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1 // Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file | 1 // Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file |
2 // for details. All rights reserved. Use of this source code is governed by a | 2 // for details. All rights reserved. Use of this source code is governed by a |
3 // BSD-style license that can be found in the LICENSE file. | 3 // BSD-style license that can be found in the LICENSE file. |
4 | 4 |
5 /// Provides support for associating a Dart type for Javascript Custom Elements. | 5 /// Provides support for associating a Dart type for Javascript Custom Elements. |
6 /// This will not work unless `dart_support.js` is loaded. | 6 /// This will not work unless `dart_support.js` is loaded. |
7 library web_components.interop; | 7 library web_components.interop; |
8 | 8 |
9 import 'dart:async' show Stream, StreamController; | 9 import 'dart:async' show Stream, StreamController; |
10 import 'dart:html' show document, Element; | 10 import 'dart:html' show document, Element; |
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22 void registerDartType(String tagName, Type dartType, {String extendsTag}) { | 22 void registerDartType(String tagName, Type dartType, {String extendsTag}) { |
23 if (!isSupported) { | 23 if (!isSupported) { |
24 throw new UnsupportedError("Couldn't find " | 24 throw new UnsupportedError("Couldn't find " |
25 "`document._registerDartTypeUpgrader`. Please make sure that " | 25 "`document._registerDartTypeUpgrader`. Please make sure that " |
26 "`packages/web_components/dart_support.js` is loaded and available " | 26 "`packages/web_components/dart_support.js` is loaded and available " |
27 "before calling this function."); | 27 "before calling this function."); |
28 } | 28 } |
29 | 29 |
30 var upgrader = document.createElementUpgrader( | 30 var upgrader = document.createElementUpgrader( |
31 dartType, extendsTag: extendsTag); | 31 dartType, extendsTag: extendsTag); |
32 _doc.callMethod('_registerDartTypeUpgrader', [tagName, upgrader.upgrade]); | 32 |
| 33 // Unfortunately the dart:html upgrader will throw on an already-upgraded |
| 34 // element, so we need to duplicate the type check to prevent that. |
| 35 // An element can be upgraded twice if it extends another element and calls |
| 36 // createdCallback on the superclass. Since that's a valid use case we must |
| 37 // wrap at both levels, and guard against it here. |
| 38 upgradeElement(e) { |
| 39 if (e.runtimeType != dartType) upgrader.upgrade(e); |
| 40 } |
| 41 |
| 42 _doc.callMethod('_registerDartTypeUpgrader', [tagName, upgradeElement]); |
33 } | 43 } |
34 | 44 |
35 /// This function is mainly used to save resources. By default, we save a log of | 45 /// This function is mainly used to save resources. By default, we save a log of |
36 /// elements that are created but have no Dart type associated with them. This | 46 /// elements that are created but have no Dart type associated with them. This |
37 /// is so we can upgrade them as soon as [registerDartType] is invoked. This | 47 /// is so we can upgrade them as soon as [registerDartType] is invoked. This |
38 /// function can be called to indicate that we no longer are interested in | 48 /// function can be called to indicate that we no longer are interested in |
39 /// logging element creations and that it is sufficient to only upgrade new | 49 /// logging element creations and that it is sufficient to only upgrade new |
40 /// elements as they are being created. Typically this is called after the last | 50 /// elements as they are being created. Typically this is called after the last |
41 /// call to [registerDartType] or as soon as you know that no element will be | 51 /// call to [registerDartType] or as soon as you know that no element will be |
42 /// created until the call to [registerDartType] is made. | 52 /// created until the call to [registerDartType] is made. |
43 void onlyUpgradeNewElements() => _doc.callMethod('_onlyUpgradeNewElements'); | 53 void onlyUpgradeNewElements() => _doc.callMethod('_onlyUpgradeNewElements'); |
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