Initial implementation of SnackBar

sky/sdk/lib/widgets/snack_bar.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 'dart:sky' as sky;
+
+import '../painting/text_style.dart';
+import '../theme/typography.dart' as typography;
+import 'flat_button.dart';
+import 'basic.dart';
+import 'default_text_style.dart';
+import 'material.dart';
+import 'theme.dart';
+
+class SnackBarAction extends Component {
+  SnackBarAction({String key, this.label, this.onPressed }) : super(key: key) {
+    assert(label != null);
+  }
+
+  final String label;
+  final Function onPressed;
+
+  void syncFields(SnackBarAction source) {
+    label = source.label;
+    onPressed = source.onPressed;
+    super.syncFields(source);
+  }

[abarth-chromium, 2015/07/06 15:16:45]

We should probably remove this function.  |label| and |onPressed| are final, so
this function will throw if called.  Fortuantely, SnackBarAction isn't stateful,
so this function never gets called.

[jackson, 2015/07/06 15:30:58]

Agree, but as we discussed, we should probably have stateful components inherit
from StatefulComponent rather than passing a boolean to super so you can't
forget to implement this function when you start adding state to a component and
you'll get an analyzer warning when you try to call super.syncFields on a
stateless component. I will investigate.

+
+  Widget build() {
+    return new Listener(
+      onGestureTap: (_) => onPressed(),
+      child: new Container(
+        margin: const EdgeDims.only(left: 24.0),
+        padding: const EdgeDims.only(top: 14.0, bottom: 14.0),
+        child: new Text(label)
+      )
+    );
+  }
+}
+
+class SnackBar extends Component {
+
+  SnackBar({
+    String key,
+    this.content,
+    this.actions
+  }) : super(key: key) {
+    assert(content != null);
+  }
+
+  final Widget content;
+  final List<SnackBarAction> actions;
+
+  void syncFields(SnackBar source) {
+    content = source.children;
+    actions = source.actions;
+    super.syncFields(source);
+  }

[abarth-chromium, 2015/07/06 15:16:45]

ditto

+
+  Widget build() {
+    List<Widget> children = [
+      new Flexible(
+        child: new Container(
+          margin: const EdgeDims.symmetric(vertical: 14.0),
+          child: new DefaultTextStyle(
+            style: typography.white.subhead,
+            child: content
+          )
+        )
+      )
+    ]..addAll(actions);
+    return new Material(
+      level: 2,
+      color: const Color(0xFF323232),
+      type: MaterialType.canvas,
+      child: new Container(
+        margin: const EdgeDims.symmetric(horizontal: 24.0),

[abarth-chromium, 2015/07/06 15:16:45]

Why margin rather than padding?  I guess it does't matter since this container
does't have a background color.

[jackson, 2015/07/06 15:30:58]

Yeah.

+        child: new DefaultTextStyle(
+          style: new TextStyle(color: Theme.of(this).accentColor),
+          child: new Flex(children)
+        )
+      )
+    );
+  }
+}