Improve RTL support (#12008)

Fix a bunch of obvious RTL bugs from code inspection.

packages/flutter/lib/src/cupertino/button.dart

@@ -61,7 +61,7 @@ class CupertinoButton extends StatefulWidget {
   /// The amount of space to surround the child inside the bounds of the button.
   ///
   /// Defaults to 16.0 pixels.
-  final EdgeInsets padding;
+  final EdgeInsetsGeometry padding;
 
   /// The color of the button's background.
   ///

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

@@ -405,7 +405,7 @@ class _LicensePageState extends State<LicensePage> {
           } else {
             assert(paragraph.indent >= 0);
             _licenses.add(new Padding(
-              padding: new EdgeInsets.only(top: 8.0, left: 16.0 * paragraph.indent),
+              padding: new EdgeInsetsDirectional.only(top: 8.0, start: 16.0 * paragraph.indent),
               child: new Text(paragraph.text)
             ));
           }

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

@@ -362,7 +362,7 @@ class DataTable extends StatelessWidget {
     ValueChanged<bool> onCheckboxChanged
   }) {
     Widget contents = new Padding(
-      padding: const EdgeInsets.fromLTRB(_kTablePadding, 0.0, _kTablePadding / 2.0, 0.0),
+      padding: const EdgeInsetsDirectional.only(start: _kTablePadding, end: _kTablePadding / 2.0),
       child: new Center(
         child: new Checkbox(
           activeColor: color,
@@ -385,7 +385,7 @@ class DataTable extends StatelessWidget {
 
   Widget _buildHeadingCell({
     BuildContext context,
-    EdgeInsets padding,
+    EdgeInsetsGeometry padding,
     Widget label,
     String tooltip,
     bool numeric,
@@ -408,7 +408,7 @@ class DataTable extends StatelessWidget {
     label = new Container(
       padding: padding,
       height: _kHeadingRowHeight,
-      alignment: new FractionalOffset(numeric ? 1.0 : 0.0, 0.5), // TODO(ianh): RTL for non-numeric
+      alignment: numeric ? FractionalOffset.centerRight : FractionalOffsetDirectional.centerStart,
       child: new AnimatedDefaultTextStyle(
         style: new TextStyle(
           // TODO(ianh): font family should be Roboto; see https://github.com/flutter/flutter/issues/3116
@@ -441,7 +441,7 @@ class DataTable extends StatelessWidget {
 
   Widget _buildDataCell({
     BuildContext context,
-    EdgeInsets padding,
+    EdgeInsetsGeometry padding,
     Widget label,
     bool numeric,
     bool placeholder,
@@ -458,7 +458,7 @@ class DataTable extends StatelessWidget {
     label = new Container(
       padding: padding,
       height: _kDataRowHeight,
-      alignment: new FractionalOffset(numeric ? 1.0 : 0.0, 0.5), // TODO(ianh): RTL for non-numeric
+      alignment: numeric ? FractionalOffset.centerRight : FractionalOffsetDirectional.centerStart,
       child: new DefaultTextStyle(
         style: new TextStyle(
           // TODO(ianh): font family should be Roboto; see https://github.com/flutter/flutter/issues/3116
@@ -544,11 +544,9 @@ class DataTable extends StatelessWidget {
 
     for (int dataColumnIndex = 0; dataColumnIndex < columns.length; dataColumnIndex += 1) {
       final DataColumn column = columns[dataColumnIndex];
-      final EdgeInsets padding = new EdgeInsets.fromLTRB(
-        dataColumnIndex == 0 ? showCheckboxColumn ? _kTablePadding / 2.0 : _kTablePadding : _kColumnSpacing / 2.0,
-        0.0,
-        dataColumnIndex == columns.length - 1 ? _kTablePadding : _kColumnSpacing / 2.0,
-        0.0
+      final EdgeInsetsDirectional padding = new EdgeInsetsDirectional.only(
+        start: dataColumnIndex == 0 ? showCheckboxColumn ? _kTablePadding / 2.0 : _kTablePadding : _kColumnSpacing / 2.0,
+        end: dataColumnIndex == columns.length - 1 ? _kTablePadding : _kColumnSpacing / 2.0,
       );
       if (dataColumnIndex == _onlyTextColumn) {
         tableColumns[displayColumnIndex] = const IntrinsicColumnWidth(flex: 1.0);

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

@@ -66,7 +66,7 @@ class Divider extends StatelessWidget {
       child: new Center(
         child: new Container(
           height: 0.0,
-          margin: new EdgeInsets.only(left: indent),
+          margin: new EdgeInsetsDirectional.only(start: indent),
           decoration: new BoxDecoration(
             border: new Border(
               bottom: new BorderSide(

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

@@ -128,7 +128,7 @@ class ExpansionPanelList extends StatelessWidget {
             )
           ),
           new Container(
-            margin: const EdgeInsets.only(right: 8.0),
+            margin: const EdgeInsetsDirectional.only(end: 8.0),
             child: new ExpandIcon(
               isExpanded: _isChildExpanded(i),
               padding: const EdgeInsets.all(16.0),

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

@@ -92,6 +92,20 @@ class _FlexibleSpaceBarState extends State<FlexibleSpaceBar> {
     return null;
   }
 
+  FractionalOffset _getTitleAlignment(bool effectiveCenterTitle) {
+    if (effectiveCenterTitle)
+      return FractionalOffset.bottomCenter;
+    final TextDirection textDirection = Directionality.of(context);
+    assert(textDirection != null);
+    switch (textDirection) {
+      case TextDirection.rtl:
+        return FractionalOffset.bottomRight;
+      case TextDirection.ltr:
+        return FractionalOffset.bottomLeft;
+    }
+    return null;
+  }
+
   @override
   Widget build(BuildContext context) {
     final _FlexibleSpaceBarSettings settings = context.inheritFromWidgetOfExactType(_FlexibleSpaceBarSettings);
@@ -138,10 +152,10 @@ class _FlexibleSpaceBarState extends State<FlexibleSpaceBar> {
         final double scaleValue = new Tween<double>(begin: 1.5, end: 1.0).lerp(t);
         final Matrix4 scaleTransform = new Matrix4.identity()
           ..scale(scaleValue, scaleValue, 1.0);
-        final FractionalOffset titleAlignment = effectiveCenterTitle ? FractionalOffset.bottomCenter : FractionalOffset.bottomLeft;
+        final FractionalOffset titleAlignment = _getTitleAlignment(effectiveCenterTitle);
         children.add(new Container(
-          padding: new EdgeInsets.only(
-            left: effectiveCenterTitle ? 0.0 : 72.0,
+          padding: new EdgeInsetsDirectional.only(
+            start: effectiveCenterTitle ? 0.0 : 72.0,
             bottom: 16.0
           ),
           child: new Transform(

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

@@ -288,7 +288,7 @@ class PaginatedDataTableState extends State<PaginatedDataTable> {
     final ThemeData themeData = Theme.of(context);
     // HEADER
     final List<Widget> headerWidgets = <Widget>[];
-    double leftPadding = 24.0;
+    double startPadding = 24.0;
     if (_selectedRowCount == 0) {
       headerWidgets.add(new Expanded(child: widget.header));
       if (widget.header is ButtonBar) {
@@ -298,7 +298,7 @@ class PaginatedDataTableState extends State<PaginatedDataTable> {
         // pixels internally on each side, yet we want the left edge of the
         // inside of the button to line up with the 24.0 left inset.
         // TODO(ianh): Better magic. See https://github.com/flutter/flutter/issues/4460
-        leftPadding = 12.0;
+        startPadding = 12.0;
       }
     } else if (_selectedRowCount == 1) {
       // TODO(ianh): Real l10n.
@@ -311,7 +311,7 @@ class PaginatedDataTableState extends State<PaginatedDataTable> {
         widget.actions.map<Widget>((Widget action) {
           return new Padding(
             // 8.0 is the default padding of an icon button
-            padding: const EdgeInsets.only(left: 24.0 - 8.0 * 2.0),
+            padding: const EdgeInsetsDirectional.only(start: 24.0 - 8.0 * 2.0),
             child: action,
           );
         }).toList()
@@ -384,7 +384,7 @@ class PaginatedDataTableState extends State<PaginatedDataTable> {
               child: new ButtonTheme.bar(
                 child: new Container(
                   height: 64.0,
-                  padding: new EdgeInsets.fromLTRB(leftPadding, 0.0, 14.0, 0.0),
+                  padding: new EdgeInsetsDirectional.only(start: startPadding, end: 14.0),
                   // TODO(ianh): This decoration will prevent ink splashes from being visible.
                   // Instead, we should have a widget that prints the decoration on the material.
                   // See https://github.com/flutter/flutter/issues/3782

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

@@ -707,7 +707,7 @@ class PopupMenuButton<T> extends StatefulWidget {
   /// Matches IconButton's 8 dps padding by default. In some cases, notably where
   /// this button appears as the trailing element of a list item, it's useful to be able
   /// to set the padding to zero.
-  final EdgeInsets padding;
+  final EdgeInsetsGeometry padding;
 
   /// If provided, the widget used for this button.
   final Widget child;

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

@@ -954,7 +954,7 @@ class _PersistentBottomSheetState extends State<_PersistentBottomSheet> {
       animation: widget.animationController,
       builder: (BuildContext context, Widget child) {
         return new Align(
-          alignment: FractionalOffset.topLeft,
+          alignment: FractionalOffsetDirectional.topStart,
           heightFactor: widget.animationController.value,
           child: child
         );

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

@@ -222,7 +222,7 @@ class SnackBar extends StatelessWidget {
         animation: heightAnimation,
         builder: (BuildContext context, Widget child) {
           return new Align(
-            alignment: FractionalOffset.topLeft,
+            alignment: FractionalOffsetDirectional.topStart,
             heightFactor: heightAnimation.value,
             child: child
           );

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

@@ -26,13 +26,13 @@ class _AccountPictures extends StatelessWidget {
   Widget build(BuildContext context) {
     return new Stack(
       children: <Widget>[
-        new Positioned(
+        new PositionedDirectional(
           top: 0.0,
-          right: 0.0,
+          end: 0.0,
           child: new Row(
             children: (otherAccountsPictures ?? <Widget>[]).take(3).map((Widget picture) {
               return new Container(
-                margin: const EdgeInsets.only(left: 16.0),
+                margin: const EdgeInsetsDirectional.only(start: 16.0),
                 width: 40.0,
                 height: 40.0,
                 child: picture
@@ -70,7 +70,7 @@ class _AccountDetails extends StatelessWidget {
   Widget addDropdownIcon(Widget line) {
     final Widget icon = new Expanded(
       child: new Align(
-        alignment: FractionalOffset.centerRight,
+        alignment: FractionalOffsetDirectional.centerEnd,
         child: new Icon(
           isOpen ? Icons.arrow_drop_up : Icons.arrow_drop_down,
           color: Colors.white

packages/flutter/lib/src/widgets/transitions.dart

@@ -103,7 +103,7 @@ class SlideTransition extends AnimatedWidget {
   /// The [position] argument must not be null.
   const SlideTransition({
     Key key,
-    @required Animation<FractionalOffset> position,
+    @required Animation<FractionalOffsetGeometry> position,
     this.transformHitTests: true,
     this.child,
   }) : super(key: key, listenable: position);
@@ -112,7 +112,7 @@ class SlideTransition extends AnimatedWidget {
   ///
   /// If the current value of the position animation is (dx, dy), the child will
   /// be translated horizontally by width * dx and vertically by height * dy.
-  Animation<FractionalOffset> get position => listenable;
+  Animation<FractionalOffsetGeometry> get position => listenable;
 
   /// Whether hit testing should be affected by the slide animation.
   ///
@@ -244,11 +244,11 @@ class SizeTransition extends AnimatedWidget {
 
   @override
   Widget build(BuildContext context) {
-    FractionalOffset alignment;
+    FractionalOffsetDirectional alignment;
     if (axis == Axis.vertical)
-      alignment = new FractionalOffset(0.0, axisAlignment);
+      alignment = new FractionalOffsetDirectional(0.0, axisAlignment);
     else
-      alignment = new FractionalOffset(axisAlignment, 0.0);
+      alignment = new FractionalOffsetDirectional(axisAlignment, 0.0);
     return new ClipRect(
       child: new Align(
         alignment: alignment,

packages/flutter/test/material/divider_test.dart

@@ -8,7 +8,14 @@ import '../rendering/mock_canvas.dart';
 
 void main() {
   testWidgets('Divider control test', (WidgetTester tester) async {
-    await tester.pumpWidget(const Center(child: const Divider()));
+    await tester.pumpWidget(
+      const Directionality(
+        textDirection: TextDirection.ltr,
+        child: const Center(
+          child: const Divider(),
+        ),
+      ),
+    );
     final RenderBox box = tester.firstRenderObject(find.byType(Divider));
     expect(box.size.height, 16.0);
     expect(find.byType(Divider), paints..path(strokeWidth: 0.0));