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Difference between revisions of "Eclipse4/RCP/Modeled UI/Listening to Model Changes"
< Eclipse4 | RCP | Modeled UI
| Line 1: | Line 1: | ||
When the model changes and it is not a no-op (for example, setting its label to its current label), an event will be dispatched to all interested event handlers. Eclipse 4 uses a [[E4/RCP/Event Model|global listener pattern]] so all handler subscriptions are done through the event broker. | When the model changes and it is not a no-op (for example, setting its label to its current label), an event will be dispatched to all interested event handlers. Eclipse 4 uses a [[E4/RCP/Event Model|global listener pattern]] so all handler subscriptions are done through the event broker. | ||
| + | ==Subscribing to model changes== | ||
Topics for event subscriptions can be generated from the <tt>UIEvents</tt> class. | Topics for event subscriptions can be generated from the <tt>UIEvents</tt> class. | ||
| Line 9: | Line 10: | ||
// subscribe only to events generated from MItems's selected attribute being switched | // subscribe only to events generated from MItems's selected attribute being switched | ||
eventBroker.subscribe(UIEvents.buildTopic(UIEvents.Item.TOPIC, UIEvents,Item.SELECTED), eventHandler); | eventBroker.subscribe(UIEvents.buildTopic(UIEvents.Item.TOPIC, UIEvents,Item.SELECTED), eventHandler); | ||
| + | </source> | ||
| + | |||
| + | ==Retrieving information from the events== | ||
| + | <source lang="java"> | ||
| + | // subscribe to all events generated from MUILabels | ||
| + | eventBroker.subscribe(UIEvents.buildTopic(UIEvents.UILabel.TOPIC, UIEvents.UILabel.LABEL), new EventHandler() { | ||
| + | public void handleEvent(Event event) { | ||
| + | Object element = event.getProperty(UIEvents.EventTags.ELEMENT); | ||
| + | if (element instanceof MToolItem) { | ||
| + | ToolItem item = (ToolItem) ((MToolItem) element).getWidget(); | ||
| + | String value = (String) event.getProperty(UIEvents.EventTags.NEW_VALUE); | ||
| + | if (value == null) { | ||
| + | item.setText(""); //$NON-NLS-1$ | ||
| + | } else { | ||
| + | item.setText(value); | ||
| + | } | ||
| + | } | ||
| + | } | ||
| + | ); | ||
</source> | </source> | ||
Revision as of 14:25, 11 April 2011
When the model changes and it is not a no-op (for example, setting its label to its current label), an event will be dispatched to all interested event handlers. Eclipse 4 uses a global listener pattern so all handler subscriptions are done through the event broker.
Subscribing to model changes
Topics for event subscriptions can be generated from the UIEvents class.
// subscribe to all events generated from MUILabels eventBroker.subscribe(UIEvents.buildTopic(UIEvents.UILabel.TOPIC), eventHandler); // subscribe only to events generated from MItems's selected attribute being switched eventBroker.subscribe(UIEvents.buildTopic(UIEvents.Item.TOPIC, UIEvents,Item.SELECTED), eventHandler);
Retrieving information from the events
// subscribe to all events generated from MUILabels eventBroker.subscribe(UIEvents.buildTopic(UIEvents.UILabel.TOPIC, UIEvents.UILabel.LABEL), new EventHandler() { public void handleEvent(Event event) { Object element = event.getProperty(UIEvents.EventTags.ELEMENT); if (element instanceof MToolItem) { ToolItem item = (ToolItem) ((MToolItem) element).getWidget(); String value = (String) event.getProperty(UIEvents.EventTags.NEW_VALUE); if (value == null) { item.setText(""); //$NON-NLS-1$ } else { item.setText(value); } } } );