如何禁用JavaFX菜单栏的助记符？

Question

在我的阶段，我像往常一样在程序的顶部插入了一个菜单栏。我想在stage中的另一个上下文中为ALT键（连同箭头键）提供一些逻辑。但每次按下ALT和箭头时，我也会无意中浏览菜单栏的菜单。

我想避免这种情况，或者更好地完全禁用这种助记行为。将所有菜单的助记词解析属性设置为false失败了。我也尝试了这种方法，但没有成功：

menubar.addEventFilter(KeyEvent.ANY, e -> e.consume());

Answer 1

或者您可以重写MenuBar皮肤。Javafx已经做出选择（或者这是一个错误？），当按下ALT键时，焦点将被赋予MenuBar，而不是释放，这是Eclipse、Netbean、......更重要的是，当按下或释放ALT_GRAPH键时，焦点不应被赋予MenuBar。

这是我提出的补丁。请注意，只有第一个差异是相关的，最后一个差异只是为了在无法访问代码时编译代码。基本上，我已经将“firstMenuRunnable”拆分为3个函数

>

仅当按下F10键时才使用FirstMenuRunTable

当菜单栏有焦点且按下ALT键时，使用DeclesionKeyPressed

当菜单栏没有焦点且ALT键被释放时，使用focusOnFirstMenuOnKeyReleased

因此，可以使用标准行为，允许加速器使用ALT键，而无需菜单栏获取焦点。

    --- com/sun/javafx/scene/control/skin/MenuBarSkin.java in C:\Program Files (x86)\Java\jdk1.8.0_131\javafx-src.zip
    +++ C:\Users\daniel\dev\xxx\Layout\src\com\stimulus\control\MenuBarSkin.java     
@@ -372,12 +491,21 @@
             scene.getAccelerators().put(acceleratorKeyCombo, firstMenuRunnable);

             // put focus on the first menu when the alt key is pressed
+            scene.addEventFilter(KeyEvent.KEY_PRESSED, e -> {
+                altDown = false;
+            });
             scene.addEventHandler(KeyEvent.KEY_PRESSED, e -> {
-                if (e.isAltDown()  && !e.isConsumed()) {
-                    firstMenuRunnable.run();
+                if (e.isAltDown() && !e.isConsumed() && e.getCode().equals(KeyCode.ALT)) {
+                    deselectMenusOnKeyPressed.run();
+                    altDown = true;
                 }
             });
+            scene.addEventHandler(KeyEvent.KEY_RELEASED, e -> {
+                if (altDown) {
+                    focusOnFirstMenuOnKeyReleased.run();
+                }
         });
+        });

         ParentTraversalEngine engine = new ParentTraversalEngine(getSkinnable());
         engine.addTraverseListener(this);
    @@ -434,7 +453,50 @@
                 }
             };

    +    private boolean menuDeselectedOnKeyPressed = false;

    +    Runnable deselectMenusOnKeyPressed = new Runnable() {
    +        public void run() {
    +            /*
    +             ** check that this menubar's container has contents,
    +             ** and that the first item is a MenuButton....
    +             ** otherwise the transfer is off!
    +             */
    +            menuDeselectedOnKeyPressed = false;
    +            if (container.getChildren().size() > 0) {
    +                if (container.getChildren().get(0) instanceof MenuButton) {
    +//                        container.getChildren().get(0).requestFocus();
    +                    if (focusedMenuIndex >= 0) {
    +                        unSelectMenus();
    +                        menuDeselectedOnKeyPressed = true;
    +                    }
    +                }
    +            }
    +        }
    +    };
    +    Runnable focusOnFirstMenuOnKeyReleased = new Runnable() {
    +        public void run() {
    +            /*
    +             ** check that this menubar's container has contents,
    +             ** and that the first item is a MenuButton....
    +             ** otherwise the transfer is off!
    +             */
    +            if (container.getChildren().size() > 0) {
    +                if (container.getChildren().get(0) instanceof MenuButton) {
    +//                        container.getChildren().get(0).requestFocus();
    +                    if (focusedMenuIndex == -1 && !menuDeselectedOnKeyPressed) {
    +                        unSelectMenus();
    +                        menuModeStart(0);
    +                        openMenuButton = ((MenuBarButton) container.getChildren().get(0));
    +                        openMenu = getSkinnable().getMenus().get(0);
    +                        openMenuButton.setHover();
    +                    }
    +                }
    +            }
    +        }
    +    };
    +
         private boolean pendingDismiss = false;

         // For testing purpose only.
    @@ -650,9 +712,23 @@
                 menuButton.textProperty().bind(menu.textProperty());
                 menuButton.graphicProperty().bind(menu.graphicProperty());
                 menuButton.styleProperty().bind(menu.styleProperty());
    +            // patch because MenuButtonSkin.AUTOHIDE is private
    +            final String AUTOHIDE;
    +            {
    +                try {
    +                    Class<?> clazz = MenuButtonSkin.class;
    +//                    System.out.println("fields = " + Arrays.asList(clazz.getDeclaredFields()).toString());
    +                    Field field = clazz.getDeclaredField("AUTOHIDE");
    +                    field.setAccessible(true);
    +                    AUTOHIDE = (String) field.get(this);
    +                    field.setAccessible(false);
    +                } catch (NoSuchFieldException | SecurityException | IllegalAccessException | IllegalArgumentException ex) {
    +                    throw new UnsupportedOperationException(ex);
    +                }
    +            }
                 menuButton.getProperties().addListener((MapChangeListener<Object, Object>) c -> {
    -                 if (c.wasAdded() && MenuButtonSkin.AUTOHIDE.equals(c.getKey())) {
    -                    menuButton.getProperties().remove(MenuButtonSkin.AUTOHIDE);
    +                if (c.wasAdded() && AUTOHIDE.equals(c.getKey())) {
    +                    menuButton.getProperties().remove(AUTOHIDE);
                         menu.hide();
                     }
                 });

下面是我的菜单栏的完整代码：

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package com.stimulus.control;

import javafx.scene.control.Menu;
import javafx.scene.control.MenuBar;
import javafx.scene.control.Skin;

/**
 *
 * @author daniel
 */
public class CustomMenuBar extends MenuBar {

    public CustomMenuBar() {
    }

    public CustomMenuBar(Menu... menus) {
        super(menus);
    }

    @Override
    protected Skin<?> createDefaultSkin() {
        return new MenuBarSkin(this) {

        };
    }

}

Answer 2

当按下ALT时，第一个菜单获得焦点，当菜单具有焦点时，无论是否按下ALT，箭头键都会在它们之间导航。因此，为了防止这种行为，您需要防止第一个菜单在按下ALT时获得焦点。

查看MenuBarSkin类的构造函数源代码，我们可以找到解决方案：

public MenuBarSkin(final MenuBar control) {
    ...
    Utils.executeOnceWhenPropertyIsNonNull(control.sceneProperty(), (Scene scene) -> {
        scene.getAccelerators().put(acceleratorKeyCombo, firstMenuRunnable);

        // put focus on the first menu when the alt key is pressed
        scene.addEventHandler(KeyEvent.KEY_PRESSED, e -> {
            if (e.isAltDown()  && !e.isConsumed()) {
                firstMenuRunnable.run();
            }
        });
    });
    ...
}

正如您所猜测的，解决方案是在ALT关闭时使用事件，但需要将EventHandler添加到场景中，而不是菜单栏中：

scene.addEventHandler(KeyEvent.KEY_PRESSED, new EventHandler<KeyEvent>() {
    @Override
    public void handle(KeyEvent event) {
        // your desired behavior
        if(event.isAltDown())
            event.consume();
    }
});