summaryrefslogtreecommitdiffstats
path: root/src/widgets/kernel/qwidgetbackingstore.cpp
blob: 1b963010d11672d044aa7161d2d0e90746b9a072 (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
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtWidgets module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 3 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL3 included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or (at your option) the GNU General
** Public license version 3 or any later version approved by the KDE Free
** Qt Foundation. The licenses are as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
** be met: https://www.gnu.org/licenses/gpl-2.0.html and
** https://www.gnu.org/licenses/gpl-3.0.html.
**
** $QT_END_LICENSE$
**
****************************************************************************/


#include "qplatformdefs.h"

#include "qwidgetbackingstore_p.h"

#include <QtCore/qglobal.h>
#include <QtCore/qdebug.h>
#include <QtCore/qvarlengtharray.h>
#include <QtGui/qevent.h>
#include <QtWidgets/qapplication.h>
#include <QtGui/qpaintengine.h>
#if QT_CONFIG(graphicsview)
#include <QtWidgets/qgraphicsproxywidget.h>
#endif

#include <private/qwidget_p.h>
#include <private/qapplication_p.h>
#include <private/qpaintengine_raster_p.h>
#if QT_CONFIG(graphicseffect)
#include <private/qgraphicseffect_p.h>
#endif
#include <QtGui/private/qwindow_p.h>
#include <QtGui/private/qhighdpiscaling_p.h>

#include <qpa/qplatformbackingstore.h>

#if defined(Q_OS_WIN) && !defined(QT_NO_PAINT_DEBUG)
#  include <QtCore/qt_windows.h>
#  include <qpa/qplatformnativeinterface.h>
#endif

#include <private/qmemory_p.h>

QT_BEGIN_NAMESPACE

extern QRegion qt_dirtyRegion(QWidget *);

#ifndef QT_NO_OPENGL
Q_GLOBAL_STATIC(QPlatformTextureList, qt_dummy_platformTextureList)
#endif

static bool hasPlatformWindow(QWidget *widget)
{
    return widget && widget->windowHandle() && widget->windowHandle()->handle();
}

/**
 * Flushes the contents of the \a backingStore into the screen area of \a widget.
 * \a region is the region to be updated in \a widget coordinates.
 */
void QWidgetBackingStore::qt_flush(QWidget *widget, const QRegion &region, QBackingStore *backingStore,
                                   QWidget *tlw, QPlatformTextureList *widgetTextures,
                                   QWidgetBackingStore *widgetBackingStore)
{
#ifdef QT_NO_OPENGL
    Q_UNUSED(widgetTextures);
    Q_ASSERT(!region.isEmpty());
#else
    Q_ASSERT(!region.isEmpty() || widgetTextures);
#endif
    Q_ASSERT(widget);
    Q_ASSERT(backingStore);
    Q_ASSERT(tlw);
#if !defined(QT_NO_PAINT_DEBUG)
    static int flushUpdate = qEnvironmentVariableIntValue("QT_FLUSH_UPDATE");
    if (flushUpdate > 0)
        QWidgetBackingStore::showYellowThing(widget, region, flushUpdate * 10, false);
#endif

    if (tlw->testAttribute(Qt::WA_DontShowOnScreen) || widget->testAttribute(Qt::WA_DontShowOnScreen))
        return;

    // Foreign Windows do not have backing store content and must not be flushed
    if (QWindow *widgetWindow = widget->windowHandle()) {
        if (widgetWindow->type() == Qt::ForeignWindow)
            return;
    }

    static bool fpsDebug = qEnvironmentVariableIntValue("QT_DEBUG_FPS");
    if (fpsDebug) {
        if (!widgetBackingStore->perfFrames++)
            widgetBackingStore->perfTime.start();
        if (widgetBackingStore->perfTime.elapsed() > 5000) {
            double fps = double(widgetBackingStore->perfFrames * 1000) / widgetBackingStore->perfTime.restart();
            qDebug("FPS: %.1f\n", fps);
            widgetBackingStore->perfFrames = 0;
        }
    }

    QPoint offset;
    if (widget != tlw)
        offset += widget->mapTo(tlw, QPoint());

    QRegion effectiveRegion = region;
#ifndef QT_NO_OPENGL
    const bool compositionWasActive = widget->d_func()->renderToTextureComposeActive;
    if (!widgetTextures) {
        widget->d_func()->renderToTextureComposeActive = false;
        // Detect the case of falling back to the normal flush path when no
        // render-to-texture widgets are visible anymore. We will force one
        // last flush to go through the OpenGL-based composition to prevent
        // artifacts. The next flush after this one will use the normal path.
        if (compositionWasActive)
            widgetTextures = qt_dummy_platformTextureList;
    } else {
        widget->d_func()->renderToTextureComposeActive = true;
    }
    // When changing the composition status, make sure the dirty region covers
    // the entire widget.  Just having e.g. the shown/hidden render-to-texture
    // widget's area marked as dirty is incorrect when changing flush paths.
    if (compositionWasActive != widget->d_func()->renderToTextureComposeActive)
        effectiveRegion = widget->rect();

    // re-test since we may have been forced to this path via the dummy texture list above
    if (widgetTextures) {
        qt_window_private(tlw->windowHandle())->compositing = true;
        widget->window()->d_func()->sendComposeStatus(widget->window(), false);
        // A window may have alpha even when the app did not request
        // WA_TranslucentBackground. Therefore the compositor needs to know whether the app intends
        // to rely on translucency, in order to decide if it should clear to transparent or opaque.
        const bool translucentBackground = widget->testAttribute(Qt::WA_TranslucentBackground);
        backingStore->handle()->composeAndFlush(widget->windowHandle(), effectiveRegion, offset,
                                                widgetTextures, translucentBackground);
        widget->window()->d_func()->sendComposeStatus(widget->window(), true);
    } else
#endif
        backingStore->flush(effectiveRegion, widget->windowHandle(), offset);
}

#ifndef QT_NO_PAINT_DEBUG
#if defined(Q_OS_WIN) && !defined(Q_OS_WINRT)

static void showYellowThing_win(QWidget *widget, const QRegion &region, int msec)
{
    // We expect to be passed a native parent.
    QWindow *nativeWindow = widget->windowHandle();
    if (!nativeWindow)
        return;
    void *hdcV = QGuiApplication::platformNativeInterface()->nativeResourceForWindow(QByteArrayLiteral("getDC"), nativeWindow);
    if (!hdcV)
        return;
    const HDC hdc = reinterpret_cast<HDC>(hdcV);

    static const COLORREF colors[] = {RGB(255, 255, 0), RGB(255, 200, 55), RGB(200, 255, 55), RGB(200, 200, 0)};

    static size_t i = 0;
    const HBRUSH brush = CreateSolidBrush(colors[i]);
    i = (i + 1) % (sizeof(colors) / sizeof(colors[0]));

    for (const QRect &rect : region) {
        RECT winRect;
        SetRect(&winRect, rect.left(), rect.top(), rect.right(), rect.bottom());
        FillRect(hdc, &winRect, brush);
    }
    DeleteObject(brush);
    QGuiApplication::platformNativeInterface()->nativeResourceForWindow(QByteArrayLiteral("releaseDC"), nativeWindow);
    ::Sleep(msec);
}
#endif //  defined(Q_OS_WIN) && !defined(Q_OS_WINRT)

void QWidgetBackingStore::showYellowThing(QWidget *widget, const QRegion &toBePainted, int msec, bool unclipped)
{
#ifdef Q_OS_WINRT
    Q_UNUSED(msec)
#endif
    QRegion paintRegion = toBePainted;
    QRect widgetRect = widget->rect();

    if (!hasPlatformWindow(widget)) {
        QWidget *nativeParent = widget->nativeParentWidget();
        const QPoint offset = widget->mapTo(nativeParent, QPoint(0, 0));
        paintRegion.translate(offset);
        widgetRect.translate(offset);
        widget = nativeParent;
    }

#if defined(Q_OS_WIN) && !defined(Q_OS_WINRT)
    Q_UNUSED(unclipped);
    showYellowThing_win(widget, paintRegion, msec);
#else
    //flags to fool painter
    bool paintUnclipped = widget->testAttribute(Qt::WA_PaintUnclipped);
    if (unclipped && !widget->d_func()->paintOnScreen())
        widget->setAttribute(Qt::WA_PaintUnclipped);

    const bool setFlag = !widget->testAttribute(Qt::WA_WState_InPaintEvent);
    if (setFlag)
        widget->setAttribute(Qt::WA_WState_InPaintEvent);

    //setup the engine
    QPaintEngine *pe = widget->paintEngine();
    if (pe) {
        pe->setSystemClip(paintRegion);
        {
            QPainter p(widget);
            p.setClipRegion(paintRegion);
            static int i = 0;
            switch (i) {
            case 0:
                p.fillRect(widgetRect, QColor(255,255,0));
                break;
            case 1:
                p.fillRect(widgetRect, QColor(255,200,55));
                break;
            case 2:
                p.fillRect(widgetRect, QColor(200,255,55));
                break;
            case 3:
                p.fillRect(widgetRect, QColor(200,200,0));
                break;
            }
            i = (i+1) & 3;
            p.end();
        }
    }

    if (setFlag)
        widget->setAttribute(Qt::WA_WState_InPaintEvent, false);

    //restore
    widget->setAttribute(Qt::WA_PaintUnclipped, paintUnclipped);

    if (pe)
        pe->setSystemClip(QRegion());

#if defined(Q_OS_UNIX)
    ::usleep(1000 * msec);
#endif
#endif // !Q_OS_WIN
}

bool QWidgetBackingStore::flushPaint(QWidget *widget, const QRegion &rgn)
{
    if (!widget)
        return false;

    int delay = 0;
    if (widget->testAttribute(Qt::WA_WState_InPaintEvent)) {
        static int flushPaintEvent = qEnvironmentVariableIntValue("QT_FLUSH_PAINT_EVENT");
        if (!flushPaintEvent)
            return false;
        delay = flushPaintEvent;
    } else {
        static int flushPaint = qEnvironmentVariableIntValue("QT_FLUSH_PAINT");
        if (!flushPaint)
            return false;
        delay = flushPaint;
    }

    QWidgetBackingStore::showYellowThing(widget, rgn, delay * 10, true);
    return true;
}

void QWidgetBackingStore::unflushPaint(QWidget *widget, const QRegion &rgn)
{
    if (widget->d_func()->paintOnScreen() || rgn.isEmpty())
        return;

    QWidget *tlw = widget->window();
    QTLWExtra *tlwExtra = tlw->d_func()->maybeTopData();
    if (!tlwExtra)
        return;

    qt_flush(widget, rgn, tlwExtra->widgetBackingStore->store, tlw, 0, tlw->d_func()->maybeBackingStore());
}
#endif // QT_NO_PAINT_DEBUG

/*
    Moves the whole rect by (dx, dy) in widget's coordinate system.
    Doesn't generate any updates.
*/
bool QWidgetBackingStore::bltRect(const QRect &rect, int dx, int dy, QWidget *widget)
{
    const QPoint pos(widget->mapTo(tlw, rect.topLeft()));
    const QRect tlwRect(QRect(pos, rect.size()));
    if (dirty.intersects(tlwRect))
        return false; // We don't want to scroll junk.
    return store->scroll(tlwRect, dx, dy);
}

/*!
    Prepares the window surface to paint a\ toClean region of the \a widget and
    updates the BeginPaintInfo struct accordingly.

    The \a toClean region might be clipped by the window surface.
*/
void QWidgetBackingStore::beginPaint(QRegion &toClean, QWidget *widget, QBackingStore *backingStore,
                                     BeginPaintInfo *returnInfo, bool toCleanIsInTopLevelCoordinates)
{
    Q_UNUSED(widget);
    Q_UNUSED(toCleanIsInTopLevelCoordinates);

    // Always flush repainted areas.
    dirtyOnScreen += toClean;

#ifdef QT_NO_PAINT_DEBUG
    backingStore->beginPaint(toClean);
#else
    returnInfo->wasFlushed = QWidgetBackingStore::flushPaint(tlw, toClean);
    // Avoid deadlock with QT_FLUSH_PAINT: the server will wait for
    // the BackingStore lock, so if we hold that, the server will
    // never release the Communication lock that we are waiting for in
    // sendSynchronousCommand
    if (!returnInfo->wasFlushed)
        backingStore->beginPaint(toClean);
#endif

    Q_UNUSED(returnInfo);
}

void QWidgetBackingStore::endPaint(const QRegion &cleaned, QBackingStore *backingStore,
        BeginPaintInfo *beginPaintInfo)
{
#ifndef QT_NO_PAINT_DEBUG
    if (!beginPaintInfo->wasFlushed)
        backingStore->endPaint();
    else
        QWidgetBackingStore::unflushPaint(tlw, cleaned);
#else
    Q_UNUSED(beginPaintInfo);
    Q_UNUSED(cleaned);
    backingStore->endPaint();
#endif

    flush();
}

/*!
    Returns the region (in top-level coordinates) that needs repaint and/or flush.

    If the widget is non-zero, only the dirty region for the widget is returned
    and the region will be in widget coordinates.
*/
QRegion QWidgetBackingStore::dirtyRegion(QWidget *widget) const
{
    const bool widgetDirty = widget && widget != tlw;
    const QRect tlwRect(topLevelRect());
    const QRect surfaceGeometry(tlwRect.topLeft(), store->size());
    if (surfaceGeometry != tlwRect && surfaceGeometry.size() != tlwRect.size()) {
        if (widgetDirty) {
            const QRect dirtyTlwRect = QRect(QPoint(), tlwRect.size());
            const QPoint offset(widget->mapTo(tlw, QPoint()));
            const QRect dirtyWidgetRect(dirtyTlwRect & widget->rect().translated(offset));
            return dirtyWidgetRect.translated(-offset);
        }
        return QRect(QPoint(), tlwRect.size());
    }

    // Calculate the region that needs repaint.
    QRegion r(dirty);
    for (int i = 0; i < dirtyWidgets.size(); ++i) {
        QWidget *w = dirtyWidgets.at(i);
        if (widgetDirty && w != widget && !widget->isAncestorOf(w))
            continue;
        r += w->d_func()->dirty.translated(w->mapTo(tlw, QPoint()));
    }

    // Append the region that needs flush.
    r += dirtyOnScreen;

    for (QWidget *w : dirtyOnScreenWidgets) {
        if (widgetDirty && w != widget && !widget->isAncestorOf(w))
            continue;
        QWidgetPrivate *wd = w->d_func();
        Q_ASSERT(wd->needsFlush);
        r += wd->needsFlush->translated(w->mapTo(tlw, QPoint()));
    }

    if (widgetDirty) {
        // Intersect with the widget geometry and translate to its coordinates.
        const QPoint offset(widget->mapTo(tlw, QPoint()));
        r &= widget->rect().translated(offset);
        r.translate(-offset);
    }
    return r;
}

/*!
    Returns the static content inside the \a parent if non-zero; otherwise the static content
    for the entire backing store is returned. The content will be clipped to \a withinClipRect
    if non-empty.
*/
QRegion QWidgetBackingStore::staticContents(QWidget *parent, const QRect &withinClipRect) const
{
    if (!parent && tlw->testAttribute(Qt::WA_StaticContents)) {
        const QSize surfaceGeometry(store->size());
        QRect surfaceRect(0, 0, surfaceGeometry.width(), surfaceGeometry.height());
        if (!withinClipRect.isEmpty())
            surfaceRect &= withinClipRect;
        return QRegion(surfaceRect);
    }

    QRegion region;
    if (parent && parent->d_func()->children.isEmpty())
        return region;

    const bool clipToRect = !withinClipRect.isEmpty();
    const int count = staticWidgets.count();
    for (int i = 0; i < count; ++i) {
        QWidget *w = staticWidgets.at(i);
        QWidgetPrivate *wd = w->d_func();
        if (!wd->isOpaque || !wd->extra || wd->extra->staticContentsSize.isEmpty()
            || !w->isVisible() || (parent && !parent->isAncestorOf(w))) {
            continue;
        }

        QRect rect(0, 0, wd->extra->staticContentsSize.width(), wd->extra->staticContentsSize.height());
        const QPoint offset = w->mapTo(parent ? parent : tlw, QPoint());
        if (clipToRect)
            rect &= withinClipRect.translated(-offset);
        if (rect.isEmpty())
            continue;

        rect &= wd->clipRect();
        if (rect.isEmpty())
            continue;

        QRegion visible(rect);
        wd->clipToEffectiveMask(visible);
        if (visible.isEmpty())
            continue;
        wd->subtractOpaqueSiblings(visible, 0, /*alsoNonOpaque=*/true);

        visible.translate(offset);
        region += visible;
    }

    return region;
}

void QWidgetBackingStore::sendUpdateRequest(QWidget *widget, UpdateTime updateTime)
{
    if (!widget)
        return;

#ifndef QT_NO_OPENGL
    // Having every repaint() leading to a sync/flush is bad as it causes
    // compositing and waiting for vsync each and every time. Change to
    // UpdateLater, except for approx. once per frame to prevent starvation in
    // case the control does not get back to the event loop.
    QWidget *w = widget->window();
    if (updateTime == UpdateNow && w && w->windowHandle() && QWindowPrivate::get(w->windowHandle())->compositing) {
        int refresh = 60;
        QScreen *ws = w->windowHandle()->screen();
        if (ws)
            refresh = ws->refreshRate();
        QWindowPrivate *wd = QWindowPrivate::get(w->windowHandle());
        if (wd->lastComposeTime.isValid()) {
            const qint64 elapsed = wd->lastComposeTime.elapsed();
            if (elapsed <= qint64(1000.0f / refresh))
                updateTime = UpdateLater;
       }
    }
#endif

    switch (updateTime) {
    case UpdateLater:
        updateRequestSent = true;
        QCoreApplication::postEvent(widget, new QEvent(QEvent::UpdateRequest), Qt::LowEventPriority);
        break;
    case UpdateNow: {
        QEvent event(QEvent::UpdateRequest);
        QCoreApplication::sendEvent(widget, &event);
        break;
        }
    }
}

static inline QRect widgetRectFor(QWidget *, const QRect &r) { return r; }
static inline QRect widgetRectFor(QWidget *widget, const QRegion &) { return widget->rect(); }

/*!
    Marks the region of the widget as dirty (if not already marked as dirty) and
    posts an UpdateRequest event to the top-level widget (if not already posted).

    If updateTime is UpdateNow, the event is sent immediately instead of posted.

    If bufferState is BufferInvalid, all widgets intersecting with the region will be dirty.

    If the widget paints directly on screen, the event is sent to the widget
    instead of the top-level widget, and bufferState is completely ignored.
*/
template <class T>
void QWidgetBackingStore::markDirty(const T &r, QWidget *widget, UpdateTime updateTime, BufferState bufferState)
{
    Q_ASSERT(tlw->d_func()->extra);
    Q_ASSERT(tlw->d_func()->extra->topextra);
    Q_ASSERT(!tlw->d_func()->extra->topextra->inTopLevelResize);
    Q_ASSERT(widget->isVisible() && widget->updatesEnabled());
    Q_ASSERT(widget->window() == tlw);
    Q_ASSERT(!r.isEmpty());

#if QT_CONFIG(graphicseffect)
    widget->d_func()->invalidateGraphicsEffectsRecursively();
#endif

    QRect widgetRect = widgetRectFor(widget, r);

    // ---------------------------------------------------------------------------

    if (widget->d_func()->paintOnScreen()) {
        if (widget->d_func()->dirty.isEmpty()) {
            widget->d_func()->dirty = r;
            sendUpdateRequest(widget, updateTime);
            return;
        } else if (qt_region_strictContains(widget->d_func()->dirty, widgetRect)) {
            if (updateTime == UpdateNow)
                sendUpdateRequest(widget, updateTime);
            return; // Already dirty
        }

        const bool eventAlreadyPosted = !widget->d_func()->dirty.isEmpty();
        widget->d_func()->dirty += r;
        if (!eventAlreadyPosted || updateTime == UpdateNow)
            sendUpdateRequest(widget, updateTime);
        return;
    }

    // ---------------------------------------------------------------------------

    if (QWidgetPrivate::get(widget)->renderToTexture) {
        if (!widget->d_func()->inDirtyList)
            addDirtyRenderToTextureWidget(widget);
        if (!updateRequestSent || updateTime == UpdateNow)
            sendUpdateRequest(tlw, updateTime);
        return;
    }

    // ---------------------------------------------------------------------------

    QRect effectiveWidgetRect = widget->d_func()->effectiveRectFor(widgetRect);
    const QPoint offset = widget->mapTo(tlw, QPoint());
    QRect translatedRect = effectiveWidgetRect.translated(offset);
#if QT_CONFIG(graphicseffect)
    // Graphics effects may exceed window size, clamp
    translatedRect = translatedRect.intersected(QRect(QPoint(), tlw->size()));
#endif
    if (qt_region_strictContains(dirty, translatedRect)) {
        if (updateTime == UpdateNow)
            sendUpdateRequest(tlw, updateTime);
        return; // Already dirty
    }

    // ---------------------------------------------------------------------------

    if (bufferState == BufferInvalid) {
        const bool eventAlreadyPosted = !dirty.isEmpty() || updateRequestSent;
#if QT_CONFIG(graphicseffect)
        if (widget->d_func()->graphicsEffect)
            dirty += widget->d_func()->effectiveRectFor(r).translated(offset);
        else
#endif
            dirty += r.translated(offset);

        if (!eventAlreadyPosted || updateTime == UpdateNow)
            sendUpdateRequest(tlw, updateTime);
        return;
    }

    // ---------------------------------------------------------------------------

    if (dirtyWidgets.isEmpty()) {
        addDirtyWidget(widget, r);
        sendUpdateRequest(tlw, updateTime);
        return;
    }

    // ---------------------------------------------------------------------------

    if (widget->d_func()->inDirtyList) {
        if (!qt_region_strictContains(widget->d_func()->dirty, effectiveWidgetRect)) {
#if QT_CONFIG(graphicseffect)
            if (widget->d_func()->graphicsEffect)
                widget->d_func()->dirty += widget->d_func()->effectiveRectFor(r);
            else
#endif
                widget->d_func()->dirty += r;
        }
    } else {
        addDirtyWidget(widget, r);
    }

    // ---------------------------------------------------------------------------

    if (updateTime == UpdateNow)
        sendUpdateRequest(tlw, updateTime);
}
template void QWidgetBackingStore::markDirty<QRect>(const QRect &, QWidget *, UpdateTime, BufferState);
template void QWidgetBackingStore::markDirty<QRegion>(const QRegion &, QWidget *, UpdateTime, BufferState);

/*!
    Marks the \a region of the \a widget as dirty on screen. The \a region will be copied from
    the backing store to the \a widget's native parent next time flush() is called.

    Paint on screen widgets are ignored.
*/
void QWidgetBackingStore::markDirtyOnScreen(const QRegion &region, QWidget *widget, const QPoint &topLevelOffset)
{
    if (!widget || widget->d_func()->paintOnScreen() || region.isEmpty())
        return;

#if 0 // Used to be included in Qt4 for Q_WS_MAC
    if (!widget->testAttribute(Qt::WA_WState_InPaintEvent))
        dirtyOnScreen += region.translated(topLevelOffset);
    return;
#endif

    // Top-level.
    if (widget == tlw) {
        if (!widget->testAttribute(Qt::WA_WState_InPaintEvent))
            dirtyOnScreen += region;
        return;
    }

    // Alien widgets.
    if (!hasPlatformWindow(widget) && !widget->isWindow()) {
        QWidget *nativeParent = widget->nativeParentWidget();        // Alien widgets with the top-level as the native parent (common case).
        if (nativeParent == tlw) {
            if (!widget->testAttribute(Qt::WA_WState_InPaintEvent))
                dirtyOnScreen += region.translated(topLevelOffset);
            return;
        }

        // Alien widgets with native parent != tlw.
        QWidgetPrivate *nativeParentPrivate = nativeParent->d_func();
        if (!nativeParentPrivate->needsFlush)
            nativeParentPrivate->needsFlush = new QRegion;
        const QPoint nativeParentOffset = widget->mapTo(nativeParent, QPoint());
        *nativeParentPrivate->needsFlush += region.translated(nativeParentOffset);
        appendDirtyOnScreenWidget(nativeParent);
        return;
    }

    // Native child widgets.
    QWidgetPrivate *widgetPrivate = widget->d_func();
    if (!widgetPrivate->needsFlush)
        widgetPrivate->needsFlush = new QRegion;
    *widgetPrivate->needsFlush += region;
    appendDirtyOnScreenWidget(widget);
}

void QWidgetBackingStore::removeDirtyWidget(QWidget *w)
{
    if (!w)
        return;

    dirtyWidgets.removeAll(w);
    dirtyOnScreenWidgets.removeAll(w);
    dirtyRenderToTextureWidgets.removeAll(w);
    resetWidget(w);

    QWidgetPrivate *wd = w->d_func();
    const int n = wd->children.count();
    for (int i = 0; i < n; ++i) {
        if (QWidget *child = qobject_cast<QWidget*>(wd->children.at(i)))
            removeDirtyWidget(child);
    }
}

void QWidgetBackingStore::updateLists(QWidget *cur)
{
    if (!cur)
        return;

    QList<QObject*> children = cur->children();
    for (int i = 0; i < children.size(); ++i) {
        QWidget *child = qobject_cast<QWidget*>(children.at(i));
        if (!child || child->isWindow())
            continue;

        updateLists(child);
    }

    if (cur->testAttribute(Qt::WA_StaticContents))
        addStaticWidget(cur);
}

QWidgetBackingStore::QWidgetBackingStore(QWidget *topLevel)
    : tlw(topLevel),
      updateRequestSent(0),
      textureListWatcher(0),
      perfFrames(0)
{
    store = tlw->backingStore();
    Q_ASSERT(store);

    // Ensure all existing subsurfaces and static widgets are added to their respective lists.
    updateLists(topLevel);
}

QWidgetBackingStore::~QWidgetBackingStore()
{
    for (int c = 0; c < dirtyWidgets.size(); ++c)
        resetWidget(dirtyWidgets.at(c));
    for (int c = 0; c < dirtyRenderToTextureWidgets.size(); ++c)
        resetWidget(dirtyRenderToTextureWidgets.at(c));
}

static QVector<QRect> getSortedRectsToScroll(const QRegion &region, int dx, int dy)
{
    QVector<QRect> rects;
    std::copy(region.begin(), region.end(), std::back_inserter(rects));
    if (rects.count() > 1) {
        std::sort(rects.begin(), rects.end(), [=](const QRect &r1, const QRect &r2) {
            if (r1.y() == r2.y()) {
                if (dx > 0)
                    return r1.x() > r2.x();
                return r1.x() < r2.x();
            }
            if (dy > 0)
                return r1.y() > r2.y();
            return r1.y() < r2.y();
        });
    }
    return rects;
}

//parent's coordinates; move whole rect; update parent and widget
//assume the screen blt has already been done, so we don't need to refresh that part
void QWidgetPrivate::moveRect(const QRect &rect, int dx, int dy)
{
    Q_Q(QWidget);
    if (!q->isVisible() || (dx == 0 && dy == 0))
        return;

    QWidget *tlw = q->window();
    QTLWExtra* x = tlw->d_func()->topData();
    if (x->inTopLevelResize)
        return;

    static const bool accelEnv = qEnvironmentVariableIntValue("QT_NO_FAST_MOVE") == 0;

    QWidget *pw = q->parentWidget();
    QPoint toplevelOffset = pw->mapTo(tlw, QPoint());
    QWidgetPrivate *pd = pw->d_func();
    QRect clipR(pd->clipRect());
    const QRect newRect(rect.translated(dx, dy));
    QRect destRect = rect.intersected(clipR);
    if (destRect.isValid())
        destRect = destRect.translated(dx, dy).intersected(clipR);
    const QRect sourceRect(destRect.translated(-dx, -dy));
    const QRect parentRect(rect & clipR);
    const bool nativeWithTextureChild = textureChildSeen && hasPlatformWindow(q);

    const bool accelerateMove = accelEnv && isOpaque && !nativeWithTextureChild
#if QT_CONFIG(graphicsview)
                          // No accelerate move for proxy widgets.
                          && !tlw->d_func()->extra->proxyWidget
#endif
            ;

    if (!accelerateMove) {
        QRegion parentR(effectiveRectFor(parentRect));
        if (!extra || !extra->hasMask) {
            parentR -= newRect;
        } else {
            // invalidateBackingStore() excludes anything outside the mask
            parentR += newRect & clipR;
        }
        pd->invalidateBackingStore(parentR);
        invalidateBackingStore((newRect & clipR).translated(-data.crect.topLeft()));
    } else {

        QWidgetBackingStore *wbs = x->widgetBackingStore.get();
        QRegion childExpose(newRect & clipR);
        QRegion overlappedExpose;

        if (sourceRect.isValid()) {
            overlappedExpose = (overlappedRegion(sourceRect) | overlappedRegion(destRect)) & clipR;

            const qreal factor = QHighDpiScaling::factor(q->windowHandle());
            if (overlappedExpose.isEmpty() || qFloor(factor) == factor) {
                const QVector<QRect> rectsToScroll
                        = getSortedRectsToScroll(QRegion(sourceRect) - overlappedExpose, dx, dy);
                for (QRect rect : rectsToScroll) {
                    if (wbs->bltRect(rect, dx, dy, pw)) {
                        childExpose -= rect.translated(dx, dy);
                    }
                }
            }

            childExpose -= overlappedExpose;
        }

        if (!pw->updatesEnabled())
            return;

        const bool childUpdatesEnabled = q->updatesEnabled();
        if (childUpdatesEnabled) {
            if (!overlappedExpose.isEmpty()) {
                overlappedExpose.translate(-data.crect.topLeft());
                invalidateBackingStore(overlappedExpose);
            }
            if (!childExpose.isEmpty()) {
                childExpose.translate(-data.crect.topLeft());
                wbs->markDirty(childExpose, q);
                isMoved = true;
            }
        }

        QRegion parentExpose(parentRect);
        parentExpose -= newRect;
        if (extra && extra->hasMask)
            parentExpose += QRegion(newRect) - extra->mask.translated(data.crect.topLeft());

        if (!parentExpose.isEmpty()) {
            wbs->markDirty(parentExpose, pw);
            pd->isMoved = true;
        }

        if (childUpdatesEnabled) {
            QRegion needsFlush(sourceRect);
            needsFlush += destRect;
            wbs->markDirtyOnScreen(needsFlush, pw, toplevelOffset);
        }
    }
}

//widget's coordinates; scroll within rect;  only update widget
void QWidgetPrivate::scrollRect(const QRect &rect, int dx, int dy)
{
    Q_Q(QWidget);
    QWidget *tlw = q->window();
    QTLWExtra* x = tlw->d_func()->topData();
    if (x->inTopLevelResize)
        return;

    QWidgetBackingStore *wbs = x->widgetBackingStore.get();
    if (!wbs)
        return;

    static const bool accelEnv = qEnvironmentVariableIntValue("QT_NO_FAST_SCROLL") == 0;

    const QRect clipR = clipRect();
    const QRect scrollRect = rect & clipR;
    const bool accelerateScroll = accelEnv && isOpaque && !q_func()->testAttribute(Qt::WA_WState_InPaintEvent);

    if (!accelerateScroll) {
        if (!overlappedRegion(scrollRect.translated(data.crect.topLeft()), true).isEmpty()) {
            QRegion region(scrollRect);
            subtractOpaqueSiblings(region);
            invalidateBackingStore(region);
        }else {
            invalidateBackingStore(scrollRect);
        }
    } else {
        const QPoint toplevelOffset = q->mapTo(tlw, QPoint());
        const QRect destRect = scrollRect.translated(dx, dy) & scrollRect;
        const QRect sourceRect = destRect.translated(-dx, -dy);

        const QRegion overlappedExpose = (overlappedRegion(scrollRect.translated(data.crect.topLeft())))
                .translated(-data.crect.topLeft()) & clipR;
        QRegion childExpose(scrollRect);

        const qreal factor = QHighDpiScaling::factor(q->windowHandle());
        if (overlappedExpose.isEmpty() || qFloor(factor) == factor) {
            const QVector<QRect> rectsToScroll
                    = getSortedRectsToScroll(QRegion(sourceRect) - overlappedExpose, dx, dy);
            for (const QRect &rect : rectsToScroll) {
                if (wbs->bltRect(rect, dx, dy, q)) {
                    childExpose -= rect.translated(dx, dy);
                }
            }
        }

        childExpose -= overlappedExpose;

        if (inDirtyList) {
            if (rect == q->rect()) {
                dirty.translate(dx, dy);
            } else {
                QRegion dirtyScrollRegion = dirty.intersected(scrollRect);
                if (!dirtyScrollRegion.isEmpty()) {
                    dirty -= dirtyScrollRegion;
                    dirtyScrollRegion.translate(dx, dy);
                    dirty += dirtyScrollRegion;
                }
            }
        }

        if (!q->updatesEnabled())
            return;

        if (!overlappedExpose.isEmpty())
            invalidateBackingStore(overlappedExpose);
        if (!childExpose.isEmpty()) {
            wbs->markDirty(childExpose, q);
            isScrolled = true;
        }

        // Instead of using native scroll-on-screen, we copy from
        // backingstore, giving only one screen update for each
        // scroll, and a solid appearance
        wbs->markDirtyOnScreen(destRect, q, toplevelOffset);
    }
}

#ifndef QT_NO_OPENGL
static void findTextureWidgetsRecursively(QWidget *tlw, QWidget *widget, QPlatformTextureList *widgetTextures, QVector<QWidget *> *nativeChildren)
{
    QWidgetPrivate *wd = QWidgetPrivate::get(widget);
    if (wd->renderToTexture) {
        QPlatformTextureList::Flags flags = wd->textureListFlags();
        const QRect rect(widget->mapTo(tlw, QPoint()), widget->size());
        widgetTextures->appendTexture(widget, wd->textureId(), rect, wd->clipRect(), flags);
    }

    for (int i = 0; i < wd->children.size(); ++i) {
        QWidget *w = qobject_cast<QWidget *>(wd->children.at(i));
        // Stop at native widgets but store them. Stop at hidden widgets too.
        if (w && !w->isWindow() && hasPlatformWindow(w))
            nativeChildren->append(w);
        if (w && !w->isWindow() && !hasPlatformWindow(w) && !w->isHidden() && QWidgetPrivate::get(w)->textureChildSeen)
            findTextureWidgetsRecursively(tlw, w, widgetTextures, nativeChildren);
    }
}

static void findAllTextureWidgetsRecursively(QWidget *tlw, QWidget *widget)
{
    // textureChildSeen does not take native child widgets into account and that's good.
    if (QWidgetPrivate::get(widget)->textureChildSeen) {
        QVector<QWidget *> nativeChildren;
        auto tl = qt_make_unique<QPlatformTextureList>();
        // Look for texture widgets (incl. widget itself) from 'widget' down,
        // but skip subtrees with a parent of a native child widget.
        findTextureWidgetsRecursively(tlw, widget, tl.get(), &nativeChildren);
        // tl may be empty regardless of textureChildSeen if we have native or hidden children.
        if (!tl->isEmpty())
            QWidgetPrivate::get(tlw)->topData()->widgetTextures.push_back(std::move(tl));
        // Native child widgets, if there was any, get their own separate QPlatformTextureList.
        for (QWidget *ncw : qAsConst(nativeChildren)) {
            if (QWidgetPrivate::get(ncw)->textureChildSeen)
                findAllTextureWidgetsRecursively(tlw, ncw);
        }
    }
}

static QPlatformTextureList *widgetTexturesFor(QWidget *tlw, QWidget *widget)
{
    for (const auto &tl : QWidgetPrivate::get(tlw)->topData()->widgetTextures) {
        Q_ASSERT(!tl->isEmpty());
        for (int i = 0; i < tl->count(); ++i) {
            QWidget *w = static_cast<QWidget *>(tl->source(i));
            if ((hasPlatformWindow(w) && w == widget) || (!hasPlatformWindow(w) && w->nativeParentWidget() == widget))
                return tl.get();
        }
    }

    if (QWidgetPrivate::get(widget)->textureChildSeen) {
        // No render-to-texture widgets in the (sub-)tree due to hidden or native
        // children. Returning null results in using the normal backingstore flush path
        // without OpenGL-based compositing. This is very desirable normally. However,
        // some platforms cannot handle switching between the non-GL and GL paths for
        // their windows so it has to be opt-in.
        static bool switchableWidgetComposition =
            QGuiApplicationPrivate::instance()->platformIntegration()
                ->hasCapability(QPlatformIntegration::SwitchableWidgetComposition);
        if (!switchableWidgetComposition)
            return qt_dummy_platformTextureList();
    }

    return 0;
}

// Watches one or more QPlatformTextureLists for changes in the lock state and
// triggers a backingstore sync when all the registered lists turn into
// unlocked state. This is essential when a custom composeAndFlush()
// implementation in a platform plugin is not synchronous and keeps
// holding on to the textures for some time even after returning from there.
QPlatformTextureListWatcher::QPlatformTextureListWatcher(QWidgetBackingStore *backingStore)
    : m_backingStore(backingStore)
{
}

void QPlatformTextureListWatcher::watch(QPlatformTextureList *textureList)
{
    connect(textureList, SIGNAL(locked(bool)), SLOT(onLockStatusChanged(bool)));
    m_locked[textureList] = textureList->isLocked();
}

bool QPlatformTextureListWatcher::isLocked() const
{
    foreach (bool v, m_locked) {
        if (v)
            return true;
    }
    return false;
}

void QPlatformTextureListWatcher::onLockStatusChanged(bool locked)
{
    QPlatformTextureList *tl = static_cast<QPlatformTextureList *>(sender());
    m_locked[tl] = locked;
    if (!isLocked())
        m_backingStore->sync();
}

#else

static QPlatformTextureList *widgetTexturesFor(QWidget *tlw, QWidget *widget)
{
    Q_UNUSED(tlw);
    Q_UNUSED(widget);
    return nullptr;
}

#endif // QT_NO_OPENGL

static inline bool discardSyncRequest(QWidget *tlw, QTLWExtra *tlwExtra)
{
    if (!tlw || !tlwExtra || !tlw->testAttribute(Qt::WA_Mapped) || !tlw->isVisible())
        return true;

    return false;
}

bool QWidgetBackingStore::syncAllowed()
{
#ifndef QT_NO_OPENGL
    QTLWExtra *tlwExtra = tlw->d_func()->maybeTopData();
    if (textureListWatcher && !textureListWatcher->isLocked()) {
        textureListWatcher->deleteLater();
        textureListWatcher = 0;
    } else if (!tlwExtra->widgetTextures.empty()) {
        bool skipSync = false;
        for (const auto &tl : tlwExtra->widgetTextures) {
            if (tl->isLocked()) {
                if (!textureListWatcher)
                    textureListWatcher = new QPlatformTextureListWatcher(this);
                if (!textureListWatcher->isLocked())
                    textureListWatcher->watch(tl.get());
                skipSync = true;
            }
        }
        if (skipSync)  // cannot compose due to widget textures being in use
            return false;
    }
#endif
    return true;
}

/*!
    Synchronizes the \a exposedRegion of the \a exposedWidget with the backing store.

    If there's nothing to repaint, the area is flushed and painting does not occur;
    otherwise the area is marked as dirty on screen and will be flushed right after
    we are done with all painting.
*/
void QWidgetBackingStore::sync(QWidget *exposedWidget, const QRegion &exposedRegion)
{
    QTLWExtra *tlwExtra = tlw->d_func()->maybeTopData();
    if (!tlw->isVisible() || !tlwExtra || tlwExtra->inTopLevelResize)
        return;

    if (!exposedWidget || !hasPlatformWindow(exposedWidget)
        || !exposedWidget->isVisible() || !exposedWidget->testAttribute(Qt::WA_Mapped)
        || !exposedWidget->updatesEnabled() || exposedRegion.isEmpty()) {
        return;
    }

    // Nothing to repaint.
    if (!isDirty() && store->size().isValid()) {
        QPlatformTextureList *tl = widgetTexturesFor(tlw, exposedWidget);
        qt_flush(exposedWidget, tl ? QRegion() : exposedRegion, store, tlw, tl, this);
        return;
    }

    if (exposedWidget != tlw)
        markDirtyOnScreen(exposedRegion, exposedWidget, exposedWidget->mapTo(tlw, QPoint()));
    else
        markDirtyOnScreen(exposedRegion, exposedWidget, QPoint());

    if (syncAllowed())
        doSync();
}

/*!
    Synchronizes the backing store, i.e. dirty areas are repainted and flushed.
*/
void QWidgetBackingStore::sync()
{
    updateRequestSent = false;
    QTLWExtra *tlwExtra = tlw->d_func()->maybeTopData();
    if (discardSyncRequest(tlw, tlwExtra)) {
        // If the top-level is minimized, it's not visible on the screen so we can delay the
        // update until it's shown again. In order to do that we must keep the dirty states.
        // These will be cleared when we receive the first expose after showNormal().
        // However, if the widget is not visible (isVisible() returns false), everything will
        // be invalidated once the widget is shown again, so clear all dirty states.
        if (!tlw->isVisible()) {
            dirty = QRegion();
            for (int i = 0; i < dirtyWidgets.size(); ++i)
                resetWidget(dirtyWidgets.at(i));
            dirtyWidgets.clear();
        }
        return;
    }

    if (syncAllowed())
        doSync();
}

void QWidgetBackingStore::doSync()
{
    const bool updatesDisabled = !tlw->updatesEnabled();
    bool repaintAllWidgets = false;

    const bool inTopLevelResize = tlw->d_func()->maybeTopData()->inTopLevelResize;
    const QRect tlwRect(topLevelRect());
    const QRect surfaceGeometry(tlwRect.topLeft(), store->size());
    if ((inTopLevelResize || surfaceGeometry.size() != tlwRect.size()) && !updatesDisabled) {
        if (hasStaticContents() && !store->size().isEmpty() ) {
            // Repaint existing dirty area and newly visible area.
            const QRect clipRect(0, 0, surfaceGeometry.width(), surfaceGeometry.height());
            const QRegion staticRegion(staticContents(0, clipRect));
            QRegion newVisible(0, 0, tlwRect.width(), tlwRect.height());
            newVisible -= staticRegion;
            dirty += newVisible;
            store->setStaticContents(staticRegion);
        } else {
            // Repaint everything.
            dirty = QRegion(0, 0, tlwRect.width(), tlwRect.height());
            for (int i = 0; i < dirtyWidgets.size(); ++i)
                resetWidget(dirtyWidgets.at(i));
            dirtyWidgets.clear();
            repaintAllWidgets = true;
        }
    }

    if (inTopLevelResize || surfaceGeometry.size() != tlwRect.size())
        store->resize(tlwRect.size());

    if (updatesDisabled)
        return;

    // Contains everything that needs repaint.
    QRegion toClean(dirty);

    // Loop through all update() widgets and remove them from the list before they are
    // painted (in case someone calls update() in paintEvent). If the widget is opaque
    // and does not have transparent overlapping siblings, append it to the
    // opaqueNonOverlappedWidgets list and paint it directly without composition.
    QVarLengthArray<QWidget *, 32> opaqueNonOverlappedWidgets;
    for (int i = 0; i < dirtyWidgets.size(); ++i) {
        QWidget *w = dirtyWidgets.at(i);
        QWidgetPrivate *wd = w->d_func();
        if (wd->data.in_destructor)
            continue;

        // Clip with mask() and clipRect().
        wd->dirty &= wd->clipRect();
        wd->clipToEffectiveMask(wd->dirty);

        // Subtract opaque siblings and children.
        bool hasDirtySiblingsAbove = false;
        // We know for sure that the widget isn't overlapped if 'isMoved' is true.
        if (!wd->isMoved)
            wd->subtractOpaqueSiblings(wd->dirty, &hasDirtySiblingsAbove);

        // Make a copy of the widget's dirty region, to restore it in case there is an opaque
        // render-to-texture child that completely covers the widget, because otherwise the
        // render-to-texture child won't be visible, due to its parent widget not being redrawn
        // with a proper blending mask.
        const QRegion dirtyBeforeSubtractedOpaqueChildren = wd->dirty;

        // Scrolled and moved widgets must draw all children.
        if (!wd->isScrolled && !wd->isMoved)
            wd->subtractOpaqueChildren(wd->dirty, w->rect());

        if (wd->dirty.isEmpty() && wd->textureChildSeen)
            wd->dirty = dirtyBeforeSubtractedOpaqueChildren;

        if (wd->dirty.isEmpty()) {
            resetWidget(w);
            continue;
        }

        const QRegion widgetDirty(w != tlw ? wd->dirty.translated(w->mapTo(tlw, QPoint()))
                                           : wd->dirty);
        toClean += widgetDirty;

#if QT_CONFIG(graphicsview)
        if (tlw->d_func()->extra->proxyWidget) {
            resetWidget(w);
            continue;
        }
#endif

        if (!hasDirtySiblingsAbove && wd->isOpaque && !dirty.intersects(widgetDirty.boundingRect())) {
            opaqueNonOverlappedWidgets.append(w);
        } else {
            resetWidget(w);
            dirty += widgetDirty;
        }
    }
    dirtyWidgets.clear();

#ifndef QT_NO_OPENGL
    // Find all render-to-texture child widgets (including self).
    // The search is cut at native widget boundaries, meaning that each native child widget
    // has its own list for the subtree below it.
    QTLWExtra *tlwExtra = tlw->d_func()->topData();
    tlwExtra->widgetTextures.clear();
    findAllTextureWidgetsRecursively(tlw, tlw);
    qt_window_private(tlw->windowHandle())->compositing = false; // will get updated in qt_flush()
#endif

    if (toClean.isEmpty()) {
        // Nothing to repaint. However renderToTexture widgets are handled
        // specially, they are not in the regular dirty list, in order to
        // prevent triggering unnecessary backingstore painting when only the
        // OpenGL content changes. Check if we have such widgets in the special
        // dirty list.
        QVarLengthArray<QWidget *, 16> paintPending;
        const int numPaintPending = dirtyRenderToTextureWidgets.count();
        paintPending.reserve(numPaintPending);
        for (int i = 0; i < numPaintPending; ++i) {
            QWidget *w = dirtyRenderToTextureWidgets.at(i);
            paintPending << w;
            resetWidget(w);
        }
        dirtyRenderToTextureWidgets.clear();
        for (int i = 0; i < numPaintPending; ++i) {
            QWidget *w = paintPending[i];
            w->d_func()->sendPaintEvent(w->rect());
            if (w != tlw) {
                QWidget *npw = w->nativeParentWidget();
                if (hasPlatformWindow(w) || (npw && npw != tlw)) {
                    if (!hasPlatformWindow(w))
                        w = npw;
                    QWidgetPrivate *wPrivate = w->d_func();
                    if (!wPrivate->needsFlush)
                        wPrivate->needsFlush = new QRegion;
                    appendDirtyOnScreenWidget(w);
                }
            }
        }

        // We might have newly exposed areas on the screen if this function was
        // called from sync(QWidget *, QRegion)), so we have to make sure those
        // are flushed. We also need to composite the renderToTexture widgets.
        flush();

        return;
    }

#ifndef QT_NO_OPENGL
    for (const auto &tl : tlwExtra->widgetTextures) {
        for (int i = 0; i < tl->count(); ++i) {
            QWidget *w = static_cast<QWidget *>(tl->source(i));
            if (dirtyRenderToTextureWidgets.contains(w)) {
                const QRect rect = tl->geometry(i); // mapped to the tlw already
                // Set a flag to indicate that the paint event for this
                // render-to-texture widget must not to be optimized away.
                w->d_func()->renderToTextureReallyDirty = 1;
                dirty += rect;
                toClean += rect;
            }
        }
    }
    for (int i = 0; i < dirtyRenderToTextureWidgets.count(); ++i)
        resetWidget(dirtyRenderToTextureWidgets.at(i));
    dirtyRenderToTextureWidgets.clear();
#endif

#if QT_CONFIG(graphicsview)
    if (tlw->d_func()->extra->proxyWidget) {
        updateStaticContentsSize();
        dirty = QRegion();
        updateRequestSent = false;
        for (const QRect &rect : toClean)
            tlw->d_func()->extra->proxyWidget->update(rect);
        return;
    }
#endif

    BeginPaintInfo beginPaintInfo;
    beginPaint(toClean, tlw, store, &beginPaintInfo);
    if (beginPaintInfo.nothingToPaint) {
        for (int i = 0; i < opaqueNonOverlappedWidgets.size(); ++i)
            resetWidget(opaqueNonOverlappedWidgets[i]);
        dirty = QRegion();
        updateRequestSent = false;
        return;
    }

    // Must do this before sending any paint events because
    // the size may change in the paint event.
    updateStaticContentsSize();
    const QRegion dirtyCopy(dirty);
    dirty = QRegion();
    updateRequestSent = false;

    // Paint opaque non overlapped widgets.
    for (int i = 0; i < opaqueNonOverlappedWidgets.size(); ++i) {
        QWidget *w = opaqueNonOverlappedWidgets[i];
        QWidgetPrivate *wd = w->d_func();

        int flags = QWidgetPrivate::DrawRecursive;
        // Scrolled and moved widgets must draw all children.
        if (!wd->isScrolled && !wd->isMoved)
            flags |= QWidgetPrivate::DontDrawOpaqueChildren;
        if (w == tlw)
            flags |= QWidgetPrivate::DrawAsRoot;

        QRegion toBePainted(wd->dirty);
        resetWidget(w);

        QPoint offset;
        if (w != tlw)
            offset += w->mapTo(tlw, QPoint());
        wd->drawWidget(store->paintDevice(), toBePainted, offset, flags, 0, this);
    }

    // Paint the rest with composition.
    if (repaintAllWidgets || !dirtyCopy.isEmpty()) {
        const int flags = QWidgetPrivate::DrawAsRoot | QWidgetPrivate::DrawRecursive;
        tlw->d_func()->drawWidget(store->paintDevice(), dirtyCopy, QPoint(), flags, 0, this);
    }

    endPaint(toClean, store, &beginPaintInfo);
}

/*!
    Flushes the contents of the backing store into the top-level widget.
    If the \a widget is non-zero, the content is flushed to the \a widget.
    If the \a surface is non-zero, the content of the \a surface is flushed.
*/
void QWidgetBackingStore::flush(QWidget *widget)
{
    const bool hasDirtyOnScreenWidgets = !dirtyOnScreenWidgets.isEmpty();
    bool flushed = false;

    // Flush the region in dirtyOnScreen.
    if (!dirtyOnScreen.isEmpty()) {
        QWidget *target = widget ? widget : tlw;
        qt_flush(target, dirtyOnScreen, store, tlw, widgetTexturesFor(tlw, tlw), this);
        dirtyOnScreen = QRegion();
        flushed = true;
    }

    // Render-to-texture widgets are not in dirtyOnScreen so flush if we have not done it above.
    if (!flushed && !hasDirtyOnScreenWidgets) {
#ifndef QT_NO_OPENGL
        if (!tlw->d_func()->topData()->widgetTextures.empty()) {
            QPlatformTextureList *tl = widgetTexturesFor(tlw, tlw);
            if (tl) {
                QWidget *target = widget ? widget : tlw;
                qt_flush(target, QRegion(), store, tlw, tl, this);
            }
        }
#endif
    }

    if (!hasDirtyOnScreenWidgets)
        return;

    for (QWidget *w : qExchange(dirtyOnScreenWidgets, {})) {
        QWidgetPrivate *wd = w->d_func();
        Q_ASSERT(wd->needsFlush);
        QPlatformTextureList *widgetTexturesForNative = wd->textureChildSeen ? widgetTexturesFor(tlw, w) : 0;
        qt_flush(w, *wd->needsFlush, store, tlw, widgetTexturesForNative, this);
        *wd->needsFlush = QRegion();
    }
}

/*!
    Invalidates the backing store when the widget is resized.
    Static areas are never invalidated unless absolutely needed.
*/
void QWidgetPrivate::invalidateBackingStore_resizeHelper(const QPoint &oldPos, const QSize &oldSize)
{
    Q_Q(QWidget);
    Q_ASSERT(!q->isWindow());
    Q_ASSERT(q->parentWidget());

    const bool staticContents = q->testAttribute(Qt::WA_StaticContents);
    const bool sizeDecreased = (data.crect.width() < oldSize.width())
                               || (data.crect.height() < oldSize.height());

    const QPoint offset(data.crect.x() - oldPos.x(), data.crect.y() - oldPos.y());
    const bool parentAreaExposed = !offset.isNull() || sizeDecreased;
    const QRect newWidgetRect(q->rect());
    const QRect oldWidgetRect(0, 0, oldSize.width(), oldSize.height());

    if (!staticContents || graphicsEffect) {
        QRegion staticChildren;
        QWidgetBackingStore *bs = 0;
        if (offset.isNull() && (bs = maybeBackingStore()))
            staticChildren = bs->staticContents(q, oldWidgetRect);
        const bool hasStaticChildren = !staticChildren.isEmpty();

        if (hasStaticChildren) {
            QRegion dirty(newWidgetRect);
            dirty -= staticChildren;
            invalidateBackingStore(dirty);
        } else {
            // Entire widget needs repaint.
            invalidateBackingStore(newWidgetRect);
        }

        if (!parentAreaExposed)
            return;

        // Invalidate newly exposed area of the parent.
        if (!graphicsEffect && extra && extra->hasMask) {
            QRegion parentExpose(extra->mask.translated(oldPos));
            parentExpose &= QRect(oldPos, oldSize);
            if (hasStaticChildren)
                parentExpose -= data.crect; // Offset is unchanged, safe to do this.
            q->parentWidget()->d_func()->invalidateBackingStore(parentExpose);
        } else {
            if (hasStaticChildren && !graphicsEffect) {
                QRegion parentExpose(QRect(oldPos, oldSize));
                parentExpose -= data.crect; // Offset is unchanged, safe to do this.
                q->parentWidget()->d_func()->invalidateBackingStore(parentExpose);
            } else {
                q->parentWidget()->d_func()->invalidateBackingStore(effectiveRectFor(QRect(oldPos, oldSize)));
            }
        }
        return;
    }

    // Move static content to its new position.
    if (!offset.isNull()) {
        if (sizeDecreased) {
            const QSize minSize(qMin(oldSize.width(), data.crect.width()),
                                qMin(oldSize.height(), data.crect.height()));
            moveRect(QRect(oldPos, minSize), offset.x(), offset.y());
        } else {
            moveRect(QRect(oldPos, oldSize), offset.x(), offset.y());
        }
    }

    // Invalidate newly visible area of the widget.
    if (!sizeDecreased || !oldWidgetRect.contains(newWidgetRect)) {
        QRegion newVisible(newWidgetRect);
        newVisible -= oldWidgetRect;
        invalidateBackingStore(newVisible);
    }

    if (!parentAreaExposed)
        return;

    // Invalidate newly exposed area of the parent.
    const QRect oldRect(oldPos, oldSize);
    if (extra && extra->hasMask) {
        QRegion parentExpose(oldRect);
        parentExpose &= extra->mask.translated(oldPos);
        parentExpose -= (extra->mask.translated(data.crect.topLeft()) & data.crect);
        q->parentWidget()->d_func()->invalidateBackingStore(parentExpose);
    } else {
        QRegion parentExpose(oldRect);
        parentExpose -= data.crect;
        q->parentWidget()->d_func()->invalidateBackingStore(parentExpose);
    }
}

/*!
    Invalidates the \a r (in widget's coordinates) of the backing store, i.e.
    all widgets intersecting with the region will be repainted when the backing
    store is synced.
*/
template <class T>
void QWidgetPrivate::invalidateBackingStore(const T &r)
{
    if (r.isEmpty())
        return;

    if (QCoreApplication::closingDown())
        return;

    Q_Q(QWidget);
    if (!q->isVisible() || !q->updatesEnabled())
        return;

    QTLWExtra *tlwExtra = q->window()->d_func()->maybeTopData();
    if (!tlwExtra || tlwExtra->inTopLevelResize || !tlwExtra->backingStore)
        return;

    T clipped(r);
    clipped &= clipRect();
    if (clipped.isEmpty())
        return;

    if (!graphicsEffect && extra && extra->hasMask) {
        QRegion masked(extra->mask);
        masked &= clipped;
        if (masked.isEmpty())
            return;

        tlwExtra->widgetBackingStore->markDirty(masked, q,
            QWidgetBackingStore::UpdateLater, QWidgetBackingStore::BufferInvalid);
    } else {
        tlwExtra->widgetBackingStore->markDirty(clipped, q,
            QWidgetBackingStore::UpdateLater, QWidgetBackingStore::BufferInvalid);
    }
}
// Needed by tst_QWidget
template Q_AUTOTEST_EXPORT void QWidgetPrivate::invalidateBackingStore<QRect>(const QRect &r);

void QWidgetPrivate::repaint_sys(const QRegion &rgn)
{
    if (data.in_destructor)
        return;

    Q_Q(QWidget);
    if (discardSyncRequest(q, maybeTopData()))
        return;

    if (q->testAttribute(Qt::WA_StaticContents)) {
        if (!extra)
            createExtra();
        extra->staticContentsSize = data.crect.size();
    }

    QPaintEngine *engine = q->paintEngine();

    // QGLWidget does not support partial updates if:
    // 1) The context is double buffered
    // 2) The context is single buffered and auto-fill background is enabled.
    const bool noPartialUpdateSupport = (engine && (engine->type() == QPaintEngine::OpenGL
                                                || engine->type() == QPaintEngine::OpenGL2))
                                        && (usesDoubleBufferedGLContext || q->autoFillBackground());
    QRegion toBePainted(noPartialUpdateSupport ? q->rect() : rgn);

#if 0 // Used to be included in Qt4 for Q_WS_MAC
    // No difference between update() and repaint() on the Mac.
    update_sys(toBePainted);
    return;
#endif

    toBePainted &= clipRect();
    clipToEffectiveMask(toBePainted);
    if (toBePainted.isEmpty())
        return; // Nothing to repaint.

#ifndef QT_NO_PAINT_DEBUG
    bool flushed = QWidgetBackingStore::flushPaint(q, toBePainted);
#endif

    drawWidget(q, toBePainted, QPoint(), QWidgetPrivate::DrawAsRoot | QWidgetPrivate::DrawPaintOnScreen, 0);

#ifndef QT_NO_PAINT_DEBUG
    if (flushed)
        QWidgetBackingStore::unflushPaint(q, toBePainted);
#endif

    if (Q_UNLIKELY(q->paintingActive()))
        qWarning("QWidget::repaint: It is dangerous to leave painters active on a widget outside of the PaintEvent");
}


QT_END_NAMESPACE

#include "moc_qwidgetbackingstore_p.cpp"