java - 当目标节点改变场景时，Ubuntu 上不会发生鼠标释放事件？

Question

这个问题涉及跨操作系统的鼠标行为；具体来说，我的代码适用于 Windows 和 Mac OS X，但不适用于 Ubuntu。

最终我想做的是制作一个特殊的 Pane 子类(“ConvertiblePane”)，它存在于主舞台/场景的父 Pane 中，但在拖动时神奇地转移到它自己的临时舞台/场景中，从而成为独立且能够放置在屏幕上的任何位置。当用户释放鼠标按钮时，ConvertiblePane 应该回到其原始父 Pane 并失去临时舞台。 (在我的完整程序中，原始父 Stage 会自行调整大小/重新定位以适应 ConvertiblePane 的放置位置。)

这让我想到了我的问题。当我在 ConvertiblePane 上按下鼠标时，它会按预期在主场景中触发 MousePress，此时 ConvertiblePane 将移至临时舞台。当我拖动鼠标时，它会在临时场景中触发 MouseDrag 并移动临时舞台。好的，太好了。

但是，当我释放鼠标按钮时，我会在不同的操作系统上遇到不同的行为。在 Windows (7) 和 Mac OS X (10.12.6) 上，在临时场景中发生 MouseRelease，按预期将 Pane 发送回其在主舞台中的原始父级。然而，在 Ubuntu 上，似乎在主场景或临时场景中都没有生成 MouseRelease。

这是作为 MCV 示例的相关代码:

import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.geometry.Point2D;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.Background;
import javafx.scene.layout.BackgroundFill;
import javafx.scene.layout.CornerRadii;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.stage.Stage;
import javafx.stage.StageStyle;

public class ConvertibleTest extends Application {           

    @Override
    public void start(Stage primaryStage) {

        // Set up the main stage and scene with a
        // Pane as root and a ConvertiblePane child:
        primaryStage.initStyle(StageStyle.TRANSPARENT);        
        Pane root = new Pane();
        ConvertiblePane conv = new ConvertiblePane();
        root.getChildren().add(conv);        
        Scene scene = new Scene(root, 400, 400, Color.PINK);
        primaryStage.setTitle("Convertible Test");
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    public static void main(String[] args) {
        launch(args);
    }    
}

class ConvertiblePane extends Pane
{    
    private final Group TEMP_ROOT = new Group();
    private final Stage TEMP_STAGE = new Stage(StageStyle.TRANSPARENT);    
    private final Scene TEMP_SCENE = new Scene(TEMP_ROOT);
    private Pane originalParent = null;
    private double deltaX = 0.0;
    private double deltaY = 0.0;
    private String name = null;

    public void onMousePress(MouseEvent event)
    {
        // Save deltaX/Y for later:
        Point2D delta = this.sceneToLocal(event.getX(), event.getY());
        deltaX = delta.getX();
        deltaY = delta.getY();  

        if (!isIndependent())
        {
            makeIndependent();
        }
    }

    public void onMouseDrag(MouseEvent event)
    {
        // Keep the TEMP_STAGE relative to the original click point:
        TEMP_STAGE.setX(event.getScreenX()-deltaX);
        TEMP_STAGE.setY(event.getScreenY()-deltaY);
    }

    public void onMouseRelease(MouseEvent event)
    {
        if (isIndependent())
        {
            returnToParent();
        }
    }

    public ConvertiblePane()
    {                         
        this.setPrefSize(100, 100);
        this.setBackground(new Background(new BackgroundFill(Color.GREEN, new CornerRadii(10), Insets.EMPTY)));
        this.setVisible(true);

        // Attach event code and report to System.out what is happening:
        this.setOnMousePressed((MouseEvent event) -> {
            if (this.getScene() == TEMP_SCENE)
                System.out.println("Pressed as Independent");
            else
                System.out.println("Pressed as Child");
            onMousePress(event);
        });
        this.setOnMouseDragged((MouseEvent event) -> {
            if (this.getScene() == TEMP_SCENE)
                System.out.println("Dragged as Independent");
            else
                System.out.println("Dragged as Child");
            onMouseDrag(event);
        });
        this.setOnMouseReleased((MouseEvent event) -> {
            if (this.getScene() == TEMP_SCENE)
                System.out.println("Released as Independent");
            else
                System.out.println("Released as Child");
            onMouseRelease(event);
        });
    }

    public boolean isIndependent()
    {
        // Return whether this ConvertiblePane is "independent" (exists in its own temp scene)
        return this.getScene() == TEMP_SCENE;
    }

    public void makeIndependent()
    {                
        // Get the point where this ConvertiblePane appears on screen:
        Point2D screenPt = this.localToScreen(0, 0);

        // Save the originaParent of this ConvertiblePane; we will return to it later:
        originalParent = (Pane)getParent();

        // Remove this ConvertiblePane from its originalParent:
        originalParent.getChildren().remove(this);

        // Set this ConvertiblePane as the root of the TEMP_SCENE on the TEMP_STAGE:
        TEMP_SCENE.setRoot(this);        
        TEMP_STAGE.setScene(TEMP_SCENE);
        System.out.println("Transferred to TEMP.");
        this.relocate(0, 0);

        // Show the TEMP_STAGE in the same location on screen where this ConvertiblePane originally was:
        TEMP_STAGE.setX(screenPt.getX());
        TEMP_STAGE.setY(screenPt.getY());                                                   
        TEMP_STAGE.show();        
    }

    public void returnToParent()
    {
        // Reset deltas:
        deltaX = 0;
        deltaY = 0;

        // Get the location of this ConvertiblePane on screen:
        Point2D screenPt = this.localToScreen(0, 0);

        // Set TEMP_ROOT as the root of TEMP_SCENE; this will allow us to detach
        // this ConvertiblePane from being the scene root (since root cannot == null).
        TEMP_SCENE.setRoot(TEMP_ROOT);

        // Hide the TEMP_STAGE:
        TEMP_STAGE.hide();        

        // Add this ConvertiblePane back to the originalParent:
        originalParent.getChildren().add(this);
        System.out.println("Transferred to MAIN.");

        // Relocate this ConvertiblePane within the originalParent to maintain its position on screen
        Point2D parentPt = originalParent.screenToLocal(screenPt);
        this.relocate(parentPt.getX(), parentPt.getY());          
    }
}

如您所见，事件处理方法中有一些基本的报告； makeIndependent() 和 returnToParent() 方法输出“Transferred to TEMP”。和“转移到 MAIN”。分别。

如果我在 ConvertiblePane 上单击鼠标，拖动几个像素，然后松开，这就是输出:

(在 Windows 或 Mac OS X 上)
孩提时代的压力
转移到 TEMP。
拖动为独立
拖动为独立
拖动为独立
作为独立发布
转移到 MAIN。

(在 Ubuntu 上)
孩提时代的压力
转移到 TEMP。
拖动为独立
拖动为独立
拖动为独立

我也试过为两个场景添加事件过滤器；但结果是一样的:MouseRelease 出现在 Win/Mac 上，但不是 Ubuntu。

如果有人能解释这种行为或提出建议，那就太好了。或者...是否有任何我可以捕获的 MouseEvents 的“全局”(场景前)创建？我的意思是，我真的不关心鼠标释放的细节；我只想要一个事件来告诉我何时将 ConvertiblePane 添加回主舞台。

谢谢!

Answer 1

在这方面花了几个星期之后，我找不到一种方法来针对这种情况在 Ubuntu 上触发适当的 MouseReleased 事件；但是，我确实想出了一个可以很好地完成工作的 hack。基本上，我不会在 MouseReleased 发生时收到通知，而是每 10 毫秒检查一次鼠标按钮是否不再按下。

解释:当节点转移到临时场景时，时间轴开始每10毫秒将鼠标指针“移动”到位。这会触发 MouseDragged 事件(如果鼠标按钮仍然按下)或 MouseMoved 事件(如果鼠标按钮向上)；这样我就可以模拟 MouseReleased 事件并调用我的过程来将节点添加回主舞台。那时，当然，我也停止了时间线。

下面是相关代码来演示这一点；也许它对其他人也有用。

// The robot is needed to "move" the mouse in place,
// triggering a MOUSE_MOVED event.
private static Robot robot = null;  
static {
    try {
        robot = new Robot();
    } catch (AWTException ex) {
        Logger.getLogger(ConvertiblePane.class.getName()).log(Level.SEVERE, null, ex);
    }
}

// clickWaiter will move the mouse in place every 10 milliseconds,
// triggering a MOUSE_MOVED event if the mouse is no longer pressed.
private final Timeline clickWaiter = new Timeline(new KeyFrame(Duration.millis(10), (ActionEvent event) -> {
    // Get the mouse position from MouseInfo class.
    Point mouse = MouseInfo.getPointerInfo().getLocation();        
    // "Move" the mouse in place to trigger a mouseMove or mouseDrag event.
    robot.mouseMove(mouse.x, mouse.y);
}));

public ConvertiblePane()
{
    ...

    // MOUSE_MOVED will be triggered by the robot when the mouse button is no longer pressed:
    TEMP_SCENE.addEventFilter(MouseEvent.MOUSE_MOVED, (MouseEvent event) ->
    {   
        if (!event.isPrimaryButtonDown())
        {
            System.out.println("Temp.release (sim)");
            clickWaiter.stop();
            // Simulate MOUSE_RELEASED event.
        }
    });
}

public void makeIndependent()
{
    ...

    // Start the clickWaiter, part of the Linux hack:
    clickWaiter.playFromStart();
}