString(SkString* str) const override {
        str->append("Sk3DShader: (");

        if (fProxy) {
            str->append("Proxy: ");
            fProxy->toString(str);
        }

        this->INHERITED::toString(str);

        str->append(")");
    }
#endif

    SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(Sk3DShader)

protected:
    void flatten(SkWriteBuffer& buffer) const override {
        buffer.writeFlattenable(fProxy);
    }

private:
    SkShader*       fProxy;

    typedef SkShader INHERITED;
};

SkFlattenable* Sk3DShader::CreateProc(SkReadBuffer& buffer) {
    SkAutoTUnref<SkShader> shader(buffer.readShader());
    return SkNEW_ARGS(Sk3DShader, (shader));
}

class Sk3DBlitter : public SkBlitter {
public:
    Sk3DBlitter(SkBlitter* proxy, SkShader::Context* shaderContext)
        : fProxy(proxy)
        , fShaderContext(shaderContext)
    {}

    void blitH(int x, int y, int width) override {
        fProxy->blitH(x, y, width);
    }

    virtual void blitAntiH(int x, int y, const SkAlpha antialias[],
                           const int16_t runs[]) override {
        fProxy->blitAntiH(x, y, antialias, runs);
    }

    void blitV(int x, int y, int height, SkAlpha alpha) override {
        fProxy->blitV(x, y, height, alpha);
    }

    void blitRect(int x, int y, int width, int height) override {
        fProxy->blitRect(x, y, width, height);
    }

    void blitMask(const SkMask& mask, const SkIRect& clip) override {
        if (mask.fFormat == SkMask::k3D_Format) {
            fShaderContext->set3DMask(&mask);

            ((SkMask*)&mask)->fFormat = SkMask::kA8_Format;
            fProxy->blitMask(mask, clip);
            ((SkMask*)&mask)->fFormat = SkMask::k3D_Format;

            fShaderContext->set3DMask(NULL);
        } else {
            fProxy->blitMask(mask, clip);
        }
    }

private:
    // Both pointers are unowned. They will be deleted by SkSmallAllocator.
    SkBlitter*          fProxy;
    SkShader::Context*  fShaderContext;
};

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

#include "SkCoreBlitters.h"

static bool just_solid_color(const SkPaint& paint) {
    if (paint.getAlpha() == 0xFF && paint.getColorFilter() == NULL) {
        SkShader* shader = paint.getShader();
        if (NULL == shader) {
            return true;
        }
    }
    return false;
}

/** By analyzing the paint (with an xfermode), we may decide we can take
    special action. This enum lists our possible actions
 */
enum XferInterp {
    kNormal_XferInterp,         // no special interpretation, draw normally
    kSrcOver_XferInterp,        // draw as if in srcover mode
    kSkipDrawing_XferInterp     // draw nothing
};

static XferInterp interpret_xfermode(const SkPaint& paint, SkXfermode* xfer,
                                     SkColorType deviceCT) {
    SkXfermode::Mode  mode;

    if (SkXfermode::AsMode(xfer, &mode)) {
        switch (mode) {
            case SkXfermode::kSrc_Mode:
                if (just_solid_color(paint)) {
                    return kSrcOver_XferInterp;
                }
                break;
            case SkXfermode::kDst_Mode:
                return kSkipDrawing_XferInterp;
            case SkXfermode::kSrcOver_Mode:
                return kSrcOver_XferInterp;
            case SkXfermode::kDstOver_Mode:
                if (kRGB_565_SkColorType == deviceCT) {
                    return kSkipDrawing_XferInterp;
                }
                break;
            case SkXfermode::kSrcIn_Mode:
                if (kRGB_565_SkColorType == deviceCT &&
                    just_solid_color(paint)) {
                    return kSrcOver_XferInterp;
                }
                break;
            case SkXfermode::kDstIn_Mode:
                if (just_solid_color(paint)) {
                    return kSkipDrawing_XferInterp;
                }
                break;
            default:
                break;
        }
    }
    return kNormal_XferInterp;
}

SkBlitter* SkBlitter::Choose(const SkBitmap& device,
                             const SkMatrix& matrix,
                             const SkPaint& origPaint,
                             SkTBlitterAllocator* allocator,
                             bool drawCoverage) {
    SkASSERT(allocator != NULL);

    // which check, in case we're being called by a client with a dummy device
    // (e.g. they have a bounder that always aborts the draw)
    if (kUnknown_SkColorType == device.colorType() ||
            (drawCoverage && (kAlpha_8_SkColorType != device.colorType()))) {
        return allocator->createT<SkNullBlitter>();
    }

    SkShader* shader = origPaint.getShader();
    SkColorFilter* cf = origPaint.getColorFilter();
    SkXfermode* mode = origPaint.getXfermode();
    Sk3DShader* shader3D = NULL;

    SkTCopyOnFirstWrite<SkPaint> paint(origPaint);

    if (origPaint.getMaskFilter() != NULL &&
            origPaint.getMaskFilter()->getFormat() == SkMask::k3D_Format) {
        shader3D = SkNEW_ARGS(Sk3DShader, (shader));
        // we know we haven't initialized lazyPaint yet, so just do it
        paint.writable()->setShader(shader3D)->unref();
        shader = shader3D;
    }

    if (mode) {
        switch (interpret_xfermode(*paint, mode, device.colorType())) {
            case kSrcOver_XferInterp:
                mode = NULL;
                paint.writable()->setXfermode(NULL);
                break;
            case kSkipDrawing_XferInterp:{
                return allocator->createT<SkNullBlitter>();
            }
            default:
                break;
        }
    }

    /*
     *  If the xfermode is CLEAR, then we can completely ignore the installed
     *  color/shader/colorfilter, and just pretend we're SRC + color==0. This
     *  will fall into our optimizations for SRC mode.
     */
    if (SkXfermode::IsMode(mode, SkXfermode::kClear_Mode)) {
        SkPaint* p = paint.writable();
        shader = p->setShader(NULL);
        cf = p->setColorFilter(NULL);
        mode = p->setXfermodeMode(SkXfermode::kSrc_Mode);
        p->setColor(0);
    }

    if (NULL == shader) {
        if (mode) {
            // xfermodes (and filters) require shaders for our current blitters
            shader = SkNEW_ARGS(SkColorShader, (paint->getColor()));
            paint.writable()->setShader(shader)->unref();
            paint.writable()->setAlpha(0xFF);
        } else if (cf) {
            // if no shader && no xfermode, we just apply the colorfilter to
            // our color and move on.
            SkPaint* writablePaint = paint.writable();
            writablePaint->setColor(cf->filterColor(paint->getColor()));
            writablePaint->setColorFilter(NULL);
            cf = NULL;
        }
    }

    if (cf) {
        SkASSERT(shader);
        shader = SkNEW_ARGS(SkFilterShader, (shader, cf));
        paint.writable()->setShader(shader)->unref();
        // blitters should ignore the presence/absence of a filter, since
        // if there is one, the shader will take care of it.
    }

    /*
     *  We create a SkShader::Context object, and store it on the blitter.
     */
    SkShader::Context* shaderContext = NULL;
    if (shader) {
        SkShader::ContextRec rec(device, *paint, matrix);
        size_t contextSize = shader->contextSize();
        if (contextSize) {
            // Try to create the ShaderContext
            void* storage = allocator->reserveT<SkShader::Context>(contextSize);
            shaderContext = shader->createContext(rec, storage);
            if (!shaderContext) {
                allocator->freeLast();
                return allocator->createT<SkNullBlitter>();
            }
            SkASSERT(shaderContext);
            SkASSERT((void*) shaderContext == storage);
        } else {
            return allocator->createT<SkNullBlitter>();
        }
    }

    SkBlitter*  blitter = NULL;
    switch (device.colorType()) {
        case kAlpha_8_SkColorType:
            if (drawCoverage) {
                SkASSERT(NULL == shader);
                SkASSERT(NULL == paint->getXfermode());
                blitter = allocator->createT<SkA8_Coverage_Blitter>(device, *paint);
            } else if (shader) {
                blitter = allocator->createT<SkA8_Shader_Blitter>(device, *paint, shaderContext);
            } else {
                blitter = allocator->createT<SkA8_Blitter>(device, *paint);
            }
            break;

        case kRGB_565_SkColorType:
            blitter = SkBlitter_ChooseD565(device, *paint, shaderContext, allocator);
            break;

        case kN32_SkColorType:
            if (shader) {
                blitter = allocator->createT<SkARGB32_Shader_Blitter>(
                        device, *paint, shaderContext);
            } else if (paint->getColor() == SK_ColorBLACK) {
                blitter = allocator->createT<SkARGB32_Black_Blitter>(device, *paint);
            } else if (paint->getAlpha() == 0xFF) {
                blitter = allocator->createT<SkARGB32_Opaque_Blitter>(device, *paint);
            } else {
                blitter = allocator->createT<SkARGB32_Blitter>(device, *paint);
            }
            break;

        default:
            SkDEBUGFAIL("unsupported device config");
            blitter = allocator->createT<SkNullBlitter>();
            break;
    }

    if (shader3D) {
        SkBlitter* innerBlitter = blitter;
        // innerBlitter was allocated by allocator, which will delete it.
        // We know shaderContext or its proxies is of type Sk3DShaderContext, so we need to
        // wrapper the blitter to notify it when we see an emboss mask.
        blitter = allocator->createT<Sk3DBlitter>(innerBlitter, shaderContext);
    }
    return blitter;
}

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

class SkTransparentShaderContext : public SkShader::Context {
public:
    SkTransparentShaderContext(const SkShader& shader, const SkShader::ContextRec& rec)
        // Override rec with the identity matrix, so it is guaranteed to be invertible.
        : INHERITED(shader, SkShader::ContextRec(*rec.fDevice, *rec.fPaint, SkMatrix::I())) {}

    void shadeSpan(int x, int y, SkPMColor colors[], int count) override {
        sk_bzero(colors, count * sizeof(SkPMColor));
    }

private:
    typedef SkShader::Context INHERITED;
};

SkShaderBlitter::SkShaderBlitter(const SkBitmap& device, const SkPaint& paint,
                                 SkShader::Context* shaderContext)
        : INHERITED(device)
        , fShader(paint.getShader())
        , fShaderContext(shaderContext) {
    SkASSERT(fShader);
    SkASSERT(fShaderContext);

    fShader->ref();
    fShaderFlags = fShaderContext->getFlags();
}

SkShaderBlitter::~SkShaderBlitter() {
    fShader->unref();
}

bool SkShaderBlitter::resetShaderContext(const SkShader::ContextRec& rec) {
    // Only destroy the old context if we have a new one. We need to ensure to have a
    // live context in fShaderContext because the storage is owned by an SkSmallAllocator
    // outside of this class.
    // The new context will be of the same size as the old one because we use the same
    // shader to create it. It is therefore safe to re-use the storage.
    fShaderContext->~Context();
    SkShader::Context* ctx = fShader->createContext(rec, (void*)fShaderContext);
    if (NULL == ctx) {
        // Need a valid context in fShaderContext's storage, so we can later (or our caller) call
        // the in-place destructor.
        SkNEW_PLACEMENT_ARGS(fShaderContext, SkTransparentShaderContext, (*fShader, rec));
        return false;
    }
    return true;
}