Fixing list tile size in the presence of a large subtitle (#17580)

Take into account the subtitle height when adjusting the height of the widget. Added a test.

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

@@ -443,11 +443,11 @@ class ListTile extends StatelessWidget {
       );
     }
 
-    const EdgeInsets _kDefaultContentPadding = const EdgeInsets.symmetric(horizontal: 16.0);
+    const EdgeInsets _defaultContentPadding = const EdgeInsets.symmetric(horizontal: 16.0);
     final TextDirection textDirection = Directionality.of(context);
     final EdgeInsets resolvedContentPadding = contentPadding?.resolve(textDirection)
       ?? tileTheme?.contentPadding?.resolve(textDirection)
-      ?? _kDefaultContentPadding;
+      ?? _defaultContentPadding;
 
     return new InkWell(
       onTap: enabled ? onTap : null,
@@ -529,8 +529,11 @@ class _RenderListTile extends RenderBox {
        _isThreeLine = isThreeLine,
        _textDirection = textDirection;
 
-  static const double _kMinLeadingWidth = 40.0;
-  static const double _kTitleGap = 16.0; // between the titles and the leading/trailing widgets
+  static const double _minLeadingWidth = 40.0;
+  // The horizontal gap between the titles and the leading/trailing widgets
+  static const double _horizontalTitleGap = 16.0;
+  // The minimum padding on the top and bottom of the title and subtitle widgets.
+  static const double _minVerticalPadding = 4.0;
 
   final Map<_ListTileSlot, RenderBox> slotToChild = <_ListTileSlot, RenderBox>{};
   final Map<RenderBox, _ListTileSlot> childToSlot = <RenderBox, _ListTileSlot>{};
@@ -664,7 +667,7 @@ class _RenderListTile extends RenderBox {
   @override
   double computeMinIntrinsicWidth(double height) {
     final double leadingWidth = leading != null
-      ? math.max(leading.getMinIntrinsicWidth(height), _kMinLeadingWidth) + _kTitleGap
+      ? math.max(leading.getMinIntrinsicWidth(height), _minLeadingWidth) + _horizontalTitleGap
       : 0.0;
     return leadingWidth
       + math.max(_minWidth(title, height), _minWidth(subtitle, height))
@@ -674,7 +677,7 @@ class _RenderListTile extends RenderBox {
   @override
   double computeMaxIntrinsicWidth(double height) {
     final double leadingWidth = leading != null
-      ? math.max(leading.getMaxIntrinsicWidth(height), _kMinLeadingWidth) + _kTitleGap
+      ? math.max(leading.getMaxIntrinsicWidth(height), _minLeadingWidth) + _horizontalTitleGap
       : 0.0;
     return leadingWidth
       + math.max(_maxWidth(title, height), _maxWidth(subtitle, height))
@@ -746,10 +749,10 @@ class _RenderListTile extends RenderBox {
     final Size trailingSize = _layoutBox(trailing, looseConstraints);
 
     final double titleStart = hasLeading
-      ? math.max(_kMinLeadingWidth, leadingSize.width) + _kTitleGap
+      ? math.max(_minLeadingWidth, leadingSize.width) + _horizontalTitleGap
       : 0.0;
     final BoxConstraints textConstraints = looseConstraints.tighten(
-      width: tileWidth - titleStart - (hasTrailing ? trailingSize.width + _kTitleGap : 0.0),
+      width: tileWidth - titleStart - (hasTrailing ? trailingSize.width + _horizontalTitleGap : 0.0),
     );
     final Size titleSize = _layoutBox(title, textConstraints);
     final Size subtitleSize = _layoutBox(subtitle, textConstraints);
@@ -770,7 +773,7 @@ class _RenderListTile extends RenderBox {
     double titleY;
     double subtitleY;
     if (!hasSubtitle) {
-      tileHeight = math.max(_defaultTileHeight, titleSize.height);
+      tileHeight = math.max(_defaultTileHeight, titleSize.height + 2.0 * _minVerticalPadding);
       titleY = (tileHeight - titleSize.height) / 2.0;
     } else {
       titleY = titleBaseline - _boxBaseline(title);
@@ -787,11 +790,13 @@ class _RenderListTile extends RenderBox {
       }
 
       // If the title or subtitle overflow tileHeight then punt: title
-      // and subtitle are arranged in a column, tileHeight = column height.
-      if (titleY < 0.0 || subtitleY > tileHeight) {
-        tileHeight = titleSize.height + subtitleSize.height;
-        titleY = 0.0;
-        subtitleY = titleSize.height;
+      // and subtitle are arranged in a column, tileHeight = column height plus
+      // _minVerticalPadding on top and bottom.
+      if (titleY < _minVerticalPadding ||
+          (subtitleY + subtitleSize.height + _minVerticalPadding) > tileHeight) {
+        tileHeight = titleSize.height + subtitleSize.height + 2.0 * _minVerticalPadding;
+        titleY = _minVerticalPadding;
+        subtitleY = titleSize.height + _minVerticalPadding;
       }
     }
 
@@ -802,7 +807,7 @@ class _RenderListTile extends RenderBox {
       case TextDirection.rtl: {
         if (hasLeading)
           _positionBox(leading, new Offset(tileWidth - leadingSize.width, leadingY));
-        final double titleX = hasTrailing ? trailingSize.width + _kTitleGap : 0.0;
+        final double titleX = hasTrailing ? trailingSize.width + _horizontalTitleGap : 0.0;
         _positionBox(title, new Offset(titleX, titleY));
         if (hasSubtitle)
           _positionBox(subtitle, new Offset(titleX, subtitleY));

packages/flutter/test/material/list_tile_test.dart

@@ -56,8 +56,9 @@ void main() {
 
     const double leftPadding = 10.0;
     const double rightPadding = 20.0;
-    Widget buildFrame({ bool dense: false, bool isTwoLine: false, bool isThreeLine: false, double textScaleFactor: 1.0 }) {
+    Widget buildFrame({ bool dense: false, bool isTwoLine: false, bool isThreeLine: false, double textScaleFactor: 1.0, double subtitleScaleFactor }) {
       hasSubtitle = isTwoLine || isThreeLine;
+      subtitleScaleFactor ??= textScaleFactor;
       return new MaterialApp(
         home: new MediaQuery(
           data: new MediaQueryData(
@@ -69,7 +70,7 @@ void main() {
               child: new ListTile(
                 leading: new Container(key: leadingKey, width: 24.0, height: 24.0),
                 title: const Text('title'),
-                subtitle: hasSubtitle ? const Text('subtitle') : null,
+                subtitle: hasSubtitle ? new Text('subtitle', textScaleFactor: subtitleScaleFactor) : null,
                 trailing: new Container(key: trailingKey, width: 24.0, height: 24.0),
                 dense: dense,
                 isThreeLine: isThreeLine,
@@ -91,6 +92,7 @@ void main() {
     double left(String text) => tester.getTopLeft(find.text(text)).dx;
     double top(String text) => tester.getTopLeft(find.text(text)).dy;
     double bottom(String text) => tester.getBottomLeft(find.text(text)).dy;
+    double height(String text) => tester.getRect(find.text(text)).height;
 
     double leftKey(Key key) => tester.getTopLeft(find.byKey(key)).dx;
     double rightKey(Key key) => tester.getTopRight(find.byKey(key)).dx;
@@ -98,7 +100,7 @@ void main() {
     double heightKey(Key key) => tester.getSize(find.byKey(key)).height;
 
     // ListTiles are contained by a SafeArea defined like this:
-    // SafeArea(top: false, bottom: false, minimim: contentPadding)
+    // SafeArea(top: false, bottom: false, minimum: contentPadding)
     // The default contentPadding is 16.0 on the left and right.
     void testHorizontalGeometry() {
       expect(leftKey(leadingKey), math.max(16.0, leftPadding));
@@ -111,9 +113,15 @@ void main() {
     }
 
     void testVerticalGeometry(double expectedHeight) {
-      expect(tester.getSize(find.byType(ListTile)), new Size(800.0, expectedHeight));
-      if (hasSubtitle)
+      final Rect tileRect = tester.getRect(find.byType(ListTile));
+      expect(tileRect.size, new Size(800.0, expectedHeight));
+      expect(top('title'), greaterThanOrEqualTo(tileRect.top));
+      if (hasSubtitle) {
         expect(top('subtitle'), greaterThanOrEqualTo(bottom('title')));
+        expect(bottom('subtitle'), lessThan(tileRect.bottom));
+      } else {
+        expect(top('title'), equals(tileRect.top + (tileRect.height - height('title')) / 2.0));
+      }
       expect(heightKey(trailingKey), 24.0);
     }
 
@@ -150,35 +158,40 @@ void main() {
     await tester.pumpWidget(buildFrame(textScaleFactor: 4.0));
     testChildren();
     testHorizontalGeometry();
-    testVerticalGeometry(64.0);
+    testVerticalGeometry(72.0);
 
     await tester.pumpWidget(buildFrame(dense: true, textScaleFactor: 4.0));
     testChildren();
     testHorizontalGeometry();
-    testVerticalGeometry(64.0);
+    testVerticalGeometry(72.0);
 
     await tester.pumpWidget(buildFrame(isTwoLine: true, textScaleFactor: 4.0));
     testChildren();
     testHorizontalGeometry();
-    testVerticalGeometry(120.0);
+    testVerticalGeometry(128.0);
+
+    // Make sure that the height of a large subtitle is taken into account.
+    await tester.pumpWidget(buildFrame(isTwoLine: true, textScaleFactor: 0.5, subtitleScaleFactor: 4.0));
+    testChildren();
+    testHorizontalGeometry();
+    testVerticalGeometry(72.0);
 
     await tester.pumpWidget(buildFrame(isTwoLine: true, dense: true, textScaleFactor: 4.0));
     testChildren();
     testHorizontalGeometry();
-    testVerticalGeometry(120.0);
+    testVerticalGeometry(128.0);
 
     await tester.pumpWidget(buildFrame(isThreeLine: true, textScaleFactor: 4.0));
     testChildren();
     testHorizontalGeometry();
-    testVerticalGeometry(120.0);
+    testVerticalGeometry(128.0);
 
     await tester.pumpWidget(buildFrame(isThreeLine: true, dense: true, textScaleFactor: 4.0));
     testChildren();
     testHorizontalGeometry();
-    testVerticalGeometry(120.0);
+    testVerticalGeometry(128.0);
   });
 
-
   testWidgets('ListTile geometry (RTL)', (WidgetTester tester) async {
     const double leftPadding = 10.0;
     const double rightPadding = 20.0;
@@ -477,7 +490,6 @@ void main() {
     expect(right('L'), 790.0); // 800 - contentPadding.start
   });
 
-
   testWidgets('ListTileTheme wide leading Widget', (WidgetTester tester) async {
     const Key leadingKey = const ValueKey<String>('L');
 
@@ -544,7 +556,5 @@ void main() {
     expect(tester.getBottomLeft(find.byKey(leadingKey)), const Offset(800.0 - 56.0, 52.0));
     expect(right('title'), 800.0 - 72.0);
     expect(right('subtitle'), 800.0 - 72.0);
-
   });
-
 }