Add LayoutRoot

sky/examples/spinning_arabic.dart

Index: sky/examples/spinning_arabic.dart
diff --git a/sky/examples/spinning_arabic.dart b/sky/examples/spinning_arabic.dart
new file mode 100644
index 0000000000000000000000000000000000000000..0c4eac1996f9e0f39f1767aa37cabb54d8aaa5da
--- /dev/null
+++ b/sky/examples/spinning_arabic.dart
@@ -0,0 +1,47 @@
+// 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:math" as math;
+import 'dart:sky';
+
+double timeBase = null;
+LayoutRoot layoutRoot = new LayoutRoot();
+
+void beginFrame(double timeStamp) {
+  if (timeBase == null)
+    timeBase = timeStamp;
+  double delta = timeStamp - timeBase;
+  PictureRecorder canvas = new PictureRecorder(view.width, view.height);
+  canvas.translate(view.width / 2.0, view.height / 2.0);
+  canvas.rotateDegrees(delta / 10);
+  canvas.drawRect(new Rect()..setLTRB(-100.0, -100.0, 100.0, 100.0),
+                  new Paint()..setARGB(255, 0, 255, 0));
+
+  double sin = math.sin(delta / 200);
+  layoutRoot.maxWidth = 150.0 + (50 * sin);
+  layoutRoot.layout();

[Hixie, 2015/05/26 18:07:16]

Why do you layout() on the layoutRoot, but paint() on the layoutRoot.rootElement
?

[eseidel, 2015/05/26 19:13:05]

No good reason.  I can trivially add paint() to the layout root object.

+
+  canvas.translate(layoutRoot.maxWidth / -2.0, (layoutRoot.maxWidth / 2.0) - 125);
+  layoutRoot.rootElement.paint(canvas);
+
+  view.picture = canvas.endRecording();
+  view.scheduleFrame();
+}
+
+void main() {
+  var document = new Document();
+  var arabic = document.createText("هذا هو قليلا طويلة من النص الذي يجب التفاف .");
+  var more = document.createText(" و أكثر قليلا لجعله أطول. ");
+  var block = document.createElement('p');
+  block.style['display'] = 'paragraph';
+  block.style['direction'] = 'rtl';
+  block.style['unicode-bidi'] = 'plaintext';
+  block.appendChild(arabic);
+  block.appendChild(more);
+
+  layoutRoot.rootElement = block;
+
+  view.setBeginFrameCallback(beginFrame);
+  view.scheduleFrame();
+}