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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 13:25, 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);
        }
      }
    }
);

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