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// 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:typed_data';
import 'dart:ui' as ui;
import 'package:flutter/widgets.dart';
import 'package:flutter/rendering.dart';
import 'package:flutter/services.dart';
import 'package:test_api/src/frontend/async_matcher.dart'; // ignore: implementation_imports
// ignore: deprecated_member_use
import 'package:test_api/test_api.dart' hide TypeMatcher, isInstanceOf;
import 'binding.dart';
import 'finders.dart';
import 'goldens.dart';
/// Render the closest [RepaintBoundary] of the [element] into an image.
/// See also:
/// * [OffsetLayer.toImage] which is the actual method being called.
Future<ui.Image> captureImage(Element element) {
assert(element.renderObject != null);
RenderObject renderObject = element.renderObject!;
while (!renderObject.isRepaintBoundary) {
renderObject = renderObject.parent! as RenderObject;
final OffsetLayer layer = renderObject.debugLayer! as OffsetLayer;
return layer.toImage(renderObject.paintBounds);
/// The matcher created by [matchesGoldenFile]. This class is enabled when the
/// test is running on a VM using conditional import.
class MatchesGoldenFile extends AsyncMatcher {
/// Creates an instance of [MatchesGoldenFile]. Called by [matchesGoldenFile].
const MatchesGoldenFile(this.key, this.version);
/// Creates an instance of [MatchesGoldenFile]. Called by [matchesGoldenFile].
MatchesGoldenFile.forStringPath(String path, this.version) : key = Uri.parse(path);
/// The [key] to the golden image.
final Uri key;
/// The [version] of the golden image.
final int? version;
Future<String?> matchAsync(dynamic item) async {
Future<ui.Image?> imageFuture;
if (item is Future<ui.Image?>) {
imageFuture = item;
} else if (item is ui.Image) {
imageFuture = Future<ui.Image>.value(item);
} else if (item is Finder) {
final Iterable<Element> elements = item.evaluate();
if (elements.isEmpty) {
return 'could not be rendered because no widget was found';
} else if (elements.length > 1) {
return 'matched too many widgets';
imageFuture = captureImage(elements.single);
} else {
throw 'must provide a Finder, Image, or Future<Image>';
final Uri testNameUri = goldenFileComparator.getTestUri(key, version);
final TestWidgetsFlutterBinding binding = TestWidgetsFlutterBinding.ensureInitialized() as TestWidgetsFlutterBinding;
return binding.runAsync<String?>(() async {
final ui.Image? image = await imageFuture;
if (image == null) {
throw 'Future<Image> completed to null';
final ByteData? bytes = await image.toByteData(format: ui.ImageByteFormat.png);
if (bytes == null)
return 'could not encode screenshot.';
if (autoUpdateGoldenFiles) {
await goldenFileComparator.update(testNameUri, bytes.buffer.asUint8List());
return null;
try {
final bool success = await, testNameUri);
return success ? null : 'does not match';
} on TestFailure catch (ex) {
return ex.message;
}, additionalTime: const Duration(minutes: 1));
Description describe(Description description) {
final Uri testNameUri = goldenFileComparator.getTestUri(key, version);
return description.add('one widget whose rasterized image matches golden image "$testNameUri"');