Add Tooltip textAlign property (#103475)

packages/flutter/lib/src/material/tooltip.dart

@@ -103,11 +103,12 @@ class Tooltip extends StatefulWidget {
     this.excludeFromSemantics,
     this.decoration,
     this.textStyle,
+    this.textAlign,
     this.waitDuration,
     this.showDuration,
-    this.child,
     this.triggerMode,
     this.enableFeedback,
+    this.child,
   }) :  assert((message == null) != (richMessage == null), 'Either `message` or `richMessage` must be specified'),
         assert(
           richMessage == null || textStyle == null,
@@ -197,6 +198,13 @@ class Tooltip extends StatefulWidget {
   /// used with [Colors.black].
   final TextStyle? textStyle;
 
+  /// How the message of the tooltip is aligned horizontally.
+  ///
+  /// If this property is null, then [TooltipThemeData.textAlign] is used.
+  /// If [TooltipThemeData.textAlign] is also null, the default value is
+  /// [TextAlign.start].
+  final TextAlign? textAlign;
+
   /// The length of time that a pointer must hover over a tooltip's widget
   /// before the tooltip will be shown.
   ///
@@ -298,6 +306,7 @@ class Tooltip extends StatefulWidget {
     properties.add(DiagnosticsProperty<Duration>('show duration', showDuration, defaultValue: null));
     properties.add(DiagnosticsProperty<TooltipTriggerMode>('triggerMode', triggerMode, defaultValue: null));
     properties.add(FlagProperty('enableFeedback', value: enableFeedback, ifTrue: 'true', showName: true));
+    properties.add(DiagnosticsProperty<TextAlign>('textAlign', textAlign, defaultValue: null));
   }
 }
 
@@ -317,12 +326,14 @@ class TooltipState extends State<Tooltip> with SingleTickerProviderStateMixin {
   static const bool _defaultExcludeFromSemantics = false;
   static const TooltipTriggerMode _defaultTriggerMode = TooltipTriggerMode.longPress;
   static const bool _defaultEnableFeedback = true;
+  static const TextAlign _defaultTextAlign = TextAlign.start;
 
   late double _height;
   late EdgeInsetsGeometry _padding;
   late EdgeInsetsGeometry _margin;
   late Decoration _decoration;
   late TextStyle _textStyle;
+  late TextAlign _textAlign;
   late double _verticalOffset;
   late bool _preferBelow;
   late bool _excludeFromSemantics;
@@ -570,6 +581,7 @@ class TooltipState extends State<Tooltip> with SingleTickerProviderStateMixin {
         onExit: _mouseIsConnected ? (_) => _handleMouseExit() : null,
         decoration: _decoration,
         textStyle: _textStyle,
+        textAlign: _textAlign,
         animation: CurvedAnimation(
           parent: _controller,
           curve: Curves.fastOutSlowIn,
@@ -691,6 +703,7 @@ class TooltipState extends State<Tooltip> with SingleTickerProviderStateMixin {
     _excludeFromSemantics = widget.excludeFromSemantics ?? tooltipTheme.excludeFromSemantics ?? _defaultExcludeFromSemantics;
     _decoration = widget.decoration ?? tooltipTheme.decoration ?? defaultDecoration;
     _textStyle = widget.textStyle ?? tooltipTheme.textStyle ?? defaultTextStyle;
+    _textAlign = widget.textAlign ?? tooltipTheme.textAlign ?? _defaultTextAlign;
     _waitDuration = widget.waitDuration ?? tooltipTheme.waitDuration ?? _defaultWaitDuration;
     _showDuration = widget.showDuration ?? tooltipTheme.showDuration ?? _defaultShowDuration;
     _hoverShowDuration = widget.showDuration ?? tooltipTheme.showDuration ?? _defaultHoverShowDuration;
@@ -786,6 +799,7 @@ class _TooltipOverlay extends StatelessWidget {
     this.margin,
     this.decoration,
     this.textStyle,
+    this.textAlign,
     required this.animation,
     required this.target,
     required this.verticalOffset,
@@ -800,6 +814,7 @@ class _TooltipOverlay extends StatelessWidget {
   final EdgeInsetsGeometry? margin;
   final Decoration? decoration;
   final TextStyle? textStyle;
+  final TextAlign? textAlign;
   final Animation<double> animation;
   final Offset target;
   final double verticalOffset;
@@ -826,6 +841,7 @@ class _TooltipOverlay extends StatelessWidget {
                 child: Text.rich(
                   richMessage,
                   style: textStyle,
+                  textAlign: textAlign,
                 ),
               ),
             ),

packages/flutter/lib/src/material/tooltip_theme.dart

@@ -35,6 +35,7 @@ class TooltipThemeData with Diagnosticable {
     this.excludeFromSemantics,
     this.decoration,
     this.textStyle,
+    this.textAlign,
     this.waitDuration,
     this.showDuration,
     this.triggerMode,
@@ -79,6 +80,9 @@ class TooltipThemeData with Diagnosticable {
   /// The style to use for the message of [Tooltip]s.
   final TextStyle? textStyle;
 
+  /// The [TextAlign] to use for the message of [Tooltip]s.
+  final TextAlign? textAlign;
+
   /// The length of time that a pointer must hover over a tooltip's widget
   /// before the tooltip will be shown.
   final Duration? waitDuration;
@@ -113,6 +117,7 @@ class TooltipThemeData with Diagnosticable {
     bool? excludeFromSemantics,
     Decoration? decoration,
     TextStyle? textStyle,
+    TextAlign? textAlign,
     Duration? waitDuration,
     Duration? showDuration,
     TooltipTriggerMode? triggerMode,
@@ -127,6 +132,7 @@ class TooltipThemeData with Diagnosticable {
       excludeFromSemantics: excludeFromSemantics ?? this.excludeFromSemantics,
       decoration: decoration ?? this.decoration,
       textStyle: textStyle ?? this.textStyle,
+      textAlign: textAlign ?? this.textAlign,
       waitDuration: waitDuration ?? this.waitDuration,
       showDuration: showDuration ?? this.showDuration,
       triggerMode: triggerMode ?? this.triggerMode,
@@ -152,6 +158,7 @@ class TooltipThemeData with Diagnosticable {
       excludeFromSemantics: t < 0.5 ? a?.excludeFromSemantics : b?.excludeFromSemantics,
       decoration: Decoration.lerp(a?.decoration, b?.decoration, t),
       textStyle: TextStyle.lerp(a?.textStyle, b?.textStyle, t),
+      textAlign: t < 0.5 ? a?.textAlign: b?.textAlign,
     );
   }
 
@@ -165,6 +172,7 @@ class TooltipThemeData with Diagnosticable {
     excludeFromSemantics,
     decoration,
     textStyle,
+    textAlign,
     waitDuration,
     showDuration,
     triggerMode,
@@ -186,6 +194,7 @@ class TooltipThemeData with Diagnosticable {
         && other.excludeFromSemantics == excludeFromSemantics
         && other.decoration == decoration
         && other.textStyle == textStyle
+        && other.textAlign == textAlign
         && other.waitDuration == waitDuration
         && other.showDuration == showDuration
         && other.triggerMode == triggerMode
@@ -203,6 +212,7 @@ class TooltipThemeData with Diagnosticable {
     properties.add(FlagProperty('semantics', value: excludeFromSemantics, ifTrue: 'excluded', showName: true));
     properties.add(DiagnosticsProperty<Decoration>('decoration', decoration, defaultValue: null));
     properties.add(DiagnosticsProperty<TextStyle>('textStyle', textStyle, defaultValue: null));
+    properties.add(DiagnosticsProperty<TextAlign>('textAlign', textAlign, defaultValue: null));
     properties.add(DiagnosticsProperty<Duration>('wait duration', waitDuration, defaultValue: null));
     properties.add(DiagnosticsProperty<Duration>('show duration', showDuration, defaultValue: null));
     properties.add(DiagnosticsProperty<TooltipTriggerMode>('triggerMode', triggerMode, defaultValue: null));

packages/flutter/test/material/tooltip_test.dart

@@ -677,6 +677,41 @@ void main() {
     expect(textStyle.decoration, TextDecoration.underline);
   });
 
+  testWidgets('Custom tooltip message textAlign', (WidgetTester tester) async {
+    Future<void> pumpTooltipWithTextAlign({TextAlign? textAlign}) async {
+      final GlobalKey<TooltipState> tooltipKey = GlobalKey<TooltipState>();
+      await tester.pumpWidget(
+        MaterialApp(
+          home: Tooltip(
+            key: tooltipKey,
+            textAlign: textAlign,
+            message: tooltipText,
+            child: Container(
+              width: 100.0,
+              height: 100.0,
+              color: Colors.green[500],
+            ),
+          ),
+        ),
+      );
+      tooltipKey.currentState?.ensureTooltipVisible();
+      await tester.pump(const Duration(seconds: 2)); // faded in, show timer started (and at 0.0)
+    }
+
+    // Default value should be TextAlign.start
+    await pumpTooltipWithTextAlign();
+    TextAlign textAlign = tester.widget<Text>(find.text(tooltipText)).textAlign!;
+    expect(textAlign, TextAlign.start);
+
+    await pumpTooltipWithTextAlign(textAlign: TextAlign.center);
+    textAlign = tester.widget<Text>(find.text(tooltipText)).textAlign!;
+    expect(textAlign, TextAlign.center);
+
+    await pumpTooltipWithTextAlign(textAlign: TextAlign.end);
+    textAlign = tester.widget<Text>(find.text(tooltipText)).textAlign!;
+    expect(textAlign, TextAlign.end);
+  });
+
   testWidgets('Tooltip overlay respects ambient Directionality', (WidgetTester tester) async {
     // Regression test for https://github.com/flutter/flutter/issues/40702.
     Widget buildApp(String text, TextDirection textDirection) {

packages/flutter/test/material/tooltip_theme_test.dart

@@ -46,6 +46,7 @@ void main() {
     expect(theme.excludeFromSemantics, null);
     expect(theme.decoration, null);
     expect(theme.textStyle, null);
+    expect(theme.textAlign, null);
     expect(theme.waitDuration, null);
     expect(theme.showDuration, null);
     expect(theme.triggerMode, null);
@@ -78,6 +79,7 @@ void main() {
       excludeFromSemantics: true,
       decoration: BoxDecoration(color: Color(0xffffffff)),
       textStyle: TextStyle(decoration: TextDecoration.underline),
+      textAlign: TextAlign.center,
       waitDuration: wait,
       showDuration: show,
       triggerMode: triggerMode,
@@ -97,6 +99,7 @@ void main() {
       'semantics: excluded',
       'decoration: BoxDecoration(color: Color(0xffffffff))',
       'textStyle: TextStyle(inherit: true, decoration: TextDecoration.underline)',
+      'textAlign: TextAlign.center',
       'wait duration: $wait',
       'show duration: $show',
       'triggerMode: $triggerMode',
@@ -651,6 +654,45 @@ void main() {
     expect(textStyle.decoration, TextDecoration.underline);
   });
 
+  testWidgets('Tooltip message textAlign - TooltipTheme', (WidgetTester tester) async {
+    Future<void> pumpTooltipWithTextAlign({TextAlign? textAlign}) async {
+      final GlobalKey<TooltipState> tooltipKey = GlobalKey<TooltipState>();
+      await tester.pumpWidget(
+        MaterialApp(
+          home: TooltipTheme(
+            data: TooltipThemeData(
+              textAlign: textAlign,
+            ),
+            child: Tooltip(
+              key: tooltipKey,
+              message: tooltipText,
+              child: Container(
+                width: 100.0,
+                height: 100.0,
+                color: Colors.green[500],
+              ),
+            ),
+          ),
+        ),
+      );
+      tooltipKey.currentState?.ensureTooltipVisible();
+      await tester.pump(const Duration(seconds: 2)); // faded in, show timer started (and at 0.0)
+    }
+
+    // Default value should be TextAlign.start
+    await pumpTooltipWithTextAlign();
+    TextAlign textAlign = tester.widget<Text>(find.text(tooltipText)).textAlign!;
+    expect(textAlign, TextAlign.start);
+
+    await pumpTooltipWithTextAlign(textAlign: TextAlign.center);
+    textAlign = tester.widget<Text>(find.text(tooltipText)).textAlign!;
+    expect(textAlign, TextAlign.center);
+
+    await pumpTooltipWithTextAlign(textAlign: TextAlign.end);
+    textAlign = tester.widget<Text>(find.text(tooltipText)).textAlign!;
+    expect(textAlign, TextAlign.end);
+  });
+
   testWidgets('Tooltip decoration - ThemeData.tooltipTheme', (WidgetTester tester) async {
     final GlobalKey key = GlobalKey();
     const Decoration customDecoration = ShapeDecoration(