Fix to the tab height (Issue #81500) (#81505)

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

@@ -70,6 +70,7 @@ class Tab extends StatelessWidget implements PreferredSizeWidget{
     this.text,
     this.icon,
     this.iconMargin = const EdgeInsets.only(bottom: 10.0),
+    this.height,
     this.child,
   }) : assert(text != null || child != null || icon != null),
        assert(text == null || child == null),
@@ -96,6 +97,13 @@ class Tab extends StatelessWidget implements PreferredSizeWidget{
   /// [text] or [child] is non-null.
   final EdgeInsetsGeometry iconMargin;
 
+  /// The height of the [Tab].
+  ///
+  /// If null, the height will be calculated based on the content of the [Tab].  When `icon` is not
+  /// null along with `child` or `text`, the default height is 72.0 pixels. Without an `icon`, the
+  /// height is 46.0 pixels.
+  final double? height;
+
   Widget _buildLabelText() {
     return child ?? Text(text!, softWrap: false, overflow: TextOverflow.fade);
   }
@@ -104,16 +112,16 @@ class Tab extends StatelessWidget implements PreferredSizeWidget{
   Widget build(BuildContext context) {
     assert(debugCheckHasMaterial(context));
 
-    final double height;
+    final double calculatedHeight;
     final Widget label;
     if (icon == null) {
-      height = _kTabHeight;
+      calculatedHeight = _kTabHeight;
       label = _buildLabelText();
     } else if (text == null && child == null) {
-      height = _kTabHeight;
+      calculatedHeight = _kTabHeight;
       label = icon!;
     } else {
-      height = _kTextAndIconTabHeight;
+      calculatedHeight = _kTextAndIconTabHeight;
       label = Column(
         mainAxisAlignment: MainAxisAlignment.center,
         crossAxisAlignment: CrossAxisAlignment.center,
@@ -128,7 +136,7 @@ class Tab extends StatelessWidget implements PreferredSizeWidget{
     }
 
     return SizedBox(
-      height: height,
+      height: height ?? calculatedHeight,
       child: Center(
         widthFactor: 1.0,
         child: label,
@@ -145,7 +153,9 @@ class Tab extends StatelessWidget implements PreferredSizeWidget{
 
   @override
   Size get preferredSize {
-    if ((text != null || child != null) && icon != null)
+    if (height != null)
+      return Size.fromHeight(height!);
+    else if ((text != null || child != null) && icon != null)
       return const Size.fromHeight(_kTextAndIconTabHeight);
     else
       return const Size.fromHeight(_kTabHeight);

packages/flutter/test/material/tabs_test.dart

@@ -3747,6 +3747,71 @@ void main() {
     expect(tabTwo.padding, expectedPaddingAdjusted);
     expect(tabThree.padding, expectedPaddingAdjusted);
   });
+
+  testWidgets('Change tab bar height', (WidgetTester tester) async {
+    await tester.pumpWidget(MaterialApp(
+      home: DefaultTabController(
+        length: 4,
+        child: Scaffold(
+          appBar: AppBar(
+            bottom: const TabBar(
+              tabs: <Widget>[
+                Tab(
+                  icon: Icon(Icons.check,size: 40),
+                  child: Text('1 - OK',style: TextStyle(fontSize: 25),),
+                  height: 85,
+                ), // icon and child
+                Tab(
+                  child: Text('2 - OK',style: TextStyle(fontSize: 25),),
+                  height: 85,
+                ), // child
+                Tab(
+                  icon: Icon(Icons.done,size: 40),
+                  height: 85,
+                ), // icon
+                Tab(
+                  text: '4 - OK',
+                  height: 85,
+                ), // text
+              ],
+            ),
+          ),
+        ),
+      ),
+    ));
+    final Tab firstTab = tester.widget(find.widgetWithIcon(Tab, Icons.check));
+    final Tab secTab = tester.widget(find.widgetWithText(Tab, '2 - OK' ));
+    final Tab thirdTab = tester.widget(find.widgetWithIcon(Tab, Icons.done));
+    final Tab fourthTab = tester.widget(find.widgetWithText(Tab, '4 - OK' ));
+    expect(firstTab.preferredSize.height, 85);
+    expect(firstTab.height, 85);
+    expect(secTab.height, 85);
+    expect(thirdTab.height, 85);
+    expect(fourthTab.height, 85);
+  });
+
+  testWidgets('Change tab bar height 2', (WidgetTester tester) async {
+    await tester.pumpWidget(MaterialApp(
+      home: DefaultTabController(
+        length: 1,
+        child: Scaffold(
+          appBar: AppBar(
+            bottom: const TabBar(
+              tabs: <Widget>[
+                Tab(
+                  icon: Icon(Icons.check,size: 40),
+                  text: '1 - OK',
+                  height: 85,
+                ), // icon and text
+              ],
+            ),
+          ),
+        ),
+      ),
+    ));
+    final Tab firstTab = tester.widget(find.widgetWithIcon(Tab, Icons.check));
+    expect(firstTab.height, 85);
+  });
 }
 
 class KeepAliveInk extends StatefulWidget {