39be1c3747
Image listeners installed in paint handlers need to know whether the listener is being called during the paint. Fixes https://github.com/flutter/flutter/issues/4937
42 lines
1.4 KiB
Dart
42 lines
1.4 KiB
Dart
// Copyright 2015 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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part of flutter_sprites;
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/// The ImageMap is a helper class for loading and keeping references to
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/// multiple images.
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class ImageMap {
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/// Creates a new ImageMap where images will be loaded from the specified
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/// [bundle].
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ImageMap(AssetBundle bundle) : _bundle = bundle;
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final AssetBundle _bundle;
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final Map<String, ui.Image> _images = new Map<String, ui.Image>();
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/// Loads a list of images given their urls.
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Future<List<ui.Image>> load(List<String> urls) {
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return Future.wait(urls.map(_loadImage));
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}
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Future<ui.Image> _loadImage(String url) async {
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ImageStream stream = new AssetImage(url, bundle: _bundle).resolve(ImageConfiguration.empty);
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Completer<ui.Image> completer = new Completer<ui.Image>();
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void listener(ImageInfo frame, bool synchronousCall) {
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final ui.Image image = frame.image;
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_images[url] = image;
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completer.complete(image);
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stream.removeListener(listener);
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}
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stream.addListener(listener);
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return completer.future;
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}
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/// Returns a preloaded image, given its [url].
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ui.Image getImage(String url) => _images[url];
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/// Returns a preloaded image, given its [url].
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ui.Image operator [](String url) => _images[url];
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}
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