M3 DatePicker landscape header text style is now TextTheme.headlineSmall (#123732)

M3 DatePicker landscape header text style is now TextTheme.headlineSmall

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

@@ -477,21 +477,28 @@ class _DatePickerDialogState extends State<DatePickerDialog> with RestorationMix
     final DatePickerThemeData defaults = DatePickerTheme.defaults(context);
     final TextTheme textTheme = theme.textTheme;
 
-    // Constrain the textScaleFactor to the largest supported value to prevent
-    // layout issues.
-    final double textScaleFactor = math.min(MediaQuery.textScaleFactorOf(context), 1.3);
+    // There's no M3 spec for a landscape layout input (not calendar)
+    // date picker. To ensure that the date displayed in the input
+    // date picker's header fits in landscape mode, we override the M3
+    // default here.
+    TextStyle? headlineStyle;
+    if (useMaterial3) {
+      headlineStyle = datePickerTheme.headerHeadlineStyle ?? defaults.headerHeadlineStyle;
+      switch (_entryMode.value) {
+        case DatePickerEntryMode.input:
+        case DatePickerEntryMode.inputOnly:
+          if (orientation == Orientation.landscape) {
+            headlineStyle = textTheme.headlineSmall;
+          }
+        case DatePickerEntryMode.calendar:
+        case DatePickerEntryMode.calendarOnly:
+          // M3 default is OK.
+      }
+    } else {
+      headlineStyle = orientation == Orientation.landscape ? textTheme.headlineSmall : textTheme.headlineMedium;
+    }
     final Color? headerForegroundColor = datePickerTheme.headerForegroundColor ?? defaults.headerForegroundColor;
-    final TextStyle? headlineStyle = useMaterial3
-      ? (datePickerTheme.headerHeadlineStyle ?? defaults.headerHeadlineStyle)?.copyWith(
-          color: headerForegroundColor,
-        )
-      // Material2 has support for landscape and the current M3 spec doesn't
-      // address this layout, so handling it separately here.
-      : (orientation == Orientation.landscape
-        ? textTheme.headlineSmall?.copyWith(color: headerForegroundColor)
-        : textTheme.headlineMedium?.copyWith(color: headerForegroundColor));
-
-    final String dateText = localizations.formatMediumDate(_selectedDate.value);
+    headlineStyle = headlineStyle?.copyWith(color: headerForegroundColor);
 
     final Widget actions = Container(
       alignment: AlignmentDirectional.centerEnd,
@@ -599,13 +606,16 @@ class _DatePickerDialogState extends State<DatePickerDialog> with RestorationMix
           ? localizations.datePickerHelpText
           : localizations.datePickerHelpText.toUpperCase()
       ),
-      titleText: dateText,
+      titleText: localizations.formatMediumDate(_selectedDate.value),
       titleStyle: headlineStyle,
       orientation: orientation,
       isShort: orientation == Orientation.landscape,
       entryModeButton: entryModeButton,
     );
 
+    // Constrain the textScaleFactor to the largest supported value to prevent
+    // layout issues.
+    final double textScaleFactor = math.min(MediaQuery.textScaleFactorOf(context), 1.3);
     final Size dialogSize = _dialogSize(context) * textScaleFactor;
     final DialogTheme dialogTheme = theme.dialogTheme;
     return Dialog(
@@ -2660,10 +2670,16 @@ class _InputDateRangePickerDialog extends StatelessWidget {
     final DatePickerThemeData datePickerTheme = DatePickerTheme.of(context);
     final DatePickerThemeData defaults = DatePickerTheme.defaults(context);
 
+    // There's no M3 spec for a landscape layout input (not calendar)
+    // date range picker. To ensure that the date range displayed in the
+    // input date range picker's header fits in landscape mode, we override
+    // the M3 default here.
+    TextStyle? headlineStyle = (orientation == Orientation.portrait)
+      ? datePickerTheme.headerHeadlineStyle ?? defaults.headerHeadlineStyle
+      : Theme.of(context).textTheme.headlineSmall;
+
     final Color? headerForegroundColor = datePickerTheme.headerForegroundColor ?? defaults.headerForegroundColor;
-    final TextStyle? headlineStyle = (datePickerTheme.headerHeadlineStyle ?? defaults.headerHeadlineStyle)?.copyWith(
-      color: headerForegroundColor,
-    );
+    headlineStyle = headlineStyle?.copyWith(color: headerForegroundColor);
 
     final String dateText = _formatDateRange(context, selectedStartDate, selectedEndDate, currentDate!);
     final String semanticDateText = selectedStartDate != null && selectedEndDate != null

packages/flutter/test/material/date_picker_test.dart

@@ -1387,6 +1387,36 @@ void main() {
       expect(find.byType(TextField), findsNothing);
     });
   });
+
+  group('Landscape input-only date picker headers use headlineSmall', () {
+    // Regression test for https://github.com/flutter/flutter/issues/122056
+
+    // Common screen size roughly based on a Pixel 1
+    const Size kCommonScreenSizePortrait = Size(1070, 1770);
+    const Size kCommonScreenSizeLandscape = Size(1770, 1070);
+
+    Future<void> showPicker(WidgetTester tester, Size size) async {
+      addTearDown(tester.view.reset);
+      tester.view.physicalSize = size;
+      tester.view.devicePixelRatio = 1.0;
+      initialEntryMode = DatePickerEntryMode.input;
+      await prepareDatePicker(tester, (Future<DateTime?> date) async { }, useMaterial3: true);
+    }
+
+    testWidgets('portrait', (WidgetTester tester) async {
+      await showPicker(tester, kCommonScreenSizePortrait);
+      expect(tester.widget<Text>(find.text('Fri, Jan 15')).style?.fontSize, 32);
+      await tester.tap(find.text('Cancel'));
+      await tester.pumpAndSettle();
+    });
+
+    testWidgets('landscape', (WidgetTester tester) async {
+      await showPicker(tester, kCommonScreenSizeLandscape);
+      expect(tester.widget<Text>(find.text('Fri, Jan 15')).style?.fontSize, 24);
+      await tester.tap(find.text('Cancel'));
+      await tester.pumpAndSettle();
+    });
+  });
 }
 
 class _RestorableDatePickerDialogTestWidget extends StatefulWidget {

packages/flutter/test/material/date_range_picker_test.dart

@@ -108,6 +108,36 @@ void main() {
     await callback(range);
   }
 
+  group('Landscape input-only date picker headers use headlineSmall', () {
+    // Regression test for https://github.com/flutter/flutter/issues/122056
+
+    // Common screen size roughly based on a Pixel 1
+    const Size kCommonScreenSizePortrait = Size(1070, 1770);
+    const Size kCommonScreenSizeLandscape = Size(1770, 1070);
+
+    Future<void> showPicker(WidgetTester tester, Size size) async {
+      addTearDown(tester.view.reset);
+      tester.view.physicalSize = size;
+      tester.view.devicePixelRatio = 1.0;
+      initialEntryMode = DatePickerEntryMode.input;
+      await preparePicker(tester, (Future<DateTimeRange?> range) async { }, useMaterial3: true);
+    }
+
+    testWidgets('portrait', (WidgetTester tester) async {
+      await showPicker(tester, kCommonScreenSizePortrait);
+      expect(tester.widget<Text>(find.text('Jan 15 – Jan 25, 2016')).style?.fontSize, 32);
+      await tester.tap(find.text('Cancel'));
+      await tester.pumpAndSettle();
+    });
+
+    testWidgets('landscape', (WidgetTester tester) async {
+      await showPicker(tester, kCommonScreenSizeLandscape);
+      expect(tester.widget<Text>(find.text('Jan 15 – Jan 25, 2016')).style?.fontSize, 24);
+      await tester.tap(find.text('Cancel'));
+      await tester.pumpAndSettle();
+    });
+  });
+
   testWidgets('Save and help text is used', (WidgetTester tester) async {
     helpText = 'help';
     saveText = 'make it so';