Wrapping leaf nodes in non polymer elements

runtime/observatory/lib/src/elements/vm_connect_target_wrapper.dart

+// Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
+// for details. 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:html';
+import 'package:observatory/app.dart';
+import 'package:observatory/service_html.dart';
+import 'vm_connect_target.dart';
+import 'shims/binding.dart';
+import 'helpers/tag.dart';
+
+class VmConnectTargetElementWrapper extends HtmlElement {
+  static final binder = new Binder<VmConnectTargetElementWrapper>(
+    const [const Binding('target')]);
+
+  static const tag =
+    const Tag<VmConnectTargetElementWrapper>('vm-connect-target');
+
+  WebSocketVMTarget _target;
+  WebSocketVMTarget get target => _target;
+  void set target(WebSocketVMTarget target) { _target = target; render(); }
+
+  VmConnectTargetElementWrapper.created() : super.created() {
+    binder.registerCallback(this);
+    createShadowRoot();
+    render();
+  }
+
+  @override
+  void attached() {
+    super.attached();
+    render();
+  }
+
+  void render() {
+    if (target == null) return;
+
+    shadowRoot.children = [
+      new VmConnectTargetElement(target: target, isCurrent: isCurrent)
+        ..onConnect.listen(connectToVm)
+        ..onDelete.listen(deleteVm)
+    ];
+  }
+
+  static ObservatoryApplication get application => ObservatoryApplication.app;
+
+  bool get isCurrent {
+    if (application.vm == null) { return false; }
+    return (application.vm as WebSocketVM).target == target;
+  }
+
+  static void connectToVm(WebSocketVMTargetEvent event) {
+    WebSocketVM currentVM = application.vm;
+    if ((currentVM == null) ||
+        currentVM.isDisconnected ||
+        (currentVM.target != event.target)) {
+      application.vm = new WebSocketVM(event.target);
+    }
+  }
+
+  static void deleteVm(WebSocketVMTargetEvent event) {
+    application.targets.remove(event.target);
+  }
+}