Restore the ListTile layout updates (#17661)

restored https://github.com/flutter/flutter/pull/17496
restored https://github.com/flutter/flutter/pull/17580

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

@@ -2,7 +2,11 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:math' as math;
+
 import 'package:flutter/widgets.dart';
+import 'package:flutter/foundation.dart';
+import 'package:flutter/rendering.dart';
 
 import 'colors.dart';
 import 'constants.dart';
@@ -42,6 +46,7 @@ class ListTileTheme extends InheritedWidget {
     this.selectedColor,
     this.iconColor,
     this.textColor,
+    this.contentPadding,
     Widget child,
   }) : super(key: key, child: child);
 
@@ -56,6 +61,7 @@ class ListTileTheme extends InheritedWidget {
     Color selectedColor,
     Color iconColor,
     Color textColor,
+    EdgeInsetsGeometry contentPadding,
     @required Widget child,
   }) {
     assert(child != null);
@@ -69,6 +75,7 @@ class ListTileTheme extends InheritedWidget {
           selectedColor: selectedColor ?? parent.selectedColor,
           iconColor: iconColor ?? parent.iconColor,
           textColor: textColor ?? parent.textColor,
+          contentPadding: contentPadding ?? parent.contentPadding,
           child: child,
         );
       },
@@ -90,6 +97,12 @@ class ListTileTheme extends InheritedWidget {
   /// If specified, the text color used for enabled [ListTile]s that are not selected.
   final Color textColor;
 
+  /// The tile's internal padding.
+  ///
+  /// Insets a [ListTile]'s contents: its [leading], [title], [subtitle],
+  /// and [trailing] widgets.
+  final EdgeInsetsGeometry contentPadding;
+
   /// The closest instance of this class that encloses the given context.
   ///
   /// Typical usage is as follows:
@@ -108,7 +121,8 @@ class ListTileTheme extends InheritedWidget {
         || style != oldWidget.style
         || selectedColor != oldWidget.selectedColor
         || iconColor != oldWidget.iconColor
-        || textColor != oldWidget.textColor;
+        || textColor != oldWidget.textColor
+        || contentPadding != oldWidget.contentPadding;
   }
 }
 
@@ -210,6 +224,7 @@ class ListTile extends StatelessWidget {
     this.trailing,
     this.isThreeLine: false,
     this.dense,
+    this.contentPadding,
     this.enabled: true,
     this.onTap,
     this.onLongPress,
@@ -251,6 +266,14 @@ class ListTile extends StatelessWidget {
   /// If this property is null then its value is based on [ListTileTheme.dense].
   final bool dense;
 
+  /// The tile's internal padding.
+  ///
+  /// Insets a [ListTile]'s contents: its [leading], [title], [subtitle],
+  /// and [trailing] widgets.
+  ///
+  /// If null, `EdgeInsets.symmetric(horizontal: 16.0)` is used.
+  final EdgeInsetsGeometry contentPadding;
+
   /// Whether this list tile is interactive.
   ///
   /// If false, this list tile is styled with the disabled color from the
@@ -347,7 +370,7 @@ class ListTile extends StatelessWidget {
     return defaultColor;
   }
 
-  bool _denseLayout(ListTileTheme tileTheme) {
+  bool _isDenseLayout(ListTileTheme tileTheme) {
     return dense != null ? dense : (tileTheme?.dense ?? false);
   }
 
@@ -366,7 +389,7 @@ class ListTile extends StatelessWidget {
       style = theme.textTheme.subhead;
     }
     final Color color = _textColor(theme, tileTheme, style.color);
-    return _denseLayout(tileTheme)
+    return _isDenseLayout(tileTheme)
       ? style.copyWith(fontSize: 13.0, color: color)
       : style.copyWith(color: color);
   }
@@ -374,7 +397,7 @@ class ListTile extends StatelessWidget {
   TextStyle _subtitleTextStyle(ThemeData theme, ListTileTheme tileTheme) {
     final TextStyle style = theme.textTheme.body1;
     final Color color = _textColor(theme, tileTheme, theme.textTheme.caption.color);
-    return _denseLayout(tileTheme)
+    return _isDenseLayout(tileTheme)
       ? style.copyWith(color: color, fontSize: 12.0)
       : style.copyWith(color: color);
   }
@@ -385,91 +408,567 @@ class ListTile extends StatelessWidget {
     final ThemeData theme = Theme.of(context);
     final ListTileTheme tileTheme = ListTileTheme.of(context);
 
-    final bool isTwoLine = !isThreeLine && subtitle != null;
-    final bool isOneLine = !isThreeLine && !isTwoLine;
-    double tileHeight;
-    if (isOneLine)
-      tileHeight = _denseLayout(tileTheme) ? 48.0 : 56.0;
-    else if (isTwoLine)
-      tileHeight = _denseLayout(tileTheme) ? 60.0 : 72.0;
-    else
-      tileHeight = _denseLayout(tileTheme) ? 76.0 : 88.0;
-
-    // Overall, the list tile is a Row() with these children.
-    final List<Widget> children = <Widget>[];
-
     IconThemeData iconThemeData;
     if (leading != null || trailing != null)
       iconThemeData = new IconThemeData(color: _iconColor(theme, tileTheme));
 
+    Widget leadingIcon;
     if (leading != null) {
-      children.add(IconTheme.merge(
+      leadingIcon = IconTheme.merge(
         data: iconThemeData,
-        child: new Container(
-          margin: const EdgeInsetsDirectional.only(end: 16.0),
-          width: 40.0,
-          alignment: AlignmentDirectional.centerStart,
         child: leading,
-        ),
-      ));
+      );
     }
 
-    final Widget primaryLine = new AnimatedDefaultTextStyle(
+    final Widget titleText = new AnimatedDefaultTextStyle(
       style: _titleTextStyle(theme, tileTheme),
       duration: kThemeChangeDuration,
-      child: title ?? new Container()
+      child: title ?? const SizedBox()
     );
-    Widget center = primaryLine;
-    if (subtitle != null && (isTwoLine || isThreeLine)) {
-      center = new Column(
-        mainAxisSize: MainAxisSize.min,
-        crossAxisAlignment: CrossAxisAlignment.start,
-        children: <Widget>[
-          primaryLine,
-          new AnimatedDefaultTextStyle(
+
+    Widget subtitleText;
+    if (subtitle != null) {
+      subtitleText = new AnimatedDefaultTextStyle(
         style: _subtitleTextStyle(theme, tileTheme),
         duration: kThemeChangeDuration,
         child: subtitle,
-          ),
-        ],
       );
     }
-    children.add(new Expanded(
-      child: center,
-    ));
 
+    Widget trailingIcon;
     if (trailing != null) {
-      children.add(IconTheme.merge(
+      trailingIcon = IconTheme.merge(
         data: iconThemeData,
-        child: new Container(
-          margin: const EdgeInsetsDirectional.only(start: 16.0),
-          alignment: AlignmentDirectional.centerEnd,
         child: trailing,
-        ),
-      ));
+      );
     }
 
+    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)
+      ?? _defaultContentPadding;
+
     return new InkWell(
       onTap: enabled ? onTap : null,
       onLongPress: enabled ? onLongPress : null,
       child: new Semantics(
         selected: selected,
         enabled: enabled,
-        child: new ConstrainedBox(
-          constraints: new BoxConstraints(minHeight: tileHeight),
-          child: new Padding(
-            padding: const EdgeInsets.symmetric(horizontal: 16.0),
-            child: new UnconstrainedBox(
-              constrainedAxis: Axis.horizontal,
         child: new SafeArea(
           top: false,
           bottom: false,
-                child: new Row(children: children),
-              ),
+          minimum: resolvedContentPadding,
+          child: new _ListTile(
+            leading: leadingIcon,
+            title: titleText,
+            subtitle: subtitleText,
+            trailing: trailingIcon,
+            isDense: _isDenseLayout(tileTheme),
+            isThreeLine: isThreeLine,
           ),
-          )
         ),
       ),
     );
   }
 }
+
+class _ListTile extends RenderObjectWidget {
+  const _ListTile({
+    Key key,
+    this.leading,
+    this.title,
+    this.subtitle,
+    this.trailing,
+    this.isThreeLine,
+    this.isDense,
+  }) : super(key: key);
+
+  final Widget leading;
+  final Widget title;
+  final Widget subtitle;
+  final Widget trailing;
+  final bool isThreeLine;
+  final bool isDense;
+
+  @override
+  _RenderListTileElement createElement() => new _RenderListTileElement(this);
+
+  @override
+  _RenderListTile createRenderObject(BuildContext context) {
+    return new _RenderListTile(
+      isThreeLine: isThreeLine,
+      isDense: isDense,
+      textDirection: Directionality.of(context),
+    );
+  }
+
+  @override
+  void updateRenderObject(BuildContext context, _RenderListTile renderObject) {
+    renderObject
+      ..isThreeLine = isThreeLine
+      ..isDense = isDense
+      ..textDirection = Directionality.of(context);
+  }
+}
+
+// Identifies the children of a _ListTileElement.
+enum _ListTileSlot {
+  leading,
+  title,
+  subtitle,
+  trailing,
+}
+
+class _RenderListTile extends RenderBox {
+  _RenderListTile({
+    bool isDense,
+    bool isThreeLine,
+    TextDirection textDirection,
+  }) : _isDense = isDense,
+       _isThreeLine = isThreeLine,
+       _textDirection = textDirection;
+
+  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>{};
+
+  RenderBox _updateChild(RenderBox oldChild, RenderBox newChild, _ListTileSlot slot) {
+    if (oldChild != null) {
+      dropChild(oldChild);
+      childToSlot.remove(oldChild);
+      slotToChild.remove(slot);
+    }
+    if (newChild != null) {
+      childToSlot[newChild] = slot;
+      slotToChild[slot] = newChild;
+      adoptChild(newChild);
+    }
+    return newChild;
+  }
+
+  RenderBox _leading;
+  RenderBox get leading => _leading;
+  set leading(RenderBox value) {
+    _leading = _updateChild(_leading, value, _ListTileSlot.leading);
+  }
+
+  RenderBox _title;
+  RenderBox get title => _title;
+  set title(RenderBox value) {
+    _title = _updateChild(_title, value, _ListTileSlot.title);
+  }
+
+  RenderBox _subtitle;
+  RenderBox get subtitle => _subtitle;
+  set subtitle(RenderBox value) {
+    _subtitle = _updateChild(_subtitle, value, _ListTileSlot.subtitle);
+  }
+
+  RenderBox _trailing;
+  RenderBox get trailing => _trailing;
+  set trailing(RenderBox value) {
+    _trailing = _updateChild(_trailing, value, _ListTileSlot.trailing);
+  }
+
+  // The returned list is ordered for hit testing.
+  Iterable<RenderBox> get _children sync *{
+    if (leading != null)
+      yield leading;
+    if (title != null)
+      yield title;
+    if (subtitle != null)
+      yield subtitle;
+    if (trailing != null)
+      yield trailing;
+  }
+
+  bool get isDense => _isDense;
+  bool _isDense;
+  set isDense(bool value) {
+    if (_isDense == value)
+      return;
+    _isDense = value;
+    markNeedsLayout();
+  }
+
+  bool get isThreeLine => _isThreeLine;
+  bool _isThreeLine;
+  set isThreeLine(bool value) {
+    if (_isThreeLine == value)
+      return;
+    _isThreeLine = value;
+    markNeedsLayout();
+  }
+
+  TextDirection get textDirection => _textDirection;
+  TextDirection _textDirection;
+  set textDirection(TextDirection value) {
+    if (_textDirection == value)
+      return;
+    _textDirection = value;
+    markNeedsLayout();
+  }
+
+  @override
+  void attach(PipelineOwner owner) {
+    super.attach(owner);
+    for (RenderBox child in _children)
+      child.attach(owner);
+  }
+
+  @override
+  void detach() {
+    super.detach();
+    for (RenderBox child in _children)
+      child.detach();
+  }
+
+  @override
+  void redepthChildren() {
+    _children.forEach(redepthChild);
+  }
+
+  @override
+  void visitChildren(RenderObjectVisitor visitor) {
+    _children.forEach(visitor);
+  }
+
+  @override
+  List<DiagnosticsNode> debugDescribeChildren() {
+    final List<DiagnosticsNode> value = <DiagnosticsNode>[];
+    void add(RenderBox child, String name) {
+      if (child != null)
+        value.add(child.toDiagnosticsNode(name: name));
+    }
+    add(leading, 'leading');
+    add(title, 'title');
+    add(subtitle, 'subtitle');
+    add(trailing, 'trailing');
+    return value;
+  }
+
+  @override
+  bool get sizedByParent => false;
+
+  static double _minWidth(RenderBox box, double height) {
+    return box == null ? 0.0 : box.getMinIntrinsicWidth(height);
+  }
+
+  static double _maxWidth(RenderBox box, double height) {
+    return box == null ? 0.0 : box.getMaxIntrinsicWidth(height);
+  }
+
+  @override
+  double computeMinIntrinsicWidth(double height) {
+    final double leadingWidth = leading != null
+      ? math.max(leading.getMinIntrinsicWidth(height), _minLeadingWidth) + _horizontalTitleGap
+      : 0.0;
+    return leadingWidth
+      + math.max(_minWidth(title, height), _minWidth(subtitle, height))
+      + _maxWidth(trailing, height);
+  }
+
+  @override
+  double computeMaxIntrinsicWidth(double height) {
+    final double leadingWidth = leading != null
+      ? math.max(leading.getMaxIntrinsicWidth(height), _minLeadingWidth) + _horizontalTitleGap
+      : 0.0;
+    return leadingWidth
+      + math.max(_maxWidth(title, height), _maxWidth(subtitle, height))
+      + _maxWidth(trailing, height);
+  }
+
+  double get _defaultTileHeight {
+    final bool hasSubtitle = subtitle != null;
+    final bool isTwoLine = !isThreeLine && hasSubtitle;
+    final bool isOneLine = !isThreeLine && !hasSubtitle;
+
+    if (isOneLine)
+      return isDense ? 48.0 : 56.0;
+    if (isTwoLine)
+      return isDense ? 64.0 : 72.0;
+    return isDense ? 76.0 : 88.0;
+  }
+
+  @override
+  double computeMinIntrinsicHeight(double width) {
+    return math.max(
+      _defaultTileHeight,
+      title.getMinIntrinsicHeight(width) + (subtitle?.getMinIntrinsicHeight(width) ?? 0.0)
+    );
+  }
+
+  @override
+  double computeMaxIntrinsicHeight(double width) {
+    return computeMinIntrinsicHeight(width);
+  }
+
+  @override
+  double computeDistanceToActualBaseline(TextBaseline baseline) {
+    assert(title != null);
+    final BoxParentData parentData = title.parentData;
+    return parentData.offset.dy + title.getDistanceToBaseline(TextBaseline.alphabetic);
+  }
+
+  static double _boxBaseline(RenderBox box) {
+    return box.getDistanceToBaseline(TextBaseline.alphabetic);
+  }
+
+  static Size _layoutBox(RenderBox box, BoxConstraints constraints) {
+    if (box == null)
+      return Size.zero;
+    box.layout(constraints, parentUsesSize: true);
+    return box.size;
+  }
+
+  static void _positionBox(RenderBox box, Offset offset) {
+    final BoxParentData parentData = box.parentData;
+    parentData.offset = offset;
+  }
+
+  // All of the dimensions below were taken from the Material Design spec:
+  // https://material.io/design/components/lists.html#specs
+  @override
+  void performLayout() {
+    final bool hasLeading = leading != null;
+    final bool hasSubtitle = subtitle != null;
+    final bool hasTrailing = trailing != null;
+    final bool isTwoLine = !isThreeLine && hasSubtitle;
+    final bool isOneLine = !isThreeLine && !hasSubtitle;
+    final BoxConstraints looseConstraints = constraints.loosen();
+
+    final double tileWidth = looseConstraints.maxWidth;
+    final Size leadingSize = _layoutBox(leading, looseConstraints);
+    final Size trailingSize = _layoutBox(trailing, looseConstraints);
+
+    final double titleStart = hasLeading
+      ? math.max(_minLeadingWidth, leadingSize.width) + _horizontalTitleGap
+      : 0.0;
+    final BoxConstraints textConstraints = looseConstraints.tighten(
+      width: tileWidth - titleStart - (hasTrailing ? trailingSize.width + _horizontalTitleGap : 0.0),
+    );
+    final Size titleSize = _layoutBox(title, textConstraints);
+    final Size subtitleSize = _layoutBox(subtitle, textConstraints);
+
+    double titleBaseline;
+    double subtitleBaseline;
+    if (isTwoLine) {
+      titleBaseline = isDense ? 28.0 : 32.0;
+      subtitleBaseline = isDense ? 48.0 : 52.0;
+    } else if (isThreeLine) {
+      titleBaseline = isDense ? 22.0 : 28.0;
+      subtitleBaseline = isDense ? 42.0 : 48.0;
+    } else {
+      assert(isOneLine);
+    }
+
+    double tileHeight;
+    double titleY;
+    double subtitleY;
+    if (!hasSubtitle) {
+      tileHeight = math.max(_defaultTileHeight, titleSize.height + 2.0 * _minVerticalPadding);
+      titleY = (tileHeight - titleSize.height) / 2.0;
+    } else {
+      titleY = titleBaseline - _boxBaseline(title);
+      subtitleY = subtitleBaseline - _boxBaseline(subtitle);
+      tileHeight = _defaultTileHeight;
+
+      // If the title and subtitle overlap, move the title upwards by half
+      // the overlap and the subtitle down by the same amount, and adjust
+      // tileHeight so that both titles fit.
+      final double titleOverlap = titleY + titleSize.height - subtitleY;
+      if (titleOverlap > 0.0) {
+        titleY -= titleOverlap / 2.0;
+        subtitleY += titleOverlap / 2.0;
+      }
+
+      // If the title or subtitle overflow tileHeight then punt: title
+      // 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;
+      }
+    }
+
+    final double leadingY = (tileHeight - leadingSize.height) / 2.0;
+    final double trailingY = (tileHeight - trailingSize.height) / 2.0;
+
+    switch (textDirection) {
+      case TextDirection.rtl: {
+        if (hasLeading)
+          _positionBox(leading, new Offset(tileWidth - leadingSize.width, leadingY));
+        final double titleX = hasTrailing ? trailingSize.width + _horizontalTitleGap : 0.0;
+        _positionBox(title, new Offset(titleX, titleY));
+        if (hasSubtitle)
+          _positionBox(subtitle, new Offset(titleX, subtitleY));
+        if (hasTrailing)
+          _positionBox(trailing, new Offset(0.0, trailingY));
+        break;
+      }
+      case TextDirection.ltr: {
+        if (hasLeading)
+          _positionBox(leading, new Offset(0.0, leadingY));
+        _positionBox(title, new Offset(titleStart, titleY));
+        if (hasSubtitle)
+          _positionBox(subtitle, new Offset(titleStart, subtitleY));
+        if (hasTrailing)
+          _positionBox(trailing, new Offset(tileWidth - trailingSize.width, trailingY));
+        break;
+      }
+    }
+
+    size = constraints.constrain(new Size(tileWidth, tileHeight));
+    assert(size.width == constraints.constrainWidth(tileWidth));
+    assert(size.height == constraints.constrainHeight(tileHeight));
+  }
+
+  @override
+  void paint(PaintingContext context, Offset offset) {
+    void doPaint(RenderBox child) {
+      if (child != null) {
+        final BoxParentData parentData = child.parentData;
+        context.paintChild(child, parentData.offset + offset);
+      }
+    }
+    doPaint(leading);
+    doPaint(title);
+    doPaint(subtitle);
+    doPaint(trailing);
+  }
+
+  @override
+  bool hitTestSelf(Offset position) => true;
+
+  @override
+  bool hitTestChildren(HitTestResult result, { @required Offset position }) {
+    assert(position != null);
+    for (RenderBox child in _children) {
+      final BoxParentData parentData = child.parentData;
+      if (child.hitTest(result, position: position - parentData.offset))
+        return true;
+    }
+    return false;
+  }
+}
+
+class _RenderListTileElement extends RenderObjectElement {
+  _RenderListTileElement(_ListTile widget) : super(widget);
+
+  final Map<_ListTileSlot, Element> slotToChild = <_ListTileSlot, Element>{};
+  final Map<Element, _ListTileSlot> childToSlot = <Element, _ListTileSlot>{};
+
+  @override
+  _ListTile get widget => super.widget;
+
+  @override
+  _RenderListTile get renderObject => super.renderObject;
+
+  @override
+  void visitChildren(ElementVisitor visitor) {
+    slotToChild.values.forEach(visitor);
+  }
+
+  @override
+  void forgetChild(Element child) {
+    assert(slotToChild.values.contains(child));
+    assert(childToSlot.keys.contains(child));
+    final _ListTileSlot slot = childToSlot[child];
+    childToSlot.remove(child);
+    slotToChild.remove(slot);
+  }
+
+  void _mountChild(Widget widget, _ListTileSlot slot) {
+    final Element oldChild = slotToChild[slot];
+    final Element newChild = updateChild(oldChild, widget, slot);
+    if (oldChild != null) {
+      slotToChild.remove(slot);
+      childToSlot.remove(oldChild);
+    }
+    if (newChild != null) {
+      slotToChild[slot] = newChild;
+      childToSlot[newChild] = slot;
+    }
+  }
+
+  @override
+  void mount(Element parent, dynamic newSlot) {
+    super.mount(parent, newSlot);
+    _mountChild(widget.leading, _ListTileSlot.leading);
+    _mountChild(widget.title, _ListTileSlot.title);
+    _mountChild(widget.subtitle, _ListTileSlot.subtitle);
+    _mountChild(widget.trailing, _ListTileSlot.trailing);
+  }
+
+  void _updateChild(Widget widget, _ListTileSlot slot) {
+    final Element oldChild = slotToChild[slot];
+    final Element newChild = updateChild(oldChild, widget, slot);
+    if (oldChild != null) {
+      childToSlot.remove(oldChild);
+      slotToChild.remove(slot);
+    }
+    if (newChild != null) {
+      slotToChild[slot] = newChild;
+      childToSlot[newChild] = slot;
+    }
+  }
+
+  @override
+  void update(_ListTile newWidget) {
+    super.update(newWidget);
+    assert(widget == newWidget);
+    _updateChild(widget.leading, _ListTileSlot.leading);
+    _updateChild(widget.title, _ListTileSlot.title);
+    _updateChild(widget.subtitle, _ListTileSlot.subtitle);
+    _updateChild(widget.trailing, _ListTileSlot.trailing);
+  }
+
+  void _updateRenderObject(RenderObject child, _ListTileSlot slot) {
+    switch (slot) {
+      case _ListTileSlot.leading:
+        renderObject.leading = child;
+        break;
+      case _ListTileSlot.title:
+        renderObject.title = child;
+        break;
+      case _ListTileSlot.subtitle:
+        renderObject.subtitle = child;
+        break;
+      case _ListTileSlot.trailing:
+        renderObject.trailing = child;
+        break;
+    }
+  }
+
+  @override
+  void insertChildRenderObject(RenderObject child, dynamic slotValue) {
+    assert(child is RenderBox);
+    assert(slotValue is _ListTileSlot);
+    final _ListTileSlot slot = slotValue;
+    _updateRenderObject(child, slot);
+    assert(renderObject.childToSlot.keys.contains(child));
+    assert(renderObject.slotToChild.keys.contains(slot));
+  }
+
+  @override
+  void removeChildRenderObject(RenderObject child) {
+    assert(child is RenderBox);
+    assert(renderObject.childToSlot.keys.contains(child));
+    _updateRenderObject(null, renderObject.childToSlot[child]);
+    assert(!renderObject.childToSlot.keys.contains(child));
+    assert(!renderObject.slotToChild.keys.contains(slot));
+  }
+
+  @override
+  void moveChildRenderObject(RenderObject child, dynamic slotValue) {
+    assert(false, 'not reachable');
+  }
+}

packages/flutter/test/material/list_tile_test.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:math' as math;
+
 import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter_test/flutter_test.dart';
@@ -54,8 +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(
@@ -67,7 +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,
@@ -89,29 +92,36 @@ 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;
     double widthKey(Key key) => tester.getSize(find.byKey(key)).width;
     double heightKey(Key key) => tester.getSize(find.byKey(key)).height;
 
-
-    // 16.0 padding to the left and right of the leading and trailing widgets
-    // plus the media padding.
+    // ListTiles are contained by a SafeArea defined like this:
+    // SafeArea(top: false, bottom: false, minimum: contentPadding)
+    // The default contentPadding is 16.0 on the left and right.
     void testHorizontalGeometry() {
-      expect(leftKey(leadingKey), 16.0 + leftPadding);
-      expect(left('title'), 72.0 + leftPadding);
+      expect(leftKey(leadingKey), math.max(16.0, leftPadding));
+      expect(left('title'), 56.0 + math.max(16.0, leftPadding));
       if (hasSubtitle)
-        expect(left('subtitle'), 72.0 + leftPadding);
+        expect(left('subtitle'), 56.0 + math.max(16.0, leftPadding));
       expect(left('title'), rightKey(leadingKey) + 32.0);
-      expect(rightKey(trailingKey), 800.0 - 16.0 - rightPadding);
+      expect(rightKey(trailingKey), 800.0 - math.max(16.0, rightPadding));
       expect(widthKey(trailingKey), 24.0);
     }
 
     void testVerticalGeometry(double expectedHeight) {
-      expect(tester.getSize(find.byType(ListTile)), new Size(800.0, expectedHeight));
-      if (hasSubtitle)
-        expect(top('subtitle'), bottom('title'));
+      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);
     }
 
@@ -133,7 +143,7 @@ void main() {
     await tester.pumpWidget(buildFrame(isTwoLine: true, dense: true));
     testChildren();
     testHorizontalGeometry();
-    testVerticalGeometry(60.0);
+    testVerticalGeometry(64.0);
 
     await tester.pumpWidget(buildFrame(isThreeLine: true));
     testChildren();
@@ -148,35 +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;
@@ -189,9 +204,9 @@ void main() {
         child: const Material(
           child: const Center(
             child: const ListTile(
-              leading: const Text('leading'),
+              leading: const Text('L'),
               title: const Text('title'),
-              trailing: const Text('trailing'),
+              trailing: const Text('T'),
             ),
           ),
         ),
@@ -202,10 +217,9 @@ void main() {
     double right(String text) => tester.getTopRight(find.text(text)).dx;
 
     void testHorizontalGeometry() {
-      expect(right('leading'), 800.0 - 16.0 - rightPadding);
-      expect(right('title'), 800.0 - 72.0 - rightPadding);
-      expect(left('leading') - right('title'), 16.0);
-      expect(left('trailing'), 16.0 + leftPadding);
+      expect(right('L'), 800.0 - math.max(16.0, rightPadding));
+      expect(right('title'), 800.0 - 56.0 - math.max(16.0, rightPadding));
+      expect(left('T'), math.max(16.0, leftPadding));
     }
 
     testHorizontalGeometry();
@@ -385,4 +399,162 @@ void main() {
 
     semantics.dispose();
   });
+
+  testWidgets('ListTile contentPadding', (WidgetTester tester) async {
+    Widget buildFrame(TextDirection textDirection) {
+      return new MediaQuery(
+        data: const MediaQueryData(
+          padding: EdgeInsets.zero,
+          textScaleFactor: 1.0
+        ),
+        child: new Directionality(
+          textDirection: textDirection,
+          child: new Material(
+            child: new Container(
+              alignment: Alignment.topLeft,
+              child: const ListTile(
+                contentPadding: const EdgeInsetsDirectional.only(
+                  start: 10.0,
+                  end: 20.0,
+                  top: 30.0,
+                  bottom: 40.0,
+                ),
+                leading: const Text('L'),
+                title: const Text('title'),
+                trailing: const Text('T'),
+              ),
+            ),
+          ),
+        ),
+      );
+    }
+
+    double left(String text) => tester.getTopLeft(find.text(text)).dx;
+    double right(String text) => tester.getTopRight(find.text(text)).dx;
+
+    await tester.pumpWidget(buildFrame(TextDirection.ltr));
+
+    expect(tester.getSize(find.byType(ListTile)), const Size(800.0, 126.0)); // 126 = 56 + 30 + 40
+    expect(left('L'), 10.0); // contentPadding.start = 10
+    expect(right('T'), 780.0); // 800 - contentPadding.end
+
+    await tester.pumpWidget(buildFrame(TextDirection.rtl));
+
+    expect(tester.getSize(find.byType(ListTile)), const Size(800.0, 126.0)); // 126 = 56 + 30 + 40
+    expect(left('T'), 20.0); // contentPadding.end = 20
+    expect(right('L'), 790.0); // 800 - contentPadding.start
+  });
+
+  testWidgets('ListTile contentPadding', (WidgetTester tester) async {
+    Widget buildFrame(TextDirection textDirection) {
+      return new MediaQuery(
+        data: const MediaQueryData(
+          padding: EdgeInsets.zero,
+          textScaleFactor: 1.0
+        ),
+        child: new Directionality(
+          textDirection: textDirection,
+          child: new Material(
+            child: new Container(
+              alignment: Alignment.topLeft,
+              child: const ListTile(
+                contentPadding: const EdgeInsetsDirectional.only(
+                  start: 10.0,
+                  end: 20.0,
+                  top: 30.0,
+                  bottom: 40.0,
+                ),
+                leading: const Text('L'),
+                title: const Text('title'),
+                trailing: const Text('T'),
+              ),
+            ),
+          ),
+        ),
+      );
+    }
+
+    double left(String text) => tester.getTopLeft(find.text(text)).dx;
+    double right(String text) => tester.getTopRight(find.text(text)).dx;
+
+    await tester.pumpWidget(buildFrame(TextDirection.ltr));
+
+    expect(tester.getSize(find.byType(ListTile)), const Size(800.0, 126.0)); // 126 = 56 + 30 + 40
+    expect(left('L'), 10.0); // contentPadding.start = 10
+    expect(right('T'), 780.0); // 800 - contentPadding.end
+
+    await tester.pumpWidget(buildFrame(TextDirection.rtl));
+
+    expect(tester.getSize(find.byType(ListTile)), const Size(800.0, 126.0)); // 126 = 56 + 30 + 40
+    expect(left('T'), 20.0); // contentPadding.end = 20
+    expect(right('L'), 790.0); // 800 - contentPadding.start
+  });
+
+  testWidgets('ListTileTheme wide leading Widget', (WidgetTester tester) async {
+    const Key leadingKey = const ValueKey<String>('L');
+
+    Widget buildFrame(double leadingWidth, TextDirection textDirection) {
+      return new MediaQuery(
+        data: const MediaQueryData(
+          padding: EdgeInsets.zero,
+          textScaleFactor: 1.0
+        ),
+        child: new Directionality(
+          textDirection: textDirection,
+          child: new Material(
+            child: new Container(
+              alignment: Alignment.topLeft,
+              child: new ListTile(
+                contentPadding: EdgeInsets.zero,
+                leading: new SizedBox(key: leadingKey, width: leadingWidth, height: 32.0),
+                title: const Text('title'),
+                subtitle: const Text('subtitle'),
+              ),
+            ),
+          ),
+        ),
+      );
+    }
+
+    double left(String text) => tester.getTopLeft(find.text(text)).dx;
+    double right(String text) => tester.getTopRight(find.text(text)).dx;
+
+    // textDirection = LTR
+
+    // Two-line tile's height = 72, leading 24x32 widget is vertically centered
+    await tester.pumpWidget(buildFrame(24.0, TextDirection.ltr));
+    expect(tester.getSize(find.byType(ListTile)), const Size(800.0, 72.0));
+    expect(tester.getTopLeft(find.byKey(leadingKey)), const Offset(0.0, 20.0));
+    expect(tester.getBottomRight(find.byKey(leadingKey)), const Offset(24.0, 52.0));
+
+    // Leading widget's width is 20, so default layout: the left edges of the
+    // title and subtitle are at 56dps (contentPadding is zero).
+    expect(left('title'), 56.0);
+    expect(left('subtitle'), 56.0);
+
+    // If the leading widget is wider than 40 it is separated from the
+    // title and subtitle by 16.
+    await tester.pumpWidget(buildFrame(56.0, TextDirection.ltr));
+    expect(tester.getSize(find.byType(ListTile)), const Size(800.0, 72.0));
+    expect(tester.getTopLeft(find.byKey(leadingKey)), const Offset(0.0, 20.0));
+    expect(tester.getBottomRight(find.byKey(leadingKey)), const Offset(56.0, 52.0));
+    expect(left('title'), 72.0);
+    expect(left('subtitle'), 72.0);
+
+    // Same tests, textDirection = RTL
+
+    await tester.pumpWidget(buildFrame(24.0, TextDirection.rtl));
+    expect(tester.getSize(find.byType(ListTile)), const Size(800.0, 72.0));
+    expect(tester.getTopRight(find.byKey(leadingKey)), const Offset(800.0, 20.0));
+    expect(tester.getBottomLeft(find.byKey(leadingKey)), const Offset(800.0 - 24.0, 52.0));
+    expect(right('title'), 800.0 - 56.0);
+    expect(right('subtitle'), 800.0 - 56.0);
+
+    await tester.pumpWidget(buildFrame(56.0, TextDirection.rtl));
+    expect(tester.getSize(find.byType(ListTile)), const Size(800.0, 72.0));
+    expect(tester.getTopRight(find.byKey(leadingKey)), const Offset(800.0, 20.0));
+    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);
+  });
 }