[flutter_markdown] Fix some memory leaks and activate leak testing [prod-leak-fix] (flutter#8367)

Author: ValentinVignal

packages/flutter_markdown/CHANGELOG.md

@@ -1,6 +1,7 @@
-## NEXT
+## 0.7.5
 
 * Updates minimum supported SDK version to Flutter 3.22/Dart 3.4.
+* Fixes some memory leaks.
 
 ## 0.7.4+3
 

packages/flutter_markdown/lib/src/builder.dart

@@ -346,16 +346,20 @@ class MarkdownBuilder implements md.NodeVisitor {
       child = builders[_blocks.last.tag!]!
           .visitText(text, styleSheet.styles[_blocks.last.tag!]);
     } else if (_blocks.last.tag == 'pre') {
-      final ScrollController preScrollController = ScrollController();
-      child = Scrollbar(
-        controller: preScrollController,
-        child: SingleChildScrollView(
-          controller: preScrollController,
-          scrollDirection: Axis.horizontal,
-          padding: styleSheet.codeblockPadding,
-          child: _buildRichText(delegate.formatText(styleSheet, text.text)),
-        ),
-      );
+      child = _ScrollControllerBuilder(
+          builder: (BuildContext context, ScrollController preScrollController,
+              Widget? child) {
+            return Scrollbar(
+              controller: preScrollController,
+              child: SingleChildScrollView(
+                controller: preScrollController,
+                scrollDirection: Axis.horizontal,
+                padding: styleSheet.codeblockPadding,
+                child: child,
+              ),
+            );
+          },
+          child: _buildRichText(delegate.formatText(styleSheet, text.text)));
     } else {
       child = _buildRichText(
         TextSpan(
@@ -448,15 +452,20 @@ class MarkdownBuilder implements md.NodeVisitor {
         }
       } else if (tag == 'table') {
         if (styleSheet.tableColumnWidth is FixedColumnWidth) {
-          final ScrollController tableScrollController = ScrollController();
-          child = Scrollbar(
-            controller: tableScrollController,
-            child: SingleChildScrollView(
-              controller: tableScrollController,
-              scrollDirection: Axis.horizontal,
-              padding: styleSheet.tablePadding,
-              child: _buildTable(),
-            ),
+          child = _ScrollControllerBuilder(
+            builder: (BuildContext context,
+                ScrollController tableScrollController, Widget? child) {
+              return Scrollbar(
+                controller: tableScrollController,
+                child: SingleChildScrollView(
+                  controller: tableScrollController,
+                  scrollDirection: Axis.horizontal,
+                  padding: styleSheet.tablePadding,
+                  child: child,
+                ),
+              );
+            },
+            child: _buildTable(),
           );
         } else {
           child = _buildTable();
@@ -1017,3 +1026,33 @@ class MarkdownBuilder implements md.NodeVisitor {
     }
   }
 }
+
+class _ScrollControllerBuilder extends StatefulWidget {
+  const _ScrollControllerBuilder({
+    required this.builder,
+    this.child,
+  });
+
+  final ValueWidgetBuilder<ScrollController> builder;
+
+  final Widget? child;
+
+  @override
+  State<_ScrollControllerBuilder> createState() =>
+      _ScrollControllerBuilderState();
+}
+
+class _ScrollControllerBuilderState extends State<_ScrollControllerBuilder> {
+  final ScrollController _controller = ScrollController();
+
+  @override
+  void dispose() {
+    _controller.dispose();
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return widget.builder(context, _controller, widget.child);
+  }
+}

packages/flutter_markdown/pubspec.yaml

@@ -4,7 +4,7 @@ description: A Markdown renderer for Flutter. Create rich text output,
   formatted with simple Markdown tags.
 repository: https://github.com/flutter/packages/tree/main/packages/flutter_markdown
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+flutter_markdown%22
-version: 0.7.4+3
+version: 0.7.5
 
 environment:
   sdk: ^3.4.0
@@ -20,6 +20,7 @@ dependencies:
 dev_dependencies:
   flutter_test:
     sdk: flutter
+  leak_tracker_flutter_testing: any
   mockito: ^5.4.4
   standard_message_codec: ^0.0.1+3
 

packages/flutter_markdown/test/custom_syntax_test.dart

@@ -276,9 +276,12 @@ class WikilinkSyntax extends md.InlineSyntax {
 class WikilinkBuilder extends MarkdownElementBuilder {
   @override
   Widget visitElementAfter(md.Element element, _) {
-    return Text.rich(TextSpan(
-        text: element.textContent,
-        recognizer: TapGestureRecognizer()..onTap = () {}));
+    final TapGestureRecognizer recognizer = TapGestureRecognizer()
+      ..onTap = () {};
+    addTearDown(recognizer.dispose);
+    return Text.rich(
+      TextSpan(text: element.textContent, recognizer: recognizer),
+    );
   }
 }
 

packages/flutter_markdown/test/flutter_test_config.dart

@@ -0,0 +1,13 @@
+// Copyright 2013 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:async';
+
+import 'package:leak_tracker_flutter_testing/leak_tracker_flutter_testing.dart';
+
+Future<void> testExecutable(FutureOr<void> Function() testMain) async {
+  LeakTesting.enable();
+  LeakTracking.warnForUnsupportedPlatforms = false;
+  await testMain();
+}

packages/flutter_markdown/test/image_test.dart

@@ -455,6 +455,7 @@ void defineTests() {
             find.byType(Container),
             matchesGoldenFile(
                 'assets/images/golden/image_test/custom_builder_asset_logo.png'));
+        imageCache.clear();
       },
       skip: kIsWeb, // Goldens are platform-specific.
     );

packages/flutter_markdown/test/link_test.dart

@@ -142,7 +142,7 @@ void defineTests() {
     testWidgets(
       'multiple inline links with same content should not throw an exception',
       (WidgetTester tester) async {
-        //Arange
+        //Arrange
         final Widget toBePumped = boilerplate(
           Column(
             children: <Widget>[
@@ -1477,6 +1477,7 @@ void defineTests() {
 
         gestureWidget.onTap!();
         expectLinkTap(linkTapResults, const MarkdownLink('moon', '/uri'));
+        imageCache.clear();
       },
     );
 

packages/flutter_markdown/test/padding_test.dart

@@ -50,6 +50,7 @@ void defineTests() {
           paddings[3].padding.along(Axis.horizontal) == paddingX * 4 * 2,
           true,
         );
+        imageCache.clear();
       },
     );
   });

packages/flutter_markdown/test/scrollable_test.dart

@@ -68,6 +68,7 @@ void defineTests() {
         final ScrollController controller = ScrollController(
           initialScrollOffset: 209.0,
         );
+        addTearDown(controller.dispose);
 
         await tester.pumpWidget(
           boilerplate(