107 lines
3.4 KiB
Dart
107 lines
3.4 KiB
Dart
import 'dart:ui' as ui show Codec;
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import 'package:aves/services/image_file_service.dart';
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import 'package:flutter/foundation.dart';
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import 'package:flutter/material.dart';
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class ThumbnailProvider extends ImageProvider<ThumbnailProviderKey> {
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ThumbnailProvider({
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@required this.uri,
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@required this.mimeType,
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@required this.rotationDegrees,
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this.extent = 0,
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this.scale = 1,
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}) : assert(uri != null),
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assert(mimeType != null),
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assert(rotationDegrees != null),
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assert(extent != null),
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assert(scale != null) {
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_cancellationKey = _buildKey(ImageConfiguration.empty);
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}
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final String uri;
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final String mimeType;
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final int rotationDegrees;
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final double extent;
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final double scale;
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Object _cancellationKey;
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@override
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Future<ThumbnailProviderKey> obtainKey(ImageConfiguration configuration) {
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// configuration can be empty (e.g. when obtaining key for eviction)
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// so we do not compute the target width/height here
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// and pass it to the key, to use it later for image loading
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return SynchronousFuture<ThumbnailProviderKey>(_buildKey(configuration));
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}
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ThumbnailProviderKey _buildKey(ImageConfiguration configuration) => ThumbnailProviderKey(
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uri: uri,
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mimeType: mimeType,
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rotationDegrees: rotationDegrees,
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extent: extent,
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scale: scale,
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);
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@override
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ImageStreamCompleter load(ThumbnailProviderKey key, DecoderCallback decode) {
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return MultiFrameImageStreamCompleter(
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codec: _loadAsync(key, decode),
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scale: key.scale,
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informationCollector: () sync* {
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yield ErrorDescription('uri=$uri, extent=$extent');
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},
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);
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}
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Future<ui.Codec> _loadAsync(ThumbnailProviderKey key, DecoderCallback decode) async {
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try {
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final bytes = await ImageFileService.getThumbnail(key.uri, key.mimeType, key.rotationDegrees, extent, extent, taskKey: _cancellationKey);
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if (bytes == null) {
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throw StateError('$uri ($mimeType) loading failed');
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}
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return await decode(bytes);
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} catch (error) {
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debugPrint('$runtimeType _loadAsync failed with uri=$uri, error=$error');
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throw StateError('$mimeType decoding failed');
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}
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}
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@override
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void resolveStreamForKey(ImageConfiguration configuration, ImageStream stream, ThumbnailProviderKey key, ImageErrorListener handleError) {
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ImageFileService.resumeThumbnail(_cancellationKey);
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super.resolveStreamForKey(configuration, stream, key, handleError);
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}
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void pause() => ImageFileService.cancelThumbnail(_cancellationKey);
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}
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class ThumbnailProviderKey {
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final String uri;
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final String mimeType;
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final int rotationDegrees;
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final double extent;
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final double scale;
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ThumbnailProviderKey({
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@required this.uri,
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@required this.mimeType,
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@required this.rotationDegrees,
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@required this.extent,
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this.scale,
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});
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@override
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bool operator ==(Object other) {
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if (other.runtimeType != runtimeType) return false;
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return other is ThumbnailProviderKey && other.uri == uri && other.mimeType == mimeType && other.rotationDegrees == rotationDegrees && other.extent == extent && other.scale == scale;
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}
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@override
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int get hashCode => hashValues(uri, mimeType, rotationDegrees, extent, scale);
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@override
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String toString() {
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return 'ThumbnailProviderKey{uri=$uri, mimeType=$mimeType, rotationDegrees=$rotationDegrees, extent=$extent, scale=$scale}';
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}
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}
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