Question

我的JComponent过于激烈地发起mouseDragged事件。当用户尝试单击时，即使鼠标仅移动了1个像素，它也会将其解释为拖动。

如何为特定组件添加规则：

除非将此视为拖拽事件鼠标移动了10个像素被压下的点。

注意：我知道这不是我操作系统中的系统设置，因为只有该组件上的事件会受到这种过度敏感的影响。

谢谢。

Answer 1

以前的答案结合在一起，具有适当的事件类型：

public class DragInsensitiveMouseClickListener implements MouseInputListener {

    protected static final int MAX_CLICK_DISTANCE = 15;

    private final MouseInputListener target;

    public MouseEvent pressed;

    public DragInsensitiveMouseClickListener(MouseInputListener target) {
        this.target = target;
    }

    @Override
    public final void mousePressed(MouseEvent e) {
        pressed = e;
        target.mousePressed(e);
    }

    private int getDragDistance(MouseEvent e) {
        int distance = 0;
        distance += Math.abs(pressed.getXOnScreen() - e.getXOnScreen());
        distance += Math.abs(pressed.getYOnScreen() - e.getYOnScreen());
        return distance;
    }

    @Override
    public final void mouseReleased(MouseEvent e) {
        target.mouseReleased(e);

        if (pressed != null) {
            if (getDragDistance(e) < MAX_CLICK_DISTANCE) {
                MouseEvent clickEvent = new MouseEvent((Component) pressed.getSource(),
                        MouseEvent.MOUSE_CLICKED, e.getWhen(), pressed.getModifiers(),
                        pressed.getX(), pressed.getY(), pressed.getXOnScreen(), pressed.getYOnScreen(),
                        pressed.getClickCount(), pressed.isPopupTrigger(), pressed.getButton());
                target.mouseClicked(clickEvent);
            }
            pressed = null;
        }
    }

    @Override
    public void mouseClicked(MouseEvent e) {
        //do nothing, handled by pressed/released handlers
    }

    @Override
    public void mouseEntered(MouseEvent e) {
        target.mouseEntered(e);
    }

    @Override
    public void mouseExited(MouseEvent e) {
        target.mouseExited(e);
    }

    @Override
    public void mouseDragged(MouseEvent e) {
        if (pressed != null) {
            if (getDragDistance(e) < MAX_CLICK_DISTANCE) return; //do not trigger drag yet (distance is in "click" perimeter
            pressed = null;
        }
        target.mouseDragged(e);
    }

    @Override
    public void mouseMoved(MouseEvent e) {
        target.mouseMoved(e);
    }
}

Answer 2

我以前必须这样做。这是我的鼠标事件处理代码，在被视为拖动之前，只减少与拖动相关的位需要几个像素。

public void mousePressed(int mod, Point loc) {
    pressLocation=copyLocation(loc,pressLocation);
    dragLocation=null;
    }

public void mouseReleased(int mod, Point loc) {
    if(pressLocation!=null && dragLocation!=null) {
        // Mouse drag reverted to mouse click - not dragged far enough
        // action for click
        pressLocation=null;
        }
    else if(dragLocation!=null) {
        // action for drag completed
        }
    else {
        // do nothing
        }

    pressLocation=null;
    dragLocation=null;
    }

public void mouseDragged(int mod, Point loc) {
    if(pressLocation!=null) {                                                   // initial drag actions following mouse press
        dragLocation=pressLocation;                                             // consider dragging to be from start point
        if(Math.abs(loc.x-pressLocation.x)<dragMinimum && Math.abs(loc.y-pressLocation.y)<dragMinimum) {
            return;                                                             // not dragged far enough to count as drag (yet)
            }
        // action drag from press location
        pressLocation=null;
        }
    else {
        // action drag from last drag location
        dragLocation=copyLocation(loc,dragLocation);
        }
    }

请注意，我也遇到了 ~~Java~~ 一些JVM在拖动后生成点击事件的问题，我必须检测并禁止它。

Answer 3

如果我正确阅读了您的问题，您就会跟踪click和mousedrag事件。你可以跟踪mousedown上的坐标，然后在mousedrag中进行简短的计算，看看鼠标是否已经移动了你想要的最小像素数？当然，您还希望在mouseup上取消/重置，或者将鼠标拖到JComponent的边界之外。

警告：我自己并没有这样做，但我认为如果是我的话我就会开始。

Answer 4

Software Monkey的代码似乎缺少一些代码，所以我写了这个解决方案：

navigationTree.addMouseListener(new DragInsensitiveMouseClickListener(10) {
    @Override
    public void mouseClicked(MouseEvent e) {
        TreePath treePath = navigationTree.getPathForLocation(e.getX(), e.getY());

        if(treePath != null) {
            processChoice();
        }
    }
});

当用户产生最多10个像素的“拖动行程”时，仍然会触发mouseClicked（）事件。

点击监听器的代码：

import java.awt.Point;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

public class DragInsensitiveMouseClickListener extends MouseAdapter {

    private final int allowedTravel;

    public Point mouseDownPoint;

    public DragInsensitiveMouseClickListener(int allowedTravel) {
        this.allowedTravel = allowedTravel;
    }

    @Override
    public void mousePressed(MouseEvent e) {
        mouseDownPoint = e.getPoint();
    }

    @Override
    public void mouseReleased(MouseEvent e) {
        double horizontalTravel = Math.abs(mouseDownPoint.getX() - e.getX());
        double verticalTravel = Math.abs(mouseDownPoint.getY() - e.getY());

        if (horizontalTravel < allowedTravel && verticalTravel < allowedTravel) {
            mouseClicked(e);
        }
    }
}

使组件对Swing中的拖动不太敏感

4 个答案: