summaryrefslogtreecommitdiffstats
path: root/src/kernel/qpngio.cpp
blob: bb76fcb02025c6a7ed06fc14335e7e45a5dbc814 (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
/****************************************************************************
**
** Implementation of PNG QImage IOHandler
**
** Created : 970521
**
** Copyright (C) 1992-2008 Trolltech ASA.  All rights reserved.
**
** This file is part of the kernel module of the Qt GUI Toolkit.
**
** This file may be used under the terms of the GNU General
** Public License versions 2.0 or 3.0 as published by the Free
** Software Foundation and appearing in the files LICENSE.GPL2
** and LICENSE.GPL3 included in the packaging of this file.
** Alternatively you may (at your option) use any later version
** of the GNU General Public License if such license has been
** publicly approved by Trolltech ASA (or its successors, if any)
** and the KDE Free Qt Foundation.
**
** Please review the following information to ensure GNU General
** Public Licensing requirements will be met:
** http://trolltech.com/products/qt/licenses/licensing/opensource/.
** If you are unsure which license is appropriate for your use, please
** review the following information:
** http://trolltech.com/products/qt/licenses/licensing/licensingoverview
** or contact the sales department at sales@trolltech.com.
**
** This file may be used under the terms of the Q Public License as
** defined by Trolltech ASA and appearing in the file LICENSE.QPL
** included in the packaging of this file.  Licensees holding valid Qt
** Commercial licenses may use this file in accordance with the Qt
** Commercial License Agreement provided with the Software.
**
** This file is provided "AS IS" with NO WARRANTY OF ANY KIND,
** INCLUDING THE WARRANTIES OF DESIGN, MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE. Trolltech reserves all rights not granted
** herein.
**
**********************************************************************/

#include "qpngio.h"

#ifndef QT_NO_IMAGEIO_PNG

#include "qasyncimageio.h"
#include "qiodevice.h"

#include <png.h>
#if PNG_LIBPNG_VER>=10500
#include <zlib.h>
#endif /* LIBPNG 1.5 */


#ifdef Q_OS_TEMP
#define CALLBACK_CALL_TYPE	__cdecl
#else
#define CALLBACK_CALL_TYPE
#endif


/*
  All PNG files load to the minimal QImage equivalent.

  All QImage formats output to reasonably efficient PNG equivalents.
  Never to grayscale.
*/

#if defined(Q_C_CALLBACKS)
extern "C" {
#endif

static
void CALLBACK_CALL_TYPE iod_read_fn(png_structp png_ptr, png_bytep data, png_size_t length)
{
    QImageIO* iio = (QImageIO*)png_get_io_ptr(png_ptr);
    QIODevice* in = iio->ioDevice();

    while (length) {
	int nr = in->readBlock((char*)data, length);
	if (nr <= 0) {
	    png_error(png_ptr, "Read Error");
	    return;
	}
	length -= nr;
    }
}


static
void CALLBACK_CALL_TYPE qpiw_write_fn( png_structp png_ptr, png_bytep data, png_size_t length )
{
    QPNGImageWriter* qpiw = (QPNGImageWriter*)png_get_io_ptr( png_ptr );
    QIODevice* out = qpiw->device();

    uint nr = out->writeBlock( (char*)data, length );
    if ( nr != length ) {
	png_error( png_ptr, "Write Error" );
	return;
    }
}


static
void CALLBACK_CALL_TYPE qpiw_flush_fn( png_structp png_ptr )
{
    QPNGImageWriter* qpiw = (QPNGImageWriter*)png_get_io_ptr( png_ptr );
    QIODevice* out = qpiw->device();

    out->flush();
}

#if defined(Q_C_CALLBACKS)
}
#endif

static
void setup_qt( QImage& image, png_structp png_ptr, png_infop info_ptr, float screen_gamma=0.0 )
{
    if ( screen_gamma != 0.0 && png_get_valid(png_ptr, info_ptr, PNG_INFO_gAMA) ) {
	double file_gamma;
	png_get_gAMA(png_ptr, info_ptr, &file_gamma);
	png_set_gamma( png_ptr, screen_gamma, file_gamma );
    }

    png_uint_32 width;
    png_uint_32 height;
    int bit_depth;
    int color_type;
    png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
	0, 0, 0);

#if PNG_LIBPNG_VER>=10500
    png_colorp info_ptr_palette = NULL;
    int info_ptr_num_palette = 0;
    if (png_get_valid(png_ptr, info_ptr, PNG_INFO_PLTE)) {
	png_get_PLTE(png_ptr, info_ptr, &info_ptr_palette, &info_ptr_num_palette);
    }

    png_bytep info_ptr_trans_alpha = NULL;
    int info_ptr_num_trans = 0;
    png_color_16p info_ptr_trans_color = NULL;

    if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) {
	png_get_tRNS(png_ptr, info_ptr, &info_ptr_trans_alpha, &info_ptr_num_trans, &info_ptr_trans_color);
    }
#endif /* LIBPNG 1.5 */

    if ( color_type == PNG_COLOR_TYPE_GRAY ) {
	// Black & White or 8-bit grayscale
#if PNG_LIBPNG_VER>=10500
	if ( bit_depth == 1 && png_get_channels(png_ptr, info_ptr) == 1 ) {
#else /* LIBPNG 1.5 */
	if ( bit_depth == 1 && info_ptr->channels == 1 ) {
#endif /* LIBPNG 1.5 */
	    png_set_invert_mono( png_ptr );
	    png_read_update_info( png_ptr, info_ptr );
	    if (!image.create( width, height, 1, 2, QImage::BigEndian ))
		return;
	    image.setColor( 1, qRgb(0,0,0) );
	    image.setColor( 0, qRgb(255,255,255) );
	} else if (bit_depth == 16 && png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) {
	    png_set_expand(png_ptr);
	    png_set_strip_16(png_ptr);
	    png_set_gray_to_rgb(png_ptr);

	    if (!image.create(width, height, 32))
		return;
	    image.setAlphaBuffer(TRUE);

	    if (QImage::systemByteOrder() == QImage::BigEndian)
		png_set_swap_alpha(png_ptr);

	    png_read_update_info(png_ptr, info_ptr);
	} else {
	    if ( bit_depth == 16 )
		png_set_strip_16(png_ptr);
	    else if ( bit_depth < 8 )
		png_set_packing(png_ptr);
	    int ncols = bit_depth < 8 ? 1 << bit_depth : 256;
	    png_read_update_info(png_ptr, info_ptr);
	    if (!image.create(width, height, 8, ncols))
		return;
	    for (int i=0; i<ncols; i++) {
		int c = i*255/(ncols-1);
		image.setColor( i, qRgba(c,c,c,0xff) );
	    }
	    if ( png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS) ) {
#if PNG_LIBPNG_VER>=10500
		const int g = info_ptr_trans_color->gray;
#elif PNG_LIBPNG_VER>=10400
		const int g = info_ptr->trans_color.gray;
#else
		const int g = info_ptr->trans_values.gray;
#endif
		if (g < ncols) {
		    image.setAlphaBuffer(TRUE);
		    image.setColor(g, image.color(g) & RGB_MASK);
		}
	    }
	}
    } else if ( color_type == PNG_COLOR_TYPE_PALETTE
     && png_get_valid(png_ptr, info_ptr, PNG_INFO_PLTE)
#if PNG_LIBPNG_VER>=10500
     && info_ptr_num_palette <= 256 )
#else /* LIBPNG 1.5 */
     && info_ptr->num_palette <= 256 )
#endif /* LIBPNG 1.5 */
    {
	// 1-bit and 8-bit color
	if ( bit_depth != 1 )
	    png_set_packing( png_ptr );
	png_read_update_info( png_ptr, info_ptr );
	png_get_IHDR(png_ptr, info_ptr,
	    &width, &height, &bit_depth, &color_type, 0, 0, 0);
#if PNG_LIBPNG_VER>=10500
	if (!image.create(width, height, bit_depth, info_ptr_num_palette,
#else /* LIBPNG 1.5 */
	if (!image.create(width, height, bit_depth, info_ptr->num_palette,
#endif /* LIBPNG 1.5 */
	    QImage::BigEndian))
	    return;
	int i = 0;
	if ( png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS) ) {
	    image.setAlphaBuffer( TRUE );

#if PNG_LIBPNG_VER>=10500
	    while ( i < info_ptr_num_trans ) {
		image.setColor(i, qRgba(
		    info_ptr_palette[i].red,
		    info_ptr_palette[i].green,
		    info_ptr_palette[i].blue,
#else /* LIBPNG 1.5 */
	    while ( i < info_ptr->num_trans ) {
		image.setColor(i, qRgba(
		    info_ptr->palette[i].red,
		    info_ptr->palette[i].green,
		    info_ptr->palette[i].blue,
#endif /* LIBPNG 1.5 */
#if PNG_LIBPNG_VER>=10500
		    info_ptr_trans_alpha[i]
#elif PNG_LIBPNG_VER>=10400
		    info_ptr->trans_alpha[i]
#else
		    info_ptr->trans[i]
#endif
		    )
		);
		i++;
	    }
	}
#if PNG_LIBPNG_VER>=10500
	while ( i < info_ptr_num_palette ) {
	    image.setColor(i, qRgba(
		info_ptr_palette[i].red,
		info_ptr_palette[i].green,
		info_ptr_palette[i].blue,
#else /* LIBPNG 1.5 */
	while ( i < info_ptr->num_palette ) {
	    image.setColor(i, qRgba(
		info_ptr->palette[i].red,
		info_ptr->palette[i].green,
		info_ptr->palette[i].blue,
#endif /* LIBPNG 1.5 */
		0xff
		)
	    );
	    i++;
	}
    } else {
	// 32-bit
	if ( bit_depth == 16 )
	    png_set_strip_16(png_ptr);

	png_set_expand(png_ptr);

	if ( color_type == PNG_COLOR_TYPE_GRAY_ALPHA )
	    png_set_gray_to_rgb(png_ptr);

	if (!image.create(width, height, 32))
	    return;

	// Only add filler if no alpha, or we can get 5 channel data.
	if (!(color_type & PNG_COLOR_MASK_ALPHA)
	   && !png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) {
	    png_set_filler(png_ptr, 0xff,
		QImage::systemByteOrder() == QImage::BigEndian ?
		    PNG_FILLER_BEFORE : PNG_FILLER_AFTER);
	    // We want 4 bytes, but it isn't an alpha channel
	} else {
	    image.setAlphaBuffer(TRUE);
	}

	if ( QImage::systemByteOrder() == QImage::BigEndian ) {
	    png_set_swap_alpha(png_ptr);
	}

	png_read_update_info(png_ptr, info_ptr);
    }

    // Qt==ARGB==Big(ARGB)==Little(BGRA)
    if ( QImage::systemByteOrder() == QImage::LittleEndian ) {
	png_set_bgr(png_ptr);
    }
}


#if defined(Q_C_CALLBACKS)
extern "C" {
#endif
static void CALLBACK_CALL_TYPE qt_png_warning(png_structp /*png_ptr*/, png_const_charp message)
{
    qWarning("libpng warning: %s", message);
}

#if defined(Q_C_CALLBACKS)
}
#endif


static
void read_png_image(QImageIO* iio)
{
    png_structp png_ptr;
    png_infop info_ptr;
    png_infop end_info;
    png_bytep* row_pointers;

    png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,0,0,0);
    if (!png_ptr) {
	iio->setStatus(-1);
	return;
    }

    png_set_error_fn(png_ptr, 0, 0, qt_png_warning);

    info_ptr = png_create_info_struct(png_ptr);
    if (!info_ptr) {
	png_destroy_read_struct(&png_ptr, 0, 0);
	iio->setStatus(-2);
	return;
    }

    end_info = png_create_info_struct(png_ptr);
    if (!end_info) {
	png_destroy_read_struct(&png_ptr, &info_ptr, 0);
	iio->setStatus(-3);
	return;
    }

#if PNG_LIBPNG_VER>=10500
    if (setjmp(png_jmpbuf(png_ptr))) {
#else /* LIBPNG 1.5 */
    if (setjmp(png_ptr->jmpbuf)) {
#endif /* LIBPNG 1.5 */
	png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
	iio->setStatus(-4);
	return;
    }

    png_set_read_fn(png_ptr, (void*)iio, iod_read_fn);
    png_read_info(png_ptr, info_ptr);

    QImage image;
    setup_qt(image, png_ptr, info_ptr, iio->gamma());
    if (image.isNull()) {
	png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
	iio->setStatus(-5);
	return;
    }

    png_uint_32 width;
    png_uint_32 height;
    int bit_depth;
    int color_type;
    png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
	0, 0, 0);

    uchar** jt = image.jumpTable();
    row_pointers=new png_bytep[height];

    for (uint y=0; y<height; y++) {
	row_pointers[y]=jt[y];
    }

    png_read_image(png_ptr, row_pointers);

#if 0 // libpng takes care of this.
png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)
    if (image.depth()==32 && png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) {
	QRgb trans = 0xFF000000 | qRgb(
#if PNG_LIBPNG_VER>=10400
	      (info_ptr->trans_color.red << 8 >> bit_depth)&0xff,
	      (info_ptr->trans_color.green << 8 >> bit_depth)&0xff,
	      (info_ptr->trans_color.blue << 8 >> bit_depth)&0xff);
#else
	      (info_ptr->trans_values.red << 8 >> bit_depth)&0xff,
	      (info_ptr->trans_values.green << 8 >> bit_depth)&0xff,
	      (info_ptr->trans_values.blue << 8 >> bit_depth)&0xff);
#endif
	for (uint y=0; y<height; y++) {
	    for (uint x=0; x<info_ptr->width; x++) {
		if (((uint**)jt)[y][x] == trans) {
		    ((uint**)jt)[y][x] &= 0x00FFFFFF;
		} else {
		}
	    }
	}
    }
#endif

    image.setDotsPerMeterX(png_get_x_pixels_per_meter(png_ptr,info_ptr));
    image.setDotsPerMeterY(png_get_y_pixels_per_meter(png_ptr,info_ptr));

#ifndef QT_NO_IMAGE_TEXT
    png_textp text_ptr;
    int num_text=0;
    png_get_text(png_ptr,info_ptr,&text_ptr,&num_text);
    while (num_text--) {
	image.setText(text_ptr->key,0,text_ptr->text);
	text_ptr++;
    }
#endif

    delete [] row_pointers;

    if ( image.hasAlphaBuffer() ) {
	// Many PNG files lie (eg. from PhotoShop). Fortunately this loop will
	// usually be quick to find those that tell the truth.
	QRgb* c;
	int n;
	if (image.depth()==32) {
	    c = (QRgb*)image.bits();
	    n = image.bytesPerLine() * image.height() / 4;
	} else {
	    c = image.colorTable();
	    n = image.numColors();
	}
	while ( n-- && qAlpha(*c++)==0xff )
	    ;
	if ( n<0 ) // LIAR!
	    image.setAlphaBuffer(FALSE);
    }

    iio->setImage(image);

    png_read_end(png_ptr, end_info);
    png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);

    iio->setStatus(0);
}

QPNGImageWriter::QPNGImageWriter(QIODevice* iod) :
    dev(iod),
    frames_written(0),
    disposal(Unspecified),
    looping(-1),
    ms_delay(-1),
    gamma(0.0)
{
}

QPNGImageWriter::~QPNGImageWriter()
{
}

void QPNGImageWriter::setDisposalMethod(DisposalMethod dm)
{
    disposal = dm;
}

void QPNGImageWriter::setLooping(int loops)
{
    looping = loops;
}

void QPNGImageWriter::setFrameDelay(int msecs)
{
    ms_delay = msecs;
}

void QPNGImageWriter::setGamma(float g)
{
    gamma = g;
}


#ifndef QT_NO_IMAGE_TEXT
static void set_text(const QImage& image, png_structp png_ptr, png_infop info_ptr, bool short_not_long)
{
    QValueList<QImageTextKeyLang> keys = image.textList();
    if ( keys.count() ) {
	png_textp text_ptr = new png_text[keys.count()];
	int i=0;
	for (QValueList<QImageTextKeyLang>::Iterator it=keys.begin();
		it != keys.end(); ++it)
	{
	    QString t = image.text(*it);
	    if ( (t.length() <= 200) == short_not_long ) {
		if ( t.length() < 40 )
		    text_ptr[i].compression = PNG_TEXT_COMPRESSION_NONE;
		else
		    text_ptr[i].compression = PNG_TEXT_COMPRESSION_zTXt;
		text_ptr[i].key = (png_charp)(*it).key.data();
		text_ptr[i].text = (png_charp)t.latin1();
		//text_ptr[i].text = qstrdup(t.latin1());
		i++;
	    }
	}
	png_set_text(png_ptr, info_ptr, text_ptr, i);
	//for (int j=0; j<i; j++)
	    //free(text_ptr[i].text);
	delete [] text_ptr;
    }
}
#endif

bool QPNGImageWriter::writeImage(const QImage& image, int off_x, int off_y)
{
    return writeImage(image, -1, off_x, off_y);
}

bool QPNGImageWriter::writeImage(const QImage& image, int quality_in, int off_x_in, int off_y_in)
{
    QPoint offset = image.offset();
    int off_x = off_x_in + offset.x();
    int off_y = off_y_in + offset.y();

    png_structp png_ptr;
    png_infop info_ptr;
    png_bytep* row_pointers;

    png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING,0,0,0);
    if (!png_ptr) {
	return FALSE;
    }

    png_set_error_fn(png_ptr, 0, 0, qt_png_warning);

    info_ptr = png_create_info_struct(png_ptr);
    if (!info_ptr) {
	png_destroy_write_struct(&png_ptr, 0);
	return FALSE;
    }

#if PNG_LIBPNG_VER>=10500
    if (setjmp(png_jmpbuf(png_ptr))) {
#else /* LIBPNG 1.5 */
    if (setjmp(png_ptr->jmpbuf)) {
#endif /* LIBPNG 1.5 */
	png_destroy_write_struct(&png_ptr, &info_ptr);
	return FALSE;
    }

    int quality = quality_in;
    if (quality >= 0) {
	if (quality > 9) {
#if defined(QT_CHECK_RANGE)
	    qWarning( "PNG: Quality %d out of range", quality );
#endif
	    quality = 9;
	}
	png_set_compression_level(png_ptr, quality);
    }

    if (gamma != 0.0) {
	png_set_gAMA(png_ptr, info_ptr, 1.0/gamma);
    }

    png_set_write_fn(png_ptr, (void*)this, qpiw_write_fn, qpiw_flush_fn);

#if PNG_LIBPNG_VER>=10500
#warning XXXtnn not too sure about this
/* 
according to png.h, channels is only used on read, not writes, so we
should be able to comment this out.
*/
#else /* LIBPNG 1.5 */
    info_ptr->channels =
	(image.depth() == 32)
	    ? (image.hasAlphaBuffer() ? 4 : 3)
	    : 1;
#endif /* LIBPNG 1.5 */

    png_set_IHDR(png_ptr, info_ptr, image.width(), image.height(),
	image.depth() == 1 ? 1 : 8 /* per channel */,
	image.depth() == 32
	    ? image.hasAlphaBuffer()
		? PNG_COLOR_TYPE_RGB_ALPHA
		: PNG_COLOR_TYPE_RGB
	    : PNG_COLOR_TYPE_PALETTE, 0, 0, 0);

#if PNG_LIBPNG_VER>=10500
    png_color_8 sig_bit;
    sig_bit.red = 8;
    sig_bit.green = 8;
    sig_bit.blue = 8;
    png_set_sBIT(png_ptr, info_ptr, &sig_bit);
#else /* LIBPNG 1.5 */
    //png_set_sBIT(png_ptr, info_ptr, 8);
    info_ptr->sig_bit.red = 8;
    info_ptr->sig_bit.green = 8;
    info_ptr->sig_bit.blue = 8;
#endif /* LIBPNG 1.5 */

    if (image.depth() == 1 && image.bitOrder() == QImage::LittleEndian)
       png_set_packswap(png_ptr);

    png_colorp palette = 0;
    png_bytep copy_trans = 0;
    if (image.numColors()) {
	// Paletted
        int num_palette = image.numColors();
	palette = new png_color[num_palette];
	png_set_PLTE(png_ptr, info_ptr, palette, num_palette);
	int* trans = new int[num_palette];
	int num_trans = 0;
#if PNG_LIBPNG_VER>=10500
	png_colorp info_ptr_palette = NULL;
	int tmp;
	png_get_PLTE(png_ptr, info_ptr, &info_ptr_palette, &tmp);
#endif /* LIBPNG 1.5 */
	for (int i=0; i<num_palette; i++) {
	    QRgb rgb=image.color(i);
#if PNG_LIBPNG_VER>=10500
	    info_ptr_palette[i].red = qRed(rgb);
	    info_ptr_palette[i].green = qGreen(rgb);
	    info_ptr_palette[i].blue = qBlue(rgb);
#else /* LIBPNG 1.5 */
	    info_ptr->palette[i].red = qRed(rgb);
	    info_ptr->palette[i].green = qGreen(rgb);
	    info_ptr->palette[i].blue = qBlue(rgb);
#endif /* LIBPNG 1.5 */
	    if (image.hasAlphaBuffer()) {
		trans[i] = rgb >> 24;
		if (trans[i] < 255) {
		    num_trans = i+1;
		}
	    }
	}
#if PNG_LIBPNG_VER>=10500
	png_set_PLTE(png_ptr, info_ptr, info_ptr_palette, num_palette);
#endif /* LIBPNG 1.5 */
	if (num_trans) {
	    copy_trans = new png_byte[num_trans];
	    for (int i=0; i<num_trans; i++)
		copy_trans[i] = trans[i];
	    png_set_tRNS(png_ptr, info_ptr, copy_trans, num_trans, 0);
	}
	delete [] trans;
    }

    if ( image.hasAlphaBuffer() ) {
#if PNG_LIBPNG_VER>=10500
        png_color_8p sig_bit;
        png_get_sBIT(png_ptr, info_ptr, &sig_bit);
        sig_bit->alpha = 8;
        png_set_sBIT(png_ptr, info_ptr, sig_bit);
#else /* LIBPNG 1.5 */
	info_ptr->sig_bit.alpha = 8;
#endif /* LIBPNG 1.5 */
    }

    // Swap ARGB to RGBA (normal PNG format) before saving on
    // BigEndian machines
    if ( QImage::systemByteOrder() == QImage::BigEndian ) {
	png_set_swap_alpha(png_ptr);
    }

    // Qt==ARGB==Big(ARGB)==Little(BGRA)
    if ( QImage::systemByteOrder() == QImage::LittleEndian ) {
	png_set_bgr(png_ptr);
    }

    if (off_x || off_y) {
	png_set_oFFs(png_ptr, info_ptr, off_x, off_y, PNG_OFFSET_PIXEL);
    }

    if ( frames_written > 0 )
	png_set_sig_bytes(png_ptr, 8);

    if ( image.dotsPerMeterX() > 0 || image.dotsPerMeterY() > 0 ) {
	png_set_pHYs(png_ptr, info_ptr,
		image.dotsPerMeterX(), image.dotsPerMeterY(),
		PNG_RESOLUTION_METER);
    }

#ifndef QT_NO_IMAGE_TEXT
    // Write short texts early.
    set_text(image,png_ptr,info_ptr,TRUE);
#endif

    png_write_info(png_ptr, info_ptr);

#ifndef QT_NO_IMAGE_TEXT
    // Write long texts later.
    set_text(image,png_ptr,info_ptr,FALSE);
#endif

    if ( image.depth() != 1 )
	png_set_packing(png_ptr);

    if ( image.depth() == 32 && !image.hasAlphaBuffer() )
	png_set_filler(png_ptr, 0,
	    QImage::systemByteOrder() == QImage::BigEndian ?
		PNG_FILLER_BEFORE : PNG_FILLER_AFTER);

    if ( looping >= 0 && frames_written == 0 ) {
	uchar data[13] = "NETSCAPE2.0";
	//                0123456789aBC
	data[0xB] = looping%0x100;
	data[0xC] = looping/0x100;
	png_write_chunk(png_ptr, (png_byte*)"gIFx", data, 13);
    }
    if ( ms_delay >= 0 || disposal!=Unspecified ) {
	uchar data[4];
	data[0] = disposal;
	data[1] = 0;
	data[2] = (ms_delay/10)/0x100; // hundredths
	data[3] = (ms_delay/10)%0x100;
	png_write_chunk(png_ptr, (png_byte*)"gIFg", data, 4);
    }

    png_uint_32 width;
    png_uint_32 height;
    int bit_depth;
    int color_type;
    png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
	0, 0, 0);

    uchar** jt = image.jumpTable();
    row_pointers=new png_bytep[height];
    uint y;
    for (y=0; y<height; y++) {
	row_pointers[y]=jt[y];
    }
    png_write_image(png_ptr, row_pointers);
    delete [] row_pointers;

    png_write_end(png_ptr, info_ptr);
    frames_written++;

    if ( palette )
	delete [] palette;
    if ( copy_trans )
	delete [] copy_trans;

    png_destroy_write_struct(&png_ptr, &info_ptr);

    return TRUE;
}

static
void write_png_image(QImageIO* iio)
{
    QPNGImageWriter writer(iio->ioDevice());
    int quality = iio->quality();
    if ( quality >= 0 ) {
	quality = QMIN( quality, 100 );
	quality = (100-quality) * 9 / 91; // map [0,100] -> [9,0]
    }
    writer.setGamma(iio->gamma());
    bool ok = writer.writeImage( iio->image(), quality );
    iio->setStatus( ok ? 0 : -1 );
}

/*!
    \class QPNGImagePacker qpngio.h
    \brief The QPNGImagePacker class creates well-compressed PNG animations.

    \ingroup images
    \ingroup graphics

    By using transparency, QPNGImagePacker allows you to build a PNG
    image from a sequence of QImages.

    Images are added using packImage().
*/


/*!
    Creates an image packer that writes PNG data to IO device \a iod
    using a \a storage_depth bit encoding (use 8 or 32, depending on
    the desired quality and compression requirements).

    If the image needs to be modified to fit in a lower-resolution
    result (e.g. converting from 32-bit to 8-bit), use the \a
    conversionflags to specify how you'd prefer this to happen.

    \sa Qt::ImageConversionFlags
*/
QPNGImagePacker::QPNGImagePacker(QIODevice* iod, int storage_depth,
	int conversionflags) :
    QPNGImageWriter(iod),
    depth(storage_depth),
    convflags(conversionflags),
    alignx(1)
{
}

/*!
    Aligns pixel differences to \a x pixels. For example, using 8 can
    improve playback on certain hardware. Normally the default of
    1-pixel alignment (i.e. no alignment) gives better compression and
    performance.
*/
void QPNGImagePacker::setPixelAlignment(int x)
{
    alignx = x;
}

/*!
    Adds the image \a img to the PNG animation, analyzing the
    differences between this and the previous image to improve
    compression.
*/
bool QPNGImagePacker::packImage(const QImage& img)
{
    QImage image = img.convertDepth(32);
    if ( previous.isNull() ) {
	// First image
	writeImage(image.convertDepth(depth,convflags));
    } else {
	bool done;
	int minx, maxx, miny, maxy;
	int w = image.width();
	int h = image.height();

	QRgb** jt = (QRgb**)image.jumpTable();
	QRgb** pjt = (QRgb**)previous.jumpTable();

	// Find left edge of change
	done = FALSE;
	for (minx = 0; minx < w && !done; minx++) {
	    for (int ty = 0; ty < h; ty++) {
		if ( jt[ty][minx] != pjt[ty][minx] ) {
		    done = TRUE;
		    break;
		}
	    }
	}
	minx--;

	// Find right edge of change
	done = FALSE;
	for (maxx = w-1; maxx >= 0 && !done; maxx--) {
	    for (int ty = 0; ty < h; ty++) {
		if ( jt[ty][maxx] != pjt[ty][maxx] ) {
		    done = TRUE;
		    break;
		}
	    }
	}
	maxx++;

	// Find top edge of change
	done = FALSE;
	for (miny = 0; miny < h && !done; miny++) {
	    for (int tx = 0; tx < w; tx++) {
		if ( jt[miny][tx] != pjt[miny][tx] ) {
		    done = TRUE;
		    break;
		}
	    }
	}
	miny--;

	// Find right edge of change
	done = FALSE;
	for (maxy = h-1; maxy >= 0 && !done; maxy--) {
	    for (int tx = 0; tx < w; tx++) {
		if ( jt[maxy][tx] != pjt[maxy][tx] ) {
		    done = TRUE;
		    break;
		}
	    }
	}
	maxy++;

	if ( minx > maxx ) minx=maxx=0;
	if ( miny > maxy ) miny=maxy=0;

	if ( alignx > 1 ) {
	    minx -= minx % alignx;
	    maxx = maxx - maxx % alignx + alignx - 1;
	}

	int dw = maxx-minx+1;
	int dh = maxy-miny+1;

	QImage diff(dw, dh, 32);

	diff.setAlphaBuffer(TRUE);
	int x, y;
	if ( alignx < 1 )
	    alignx = 1;
	for (y = 0; y < dh; y++) {
	    QRgb* li = (QRgb*)image.scanLine(y+miny)+minx;
	    QRgb* lp = (QRgb*)previous.scanLine(y+miny)+minx;
	    QRgb* ld = (QRgb*)diff.scanLine(y);
	    if ( alignx ) {
		for (x = 0; x < dw; x+=alignx) {
		    int i;
		    for (i=0; i<alignx; i++) {
			if ( li[x+i] != lp[x+i] )
			    break;
		    }
		    if ( i == alignx ) {
			// All the same
			for (i=0; i<alignx; i++) {
			    ld[x+i] = qRgba(0,0,0,0);
			}
		    } else {
			// Some different
			for (i=0; i<alignx; i++) {
			    ld[x+i] = 0xff000000 | li[x+i];
			}
		    }
		}
	    } else {
		for (x = 0; x < dw; x++) {
		    if ( li[x] != lp[x] )
			ld[x] = 0xff000000 | li[x];
		    else
			ld[x] = qRgba(0,0,0,0);
		}
	    }
	}

	diff = diff.convertDepth(depth,convflags);
	if ( !writeImage(diff, minx, miny) )
	    return FALSE;
    }
    previous = image;
    return TRUE;
}


#ifndef QT_NO_ASYNC_IMAGE_IO

class QPNGFormat : public QImageFormat {
public:
    QPNGFormat();
    virtual ~QPNGFormat();

    int decode(QImage& img, QImageConsumer* consumer,
	    const uchar* buffer, int length);

    void info(png_structp png_ptr, png_infop info);
    void row(png_structp png_ptr, png_bytep new_row,
		png_uint_32 row_num, int pass);
    void end(png_structp png_ptr, png_infop info);
#ifdef PNG_USER_CHUNKS_SUPPORTED
    int user_chunk(png_structp png_ptr,
	    png_bytep data, png_uint_32 length);
#endif

private:
    // Animation-level information
    enum { MovieStart, FrameStart, Inside, End } state;
    int first_frame;
    int base_offx;
    int base_offy;

    // Image-level information
    png_structp png_ptr;
    png_infop info_ptr;

    // Temporary locals during single data-chunk processing
    QImageConsumer* consumer;
    QImage* image;
    int unused_data;
};

class QPNGFormatType : public QImageFormatType
{
    QImageFormat* decoderFor(const uchar* buffer, int length);
    const char* formatName() const;
};


/*
  \class QPNGFormat qpngio.h
  \brief The QPNGFormat class provides an incremental image decoder for PNG
  image format.

  \ingroup images
  \ingroup graphics

  This subclass of QImageFormat decodes PNG format images,
  including animated PNGs.

  Animated PNG images are standard PNG images. The PNG standard
  defines two extension chunks that are useful for animations:

  \list
    \i gIFg - GIF-like Graphic Control Extension.
     This includes frame disposal, user input flag (we ignore this),
	    and inter-frame delay.
   \i gIFx - GIF-like Application Extension.
    This is multi-purpose, but we just use the Netscape extension
	    which specifies looping.
  \endlist

  The subimages usually contain a offset chunk (oFFs) but need not.

  The first image defines the "screen" size. Any subsequent image that
  doesn't fit is clipped.
*/
/* ###TODO: decide on this point. gIFg gives disposal types, so it can be done.
  All images paste (\e not composite, just place all-channel copying)
  over the previous image to produce a subsequent frame.
*/

/*
  \class QPNGFormatType qasyncimageio.h
  \brief The QPNGFormatType class provides an incremental image decoder
  for PNG image format.

  \ingroup images
  \ingroup graphics
  \ingroup io

  This subclass of QImageFormatType recognizes PNG format images, creating
  a QPNGFormat when required. An instance of this class is created
  automatically before any other factories, so you should have no need for
  such objects.
*/

QImageFormat* QPNGFormatType::decoderFor(
    const uchar* buffer, int length)
{
    if (length < 8) return 0;
    if (buffer[0]==137
     && buffer[1]=='P'
     && buffer[2]=='N'
     && buffer[3]=='G'
     && buffer[4]==13
     && buffer[5]==10
     && buffer[6]==26
     && buffer[7]==10)
	return new QPNGFormat;
    return 0;
}

const char* QPNGFormatType::formatName() const
{
    return "PNG";
}

#if defined(Q_C_CALLBACKS)
extern "C" {
#endif

static void
CALLBACK_CALL_TYPE info_callback(png_structp png_ptr, png_infop info)
{
    QPNGFormat* that = (QPNGFormat*)png_get_progressive_ptr(png_ptr);
    that->info(png_ptr,info);
}

static void
CALLBACK_CALL_TYPE row_callback(png_structp png_ptr, png_bytep new_row,
   png_uint_32 row_num, int pass)
{
    QPNGFormat* that = (QPNGFormat*)png_get_progressive_ptr(png_ptr);
    that->row(png_ptr,new_row,row_num,pass);
}

static void
CALLBACK_CALL_TYPE end_callback(png_structp png_ptr, png_infop info)
{
    QPNGFormat* that = (QPNGFormat*)png_get_progressive_ptr(png_ptr);
    that->end(png_ptr,info);
}

#if 0
#ifdef PNG_USER_CHUNKS_SUPPORTED
static int
CALLBACK_CALL_TYPE user_chunk_callback(png_structp png_ptr,
         png_unknown_chunkp chunk)
{
    QPNGFormat* that = (QPNGFormat*)png_get_progressive_ptr(png_ptr);
    return that->user_chunk(png_ptr,chunk->data,chunk->size);
}
#endif
#endif

#if defined(Q_C_CALLBACKS)
}
#endif


/*!
    Constructs a QPNGFormat object.
*/
QPNGFormat::QPNGFormat()
{
    state = MovieStart;
    first_frame = 1;
    base_offx = 0;
    base_offy = 0;
    png_ptr = 0;
    info_ptr = 0;
}


/*!
    Destroys a QPNGFormat object.
*/
QPNGFormat::~QPNGFormat()
{
    if ( png_ptr )
        png_destroy_read_struct(&png_ptr, &info_ptr, 0);
}


/*!
    This function decodes some data into image changes.

    Returns the number of bytes consumed.
*/
int QPNGFormat::decode(QImage& img, QImageConsumer* cons,
	const uchar* buffer, int length)
{
    consumer = cons;
    image = &img;

    if ( state != Inside ) {
	png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, 0, 0, 0);
	if (!png_ptr) {
	    info_ptr = 0;
	    image = 0;
		return -1;
	}

	png_set_error_fn(png_ptr, 0, 0, qt_png_warning);
	png_set_compression_level(png_ptr, 9);

	info_ptr = png_create_info_struct(png_ptr);
	if (!info_ptr) {
	    png_destroy_read_struct(&png_ptr, &info_ptr, 0);
	    image = 0;
	    return -1;
	}

#if PNG_LIBPNG_VER>=10500
	if (setjmp(png_jmpbuf(png_ptr))) {
#else /* LIBPNG 1.5 */
	if (setjmp((png_ptr)->jmpbuf)) {
#endif /* LIBPNG 1.5 */
	    png_destroy_read_struct(&png_ptr, &info_ptr, 0);
	    image = 0;
	    return -1;
	}

	png_set_progressive_read_fn(png_ptr, (void *)this,
	                            info_callback, row_callback, end_callback);

#ifdef PNG_USER_CHUNKS_SUPPORTED
	// Can't do this yet. libpng has a crash bug with unknown (user) chunks.
	// Warwick has sent them a patch.
	// png_set_read_user_chunk_fn(png_ptr, 0, user_chunk_callback);
	// png_set_keep_unknown_chunks(png_ptr, 2/*HANDLE_CHUNK_IF_SAFE*/, 0, 0);
#endif

	if ( state != MovieStart && *buffer != 0211 ) {
	    // Good, no signature - the preferred way to concat PNG images.
	    // Skip them.
	    png_set_sig_bytes(png_ptr, 8);
	}

	state = Inside;
    }

    if ( !png_ptr ) return 0;

#if PNG_LIBPNG_VER>=10500
    if (setjmp(png_jmpbuf(png_ptr))) {
#else /* LIBPNG 1.5 */
    if (setjmp(png_ptr->jmpbuf)) {
#endif /* LIBPNG 1.5 */
	png_destroy_read_struct(&png_ptr, &info_ptr, 0);
	image = 0;
	state = MovieStart;
	return -1;
    }
    unused_data = 0;
    png_process_data(png_ptr, info_ptr, (png_bytep)buffer, length);
    int l = length - unused_data;

    // TODO: send incremental stuff to consumer (optional)

    if ( state != Inside ) {
	if ( png_ptr )
	    png_destroy_read_struct(&png_ptr, &info_ptr, 0);
    }

    image = 0;
    return l;
}

void QPNGFormat::info(png_structp png, png_infop)
{
    png_set_interlace_handling(png);
    setup_qt(*image, png, info_ptr);
}

void QPNGFormat::row(png_structp png, png_bytep new_row,
    png_uint_32 row_num, int)
{
    uchar* old_row = image->scanLine(row_num);
    png_progressive_combine_row(png, old_row, new_row);
}


void QPNGFormat::end(png_structp png, png_infop info)
{
    int offx = png_get_x_offset_pixels(png,info) - base_offx;
    int offy = png_get_y_offset_pixels(png,info) - base_offy;
    if ( first_frame ) {
	base_offx = offx;
	base_offy = offy;
	first_frame = 0;
    }
    image->setOffset(QPoint(offx,offy));
    image->setDotsPerMeterX(png_get_x_pixels_per_meter(png,info));
    image->setDotsPerMeterY(png_get_y_pixels_per_meter(png,info));
#ifndef QT_NO_IMAGE_TEXT
    png_textp text_ptr;
    int num_text=0;
    png_get_text(png,info,&text_ptr,&num_text);
    while (num_text--) {
	image->setText(text_ptr->key,0,text_ptr->text);
	text_ptr++;
    }
#endif
    QRect r(0,0,image->width(),image->height());
    consumer->frameDone(QPoint(offx,offy),r);
    consumer->end();
    state = FrameStart;
#if PNG_LIBPNG_VER>=10500
    unused_data = png_process_data_pause(png, 0);
#else /* LIBPNG 1.5 */
    unused_data = (int)png->buffer_size; // Since libpng doesn't tell us
#endif /* LIBPNG 1.5 */
}

#ifdef PNG_USER_CHUNKS_SUPPORTED

/*
#ifndef QT_NO_IMAGE_TEXT
static bool skip(png_uint_32& max, png_bytep& data)
{
    while (*data) {
	if ( !max ) return FALSE;
	max--;
	data++;
    }
    if ( !max ) return FALSE;
    max--;
    data++; // skip to after NUL
    return TRUE;
}
#endif
*/

int QPNGFormat::user_chunk(png_structp png,
	    png_bytep data, png_uint_32 length)
{
#if 0 // NOT SUPPORTED: experimental PNG animation.
    // qDebug("Got %ld-byte %s chunk", length, png->chunk_name);
    if ( 0==qstrcmp((char*)png->chunk_name, "gIFg")
	    && length == 4 ) {

	//QPNGImageWriter::DisposalMethod disposal =
	//  (QPNGImageWriter::DisposalMethod)data[0];
	// ### TODO: use the disposal method
	int ms_delay = ((data[2] << 8) | data[3])*10;
	consumer->setFramePeriod(ms_delay);
	return 1;
    } else if ( 0==qstrcmp((char*)png->chunk_name, "gIFx")
	    && length == 13 ) {
	if ( qstrncmp((char*)data,"NETSCAPE2.0",11)==0 ) {
	    int looping = (data[0xC]<<8)|data[0xB];
	    consumer->setLooping(looping);
	    return 1;
	}
    }
#else
    Q_UNUSED( png )
    Q_UNUSED( data )
    Q_UNUSED( length )
#endif

#ifndef QT_NO_IMAGE_TEXT
    /*

    libpng now supports this chunk.


    if ( 0==qstrcmp((char*)png->chunk_name, "iTXt") && length>=6 ) {
	const char* keyword = (const char*)data;
	if ( !skip(length,data) ) return 0;
	if ( length >= 4 ) {
	    char compression_flag = *data++;
	    char compression_method = *data++;
	    if ( compression_flag == compression_method ) {
		// fool the compiler into thinking they're used
	    }
	    const char* lang = (const char*)data;
	    if ( !skip(length,data) ) return 0;
	    // const char* keyword_utf8 = (const char*)data;
	    if ( !skip(length,data) ) return 0;
	    const char* text_utf8 = (const char*)data;
	    if ( !skip(length,data) ) return 0;
	    QString text = QString::fromUtf8(text_utf8);
	    image->setText(keyword,lang[0] ? lang : 0,text);
	    return 1;
	}
    }
    */
#endif

    return 0;
}
#endif


static QPNGFormatType* globalPngFormatTypeObject = 0;

#endif // QT_NO_ASYNC_IMAGE_IO

static bool done = FALSE;
void qCleanupPngIO()
{
#ifndef QT_NO_ASYNC_IMAGE_IO
    if ( globalPngFormatTypeObject ) {
	delete globalPngFormatTypeObject;
	globalPngFormatTypeObject = 0;
    }
#endif
    done = FALSE;
}

void qInitPngIO()
{
    if ( !done ) {
	done = TRUE;
	QImageIO::defineIOHandler( "PNG", "^.PNG\r", 0, read_png_image,
				   write_png_image);
#ifndef QT_NO_ASYNC_IMAGE_IO
	globalPngFormatTypeObject = new QPNGFormatType;
#endif
	qAddPostRoutine( qCleanupPngIO );
    }
}

void qt_zlib_compression_hack()
{
    compress(0,0,0,0);
    uncompress(0,0,0,0);
}

#endif // QT_NO_IMAGEIO_PNG