將上下文菜單附加到GWT MenuItem

Question

GWT MenuItem擴展UIObject - 任何想法如何添加事件處理程序，例如我想要一個特殊的上下文菜單，右鍵單擊MenuItem。謝謝！

Answer 1

可以使用MenuItem對象的基礎元素：

final Element element = menuItem.getElement(); 
Event.addNativePreviewHandler(new Event.NativePreviewHandler() { 
    @Override 
    public void onPreviewNativeEvent(Event.NativePreviewEvent event) { 
     if (event.getTypeInt() == Event.ONMOUSEDOWN 
       && event.getNativeEvent().getButton() == Event.BUTTON_RIGHT 
       && event.getNativeEvent().getEventTarget().equals(element)) { 
      showSpecialMenu(); 
     } 
    } 
}); 

Event.sinkEvents(element, Event.ONMOUSEDOWN); 

或像這樣（你也可以防止默認的上下文菜單）：

final Element element = menuItem.getElement(); 
Event.addNativePreviewHandler(new Event.NativePreviewHandler() { 
    @Override 
    public void onPreviewNativeEvent(Event.NativePreviewEvent event) { 
     if (event.getTypeInt() == Event.ONCONTEXTMENU && event.getNativeEvent().getEventTarget().equals(element)) { 
      // prevent default context menu 
      event.getNativeEvent().stopPropagation(); 
      event.getNativeEvent().preventDefault(); 

      // show custom context menu 
      showSpecialMenu(); 
     } 
    } 
}); 

Event.sinkEvents(element, Event.ONCONTEXTMENU); 

你都可以做這樣的：

...... 
Event.sinkEvents(element, Event.ONCONTEXTMENU | Event.ONMOUSEDOWN);