Index: sky/sdk/lib/framework/rendering/render_flex.dart |
diff --git a/sky/sdk/lib/framework/rendering/render_flex.dart b/sky/sdk/lib/framework/rendering/render_flex.dart |
new file mode 100644 |
index 0000000000000000000000000000000000000000..9e9d8ed0ad6f812edd5805b0b66fc215676ca5dc |
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+++ b/sky/sdk/lib/framework/rendering/render_flex.dart |
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+// 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 'dart:sky' as sky; |
+import 'render_node.dart'; |
+import 'render_box.dart'; |
+import 'render_node.dart'; |
+ |
+class FlexBoxParentData extends BoxParentData with ContainerParentDataMixin<RenderBox> { |
+ int flex; |
+ void merge(FlexBoxParentData other) { |
+ if (other.flex != null) |
+ flex = other.flex; |
+ super.merge(other); |
+ } |
+} |
+ |
+enum FlexDirection { Horizontal, Vertical } |
+ |
+class RenderFlex extends RenderBox with ContainerRenderNodeMixin<RenderBox, FlexBoxParentData>, |
+ RenderBoxContainerDefaultsMixin<RenderBox, FlexBoxParentData> { |
+ // lays out RenderBox children using flexible layout |
+ |
+ RenderFlex({ |
+ FlexDirection direction: FlexDirection.Horizontal |
+ }) : _direction = direction; |
+ |
+ FlexDirection _direction; |
+ FlexDirection get direction => _direction; |
+ void set direction (FlexDirection value) { |
+ if (_direction != value) { |
+ _direction = value; |
+ markNeedsLayout(); |
+ } |
+ } |
+ |
+ void setParentData(RenderBox child) { |
+ if (child.parentData is! FlexBoxParentData) |
+ child.parentData = new FlexBoxParentData(); |
+ } |
+ |
+ bool get sizedByParent => true; |
+ void performResize() { |
+ size = constraints.constrain(new sky.Size(constraints.maxWidth, constraints.maxHeight)); |
+ assert(size.height < double.INFINITY); |
+ assert(size.width < double.INFINITY); |
+ } |
+ |
+ int _getFlex(RenderBox child) { |
+ assert(child.parentData is FlexBoxParentData); |
+ return child.parentData.flex != null ? child.parentData.flex : 0; |
+ } |
+ |
+ void performLayout() { |
+ // Based on http://www.w3.org/TR/css-flexbox-1/ Section 9.7 Resolving Flexible Lengths |
+ // Steps 1-3. Determine used flex factor, size inflexible items, calculate free space |
+ int totalFlex = 0; |
+ assert(constraints != null); |
+ double freeSpace = (_direction == FlexDirection.Horizontal) ? constraints.maxWidth : constraints.maxHeight; |
+ RenderBox child = firstChild; |
+ while (child != null) { |
+ int flex = _getFlex(child); |
+ if (flex > 0) { |
+ totalFlex += child.parentData.flex; |
+ } else { |
+ BoxConstraints innerConstraints = new BoxConstraints(maxHeight: constraints.maxHeight, |
+ maxWidth: constraints.maxWidth); |
+ child.layout(innerConstraints, parentUsesSize: true); |
+ freeSpace -= (_direction == FlexDirection.Horizontal) ? child.size.width : child.size.height; |
+ } |
+ child = child.parentData.nextSibling; |
+ } |
+ |
+ // Steps 4-5. Distribute remaining space to flexible children. |
+ double spacePerFlex = totalFlex > 0 ? (freeSpace / totalFlex) : 0.0; |
+ double usedSpace = 0.0; |
+ child = firstChild; |
+ while (child != null) { |
+ int flex = _getFlex(child); |
+ if (flex > 0) { |
+ double spaceForChild = spacePerFlex * flex; |
+ BoxConstraints innerConstraints; |
+ switch (_direction) { |
+ case FlexDirection.Horizontal: |
+ innerConstraints = new BoxConstraints(maxHeight: constraints.maxHeight, |
+ minWidth: spaceForChild, |
+ maxWidth: spaceForChild); |
+ break; |
+ case FlexDirection.Vertical: |
+ innerConstraints = new BoxConstraints(minHeight: spaceForChild, |
+ maxHeight: spaceForChild, |
+ maxWidth: constraints.maxWidth); |
+ break; |
+ } |
+ child.layout(innerConstraints, parentUsesSize: true); |
+ } |
+ |
+ // For now, center the flex items in the cross direction |
+ switch (_direction) { |
+ case FlexDirection.Horizontal: |
+ child.parentData.position = new sky.Point(usedSpace, size.height / 2.0 - child.size.height / 2.0); |
+ usedSpace += child.size.width; |
+ break; |
+ case FlexDirection.Vertical: |
+ child.parentData.position = new sky.Point(size.width / 2.0 - child.size.width / 2.0, usedSpace); |
+ usedSpace += child.size.height; |
+ break; |
+ } |
+ child = child.parentData.nextSibling; |
+ } |
+ } |
+ |
+ void hitTestChildren(HitTestResult result, { sky.Point position }) { |
+ defaultHitTestChildren(result, position: position); |
+ } |
+ |
+ void paint(RenderNodeDisplayList canvas) { |
+ defaultPaint(canvas); |
+ } |
+} |