Programmazione:Java/Eclipse RCP/Documentazione Framework/DropdownSelectionListener

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Questo listener viene utilizzato per gestire il dropdown di un CoolItem quando diventa troppo lungo...

/**

* This class provides the "drop down" functionality for our dropdown tool items.
*/

public class DropdownSelectionListener extends SelectionAdapter {

  private ToolItem dropdown;

  private Menu menu;

  /**
   * Constructs a DropdownSelectionListener
   * 
   * @param dropdown
   *           the dropdown this listener belongs to
   */
  public DropdownSelectionListener(ToolItem dropdown) {
     this.dropdown = dropdown;
     menu = new Menu(dropdown.getParent().getShell());
  }

  /**
   * Adds an item to the dropdown list
   * 
   * @param item
   *           the item to add
   */
  public void add(String item) {
     MenuItem menuItem = new MenuItem(menu, SWT.NONE);
     menuItem.setText(item);
     menuItem.addSelectionListener(new SelectionAdapter() {
        public void widgetSelected(SelectionEvent event) {
           MenuItem selected = (MenuItem) event.widget;
           dropdown.setText(selected.getText());
        }
     });
  }

  /**
   * Called when either the button itself or the dropdown arrow is clicked
   * 
   * @param event
   *           the event that trigged this call
   */
  public void widgetSelected(SelectionEvent event) {
     // If they clicked the arrow, we show the list
     if (event.detail == SWT.ARROW) {
        // Determine where to put the dropdown list
        ToolItem item = (ToolItem) event.widget;
        Rectangle rect = item.getBounds();
        Point pt = item.getParent().toDisplay(new Point(rect.x, rect.y));
        menu.setLocation(pt.x, pt.y + rect.height);
        menu.setVisible(true);
     } 
     else {
        ToolItem item = (ToolItem) event.widget;
        item.setSelection(!item.getSelection());
     }
  }

}