ContextMenu并以编程方式选择一个项目 [英] ContextMenu and programmatically selecting an item

问题描述

似乎没有用于以编程方式选择" ContextMenu项的API?选择我"的意思是点击向上和向下键(或将鼠标悬停在某个项目上).当显示ContextMenu时，我真的只需要选择第一项.我试图在显示菜单时触发向下的按键事件，但是什么也没发生..也许是我错误地构造了该事件.

There does not seem to be API for programmatically "selecting" ContextMenu items? By selecting I mean the equivalent of tapping up and down keys (or hovering the mouse over an item). I really only need to select the first item, when a ContextMenu is shown. I attempted to fire a down keyevent upon showing the menu, but nothing happened.. perhaps I constructed the event wrongly.

推荐答案

要使其正常工作，我们可以使用一些私有API. ContextMenu外观(ContextMenuSkin)使用ContextMenuContent对象作为包含所有项目的容器.

To get this working, we could use some private API. ContextMenu skin (ContextMenuSkin) uses a ContextMenuContent object, as a container with all the items.

我们只需要为这些项目中的第一个请求焦点.

We just need to request the focus for the first of these items.

但是为此，我们可以使用一些查找来找到第一个menu-item CSS选择器.必须在显示阶段之后执行此操作.

But for this we could just use some lookups to find the first menu-item CSS selector. This has to be done after the stage has been shown.

此示例将显示一个上下文菜单，重点放在第一项上:

This example will show a context menu with focus on the first item:

@Override
public void start(Stage primaryStage) {

    MenuItem cmItem1 = new MenuItem("Item 1");
    cmItem1.setOnAction(e->System.out.println("Item 1"));
    MenuItem cmItem2 = new MenuItem("Item 2");
    cmItem2.setOnAction(e->System.out.println("Item 2"));

    final ContextMenu cm = new ContextMenu(cmItem1,cmItem2);

    Scene scene = new Scene(new StackPane(), 300, 250);

    primaryStage.setScene(scene);
    primaryStage.show();

    scene.setOnMouseClicked(t -> {
        if(t.getButton()==MouseButton.SECONDARY){
            cm.show(scene.getWindow(),t.getScreenX(),t.getScreenY());

            // Request focus on first item
            cm.getSkin().getNode().lookup(".menu-item").requestFocus();
        }
    });        
}

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