Migrates to null safety (#22)
diff --git a/packages/flutter_image/CHANGELOG.md b/packages/flutter_image/CHANGELOG.md
index cfb10e5..6d9ac91 100644
--- a/packages/flutter_image/CHANGELOG.md
+++ b/packages/flutter_image/CHANGELOG.md
@@ -1,5 +1,10 @@
# Changelog
+## 4.0.0
+
+- Migrates to null safety
+- **Breaking change**: `NetworkImageWithRetry.load` now throws a `FetchFailure` if the fetched image data is zero bytes.
+
## 3.0.0
* **Breaking change**. Updates for Flutter 1.10.15.
diff --git a/packages/flutter_image/lib/network.dart b/packages/flutter_image/lib/network.dart
index 3f91fcb..41db7c3 100644
--- a/packages/flutter_image/lib/network.dart
+++ b/packages/flutter_image/lib/network.dart
@@ -29,10 +29,11 @@
/// Creates an object that fetches the image at the given [url].
///
/// The arguments must not be null.
- const NetworkImageWithRetry(this.url, { this.scale = 1.0, this.fetchStrategy = defaultFetchStrategy })
- : assert(url != null),
- assert(scale != null),
- assert(fetchStrategy != null);
+ const NetworkImageWithRetry(
+ this.url, {
+ this.scale = 1.0,
+ this.fetchStrategy = defaultFetchStrategy,
+ });
/// The HTTP client used to download images.
static final io.HttpClient _client = io.HttpClient();
@@ -57,10 +58,12 @@
/// This indirection is necessary because [defaultFetchStrategy] is used as
/// the default constructor argument value, which requires that it be a const
/// expression.
- static final FetchStrategy _defaultFetchStrategyFunction = const FetchStrategyBuilder().build();
+ static final FetchStrategy _defaultFetchStrategyFunction =
+ const FetchStrategyBuilder().build();
/// The [FetchStrategy] that [NetworkImageWithRetry] uses by default.
- static Future<FetchInstructions> defaultFetchStrategy(Uri uri, FetchFailure failure) {
+ static Future<FetchInstructions> defaultFetchStrategy(
+ Uri uri, FetchFailure? failure) {
return _defaultFetchStrategyFunction(uri, failure);
}
@@ -71,37 +74,34 @@
@override
ImageStreamCompleter load(NetworkImageWithRetry key, DecoderCallback decode) {
- return OneFrameImageStreamCompleter(
- _loadWithRetry(key, decode),
+ return OneFrameImageStreamCompleter(_loadWithRetry(key, decode),
informationCollector: () sync* {
- yield ErrorDescription('Image provider: $this');
- yield ErrorDescription('Image key: $key');
- }
- );
+ yield ErrorDescription('Image provider: $this');
+ yield ErrorDescription('Image key: $key');
+ });
}
- void _debugCheckInstructions(FetchInstructions instructions) {
+ void _debugCheckInstructions(FetchInstructions? instructions) {
assert(() {
if (instructions == null) {
if (fetchStrategy == defaultFetchStrategy) {
throw StateError(
- 'The default FetchStrategy returned null FetchInstructions. This\n'
- 'is likely a bug in $runtimeType. Please file a bug at\n'
- 'https://github.com/flutter/flutter/issues.'
- );
+ 'The default FetchStrategy returned null FetchInstructions. This\n'
+ 'is likely a bug in $runtimeType. Please file a bug at\n'
+ 'https://github.com/flutter/flutter/issues.');
} else {
throw StateError(
- 'The custom FetchStrategy used to fetch $url returned null\n'
- 'FetchInstructions. FetchInstructions must never be null, but\n'
- 'instead instruct to either make another fetch attempt or give up.'
- );
+ 'The custom FetchStrategy used to fetch $url returned null\n'
+ 'FetchInstructions. FetchInstructions must never be null, but\n'
+ 'instead instruct to either make another fetch attempt or give up.');
}
}
return true;
}());
}
- Future<ImageInfo> _loadWithRetry(NetworkImageWithRetry key, DecoderCallback decode) async {
+ Future<ImageInfo> _loadWithRetry(
+ NetworkImageWithRetry key, DecoderCallback decode) async {
assert(key == this);
final Stopwatch stopwatch = Stopwatch()..start();
@@ -109,16 +109,19 @@
FetchInstructions instructions = await fetchStrategy(resolved, null);
_debugCheckInstructions(instructions);
int attemptCount = 0;
- FetchFailure lastFailure;
+ FetchFailure? lastFailure;
while (!instructions.shouldGiveUp) {
attemptCount += 1;
- io.HttpClientRequest request;
+ io.HttpClientRequest? request;
try {
- request = await _client.getUrl(instructions.uri).timeout(instructions.timeout);
- final io.HttpClientResponse response = await request.close().timeout(instructions.timeout);
+ request = await _client
+ .getUrl(instructions.uri)
+ .timeout(instructions.timeout);
+ final io.HttpClientResponse response =
+ await request.close().timeout(instructions.timeout);
- if (response == null || response.statusCode != 200) {
+ if (response.statusCode != 200) {
throw FetchFailure._(
totalDuration: stopwatch.elapsed,
attemptCount: attemptCount,
@@ -126,21 +129,25 @@
);
}
- final _Uint8ListBuilder builder = await response.fold(
- _Uint8ListBuilder(),
+ final _Uint8ListBuilder builder = await response
+ .fold(
+ _Uint8ListBuilder(),
(_Uint8ListBuilder buffer, List<int> bytes) => buffer..add(bytes),
- ).timeout(instructions.timeout);
+ )
+ .timeout(instructions.timeout);
final Uint8List bytes = builder.data;
- if (bytes.lengthInBytes == 0)
- return null;
+ if (bytes.lengthInBytes == 0) {
+ throw FetchFailure._(
+ totalDuration: stopwatch.elapsed,
+ attemptCount: attemptCount,
+ httpStatusCode: response.statusCode,
+ );
+ }
final ui.Codec codec = await decode(bytes);
final ui.Image image = (await codec.getNextFrame()).image;
- if (image == null)
- return null;
-
return ImageInfo(
image: image,
scale: key.scale,
@@ -159,27 +166,31 @@
}
}
- if (instructions.alternativeImage != null)
- return instructions.alternativeImage;
+ if (instructions.alternativeImage != null) {
+ return instructions.alternativeImage!;
+ }
assert(lastFailure != null);
- FlutterError.onError(FlutterErrorDetails(
- exception: lastFailure,
- library: 'package:flutter_image',
- context: ErrorDescription('$runtimeType failed to load ${instructions.uri}'),
- ));
+ if (FlutterError.onError != null) {
+ FlutterError.onError!(FlutterErrorDetails(
+ exception: lastFailure!,
+ library: 'package:flutter_image',
+ context:
+ ErrorDescription('$runtimeType failed to load ${instructions.uri}'),
+ ));
+ }
- return null;
+ throw lastFailure!;
}
@override
bool operator ==(dynamic other) {
- if (other.runtimeType != runtimeType)
+ if (other.runtimeType != runtimeType) {
return false;
+ }
final NetworkImageWithRetry typedOther = other;
- return url == typedOther.url
- && scale == typedOther.scale;
+ return url == typedOther.url && scale == typedOther.scale;
}
@override
@@ -207,26 +218,26 @@
/// [NetworkImageWithRetry] to try again.
///
/// See [NetworkImageWithRetry.defaultFetchStrategy] for an example.
-typedef FetchStrategy = Future<FetchInstructions> Function(Uri uri, FetchFailure failure);
+typedef FetchStrategy = Future<FetchInstructions> Function(
+ Uri uri, FetchFailure? failure);
/// Instructions [NetworkImageWithRetry] uses to fetch the image.
@immutable
class FetchInstructions {
/// Instructs [NetworkImageWithRetry] to give up trying to download the image.
const FetchInstructions.giveUp({
- @required this.uri,
+ required this.uri,
this.alternativeImage,
- })
- : shouldGiveUp = true,
- timeout = null;
+ }) : shouldGiveUp = true,
+ timeout = Duration.zero;
/// Instructs [NetworkImageWithRetry] to attempt to download the image from
/// the given [uri] and [timeout] if it takes too long.
const FetchInstructions.attempt({
- @required this.uri,
- @required this.timeout,
- }) : shouldGiveUp = false,
- alternativeImage = null;
+ required this.uri,
+ required this.timeout,
+ }) : shouldGiveUp = false,
+ alternativeImage = null;
/// Instructs to give up trying.
///
@@ -241,16 +252,16 @@
final Uri uri;
/// Instructs to give up and use this image instead.
- final Future<ImageInfo> alternativeImage;
+ final Future<ImageInfo>? alternativeImage;
@override
String toString() {
return '$runtimeType(\n'
- ' shouldGiveUp: $shouldGiveUp\n'
- ' timeout: $timeout\n'
- ' uri: $uri\n'
- ' alternativeImage?: ${alternativeImage != null ? 'yes' : 'no'}\n'
- ')';
+ ' shouldGiveUp: $shouldGiveUp\n'
+ ' timeout: $timeout\n'
+ ' uri: $uri\n'
+ ' alternativeImage?: ${alternativeImage != null ? 'yes' : 'no'}\n'
+ ')';
}
}
@@ -258,12 +269,11 @@
@immutable
class FetchFailure implements Exception {
const FetchFailure._({
- @required this.totalDuration,
- @required this.attemptCount,
+ required this.totalDuration,
+ required this.attemptCount,
this.httpStatusCode,
this.originalException,
- }) : assert(totalDuration != null),
- assert(attemptCount > 0);
+ }) : assert(attemptCount > 0);
/// The total amount of time it has taken so far to download the image.
final Duration totalDuration;
@@ -276,7 +286,7 @@
final int attemptCount;
/// HTTP status code, such as 500.
- final int httpStatusCode;
+ final int? httpStatusCode;
/// The exception that caused the fetch failure.
final dynamic originalException;
@@ -294,7 +304,7 @@
/// An indefinitely growing builder of a [Uint8List].
class _Uint8ListBuilder {
- static const int _kInitialSize = 100000; // 100KB-ish
+ static const int _kInitialSize = 100000; // 100KB-ish
int _usedLength = 0;
Uint8List _buffer = Uint8List(_kInitialSize);
@@ -344,20 +354,16 @@
this.maxAttempts = 5,
this.initialPauseBetweenRetries = const Duration(seconds: 1),
this.exponentialBackoffMultiplier = 2,
- this.transientHttpStatusCodePredicate = defaultTransientHttpStatusCodePredicate,
- }) : assert(timeout != null),
- assert(totalFetchTimeout != null),
- assert(maxAttempts != null),
- assert(initialPauseBetweenRetries != null),
- assert(exponentialBackoffMultiplier != null),
- assert(transientHttpStatusCodePredicate != null);
+ this.transientHttpStatusCodePredicate =
+ defaultTransientHttpStatusCodePredicate,
+ });
/// A list of HTTP status codes that can generally be retried.
///
/// You may want to use a different list depending on the needs of your
/// application.
static const List<int> defaultTransientHttpStatusCodes = <int>[
- 0, // Network error
+ 0, // Network error
408, // Request timeout
500, // Internal server error
502, // Bad gateway
@@ -395,7 +401,7 @@
/// Builds a [FetchStrategy] that operates using the properties of this
/// builder.
FetchStrategy build() {
- return (Uri uri, FetchFailure failure) async {
+ return (Uri uri, FetchFailure? failure) async {
if (failure == null) {
// First attempt. Just load.
return FetchInstructions.attempt(
@@ -404,18 +410,21 @@
);
}
- final bool isRetriableFailure = transientHttpStatusCodePredicate(failure.httpStatusCode) ||
+ final bool isRetriableFailure = (failure.httpStatusCode != null &&
+ transientHttpStatusCodePredicate(failure.httpStatusCode!)) ||
failure.originalException is io.SocketException;
// If cannot retry, give up.
- if (!isRetriableFailure || // retrying will not help
- failure.totalDuration > totalFetchTimeout || // taking too long
- failure.attemptCount > maxAttempts) { // too many attempts
+ if (!isRetriableFailure || // retrying will not help
+ failure.totalDuration > totalFetchTimeout || // taking too long
+ failure.attemptCount > maxAttempts) {
+ // too many attempts
return FetchInstructions.giveUp(uri: uri);
}
// Exponential back-off.
- final Duration pauseBetweenRetries = initialPauseBetweenRetries * math.pow(exponentialBackoffMultiplier, failure.attemptCount - 1);
+ final Duration pauseBetweenRetries = initialPauseBetweenRetries *
+ math.pow(exponentialBackoffMultiplier, failure.attemptCount - 1);
await Future<void>.delayed(pauseBetweenRetries);
// Retry.
diff --git a/packages/flutter_image/pubspec.yaml b/packages/flutter_image/pubspec.yaml
index f930dee..399114c 100644
--- a/packages/flutter_image/pubspec.yaml
+++ b/packages/flutter_image/pubspec.yaml
@@ -1,5 +1,5 @@
name: flutter_image
-version: 3.0.0
+version: 4.0.0
description: >
Image utilities for Flutter: providers, effects, etc
author: Flutter Team <flutter-dev@googlegroups.com>
@@ -12,9 +12,9 @@
dev_dependencies:
flutter_test:
sdk: flutter
- quiver: '>=0.24.0 <3.0.0'
+ quiver: ^3.0.0
test: any
environment:
- sdk: ">=2.0.0-dev.28.0 <3.0.0"
+ sdk: ">=2.12.0 <3.0.0"
flutter: ">=1.10.15-pre.144"
diff --git a/packages/flutter_image/test/network_test.dart b/packages/flutter_image/test/network_test.dart
index d9dd426..4652ac3 100644
--- a/packages/flutter_image/test/network_test.dart
+++ b/packages/flutter_image/test/network_test.dart
@@ -19,122 +19,134 @@
HttpOverrides.global = null;
group('NetworkImageWithRetry', () {
- setUp(() {
- FlutterError.onError = (FlutterErrorDetails error) {
- fail('$error');
- };
+ group('succeeds', () {
+ setUp(() {
+ FlutterError.onError = (FlutterErrorDetails error) {
+ fail('$error');
+ };
+ });
+
+ tearDown(() {
+ FlutterError.onError = FlutterError.dumpErrorToConsole;
+ });
+
+ test('loads image from network', () async {
+ final NetworkImageWithRetry subject = NetworkImageWithRetry(
+ _imageUrl('immediate_success.png'),
+ );
+
+ assertThatImageLoadingSucceeds(subject);
+ });
+
+ test('succeeds on successful retry', () async {
+ final NetworkImageWithRetry subject = NetworkImageWithRetry(
+ _imageUrl('error.png'),
+ fetchStrategy: (Uri uri, FetchFailure? failure) async {
+ if (failure == null) {
+ return FetchInstructions.attempt(
+ uri: uri,
+ timeout: const Duration(minutes: 1),
+ );
+ } else {
+ expect(failure.attemptCount, lessThan(2));
+ return FetchInstructions.attempt(
+ uri: Uri.parse(_imageUrl('immediate_success.png')),
+ timeout: const Duration(minutes: 1),
+ );
+ }
+ },
+ );
+ assertThatImageLoadingSucceeds(subject);
+ });
});
- tearDown(() {
- FlutterError.onError = FlutterError.dumpErrorToConsole;
- });
-
- test('loads image from network', () async {
- final NetworkImageWithRetry subject = NetworkImageWithRetry(
- _imageUrl('immediate_success.png'),
- );
-
- subject.load(subject, PaintingBinding.instance.instantiateImageCodec).addListener(
- ImageStreamListener(expectAsync2((ImageInfo image, bool synchronousCall) {
- expect(image.image.height, 1);
- expect(image.image.width, 1);
- })),
- );
- });
-
- test('retries 6 times then gives up', () async {
+ group('fails', () {
final List<FlutterErrorDetails> errorLog = <FlutterErrorDetails>[];
- FlutterError.onError = errorLog.add;
+ FakeAsync fakeAsync = FakeAsync();
- final FakeAsync fakeAsync = FakeAsync();
- final dynamic maxAttemptCountReached = expectAsync0(() {});
+ setUp(() {
+ FlutterError.onError = errorLog.add;
+ });
- int attemptCount = 0;
- Future<void> onAttempt() async {
- expect(attemptCount, lessThan(7));
- if (attemptCount == 6) {
- maxAttemptCountReached();
- }
- await Future<void>.delayed(Duration.zero);
- fakeAsync.elapse(const Duration(seconds: 60));
- attemptCount++;
- }
+ tearDown(() {
+ fakeAsync = FakeAsync();
+ errorLog.clear();
+ FlutterError.onError = FlutterError.dumpErrorToConsole;
+ });
- final NetworkImageWithRetry subject = NetworkImageWithRetry(
- _imageUrl('error.png'),
- fetchStrategy: (Uri uri, FetchFailure failure) {
- Timer.run(onAttempt);
- return fakeAsync.run((FakeAsync fakeAsync) {
- return NetworkImageWithRetry.defaultFetchStrategy(uri, failure);
- });
- },
- );
+ test('retries 6 times then gives up', () async {
+ final dynamic maxAttemptCountReached = expectAsync0(() {});
- subject.load(subject, PaintingBinding.instance.instantiateImageCodec).addListener(
- ImageStreamListener(expectAsync2((ImageInfo image, bool synchronousCall) {
- expect(errorLog.single.exception, isInstanceOf<FetchFailure>());
- expect(image, null);
- })),
- );
- });
-
- test('gives up immediately on non-retriable errors (HTTP 404)', () async {
- final List<FlutterErrorDetails> errorLog = <FlutterErrorDetails>[];
- FlutterError.onError = errorLog.add;
-
- final FakeAsync fakeAsync = FakeAsync();
-
- int attemptCount = 0;
- Future<void> onAttempt() async {
- expect(attemptCount, lessThan(2));
- await Future<void>.delayed(Duration.zero);
- fakeAsync.elapse(const Duration(seconds: 60));
- attemptCount++;
- }
-
- final NetworkImageWithRetry subject = NetworkImageWithRetry(
- _imageUrl('does_not_exist.png'),
- fetchStrategy: (Uri uri, FetchFailure failure) {
- Timer.run(onAttempt);
- return fakeAsync.run((FakeAsync fakeAsync) {
- return NetworkImageWithRetry.defaultFetchStrategy(uri, failure);
- });
- },
- );
-
- subject.load(subject, PaintingBinding.instance.instantiateImageCodec).addListener(
- ImageStreamListener(expectAsync2((ImageInfo image, bool synchronousCall) {
- expect(errorLog.single.exception, isInstanceOf<FetchFailure>());
- expect(image, null);
- })),
- );
- });
-
- test('succeeds on successful retry', () async {
- final NetworkImageWithRetry subject = NetworkImageWithRetry(
- _imageUrl('error.png'),
- fetchStrategy: (Uri uri, FetchFailure failure) async {
- if (failure == null) {
- return FetchInstructions.attempt(
- uri: uri,
- timeout: const Duration(minutes: 1),
- );
- } else {
- expect(failure.attemptCount, lessThan(2));
- return FetchInstructions.attempt(
- uri: Uri.parse(_imageUrl('immediate_success.png')),
- timeout: const Duration(minutes: 1),
- );
+ int attemptCount = 0;
+ Future<void> onAttempt() async {
+ expect(attemptCount, lessThan(7));
+ if (attemptCount == 6) {
+ maxAttemptCountReached();
}
- },
- );
+ await Future<void>.delayed(Duration.zero);
+ fakeAsync.elapse(const Duration(seconds: 60));
+ attemptCount++;
+ }
- subject.load(subject, PaintingBinding.instance.instantiateImageCodec).addListener(
- ImageStreamListener(expectAsync2((ImageInfo image, bool synchronousCall) {
- expect(image.image.height, 1);
- expect(image.image.width, 1);
- })),
- );
+ final NetworkImageWithRetry subject = NetworkImageWithRetry(
+ _imageUrl('error.png'),
+ fetchStrategy: (Uri uri, FetchFailure? failure) {
+ Timer.run(onAttempt);
+ return fakeAsync.run((FakeAsync fakeAsync) {
+ return NetworkImageWithRetry.defaultFetchStrategy(uri, failure);
+ });
+ },
+ );
+
+ assertThatImageLoadingFails(subject, errorLog);
+ });
+
+ test('gives up immediately on non-retriable errors (HTTP 404)', () async {
+ int attemptCount = 0;
+ Future<void> onAttempt() async {
+ expect(attemptCount, lessThan(2));
+ await Future<void>.delayed(Duration.zero);
+ fakeAsync.elapse(const Duration(seconds: 60));
+ attemptCount++;
+ }
+
+ final NetworkImageWithRetry subject = NetworkImageWithRetry(
+ _imageUrl('does_not_exist.png'),
+ fetchStrategy: (Uri uri, FetchFailure? failure) {
+ Timer.run(onAttempt);
+ return fakeAsync.run((FakeAsync fakeAsync) {
+ return NetworkImageWithRetry.defaultFetchStrategy(uri, failure);
+ });
+ },
+ );
+
+ assertThatImageLoadingFails(subject, errorLog);
+ });
});
});
}
+
+void assertThatImageLoadingFails(
+ NetworkImageWithRetry subject, List<FlutterErrorDetails> errorLog) {
+ subject
+ .load(subject, PaintingBinding.instance!.instantiateImageCodec)
+ .addListener(ImageStreamListener(
+ (ImageInfo image, bool synchronousCall) {},
+ onError: expectAsync2((Object error, StackTrace? _) {
+ expect(errorLog.single.exception, isInstanceOf<FetchFailure>());
+ expect(error, isInstanceOf<FetchFailure>());
+ expect(error, equals(errorLog.single.exception));
+ }),
+ ));
+}
+
+void assertThatImageLoadingSucceeds(NetworkImageWithRetry subject) {
+ subject
+ .load(subject, PaintingBinding.instance!.instantiateImageCodec)
+ .addListener(
+ ImageStreamListener(expectAsync2((ImageInfo image, bool synchronousCall) {
+ expect(image.image.height, 1);
+ expect(image.image.width, 1);
+ })),
+ );
+}
