61 lines
2.0 KiB
Dart
61 lines
2.0 KiB
Dart
// Copyright 2014 The Flutter 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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import 'dart:async';
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import 'dart:typed_data';
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import 'dart:ui' as ui;
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import 'test_async_utils.dart';
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final Map<int, ui.Image> _cache = <int, ui.Image>{};
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/// Creates an arbitrarily sized image for testing.
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///
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/// If the [cache] parameter is set to true, the image will be cached for the
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/// rest of this suite. This is normally desirable, assuming a test suite uses
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/// images with the same dimensions in most tests, as it will save on memory
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/// usage and CPU time over the course of the suite. However, it should be
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/// avoided for images that are used only once in a test suite, especially if
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/// the image is large, as it will require holding on to the memory for that
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/// image for the duration of the suite.
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///
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/// This method requires real async work, and will not work properly in the
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/// [FakeAsync] zones set up by [testWidgets]. Typically, it should be invoked
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/// as a setup step before [testWidgets] are run, such as [setUp] or [setUpAll].
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/// If needed, it can be invoked using [WidgetTester.runAsync].
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Future<ui.Image> createTestImage({
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int width = 1,
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int height = 1,
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bool cache = true,
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}) => TestAsyncUtils.guard(() async {
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assert(width != null && width > 0);
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assert(height != null && height > 0);
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assert(cache != null);
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final int cacheKey = Object.hash(width, height);
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if (cache && _cache.containsKey(cacheKey)) {
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return _cache[cacheKey]!.clone();
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}
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final ui.Image image = await _createImage(width, height);
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if (cache) {
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_cache[cacheKey] = image.clone();
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}
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return image;
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});
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Future<ui.Image> _createImage(int width, int height) async {
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final Completer<ui.Image> completer = Completer<ui.Image>();
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ui.decodeImageFromPixels(
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Uint8List.fromList(List<int>.filled(width * height * 4, 0)),
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width,
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height,
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ui.PixelFormat.rgba8888,
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(ui.Image image) {
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completer.complete(image);
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},
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);
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return completer.future;
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}
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