2014-09-10 15:53:32 +00:00
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chapter.of: Widgets
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created: 20140715080302422
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modified: 20140717181635787
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sub.num: 1
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tags: doc
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title: Messages
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Messages are events that are triggered by the user. They are generated by widgets for example when the user clicks on a ~ButtonWidget.
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2014-09-12 16:27:58 +00:00
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Each message has a type property like "tm-delete-tiddler" and a parameter.
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2014-09-10 15:53:32 +00:00
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2014-11-28 10:06:17 +00:00
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```js
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2014-09-12 16:27:58 +00:00
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{type: "tm-delete-tiddler", param: "MyOldTiddler"}
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2014-09-10 15:53:32 +00:00
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```
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When such a message is created by a widget it sends the message to it's parent widget which sends it to it's own parent widget and so on.
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On this way each widget can try to dispatch the message.
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This concept is realised in the base widget object.
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It provides a function ``dispatchEvent(message)`` which is called by the children to bubble the message up the widget tree.
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Another function ``addEventListener(type,listener)`` can be used to bind a function to a specific message type.
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If the listener returns false, the message is send to the parent widget.
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The TiddlyWiki core plug-in handles a lot of messages in the [[NavigatorWidget|RootWidget and Rendering Startup]].
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