107 lines
3.3 KiB
Dart
107 lines
3.3 KiB
Dart
import 'dart:async';
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import 'dart:math';
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import 'dart:ui' as ui;
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import 'package:aves/services/common/services.dart';
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import 'package:equatable/equatable.dart';
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import 'package:flutter/foundation.dart';
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import 'package:flutter/widgets.dart';
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class RegionProvider extends ImageProvider<RegionProviderKey> {
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final RegionProviderKey key;
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RegionProvider(this.key);
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@override
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Future<RegionProviderKey> obtainKey(ImageConfiguration configuration) {
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return SynchronousFuture<RegionProviderKey>(key);
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}
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@override
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ImageStreamCompleter loadImage(RegionProviderKey key, ImageDecoderCallback decode) {
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return MultiFrameImageStreamCompleter(
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codec: _loadAsync(key, decode),
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scale: 1.0,
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informationCollector: () sync* {
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yield ErrorDescription('uri=${key.uri}, pageId=${key.pageId}, mimeType=${key.mimeType}, region=${key.region}');
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},
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);
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}
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Future<ui.Codec> _loadAsync(RegionProviderKey key, ImageDecoderCallback decode) async {
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final uri = key.uri;
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final mimeType = key.mimeType;
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final pageId = key.pageId;
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try {
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final bytes = await mediaFetchService.getRegion(
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uri,
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mimeType,
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key.rotationDegrees,
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key.isFlipped,
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key.sampleSize,
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key.region,
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key.imageSize,
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pageId: pageId,
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sizeBytes: key.sizeBytes,
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taskKey: key,
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);
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if (bytes.isEmpty) {
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throw StateError('$uri ($mimeType) region loading failed');
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}
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final trailerOffset = bytes.length - 4 * 2;
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final trailer = ByteData.sublistView(bytes, trailerOffset);
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final bitmapWidth = trailer.getUint32(0);
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final bitmapHeight = trailer.getUint32(4);
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final buffer = await ui.ImmutableBuffer.fromUint8List(bytes);
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final descriptor = ui.ImageDescriptor.raw(
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buffer,
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width: bitmapWidth,
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height: bitmapHeight,
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pixelFormat: ui.PixelFormat.rgba8888,
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);
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return descriptor.instantiateCodec();
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} catch (error) {
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// loading may fail if the provided MIME type is incorrect (e.g. the Media Store may report a JPEG as a TIFF)
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debugPrint('$runtimeType _loadAsync failed with mimeType=$mimeType, uri=$uri, error=$error');
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throw StateError('$mimeType region decoding failed (page $pageId)');
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}
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}
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@override
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void resolveStreamForKey(ImageConfiguration configuration, ImageStream stream, RegionProviderKey key, ImageErrorListener handleError) {
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mediaFetchService.resumeLoading(key);
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super.resolveStreamForKey(configuration, stream, key, handleError);
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}
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void pause() => mediaFetchService.cancelRegion(key);
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}
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@immutable
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class RegionProviderKey extends Equatable {
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// do not store the entry as it is, because the key should be constant
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// but the entry attributes may change over time
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final String uri, mimeType;
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final int? pageId, sizeBytes;
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final int rotationDegrees, sampleSize;
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final bool isFlipped;
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final Rectangle<int> region;
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final Size imageSize;
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@override
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List<Object?> get props => [uri, pageId, rotationDegrees, isFlipped, sampleSize, region, imageSize];
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const RegionProviderKey({
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required this.uri,
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required this.mimeType,
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required this.pageId,
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required this.sizeBytes,
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required this.rotationDegrees,
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required this.isFlipped,
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required this.sampleSize,
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required this.region,
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required this.imageSize,
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});
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}
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