-
Notifications
You must be signed in to change notification settings - Fork 26.8k
/
decoration_image.dart
854 lines (789 loc) · 31.6 KB
/
decoration_image.dart
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
// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
import 'dart:developer' as developer;
import 'dart:math' as math;
import 'dart:ui' as ui show FlutterView, Image;
import 'package:flutter/foundation.dart';
import 'package:flutter/scheduler.dart';
import 'alignment.dart';
import 'basic_types.dart';
import 'binding.dart';
import 'borders.dart';
import 'box_fit.dart';
import 'debug.dart';
import 'image_provider.dart';
import 'image_stream.dart';
/// How to paint any portions of a box not covered by an image.
enum ImageRepeat {
/// Repeat the image in both the x and y directions until the box is filled.
repeat,
/// Repeat the image in the x direction until the box is filled horizontally.
repeatX,
/// Repeat the image in the y direction until the box is filled vertically.
repeatY,
/// Leave uncovered portions of the box transparent.
noRepeat,
}
/// An image for a box decoration.
///
/// The image is painted using [paintImage], which describes the meanings of the
/// various fields on this class in more detail.
@immutable
class DecorationImage {
/// Creates an image to show in a [BoxDecoration].
const DecorationImage({
required this.image,
this.onError,
this.colorFilter,
this.fit,
this.alignment = Alignment.center,
this.centerSlice,
this.repeat = ImageRepeat.noRepeat,
this.matchTextDirection = false,
this.scale = 1.0,
this.opacity = 1.0,
this.filterQuality = FilterQuality.low,
this.invertColors = false,
this.isAntiAlias = false,
});
/// The image to be painted into the decoration.
///
/// Typically this will be an [AssetImage] (for an image shipped with the
/// application) or a [NetworkImage] (for an image obtained from the network).
final ImageProvider image;
/// An optional error callback for errors emitted when loading [image].
final ImageErrorListener? onError;
/// A color filter to apply to the image before painting it.
final ColorFilter? colorFilter;
/// How the image should be inscribed into the box.
///
/// The default is [BoxFit.scaleDown] if [centerSlice] is null, and
/// [BoxFit.fill] if [centerSlice] is not null.
///
/// See the discussion at [paintImage] for more details.
final BoxFit? fit;
/// How to align the image within its bounds.
///
/// The alignment aligns the given position in the image to the given position
/// in the layout bounds. For example, an [Alignment] alignment of (-1.0,
/// -1.0) aligns the image to the top-left corner of its layout bounds, while a
/// [Alignment] alignment of (1.0, 1.0) aligns the bottom right of the
/// image with the bottom right corner of its layout bounds. Similarly, an
/// alignment of (0.0, 1.0) aligns the bottom middle of the image with the
/// middle of the bottom edge of its layout bounds.
///
/// To display a subpart of an image, consider using a [CustomPainter] and
/// [Canvas.drawImageRect].
///
/// If the [alignment] is [TextDirection]-dependent (i.e. if it is a
/// [AlignmentDirectional]), then a [TextDirection] must be available
/// when the image is painted.
///
/// Defaults to [Alignment.center].
///
/// See also:
///
/// * [Alignment], a class with convenient constants typically used to
/// specify an [AlignmentGeometry].
/// * [AlignmentDirectional], like [Alignment] for specifying alignments
/// relative to text direction.
final AlignmentGeometry alignment;
/// The center slice for a nine-patch image.
///
/// The region of the image inside the center slice will be stretched both
/// horizontally and vertically to fit the image into its destination. The
/// region of the image above and below the center slice will be stretched
/// only horizontally and the region of the image to the left and right of
/// the center slice will be stretched only vertically.
///
/// The stretching will be applied in order to make the image fit into the box
/// specified by [fit]. When [centerSlice] is not null, [fit] defaults to
/// [BoxFit.fill], which distorts the destination image size relative to the
/// image's original aspect ratio. Values of [BoxFit] which do not distort the
/// destination image size will result in [centerSlice] having no effect
/// (since the nine regions of the image will be rendered with the same
/// scaling, as if it wasn't specified).
final Rect? centerSlice;
/// How to paint any portions of the box that would not otherwise be covered
/// by the image.
final ImageRepeat repeat;
/// Whether to paint the image in the direction of the [TextDirection].
///
/// If this is true, then in [TextDirection.ltr] contexts, the image will be
/// drawn with its origin in the top left (the "normal" painting direction for
/// images); and in [TextDirection.rtl] contexts, the image will be drawn with
/// a scaling factor of -1 in the horizontal direction so that the origin is
/// in the top right.
final bool matchTextDirection;
/// Defines image pixels to be shown per logical pixels.
///
/// By default the value of scale is 1.0. The scale for the image is
/// calculated by multiplying [scale] with [scale] of the given [ImageProvider].
final double scale;
/// If non-null, the value is multiplied with the opacity of each image
/// pixel before painting onto the canvas.
///
/// This is more efficient than using [Opacity] or [FadeTransition] to
/// change the opacity of an image.
final double opacity;
/// Used to set the filterQuality of the image.
///
/// Defaults to [FilterQuality.low] to scale the image, which corresponds to
/// bilinear interpolation.
final FilterQuality filterQuality;
/// Whether the colors of the image are inverted when drawn.
///
/// Inverting the colors of an image applies a new color filter to the paint.
/// If there is another specified color filter, the invert will be applied
/// after it. This is primarily used for implementing smart invert on iOS.
///
/// See also:
///
/// * [Paint.invertColors], for the dart:ui implementation.
final bool invertColors;
/// Whether to paint the image with anti-aliasing.
///
/// Anti-aliasing alleviates the sawtooth artifact when the image is rotated.
final bool isAntiAlias;
/// Creates a [DecorationImagePainter] for this [DecorationImage].
///
/// The `onChanged` argument will be called whenever the image needs to be
/// repainted, e.g. because it is loading incrementally or because it is
/// animated.
DecorationImagePainter createPainter(VoidCallback onChanged) {
return _DecorationImagePainter._(this, onChanged);
}
@override
bool operator ==(Object other) {
if (identical(this, other)) {
return true;
}
if (other.runtimeType != runtimeType) {
return false;
}
return other is DecorationImage
&& other.image == image
&& other.colorFilter == colorFilter
&& other.fit == fit
&& other.alignment == alignment
&& other.centerSlice == centerSlice
&& other.repeat == repeat
&& other.matchTextDirection == matchTextDirection
&& other.scale == scale
&& other.opacity == opacity
&& other.filterQuality == filterQuality
&& other.invertColors == invertColors
&& other.isAntiAlias == isAntiAlias;
}
@override
int get hashCode => Object.hash(
image,
colorFilter,
fit,
alignment,
centerSlice,
repeat,
matchTextDirection,
scale,
opacity,
filterQuality,
invertColors,
isAntiAlias,
);
@override
String toString() {
final List<String> properties = <String>[
'$image',
if (colorFilter != null)
'$colorFilter',
if (fit != null &&
!(fit == BoxFit.fill && centerSlice != null) &&
!(fit == BoxFit.scaleDown && centerSlice == null))
'$fit',
'$alignment',
if (centerSlice != null)
'centerSlice: $centerSlice',
if (repeat != ImageRepeat.noRepeat)
'$repeat',
if (matchTextDirection)
'match text direction',
'scale ${scale.toStringAsFixed(1)}',
'opacity ${opacity.toStringAsFixed(1)}',
'$filterQuality',
if (invertColors)
'invert colors',
if (isAntiAlias)
'use anti-aliasing',
];
return '${objectRuntimeType(this, 'DecorationImage')}(${properties.join(", ")})';
}
/// Linearly interpolates between two [DecorationImage]s.
///
/// The `t` argument represents position on the timeline, with 0.0 meaning
/// that the interpolation has not started, returning `a`, 1.0 meaning that
/// the interpolation has finished, returning `b`, and values in between
/// meaning that the interpolation is at the relevant point on the timeline
/// between `a` and `this`. The interpolation can be extrapolated beyond 0.0
/// and 1.0, so negative values and values greater than 1.0 are valid (and can
/// easily be generated by curves such as [Curves.elasticInOut]).
///
/// Values for `t` are usually obtained from an [Animation<double>], such as
/// an [AnimationController].
static DecorationImage? lerp(DecorationImage? a, DecorationImage? b, double t) {
if (identical(a, b) || t == 0.0) {
return a;
}
if (t == 1.0) {
return b;
}
return _BlendedDecorationImage(a, b, t);
}
}
/// The painter for a [DecorationImage].
///
/// To obtain a painter, call [DecorationImage.createPainter].
///
/// To paint, call [paint]. The `onChanged` callback passed to
/// [DecorationImage.createPainter] will be called if the image needs to paint
/// again (e.g. because it is animated or because it had not yet loaded the
/// first time the [paint] method was called).
///
/// This object should be disposed using the [dispose] method when it is no
/// longer needed.
abstract interface class DecorationImagePainter {
/// Draw the image onto the given canvas.
///
/// The image is drawn at the position and size given by the `rect` argument.
///
/// The image is clipped to the given `clipPath`, if any.
///
/// The `configuration` object is used to resolve the image (e.g. to pick
/// resolution-specific assets), and to implement the
/// [DecorationImage.matchTextDirection] feature.
///
/// If the image needs to be painted again, e.g. because it is animated or
/// because it had not yet been loaded the first time this method was called,
/// then the `onChanged` callback passed to [DecorationImage.createPainter]
/// will be called.
///
/// The `blend` argument specifies the opacity that should be applied to the
/// image due to this image being blended with another. The `blendMode`
/// argument can be specified to override the [DecorationImagePainter]'s
/// default [BlendMode] behavior. It is usually set to [BlendMode.srcOver] if
/// this is the first or only image being blended, and [BlendMode.plus] if it
/// is being blended with an image below.
void paint(Canvas canvas, Rect rect, Path? clipPath, ImageConfiguration configuration, { double blend = 1.0, BlendMode blendMode = BlendMode.srcOver });
/// Releases the resources used by this painter.
///
/// This should be called whenever the painter is no longer needed.
///
/// After this method has been called, the object is no longer usable.
void dispose();
}
class _DecorationImagePainter implements DecorationImagePainter {
_DecorationImagePainter._(this._details, this._onChanged) {
// TODO(polina-c): stop duplicating code across disposables
// https://github.com/flutter/flutter/issues/137435
if (kFlutterMemoryAllocationsEnabled) {
FlutterMemoryAllocations.instance.dispatchObjectCreated(
library: 'package:flutter/painting.dart',
className: '$_DecorationImagePainter',
object: this,
);
}
}
final DecorationImage _details;
final VoidCallback _onChanged;
ImageStream? _imageStream;
ImageInfo? _image;
@override
void paint(Canvas canvas, Rect rect, Path? clipPath, ImageConfiguration configuration, { double blend = 1.0, BlendMode blendMode = BlendMode.srcOver }) {
bool flipHorizontally = false;
if (_details.matchTextDirection) {
assert(() {
// We check this first so that the assert will fire immediately, not just
// when the image is ready.
if (configuration.textDirection == null) {
throw FlutterError.fromParts(<DiagnosticsNode>[
ErrorSummary('DecorationImage.matchTextDirection can only be used when a TextDirection is available.'),
ErrorDescription(
'When DecorationImagePainter.paint() was called, there was no text direction provided '
'in the ImageConfiguration object to match.',
),
DiagnosticsProperty<DecorationImage>('The DecorationImage was', _details, style: DiagnosticsTreeStyle.errorProperty),
DiagnosticsProperty<ImageConfiguration>('The ImageConfiguration was', configuration, style: DiagnosticsTreeStyle.errorProperty),
]);
}
return true;
}());
if (configuration.textDirection == TextDirection.rtl) {
flipHorizontally = true;
}
}
final ImageStream newImageStream = _details.image.resolve(configuration);
if (newImageStream.key != _imageStream?.key) {
final ImageStreamListener listener = ImageStreamListener(
_handleImage,
onError: _details.onError,
);
_imageStream?.removeListener(listener);
_imageStream = newImageStream;
_imageStream!.addListener(listener);
}
if (_image == null) {
return;
}
if (clipPath != null) {
canvas.save();
canvas.clipPath(clipPath);
}
paintImage(
canvas: canvas,
rect: rect,
image: _image!.image,
debugImageLabel: _image!.debugLabel,
scale: _details.scale * _image!.scale,
colorFilter: _details.colorFilter,
fit: _details.fit,
alignment: _details.alignment.resolve(configuration.textDirection),
centerSlice: _details.centerSlice,
repeat: _details.repeat,
flipHorizontally: flipHorizontally,
opacity: _details.opacity * blend,
filterQuality: _details.filterQuality,
invertColors: _details.invertColors,
isAntiAlias: _details.isAntiAlias,
blendMode: blendMode,
);
if (clipPath != null) {
canvas.restore();
}
}
void _handleImage(ImageInfo value, bool synchronousCall) {
if (_image == value) {
return;
}
if (_image != null && _image!.isCloneOf(value)) {
value.dispose();
return;
}
_image?.dispose();
_image = value;
if (!synchronousCall) {
_onChanged();
}
}
@override
void dispose() {
if (kFlutterMemoryAllocationsEnabled) {
FlutterMemoryAllocations.instance.dispatchObjectDisposed(object: this);
}
_imageStream?.removeListener(ImageStreamListener(
_handleImage,
onError: _details.onError,
));
_image?.dispose();
_image = null;
}
@override
String toString() {
return '${objectRuntimeType(this, 'DecorationImagePainter')}(stream: $_imageStream, image: $_image) for $_details';
}
}
/// Used by [paintImage] to report image sizes drawn at the end of the frame.
Map<String, ImageSizeInfo> _pendingImageSizeInfo = <String, ImageSizeInfo>{};
/// [ImageSizeInfo]s that were reported on the last frame.
///
/// Used to prevent duplicative reports from frame to frame.
Set<ImageSizeInfo> _lastFrameImageSizeInfo = <ImageSizeInfo>{};
/// Flushes inter-frame tracking of image size information from [paintImage].
///
/// Has no effect if asserts are disabled.
@visibleForTesting
void debugFlushLastFrameImageSizeInfo() {
assert(() {
_lastFrameImageSizeInfo = <ImageSizeInfo>{};
return true;
}());
}
/// Paints an image into the given rectangle on the canvas.
///
/// The arguments have the following meanings:
///
/// * `canvas`: The canvas onto which the image will be painted.
///
/// * `rect`: The region of the canvas into which the image will be painted.
/// The image might not fill the entire rectangle (e.g., depending on the
/// `fit`). If `rect` is empty, nothing is painted.
///
/// * `image`: The image to paint onto the canvas.
///
/// * `scale`: The number of image pixels for each logical pixel.
///
/// * `opacity`: The opacity to paint the image onto the canvas with.
///
/// * `colorFilter`: If non-null, the color filter to apply when painting the
/// image.
///
/// * `fit`: How the image should be inscribed into `rect`. If null, the
/// default behavior depends on `centerSlice`. If `centerSlice` is also null,
/// the default behavior is [BoxFit.scaleDown]. If `centerSlice` is
/// non-null, the default behavior is [BoxFit.fill]. See [BoxFit] for
/// details.
///
/// * `alignment`: How the destination rectangle defined by applying `fit` is
/// aligned within `rect`. For example, if `fit` is [BoxFit.contain] and
/// `alignment` is [Alignment.bottomRight], the image will be as large
/// as possible within `rect` and placed with its bottom right corner at the
/// bottom right corner of `rect`. Defaults to [Alignment.center].
///
/// * `centerSlice`: The image is drawn in nine portions described by splitting
/// the image by drawing two horizontal lines and two vertical lines, where
/// `centerSlice` describes the rectangle formed by the four points where
/// these four lines intersect each other. (This forms a 3-by-3 grid
/// of regions, the center region being described by `centerSlice`.)
/// The four regions in the corners are drawn, without scaling, in the four
/// corners of the destination rectangle defined by applying `fit`. The
/// remaining five regions are drawn by stretching them to fit such that they
/// exactly cover the destination rectangle while maintaining their relative
/// positions. See also [Canvas.drawImageNine].
///
/// * `repeat`: If the image does not fill `rect`, whether and how the image
/// should be repeated to fill `rect`. By default, the image is not repeated.
/// See [ImageRepeat] for details.
///
/// * `flipHorizontally`: Whether to flip the image horizontally. This is
/// occasionally used with images in right-to-left environments, for images
/// that were designed for left-to-right locales (or vice versa). Be careful,
/// when using this, to not flip images with integral shadows, text, or other
/// effects that will look incorrect when flipped.
///
/// * `invertColors`: Inverting the colors of an image applies a new color
/// filter to the paint. If there is another specified color filter, the
/// invert will be applied after it. This is primarily used for implementing
/// smart invert on iOS.
///
/// * `filterQuality`: Use this to change the quality when scaling an image.
/// Use the [FilterQuality.low] quality setting to scale the image, which corresponds to
/// bilinear interpolation, rather than the default [FilterQuality.none] which corresponds
/// to nearest-neighbor.
///
/// See also:
///
/// * [paintBorder], which paints a border around a rectangle on a canvas.
/// * [DecorationImage], which holds a configuration for calling this function.
/// * [BoxDecoration], which uses this function to paint a [DecorationImage].
void paintImage({
required Canvas canvas,
required Rect rect,
required ui.Image image,
String? debugImageLabel,
double scale = 1.0,
double opacity = 1.0,
ColorFilter? colorFilter,
BoxFit? fit,
Alignment alignment = Alignment.center,
Rect? centerSlice,
ImageRepeat repeat = ImageRepeat.noRepeat,
bool flipHorizontally = false,
bool invertColors = false,
FilterQuality filterQuality = FilterQuality.low,
bool isAntiAlias = false,
BlendMode blendMode = BlendMode.srcOver,
}) {
assert(
image.debugGetOpenHandleStackTraces()?.isNotEmpty ?? true,
'Cannot paint an image that is disposed.\n'
'The caller of paintImage is expected to wait to dispose the image until '
'after painting has completed.',
);
if (rect.isEmpty) {
return;
}
Size outputSize = rect.size;
Size inputSize = Size(image.width.toDouble(), image.height.toDouble());
Offset? sliceBorder;
if (centerSlice != null) {
sliceBorder = inputSize / scale - centerSlice.size as Offset;
outputSize = outputSize - sliceBorder as Size;
inputSize = inputSize - sliceBorder * scale as Size;
}
fit ??= centerSlice == null ? BoxFit.scaleDown : BoxFit.fill;
assert(centerSlice == null || (fit != BoxFit.none && fit != BoxFit.cover));
final FittedSizes fittedSizes = applyBoxFit(fit, inputSize / scale, outputSize);
final Size sourceSize = fittedSizes.source * scale;
Size destinationSize = fittedSizes.destination;
if (centerSlice != null) {
outputSize += sliceBorder!;
destinationSize += sliceBorder;
// We don't have the ability to draw a subset of the image at the same time
// as we apply a nine-patch stretch.
assert(sourceSize == inputSize, 'centerSlice was used with a BoxFit that does not guarantee that the image is fully visible.');
}
if (repeat != ImageRepeat.noRepeat && destinationSize == outputSize) {
// There's no need to repeat the image because we're exactly filling the
// output rect with the image.
repeat = ImageRepeat.noRepeat;
}
final Paint paint = Paint()..isAntiAlias = isAntiAlias;
if (colorFilter != null) {
paint.colorFilter = colorFilter;
}
paint.color = Color.fromRGBO(0, 0, 0, clampDouble(opacity, 0.0, 1.0));
paint.filterQuality = filterQuality;
paint.invertColors = invertColors;
paint.blendMode = blendMode;
final double halfWidthDelta = (outputSize.width - destinationSize.width) / 2.0;
final double halfHeightDelta = (outputSize.height - destinationSize.height) / 2.0;
final double dx = halfWidthDelta + (flipHorizontally ? -alignment.x : alignment.x) * halfWidthDelta;
final double dy = halfHeightDelta + alignment.y * halfHeightDelta;
final Offset destinationPosition = rect.topLeft.translate(dx, dy);
final Rect destinationRect = destinationPosition & destinationSize;
// Set to true if we added a saveLayer to the canvas to invert/flip the image.
bool invertedCanvas = false;
// Output size and destination rect are fully calculated.
// Implement debug-mode and profile-mode features:
// - cacheWidth/cacheHeight warning
// - debugInvertOversizedImages
// - debugOnPaintImage
// - Flutter.ImageSizesForFrame events in timeline
if (!kReleaseMode) {
// We can use the devicePixelRatio of the views directly here (instead of
// going through a MediaQuery) because if it changes, whatever is aware of
// the MediaQuery will be repainting the image anyways.
// Furthermore, for the memory check below we just assume that all images
// are decoded for the view with the highest device pixel ratio and use that
// as an upper bound for the display size of the image.
final double maxDevicePixelRatio = PaintingBinding.instance.platformDispatcher.views.fold(
0.0,
(double previousValue, ui.FlutterView view) => math.max(previousValue, view.devicePixelRatio),
);
final ImageSizeInfo sizeInfo = ImageSizeInfo(
// Some ImageProvider implementations may not have given this.
source: debugImageLabel ?? '<Unknown Image(${image.width}×${image.height})>',
imageSize: Size(image.width.toDouble(), image.height.toDouble()),
displaySize: outputSize * maxDevicePixelRatio,
);
assert(() {
if (debugInvertOversizedImages &&
sizeInfo.decodedSizeInBytes > sizeInfo.displaySizeInBytes + debugImageOverheadAllowance) {
final int overheadInKilobytes = (sizeInfo.decodedSizeInBytes - sizeInfo.displaySizeInBytes) ~/ 1024;
final int outputWidth = sizeInfo.displaySize.width.toInt();
final int outputHeight = sizeInfo.displaySize.height.toInt();
FlutterError.reportError(FlutterErrorDetails(
exception: 'Image $debugImageLabel has a display size of '
'$outputWidth×$outputHeight but a decode size of '
'${image.width}×${image.height}, which uses an additional '
'${overheadInKilobytes}KB (assuming a device pixel ratio of '
'$maxDevicePixelRatio).\n\n'
'Consider resizing the asset ahead of time, supplying a cacheWidth '
'parameter of $outputWidth, a cacheHeight parameter of '
'$outputHeight, or using a ResizeImage.',
library: 'painting library',
context: ErrorDescription('while painting an image'),
));
// Invert the colors of the canvas.
canvas.saveLayer(
destinationRect,
Paint()..colorFilter = const ColorFilter.matrix(<double>[
-1, 0, 0, 0, 255,
0, -1, 0, 0, 255,
0, 0, -1, 0, 255,
0, 0, 0, 1, 0,
]),
);
// Flip the canvas vertically.
final double dy = -(rect.top + rect.height / 2.0);
canvas.translate(0.0, -dy);
canvas.scale(1.0, -1.0);
canvas.translate(0.0, dy);
invertedCanvas = true;
}
return true;
}());
// Avoid emitting events that are the same as those emitted in the last frame.
if (!_lastFrameImageSizeInfo.contains(sizeInfo)) {
final ImageSizeInfo? existingSizeInfo = _pendingImageSizeInfo[sizeInfo.source];
if (existingSizeInfo == null || existingSizeInfo.displaySizeInBytes < sizeInfo.displaySizeInBytes) {
_pendingImageSizeInfo[sizeInfo.source!] = sizeInfo;
}
debugOnPaintImage?.call(sizeInfo);
SchedulerBinding.instance.addPostFrameCallback((Duration timeStamp) {
_lastFrameImageSizeInfo = _pendingImageSizeInfo.values.toSet();
if (_pendingImageSizeInfo.isEmpty) {
return;
}
developer.postEvent(
'Flutter.ImageSizesForFrame',
<String, Object>{
for (final ImageSizeInfo imageSizeInfo in _pendingImageSizeInfo.values)
imageSizeInfo.source!: imageSizeInfo.toJson(),
},
);
_pendingImageSizeInfo = <String, ImageSizeInfo>{};
}, debugLabel: 'paintImage.recordImageSizes');
}
}
final bool needSave = centerSlice != null || repeat != ImageRepeat.noRepeat || flipHorizontally;
if (needSave) {
canvas.save();
}
if (repeat != ImageRepeat.noRepeat) {
canvas.clipRect(rect);
}
if (flipHorizontally) {
final double dx = -(rect.left + rect.width / 2.0);
canvas.translate(-dx, 0.0);
canvas.scale(-1.0, 1.0);
canvas.translate(dx, 0.0);
}
if (centerSlice == null) {
final Rect sourceRect = alignment.inscribe(
sourceSize, Offset.zero & inputSize,
);
if (repeat == ImageRepeat.noRepeat) {
canvas.drawImageRect(image, sourceRect, destinationRect, paint);
} else {
for (final Rect tileRect in _generateImageTileRects(rect, destinationRect, repeat)) {
canvas.drawImageRect(image, sourceRect, tileRect, paint);
}
}
} else {
canvas.scale(1 / scale);
if (repeat == ImageRepeat.noRepeat) {
canvas.drawImageNine(image, _scaleRect(centerSlice, scale), _scaleRect(destinationRect, scale), paint);
} else {
for (final Rect tileRect in _generateImageTileRects(rect, destinationRect, repeat)) {
canvas.drawImageNine(image, _scaleRect(centerSlice, scale), _scaleRect(tileRect, scale), paint);
}
}
}
if (needSave) {
canvas.restore();
}
if (invertedCanvas) {
canvas.restore();
}
}
Iterable<Rect> _generateImageTileRects(Rect outputRect, Rect fundamentalRect, ImageRepeat repeat) {
int startX = 0;
int startY = 0;
int stopX = 0;
int stopY = 0;
final double strideX = fundamentalRect.width;
final double strideY = fundamentalRect.height;
if (repeat == ImageRepeat.repeat || repeat == ImageRepeat.repeatX) {
startX = ((outputRect.left - fundamentalRect.left) / strideX).floor();
stopX = ((outputRect.right - fundamentalRect.right) / strideX).ceil();
}
if (repeat == ImageRepeat.repeat || repeat == ImageRepeat.repeatY) {
startY = ((outputRect.top - fundamentalRect.top) / strideY).floor();
stopY = ((outputRect.bottom - fundamentalRect.bottom) / strideY).ceil();
}
return <Rect>[
for (int i = startX; i <= stopX; ++i)
for (int j = startY; j <= stopY; ++j)
fundamentalRect.shift(Offset(i * strideX, j * strideY)),
];
}
Rect _scaleRect(Rect rect, double scale) => Rect.fromLTRB(rect.left * scale, rect.top * scale, rect.right * scale, rect.bottom * scale);
// Implements DecorationImage.lerp when the image is different.
//
// This class just paints both decorations on top of each other, blended together.
//
// The Decoration properties are faked by just forwarded to the target image.
class _BlendedDecorationImage implements DecorationImage {
const _BlendedDecorationImage(this.a, this.b, this.t) : assert(a != null || b != null);
final DecorationImage? a;
final DecorationImage? b;
final double t;
@override
ImageProvider get image => b?.image ?? a!.image;
@override
ImageErrorListener? get onError => b?.onError ?? a!.onError;
@override
ColorFilter? get colorFilter => b?.colorFilter ?? a!.colorFilter;
@override
BoxFit? get fit => b?.fit ?? a!.fit;
@override
AlignmentGeometry get alignment => b?.alignment ?? a!.alignment;
@override
Rect? get centerSlice => b?.centerSlice ?? a!.centerSlice;
@override
ImageRepeat get repeat => b?.repeat ?? a!.repeat;
@override
bool get matchTextDirection => b?.matchTextDirection ?? a!.matchTextDirection;
@override
double get scale => b?.scale ?? a!.scale;
@override
double get opacity => b?.opacity ?? a!.opacity;
@override
FilterQuality get filterQuality => b?.filterQuality ?? a!.filterQuality;
@override
bool get invertColors => b?.invertColors ?? a!.invertColors;
@override
bool get isAntiAlias => b?.isAntiAlias ?? a!.isAntiAlias;
@override
DecorationImagePainter createPainter(VoidCallback onChanged) {
return _BlendedDecorationImagePainter._(
a?.createPainter(onChanged),
b?.createPainter(onChanged),
t,
);
}
@override
bool operator ==(Object other) {
if (identical(this, other)) {
return true;
}
if (other.runtimeType != runtimeType) {
return false;
}
return other is _BlendedDecorationImage
&& other.a == a
&& other.b == b
&& other.t == t;
}
@override
int get hashCode => Object.hash(a, b, t);
@override
String toString() {
return '${objectRuntimeType(this, '_BlendedDecorationImage')}($a, $b, $t)';
}
}
class _BlendedDecorationImagePainter implements DecorationImagePainter {
_BlendedDecorationImagePainter._(this.a, this.b, this.t) {
// TODO(polina-c): stop duplicating code across disposables
// https://github.com/flutter/flutter/issues/137435
if (kFlutterMemoryAllocationsEnabled) {
FlutterMemoryAllocations.instance.dispatchObjectCreated(
library: 'package:flutter/painting.dart',
className: '$_BlendedDecorationImagePainter',
object: this,
);
}
}
final DecorationImagePainter? a;
final DecorationImagePainter? b;
final double t;
@override
void paint(Canvas canvas, Rect rect, Path? clipPath, ImageConfiguration configuration, { double blend = 1.0, BlendMode blendMode = BlendMode.srcOver }) {
canvas.saveLayer(null, Paint());
a?.paint(canvas, rect, clipPath, configuration, blend: blend * (1.0 - t), blendMode: blendMode);
b?.paint(canvas, rect, clipPath, configuration, blend: blend * t, blendMode: a != null ? BlendMode.plus : blendMode);
canvas.restore();
}
@override
void dispose() {
if (kFlutterMemoryAllocationsEnabled) {
FlutterMemoryAllocations.instance.dispatchObjectDisposed(object: this);
}
a?.dispose();
b?.dispose();
}
@override
String toString() {
return '${objectRuntimeType(this, '_BlendedDecorationImagePainter')}($a, $b, $t)';
}
}