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feat: shrink_wrapped_scroll_view (#41)
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148 changes: 148 additions & 0 deletions
148
packages/nilts/lib/src/lints/shrink_wrapped_scroll_view.dart
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,148 @@ | ||
| // ignore_for_file: comment_references | ||
|
|
||
| import 'package:analyzer/dart/ast/ast.dart'; | ||
| import 'package:analyzer/error/error.dart'; | ||
| import 'package:analyzer/error/listener.dart'; | ||
| import 'package:custom_lint_builder/custom_lint_builder.dart'; | ||
| import 'package:nilts/src/change_priority.dart'; | ||
| import 'package:nilts/src/utils/library_element_ext.dart'; | ||
|
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| /// A class for `shrink_wrapped_scroll_view` rule. | ||
| /// | ||
| /// This rule checks if the content of the scroll view is shrink wrapped. | ||
| /// | ||
| /// - Target SDK: Any versions nilts supports | ||
| /// - Rule type: Practice | ||
| /// - Maturity level: Experimental | ||
| /// - Quick fix: ✅ | ||
| /// | ||
| /// **Consider** removing `shrinkWrap` argument and update the Widget not to | ||
| /// shrink wrap. | ||
| /// Shrink wrapping the content of the scroll view is | ||
| /// significantly more expensive than expanding to the maximum allowed size | ||
| /// because the content can expand and contract during scrolling, | ||
| /// which means the size of the scroll view needs to be recomputed | ||
| /// whenever the scroll position changes. | ||
| /// | ||
| /// You can avoid shrink wrap with 3 steps below | ||
| /// in case of your scroll view is nested. | ||
| /// | ||
| /// 1. Replace the parent scroll view with [CustomScrollView]. | ||
| /// 2. Replace the child scroll view with [SliverListView] or [SliverGridView]. | ||
| /// 3. Set [SliverChildBuilderDelegate] to `delegate` argument of | ||
| /// [SliverListView] or [SliverGridView]. | ||
| /// | ||
| /// **BAD:** | ||
| /// ```dart | ||
| /// ListView(shrinkWrap: true) | ||
| /// ``` | ||
| /// | ||
| /// **GOOD:** | ||
| /// ```dart | ||
| /// ListView(shrinkWrap: false) | ||
| /// ``` | ||
| /// | ||
| /// See also: | ||
| /// | ||
| /// - [shrinkWrap property - ScrollView class - widgets library - Dart API](https://api.flutter.dev/flutter/widgets/ScrollView/shrinkWrap.html) | ||
| /// - [ShrinkWrap vs Slivers | Decoding Flutter - YouTube](https://youtu.be/LUqDNnv_dh0) | ||
| class ShrinkWrappedScrollView extends DartLintRule { | ||
| /// Create a new instance of [ShrinkWrappedScrollView]. | ||
| const ShrinkWrappedScrollView() : super(code: _code); | ||
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| static const _code = LintCode( | ||
| name: 'shrink_wrapped_scroll_view', | ||
| problemMessage: 'Shrink wrapping the content of the scroll view is ' | ||
| 'significantly more expensive than ' | ||
| 'expanding to the maximum allowed size.', | ||
| url: 'https://github.com/ronnnnn/nilts#shrink_wrapped_scroll_view', | ||
| ); | ||
|
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||
| @override | ||
| void run( | ||
| CustomLintResolver resolver, | ||
| ErrorReporter reporter, | ||
| CustomLintContext context, | ||
| ) { | ||
| context.registry.addInstanceCreationExpression((node) { | ||
| // Do nothing if the package of constructor is not `flutter`. | ||
| final constructorName = node.constructorName; | ||
| final library = constructorName.staticElement?.library; | ||
| if (library == null) return; | ||
| if (!library.isFlutter) return; | ||
|
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| // Do nothing if the constructor is not sub class of `ScrollView`. | ||
| if (!_scrollViewSubClasses.contains(constructorName.type.element?.name)) { | ||
| return; | ||
| } | ||
|
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| // Do nothing if the constructor doesn't have `shrinkWrap` argument. | ||
| final arguments = node.argumentList.arguments; | ||
| final isShrinkWrapSet = arguments.any( | ||
| (argument) => | ||
| argument is NamedExpression && | ||
| argument.name.label.name == 'shrinkWrap', | ||
| ); | ||
| if (!isShrinkWrapSet) return; | ||
|
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| // Do nothing if `shrinkWrap: true` is not set. | ||
| final isShrinkWrapped = arguments.any( | ||
| (argument) => | ||
| argument is NamedExpression && | ||
| argument.name.label.name == 'shrinkWrap' && | ||
| argument.expression is BooleanLiteral && | ||
| (argument.expression as BooleanLiteral).value, | ||
| ); | ||
| if (!isShrinkWrapped) return; | ||
|
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| reporter.reportErrorForNode(_code, node); | ||
| }); | ||
| } | ||
|
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| @override | ||
| List<Fix> getFixes() => [ | ||
| _RemoveShrinkWrapArgument(), | ||
| ]; | ||
| } | ||
|
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| class _RemoveShrinkWrapArgument extends DartFix { | ||
| @override | ||
| void run( | ||
| CustomLintResolver resolver, | ||
| ChangeReporter reporter, | ||
| CustomLintContext context, | ||
| AnalysisError analysisError, | ||
| List<AnalysisError> others, | ||
| ) { | ||
| context.registry.addInstanceCreationExpression((node) { | ||
| if (!node.sourceRange.intersects(analysisError.sourceRange)) return; | ||
|
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| // Do nothing if the constructor is not sub class of `ScrollView`. | ||
| final constructorName = node.constructorName; | ||
| if (!_scrollViewSubClasses.contains(constructorName.type.element?.name)) { | ||
| return; | ||
| } | ||
|
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| reporter | ||
| .createChangeBuilder( | ||
| message: 'Remove shrinkWrap', | ||
| priority: ChangePriority.removeShrinkWrap, | ||
| ) | ||
| .addDartFileEdit((builder) { | ||
| final arguments = node.argumentList.arguments; | ||
| final argument = arguments.firstWhere( | ||
| (argument) => | ||
| argument is NamedExpression && | ||
| argument.name.label.name == 'shrinkWrap', | ||
| ); | ||
| builder.addDeletion(argument.sourceRange); | ||
| }); | ||
| }); | ||
| } | ||
| } | ||
|
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| const _scrollViewSubClasses = [ | ||
| 'ListView', | ||
| 'GridView', | ||
| 'CustomScrollView', | ||
| ]; |
79 changes: 79 additions & 0 deletions
79
packages/nilts_test/test/lints/shrink_wrapped_scroll_view.dart
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,79 @@ | ||
| // ignore_for_file: avoid_redundant_argument_values | ||
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| import 'package:flutter/material.dart'; | ||
|
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| void main() { | ||
| runApp(const MainApp()); | ||
| } | ||
|
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| class MainApp extends StatelessWidget { | ||
| const MainApp({super.key}); | ||
|
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| @override | ||
| Widget build(BuildContext context) { | ||
| return MaterialApp( | ||
| home: Scaffold( | ||
| body: Column( | ||
| children: [ | ||
| ListView(), | ||
| ListView(shrinkWrap: false), | ||
| // expect_lint: shrink_wrapped_scroll_view | ||
| ListView(shrinkWrap: true), | ||
| // expect_lint: shrink_wrapped_scroll_view | ||
| ListView.builder( | ||
| itemBuilder: (_, __) => null, | ||
| shrinkWrap: true, | ||
| ), | ||
| // expect_lint: shrink_wrapped_scroll_view | ||
| ListView.custom( | ||
| childrenDelegate: SliverChildListDelegate([]), | ||
| shrinkWrap: true, | ||
| ), | ||
| // expect_lint: shrink_wrapped_scroll_view | ||
| ListView.separated( | ||
| itemBuilder: (_, __) => null, | ||
| separatorBuilder: (_, __) => const SizedBox.shrink(), | ||
| itemCount: 0, | ||
| shrinkWrap: true, | ||
| ), | ||
| // expect_lint: shrink_wrapped_scroll_view | ||
| GridView( | ||
| gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount( | ||
| crossAxisCount: 2, | ||
| ), | ||
| shrinkWrap: true, | ||
| ), | ||
| // expect_lint: shrink_wrapped_scroll_view | ||
| GridView.builder( | ||
| gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount( | ||
| crossAxisCount: 2, | ||
| ), | ||
| itemBuilder: (_, __) => null, | ||
| shrinkWrap: true, | ||
| ), | ||
| // expect_lint: shrink_wrapped_scroll_view | ||
| GridView.custom( | ||
| gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount( | ||
| crossAxisCount: 2, | ||
| ), | ||
| childrenDelegate: SliverChildListDelegate([]), | ||
| shrinkWrap: true, | ||
| ), | ||
| // expect_lint: shrink_wrapped_scroll_view | ||
| GridView.count( | ||
| crossAxisCount: 2, | ||
| shrinkWrap: true, | ||
| ), | ||
| // expect_lint: shrink_wrapped_scroll_view | ||
| GridView.extent( | ||
| maxCrossAxisExtent: 2, | ||
| shrinkWrap: true, | ||
| ), | ||
| // expect_lint: shrink_wrapped_scroll_view | ||
| const CustomScrollView(shrinkWrap: true), | ||
| ], | ||
| ), | ||
| ), | ||
| ); | ||
| } | ||
| } |