Add support for RTL to Wrap (#11809)

Fixes #11389

packages/flutter/lib/src/rendering/flex.dart

@@ -359,8 +359,8 @@ class RenderFlex extends RenderBox with ContainerRenderObjectMixin<RenderBox, Fl
   /// Determines the order to lay children out horizontally and how to interpret
   /// `start` and `end` in the horizontal direction.
   ///
-  /// If the [direction] is [Axis.horizontal], this controls which order
-  /// children are painted in (left-to-right or right-to-left), and the meaning
+  /// If the [direction] is [Axis.horizontal], this controls the order in which
+  /// children are positioned (left-to-right or right-to-left), and the meaning
   /// of the [mainAxisAlignment] property's [MainAxisAlignment.start] and
   /// [MainAxisAlignment.end] values.
   ///

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

@@ -2740,9 +2740,9 @@ class Flex extends MultiChildRenderObjectWidget {
   ///
   /// Defaults to the ambient [Directionality].
   ///
-  /// If the [direction] is [Axis.horizontal], this controls which order
-  /// children are painted in (left-to-right or right-to-left), and the meaning
-  /// of the [mainAxisAlignment] property's [MainAxisAlignment.start] and
+  /// If the [direction] is [Axis.horizontal], this controls the order in which
+  /// the children are positioned (left-to-right or right-to-left), and the
+  /// meaning of the [mainAxisAlignment] property's [MainAxisAlignment.start] and
   /// [MainAxisAlignment.end] values.
   ///
   /// If the [direction] is [Axis.horizontal], and either the
@@ -3321,6 +3321,12 @@ class Wrap extends MultiChildRenderObjectWidget {
   ///
   /// By default, the wrap layout is horizontal and both the children and the
   /// runs are aligned to the start.
+  ///
+  /// The [textDirection] argument defaults to the ambient [Directionality], if
+  /// any. If there is no ambient directionality, and a text direction is going
+  /// to be necessary to decide which direction to lay the children in or to
+  /// disambiguate `start` or `end` values for the main or cross axis
+  /// directions, the [textDirection] must not be null.
   Wrap({
     Key key,
     this.direction: Axis.horizontal,
@@ -3329,6 +3335,8 @@ class Wrap extends MultiChildRenderObjectWidget {
     this.runAlignment: WrapAlignment.start,
     this.runSpacing: 0.0,
     this.crossAxisAlignment: WrapCrossAlignment.start,
+    this.textDirection,
+    this.verticalDirection: VerticalDirection.down,
     List<Widget> children: const <Widget>[],
   }) : super(key: key, children: children);
 
@@ -3412,6 +3420,58 @@ class Wrap extends MultiChildRenderObjectWidget {
   ///    other in the cross axis.
   final WrapCrossAlignment crossAxisAlignment;
 
+  /// Determines the order to lay children out horizontally and how to interpret
+  /// `start` and `end` in the horizontal direction.
+  ///
+  /// Defaults to the ambient [Directionality].
+  ///
+  /// If the [direction] is [Axis.horizontal], this controls order in which the
+  /// children are positioned (left-to-right or right-to-left), and the meaning
+  /// of the [alignment] property's [WrapAlignment.start] and
+  /// [WrapAlignment.end] values.
+  ///
+  /// If the [direction] is [Axis.horizontal], and either the
+  /// [alignment] is either [WrapAlignment.start] or [WrapAlignment.end], or
+  /// there's more than one child, then the [textDirection] (or the ambient
+  /// [Directionality]) must not be null.
+  ///
+  /// If the [direction] is [Axis.vertical], this controls the order in which
+  /// runs are positioned, the meaning of the [runAlignment] property's
+  /// [WrapAlignment.start] and [WrapAlignment.end] values, as well as the
+  /// [crossAxisAlignment] property's [WrapCrossAlignment.start] and
+  /// [WrapCrossAlignment.end] values.
+  ///
+  /// If the [direction] is [Axis.vertical], and either the
+  /// [runAlignment] is either [WrapAlignment.start] or [WrapAlignment.end], the
+  /// [crossAxisAlignment] is either [WrapCrossAlignment.start] or
+  /// [WrapCrossAlignment.end], or there's more than one child, then the
+  /// [textDirection] (or the ambient [Directionality]) must not be null.
+  final TextDirection textDirection;
+
+  /// Determines the order to lay children out vertically and how to interpret
+  /// `start` and `end` in the vertical direction.
+  ///
+  /// If the [direction] is [Axis.vertical], this controls which order children
+  /// are painted in (down or up), the meaning of the [alignment] property's
+  /// [WrapAlignment.start] and [WrapAlignment.end] values.
+  ///
+  /// If the [direction] is [Axis.vertical], and either the [alignment]
+  /// is either [WrapAlignment.start] or [WrapAlignment.end], or there's
+  /// more than one child, then the [verticalDirection] must not be null.
+  ///
+  /// If the [direction] is [Axis.horizontal], this controls the order in which
+  /// runs are positioned, the meaning of the [runAlignment] property's
+  /// [WrapAlignment.start] and [WrapAlignment.end] values, as well as the
+  /// [crossAxisAlignment] property's [WrapCrossAlignment.start] and
+  /// [WrapCrossAlignment.end] values.
+  ///
+  /// If the [direction] is [Axis.horizontal], and either the
+  /// [runAlignment] is either [WrapAlignment.start] or [WrapAlignment.end], the
+  /// [crossAxisAlignment] is either [WrapCrossAlignment.start] or
+  /// [WrapCrossAlignment.end], or there's more than one child, then the
+  /// [verticalDirection] must not be null.
+  final VerticalDirection verticalDirection;
+
   @override
   RenderWrap createRenderObject(BuildContext context) {
     return new RenderWrap(
@@ -3421,6 +3481,8 @@ class Wrap extends MultiChildRenderObjectWidget {
       runAlignment: runAlignment,
       runSpacing: runSpacing,
       crossAxisAlignment: crossAxisAlignment,
+      textDirection: textDirection ?? Directionality.of(context),
+      verticalDirection: verticalDirection,
     );
   }
 
@@ -3432,7 +3494,22 @@ class Wrap extends MultiChildRenderObjectWidget {
       ..spacing = spacing
       ..runAlignment = runAlignment
       ..runSpacing = runSpacing
-      ..crossAxisAlignment = crossAxisAlignment;
+      ..crossAxisAlignment = crossAxisAlignment
+      ..textDirection = textDirection ?? Directionality.of(context)
+      ..verticalDirection = verticalDirection;
+  }
+
+  @override
+  void debugFillProperties(DiagnosticPropertiesBuilder description) {
+    super.debugFillProperties(description);
+    description.add(new EnumProperty<Axis>('direction', direction));
+    description.add(new EnumProperty<WrapAlignment>('alignment', alignment));
+    description.add(new DoubleProperty('spacing', spacing));
+    description.add(new EnumProperty<WrapAlignment>('runAlignment', runAlignment));
+    description.add(new DoubleProperty('runSpacing', runSpacing));
+    description.add(new DoubleProperty('crossAxisAlignment', runSpacing));
+    description.add(new EnumProperty<TextDirection>('textDirection', textDirection, defaultValue: null));
+    description.add(new EnumProperty<VerticalDirection>('verticalDirection', verticalDirection, defaultValue: VerticalDirection.down));
   }
 }