Merge pull request #1164 from Hixie/AnimatedPositioned

AnimatedPositioned

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

@@ -1023,15 +1023,15 @@ class Positioned extends ParentDataWidget<StackRenderObjectWidgetBase> {
   Positioned({
     Key key,
     Widget child,
+    this.left,
     this.top,
     this.right,
     this.bottom,
-    this.left,
     this.width,
     this.height
   }) : super(key: key, child: child) {
-    assert(top == null || bottom == null || height == null);
     assert(left == null || right == null || width == null);
+    assert(top == null || bottom == null || height == null);
   }
 
   Positioned.fromRect({
@@ -1046,6 +1046,9 @@ class Positioned extends ParentDataWidget<StackRenderObjectWidgetBase> {
        bottom = null,
        super(key: key, child: child);
 
+  /// The offset of the child's left edge from the left of the stack.
+  final double left;
+
   /// The offset of the child's top edge from the top of the stack.
   final double top;
 
@@ -1055,17 +1058,16 @@ class Positioned extends ParentDataWidget<StackRenderObjectWidgetBase> {
   /// The offset of the child's bottom edge from the bottom of the stack.
   final double bottom;
 
-  /// The offset of the child's left edge from the left of the stack.
-  final double left;
-
   /// The child's width.
   ///
-  /// Ignored if both left and right are non-null.
+  /// Only two out of the three horizontal values (left, right, width) can be
+  /// set. The third must be null.
   final double width;
 
   /// The child's height.
   ///
-  /// Ignored if both top and bottom are non-null.
+  /// Only two out of the three vertical values (top, bottom, height) can be
+  /// set. The third must be null.
   final double height;
 
   void applyParentData(RenderObject renderObject) {
@@ -1073,6 +1075,11 @@ class Positioned extends ParentDataWidget<StackRenderObjectWidgetBase> {
     final StackParentData parentData = renderObject.parentData;
     bool needsLayout = false;
 
+    if (parentData.left != left) {
+      parentData.left = left;
+      needsLayout = true;
+    }
+
     if (parentData.top != top) {
       parentData.top = top;
       needsLayout = true;
@@ -1088,11 +1095,6 @@ class Positioned extends ParentDataWidget<StackRenderObjectWidgetBase> {
       needsLayout = true;
     }
 
-    if (parentData.left != left) {
-      parentData.left = left;
-      needsLayout = true;
-    }
-
     if (parentData.width != width) {
       parentData.width = width;
       needsLayout = true;

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

@@ -226,7 +226,11 @@ class AnimatedRelativeRectValue extends AnimatedValue<RelativeRect> {
   RelativeRect lerp(double t) => RelativeRect.lerp(begin, end, t);
 }
 
-/// Animated version of [Positioned].
+/// Animated version of [Positioned] which takes a specific
+/// [AnimatedRelativeRectValue] and a [PerformanceView] to transition the
+/// child's position from a start position to and end position over the lifetime
+/// of the performance.
+///
 /// Only works if it's the child of a [Stack].
 class PositionedTransition extends TransitionWithChild {
   PositionedTransition({

packages/flutter/lib/widgets.dart

@@ -5,7 +5,6 @@
 /// The Flutter widget framework.
 library widgets;
 
-export 'src/widgets/animated_container.dart';
 export 'src/widgets/basic.dart';
 export 'src/widgets/binding.dart';
 export 'src/widgets/dismissable.dart';
@@ -18,6 +17,7 @@ export 'src/widgets/gesture_detector.dart';
 export 'src/widgets/gridpaper.dart';
 export 'src/widgets/heroes.dart';
 export 'src/widgets/homogeneous_viewport.dart';
+export 'src/widgets/implicit_animations.dart';
 export 'src/widgets/locale_query.dart';
 export 'src/widgets/media_query.dart';
 export 'src/widgets/mimic.dart';

packages/flutter/test/widget/animated_container_test.dart

@@ -30,7 +30,7 @@ void main() {
         )
       );
 
-      RenderDecoratedBox box = key.currentState.context.findRenderObject();
+      RenderDecoratedBox box = key.currentContext.findRenderObject();
       actualDecoration = box.decoration;
       expect(actualDecoration.backgroundColor, equals(decorationA.backgroundColor));
 
@@ -42,7 +42,7 @@ void main() {
         )
       );
 
-      expect(key.currentState.context.findRenderObject(), equals(box));
+      expect(key.currentContext.findRenderObject(), equals(box));
       actualDecoration = box.decoration;
       expect(actualDecoration.backgroundColor, equals(decorationA.backgroundColor));
 

packages/flutter/test/widget/animated_positioned_test.dart

+// Copyright 2015 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/rendering.dart';
+import 'package:flutter/widgets.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('AnimatedPositioned - basics', () {
+    testWidgets((WidgetTester tester) {
+      GlobalKey key = new GlobalKey();
+
+      RenderBox box;
+
+      tester.pumpWidget(
+        new Stack(
+          <Widget>[
+            new AnimatedPositioned(
+              child: new Container(key: key),
+              left: 50.0,
+              top: 30.0,
+              width: 70.0,
+              height: 110.0,
+              duration: const Duration(seconds: 2)
+            )
+          ]
+        )
+      );
+
+      box = key.currentContext.findRenderObject();
+      expect(box.localToGlobal(box.size.center(Point.origin)), equals(const Point(50.0 + 70.0 / 2.0, 30.0 + 110.0 / 2.0)));
+
+      tester.pump(const Duration(seconds: 1));
+
+      box = key.currentContext.findRenderObject();
+      expect(box.localToGlobal(box.size.center(Point.origin)), equals(const Point(50.0 + 70.0 / 2.0, 30.0 + 110.0 / 2.0)));
+
+      tester.pumpWidget(
+        new Stack(
+          <Widget>[
+            new AnimatedPositioned(
+              child: new Container(key: key),
+              left: 37.0,
+              top: 31.0,
+              width: 59.0,
+              height: 71.0,
+              duration: const Duration(seconds: 2)
+            )
+          ]
+        )
+      );
+
+      box = key.currentContext.findRenderObject();
+      expect(box.localToGlobal(box.size.center(Point.origin)), equals(const Point(50.0 + 70.0 / 2.0, 30.0 + 110.0 / 2.0)));
+
+      tester.pump(const Duration(seconds: 1));
+
+      box = key.currentContext.findRenderObject();
+      expect(box.localToGlobal(box.size.center(Point.origin)), equals(const Point(50.0 - (50.0 - 37.0) / 2.0 + (70.0 - (70.0 - 59.0) / 2.0) / 2.0,
+                                                                                  30.0 + (31.0 - 30.0) / 2.0 + (110.0 - (110.0 - 71.0) / 2.0) / 2.0)));
+
+      tester.pump(const Duration(seconds: 1));
+
+      box = key.currentContext.findRenderObject();
+      expect(box.localToGlobal(box.size.center(Point.origin)), equals(const Point(37.0 + 59.0 / 2.0, 31.0 + 71.0 / 2.0)));
+
+    });
+  });
+
+  test('AnimatedPositioned - interrupted animation', () {
+    testWidgets((WidgetTester tester) {
+      GlobalKey key = new GlobalKey();
+
+      RenderBox box;
+
+      tester.pumpWidget(
+        new Stack(
+          <Widget>[
+            new AnimatedPositioned(
+              child: new Container(key: key),
+              left: 0.0,
+              top: 0.0,
+              width: 100.0,
+              height: 100.0,
+              duration: const Duration(seconds: 2)
+            )
+          ]
+        )
+      );
+
+      box = key.currentContext.findRenderObject();
+      expect(box.localToGlobal(box.size.center(Point.origin)), equals(const Point(50.0, 50.0)));
+
+      tester.pump(const Duration(seconds: 1));
+
+      box = key.currentContext.findRenderObject();
+      expect(box.localToGlobal(box.size.center(Point.origin)), equals(const Point(50.0, 50.0)));
+
+      tester.pumpWidget(
+        new Stack(
+          <Widget>[
+            new AnimatedPositioned(
+              child: new Container(key: key),
+              left: 100.0,
+              top: 100.0,
+              width: 100.0,
+              height: 100.0,
+              duration: const Duration(seconds: 2)
+            )
+          ]
+        )
+      );
+
+      box = key.currentContext.findRenderObject();
+      expect(box.localToGlobal(box.size.center(Point.origin)), equals(const Point(50.0, 50.0)));
+
+      tester.pump(const Duration(seconds: 1));
+
+      box = key.currentContext.findRenderObject();
+      expect(box.localToGlobal(box.size.center(Point.origin)), equals(const Point(100.0, 100.0)));
+
+      tester.pumpWidget(
+        new Stack(
+          <Widget>[
+            new AnimatedPositioned(
+              child: new Container(key: key),
+              left: 150.0,
+              top: 150.0,
+              width: 100.0,
+              height: 100.0,
+              duration: const Duration(seconds: 2)
+            )
+          ]
+        )
+      );
+
+      box = key.currentContext.findRenderObject();
+      expect(box.localToGlobal(box.size.center(Point.origin)), equals(const Point(100.0, 100.0)));
+
+      tester.pump(const Duration(seconds: 1));
+
+      box = key.currentContext.findRenderObject();
+      expect(box.localToGlobal(box.size.center(Point.origin)), equals(const Point(150.0, 150.0)));
+
+      tester.pump(const Duration(seconds: 1));
+
+      box = key.currentContext.findRenderObject();
+      expect(box.localToGlobal(box.size.center(Point.origin)), equals(const Point(200.0, 200.0)));
+
+    });
+  });
+
+  test('AnimatedPositioned - switching variables', () {
+    testWidgets((WidgetTester tester) {
+      GlobalKey key = new GlobalKey();
+
+      RenderBox box;
+
+      tester.pumpWidget(
+        new Stack(
+          <Widget>[
+            new AnimatedPositioned(
+              child: new Container(key: key),
+              left: 0.0,
+              top: 0.0,
+              width: 100.0,
+              height: 100.0,
+              duration: const Duration(seconds: 2)
+            )
+          ]
+        )
+      );
+
+      box = key.currentContext.findRenderObject();
+      expect(box.localToGlobal(box.size.center(Point.origin)), equals(const Point(50.0, 50.0)));
+
+      tester.pump(const Duration(seconds: 1));
+
+      box = key.currentContext.findRenderObject();
+      expect(box.localToGlobal(box.size.center(Point.origin)), equals(const Point(50.0, 50.0)));
+
+      tester.pumpWidget(
+        new Stack(
+          <Widget>[
+            new AnimatedPositioned(
+              child: new Container(key: key),
+              left: 0.0,
+              top: 100.0,
+              right: 100.0, // 700.0 from the left
+              height: 100.0,
+              duration: const Duration(seconds: 2)
+            )
+          ]
+        )
+      );
+
+      box = key.currentContext.findRenderObject();
+      expect(box.localToGlobal(box.size.center(Point.origin)), equals(const Point(350.0, 50.0)));
+
+      tester.pump(const Duration(seconds: 1));
+
+      box = key.currentContext.findRenderObject();
+      expect(box.localToGlobal(box.size.center(Point.origin)), equals(const Point(350.0, 100.0)));
+
+      tester.pump(const Duration(seconds: 1));
+
+      box = key.currentContext.findRenderObject();
+      expect(box.localToGlobal(box.size.center(Point.origin)), equals(const Point(350.0, 150.0)));
+
+    });
+  });
+
+}