BoxDecoration.borderRadius and RoundedRectangleBorder.borderRadius RTL (#12603)

packages/flutter/lib/src/painting/border_radius.dart

@@ -117,8 +117,9 @@ abstract class BorderRadiusGeometry {
 
   /// Linearly interpolate between two [BorderRadiusGeometry] objects.
   ///
-  /// If either is null, this function interpolates from [BorderRadius.zero], and
-  /// the result is an object of the same type as the non-null argument.
+  /// If either is null, this function interpolates from [BorderRadius.zero],
+  /// and the result is an object of the same type as the non-null argument. (If
+  /// both are null, this returns null.)
   ///
   /// If [lerp] is applied to two objects of the same type ([BorderRadius] or
   /// [BorderRadiusDirectional]), an object of that type will be returned (though
@@ -126,6 +127,8 @@ abstract class BorderRadiusGeometry {
   /// representing a combination of both is returned. That object can be turned
   /// into a concrete [BorderRadius] using [resolve].
   static BorderRadiusGeometry lerp(BorderRadiusGeometry a, BorderRadiusGeometry b, double t) {
+    if (a == null && b == null)
+      return null;
     a ??= BorderRadius.zero;
     b ??= BorderRadius.zero;
     return a.add((b.subtract(a)) * t);

packages/flutter/lib/src/painting/box_decoration.dart

@@ -123,7 +123,7 @@ class BoxDecoration extends Decoration {
   ///
   /// Applies only to boxes with rectangular shapes; ignored if [shape] is not
   /// [BoxShape.rectangle].
-  final BorderRadius borderRadius;
+  final BorderRadiusGeometry borderRadius;
 
   /// A list of shadows cast by this box behind the box.
   ///
@@ -159,7 +159,7 @@ class BoxDecoration extends Decoration {
       color: Color.lerp(null, color, factor),
       image: image, // TODO(ianh): fade the image from transparent
       border: BoxBorder.lerp(null, border, factor),
-      borderRadius: BorderRadius.lerp(null, borderRadius, factor),
+      borderRadius: BorderRadiusGeometry.lerp(null, borderRadius, factor),
       boxShadow: BoxShadow.lerpList(null, boxShadow, factor),
       gradient: gradient?.scale(factor),
       shape: shape,
@@ -223,7 +223,7 @@ class BoxDecoration extends Decoration {
       color: Color.lerp(a.color, b.color, t),
       image: t < 0.5 ? a.image : b.image, // TODO(ianh): cross-fade the image
       border: BoxBorder.lerp(a.border, b.border, t),
-      borderRadius: BorderRadius.lerp(a.borderRadius, b.borderRadius, t),
+      borderRadius: BorderRadiusGeometry.lerp(a.borderRadius, b.borderRadius, t),
       boxShadow: BoxShadow.lerpList(a.boxShadow, b.boxShadow, t),
       gradient: Gradient.lerp(a.gradient, b.gradient, t),
       shape: t < 0.5 ? a.shape : b.shape,
@@ -269,20 +269,20 @@ class BoxDecoration extends Decoration {
     properties.add(new DiagnosticsProperty<Color>('color', color, defaultValue: null));
     properties.add(new DiagnosticsProperty<DecorationImage>('image', image, defaultValue: null));
     properties.add(new DiagnosticsProperty<BoxBorder>('border', border, defaultValue: null));
-    properties.add(new DiagnosticsProperty<BorderRadius>('borderRadius', borderRadius, defaultValue: null));
+    properties.add(new DiagnosticsProperty<BorderRadiusGeometry>('borderRadius', borderRadius, defaultValue: null));
     properties.add(new IterableProperty<BoxShadow>('boxShadow', boxShadow, defaultValue: null, style: DiagnosticsTreeStyle.whitespace));
     properties.add(new DiagnosticsProperty<Gradient>('gradient', gradient, defaultValue: null));
     properties.add(new EnumProperty<BoxShape>('shape', shape, defaultValue: BoxShape.rectangle));
   }
 
   @override
-  bool hitTest(Size size, Offset position) {
+  bool hitTest(Size size, Offset position, { TextDirection textDirection }) {
     assert(shape != null);
     assert((Offset.zero & size).contains(position));
     switch (shape) {
       case BoxShape.rectangle:
         if (borderRadius != null) {
-          final RRect bounds = borderRadius.toRRect(Offset.zero & size);
+          final RRect bounds = borderRadius.resolve(textDirection).toRRect(Offset.zero & size);
           return bounds.contains(position);
         }
         return true;
@@ -332,7 +332,7 @@ class _BoxDecorationPainter extends BoxPainter {
     return _cachedBackgroundPaint;
   }
 
-  void _paintBox(Canvas canvas, Rect rect, Paint paint) {
+  void _paintBox(Canvas canvas, Rect rect, Paint paint, TextDirection textDirection) {
     switch (_decoration.shape) {
       case BoxShape.circle:
         assert(_decoration.borderRadius == null);
@@ -344,13 +344,13 @@ class _BoxDecorationPainter extends BoxPainter {
         if (_decoration.borderRadius == null) {
           canvas.drawRect(rect, paint);
         } else {
-          canvas.drawRRect(_decoration.borderRadius.toRRect(rect), paint);
+          canvas.drawRRect(_decoration.borderRadius.resolve(textDirection).toRRect(rect), paint);
         }
         break;
     }
   }
 
-  void _paintShadows(Canvas canvas, Rect rect) {
+  void _paintShadows(Canvas canvas, Rect rect, TextDirection textDirection) {
     if (_decoration.boxShadow == null)
       return;
     for (BoxShadow boxShadow in _decoration.boxShadow) {
@@ -358,13 +358,13 @@ class _BoxDecorationPainter extends BoxPainter {
         ..color = boxShadow.color
         ..maskFilter = new MaskFilter.blur(BlurStyle.normal, boxShadow.blurSigma);
       final Rect bounds = rect.shift(boxShadow.offset).inflate(boxShadow.spreadRadius);
-      _paintBox(canvas, bounds, paint);
+      _paintBox(canvas, bounds, paint, textDirection);
     }
   }
 
-  void _paintBackgroundColor(Canvas canvas, Rect rect) {
+  void _paintBackgroundColor(Canvas canvas, Rect rect, TextDirection textDirection) {
     if (_decoration.color != null || _decoration.gradient != null)
-      _paintBox(canvas, rect, _getBackgroundPaint(rect));
+      _paintBox(canvas, rect, _getBackgroundPaint(rect), textDirection);
   }
 
   ImageStream _imageStream;
@@ -399,7 +399,7 @@ class _BoxDecorationPainter extends BoxPainter {
     if (_decoration.shape == BoxShape.circle)
       clipPath = new Path()..addOval(rect);
     else if (_decoration.borderRadius != null)
-      clipPath = new Path()..addRRect(_decoration.borderRadius.toRRect(rect));
+      clipPath = new Path()..addRRect(_decoration.borderRadius.resolve(configuration.textDirection).toRRect(rect));
     if (clipPath != null) {
       canvas.save();
       canvas.clipPath(clipPath);
@@ -444,8 +444,9 @@ class _BoxDecorationPainter extends BoxPainter {
     assert(configuration != null);
     assert(configuration.size != null);
     final Rect rect = offset & configuration.size;
-    _paintShadows(canvas, rect);
-    _paintBackgroundColor(canvas, rect);
+    final TextDirection textDirection = configuration.textDirection;
+    _paintShadows(canvas, rect, textDirection);
+    _paintBackgroundColor(canvas, rect, textDirection);
     _paintBackgroundImage(canvas, rect, configuration);
     _decoration.border?.paint(
       canvas,

packages/flutter/lib/src/painting/decoration.dart

@@ -122,7 +122,12 @@ abstract class Decoration extends Diagnosticable {
   /// if the decoration only draws a circle, this function might
   /// return true if the point was inside the circle and false
   /// otherwise.
-  bool hitTest(Size size, Offset position) => true;
+  ///
+  /// The decoration may be sensitive to the [TextDirection]. The
+  /// `textDirection` argument should therefore be provided. If it is known that
+  /// the decoration is not affected by the text direction, then the argument
+  /// may be ommitted or set to null.
+  bool hitTest(Size size, Offset position, { TextDirection textDirection }) => true;
 
   /// Returns a [BoxPainter] that will paint this decoration.
   ///

packages/flutter/lib/src/painting/flutter_logo.dart

@@ -195,7 +195,7 @@ class FlutterLogoDecoration extends Decoration {
 
   @override
   // TODO(ianh): better hit testing
-  bool hitTest(Size size, Offset position) => true;
+  bool hitTest(Size size, Offset position, { TextDirection textDirection }) => true;
 
   @override
   BoxPainter createBoxPainter([VoidCallback onChanged]) {

packages/flutter/lib/src/painting/rounded_rectangle_border.dart

@@ -38,7 +38,7 @@ class RoundedRectangleBorder extends ShapeBorder {
   final BorderSide side;
 
   /// The radii for each corner.
-  final BorderRadius borderRadius;
+  final BorderRadiusGeometry borderRadius;
 
   @override
   EdgeInsetsGeometry get dimensions {
@@ -92,13 +92,13 @@ class RoundedRectangleBorder extends ShapeBorder {
   @override
   Path getInnerPath(Rect rect, { TextDirection textDirection }) {
     return new Path()
-      ..addRRect(borderRadius.toRRect(rect).deflate(side.width));
+      ..addRRect(borderRadius.resolve(textDirection).toRRect(rect).deflate(side.width));
   }
 
   @override
   Path getOuterPath(Rect rect, { TextDirection textDirection }) {
     return new Path()
-      ..addRRect(borderRadius.toRRect(rect));
+      ..addRRect(borderRadius.resolve(textDirection).toRRect(rect));
   }
 
   @override
@@ -109,9 +109,9 @@ class RoundedRectangleBorder extends ShapeBorder {
       case BorderStyle.solid:
         final double width = side.width;
         if (width == 0.0) {
-          canvas.drawRRect(borderRadius.toRRect(rect), side.toPaint());
+          canvas.drawRRect(borderRadius.resolve(textDirection).toRRect(rect), side.toPaint());
         } else {
-          final RRect outer = borderRadius.toRRect(rect);
+          final RRect outer = borderRadius.resolve(textDirection).toRRect(rect);
           final RRect inner = outer.deflate(width);
           final Paint paint = new Paint()
             ..color = side.color;

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

@@ -1482,7 +1482,7 @@ class RenderDecoratedBox extends RenderProxyBox {
     @required Decoration decoration,
     DecorationPosition position: DecorationPosition.background,
     ImageConfiguration configuration: ImageConfiguration.empty,
-    RenderBox child
+    RenderBox child,
   }) : assert(decoration != null),
        assert(position != null),
        assert(configuration != null),
@@ -1522,6 +1522,9 @@ class RenderDecoratedBox extends RenderProxyBox {
   /// The settings to pass to the decoration when painting, so that it can
   /// resolve images appropriately. See [ImageProvider.resolve] and
   /// [BoxPainter.paint].
+  ///
+  /// The [ImageConfiguration.textDirection] field is also used by
+  /// direction-sensitive [Decoration]s for painting and hit-testing.
   ImageConfiguration get configuration => _configuration;
   ImageConfiguration _configuration;
   set configuration(ImageConfiguration value) {
@@ -1541,7 +1544,7 @@ class RenderDecoratedBox extends RenderProxyBox {
 
   @override
   bool hitTestSelf(Offset position) {
-    return _decoration.hitTest(size, position);
+    return _decoration.hitTest(size, position, textDirection: configuration.textDirection);
   }
 
   @override

packages/flutter/test/painting/box_decoration_test.dart

@@ -0,0 +1,45 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:flutter/painting.dart';
+
+import '../rendering/mock_canvas.dart';
+
+void main() {
+  test('BoxDecoration with BorderRadiusDirectional', () {
+    final BoxDecoration decoration = const BoxDecoration(
+      color: const Color(0xFF000000),
+      borderRadius: const BorderRadiusDirectional.only(topStart: const Radius.circular(100.0)),
+    );
+    final BoxPainter painter = decoration.createBoxPainter();
+    const Size size = const Size(1000.0, 1000.0);
+    expect(
+      (Canvas canvas) {
+        painter.paint(
+          canvas,
+          const Offset(0.0, 0.0),
+          const ImageConfiguration(size: size, textDirection: TextDirection.rtl),
+        );
+      },
+      paints
+        ..rrect(rrect: new RRect.fromRectAndCorners(Offset.zero & size, topRight: const Radius.circular(100.0)))
+    );
+    expect(decoration.hitTest(size, const Offset(10.0, 10.0), textDirection: TextDirection.rtl), isTrue);
+    expect(decoration.hitTest(size, const Offset(990.0, 10.0), textDirection: TextDirection.rtl), isFalse);
+    expect(
+      (Canvas canvas) {
+        painter.paint(
+          canvas,
+          const Offset(0.0, 0.0),
+          const ImageConfiguration(size: size, textDirection: TextDirection.ltr),
+        );
+      },
+      paints
+        ..rrect(rrect: new RRect.fromRectAndCorners(Offset.zero & size, topLeft: const Radius.circular(100.0)))
+    );
+    expect(decoration.hitTest(size, const Offset(10.0, 10.0), textDirection: TextDirection.ltr), isFalse);
+    expect(decoration.hitTest(size, const Offset(990.0, 10.0), textDirection: TextDirection.ltr), isTrue);
+  });
+}

packages/flutter/test/widgets/transitions_test.dart

@@ -138,7 +138,7 @@ void main() {
       expect(border.left.width, closeTo(1.9, 0.1));
       expect(border.left.style, BorderStyle.solid);
       expect(border.left.color, const Color(0xFF151515));
-      expect(actualDecoration.borderRadius.topLeft.x, closeTo(6.8, 0.1));
+      expect(actualDecoration.borderRadius.resolve(TextDirection.ltr).topLeft.x, closeTo(6.8, 0.1));
       expect(actualDecoration.shape, BoxShape.rectangle);
       expect(actualDecoration.boxShadow[0].blurRadius, closeTo(3.1, 0.1));
       expect(actualDecoration.boxShadow[0].spreadRadius, closeTo(1.2, 0.1));