使用mouseDrag滚动时临时禁用或阻止重新绘制JViewPort

我在您的DragListener代码中添加了一个hack。基本上，它会在您拖动时删除布局管理器，因此重新验证无效，并且在释放鼠标时会恢复布局管理器：

import java.awt.*;import java.awt.Container;import java.awt.MouseInfo;import java.awt.Point;import java.awt.Rectangle;import java.awt.event.MouseEvent;import javax.swing.JViewport;import javax.swing.SwingUtilities;import javax.swing.event.MouseInputAdapter;public class DragListener extends MouseInputAdapter{    private Point location;    private MouseEvent pressed;    private MouseEvent dragged;    private MouseEvent dropped;    private LayoutManager layout;    @Override    public void mousePressed(MouseEvent me)    {        pressed = me;        Component component = me.getComponent();        Container parent = component.getParent();        parent.setPreferredSize(parent.getPreferredSize());        layout = parent.getLayout();        parent.setLayout(null);    }    @Override    public void mouseDragged(MouseEvent me)    {        dragged = me;        Component component = dragged.getComponent();        Container parent = component.getParent();        Container superParent = parent.getParent();        if(superParent instanceof JViewport)        { JViewport vp = (JViewport)superParent; Rectangle vpb = vp.getBounds(); Point pt = MouseInfo.getPointerInfo().getLocation(); SwingUtilities.convertPointFromScreen(pt, vp); if(!vpb.contains(pt)) {     int yDiff = (pt.y < vpb.y ) ? pt.y : pt.y - vpb.height;     vpb.translate(0, yDiff);     vp.scrollRectToVisible(vpb); }        }        location = component.getLocation(location);        int x = location.x - pressed.getX() + me.getX();        int y = location.y - pressed.getY() + me.getY();        component.setLocation(x, y);    }    // Mouse release omitted    @Override    public void mouseReleased(MouseEvent me)    {        Component component = me.getComponent();        Container parent = component.getParent();        parent.setPreferredSize( null );        parent.setLayout(layout);        parent.validate();        parent.repaint();    }}

当然，我假设您的真正的mouseReleased代码将具有将按钮插入Container中适当位置的逻辑，因此其实际位置可以由GridLayout维护，否则组件将回到其原始位置。

编辑：

这是释放鼠标按钮时将按钮移到新位置的版本。有点复杂，因为您需要担心ZOrder。那就是将组件向下拖动是可以的。但是，如果尝试向上拖动组件，则该组件会在其他按钮下方绘制。临时重置ZOrder可解决此问题。

伙计，代码开始成为一个大问题：）临时的null布局和临时的ZOrder。

无论如何，这里是代码：

import java.awt.*;import java.awt.Container;import java.awt.MouseInfo;import java.awt.Point;import java.awt.Rectangle;import java.awt.event.MouseEvent;import javax.swing.*;import javax.swing.SwingUtilities;import javax.swing.event.MouseInputAdapter;public class DragListener extends MouseInputAdapter{    private Point location;    private MouseEvent pressed;    private MouseEvent dragged;    private MouseEvent dropped;    private LayoutManager layout;    private Rectangle originalBounds;    private int originalZOrder;    @Override    public void mousePressed(MouseEvent me)    {        pressed = me;        Component component = me.getComponent();        Container parent = component.getParent();        originalBounds = component.getBounds();        originalZOrder = parent.getComponentZOrder(component);        parent.setPreferredSize(parent.getPreferredSize());        layout = parent.getLayout();        parent.setLayout(null);        parent.setComponentZOrder(component, 0);    }    @Override    public void mouseDragged(MouseEvent me)    {        JComponent source = (JComponent) me.getComponent();        JComponent parent = (JComponent) source.getParent();        Point p = me.getPoint();        p = SwingUtilities.convertPoint(source, p, parent);        Rectangle bounds = source.getBounds();        bounds.setLocation(p);        bounds.x -= pressed.getX();        bounds.y -= pressed.getY();        source.setLocation(0, bounds.y);        parent.scrollRectToVisible(bounds);    }    @Override    public void mouseReleased(MouseEvent me)    {        boolean moved = false;        Component component = me.getComponent();        Container parent = component.getParent();        Point location = component.getLocation();        if (location.y < 0)        { parent.add(component, 0); moved = true;        }        else        { for (int i = 0; i < parent.getComponentCount(); i++) {     Component c = parent.getComponent(i);     Rectangle bounds = c.getBounds();     if (c == component)         bounds = originalBounds;     //  Component is released in the space originally occupied     //  by the component or over an existing component     if (bounds.contains(0, location.y))     {         if (c == component)         {  parent.setComponentZOrder(component, originalZOrder);         }         else         {  parent.add(component, i);         }         moved = true;         break;     } }        }        //  Component is positioned below all components in the container        if (!moved)        { parent.add(component, parent.getComponentCount() - 1);        }        //  Restore layout manager        parent.setPreferredSize( null );        parent.setLayout(layout);        parent.validate();        parent.repaint();        component.requestFocusInWindow();    }    private static void createAndShowGUI()    {        JPanel panel = new JPanel( new GridLayout(0, 1) );        DragListener drag = new DragListener();        for (int i = 0; i <10; i++)        { JButton button = new JButton("" + i); button.setFont(new java.awt.Font("Tahoma", 1, 48)); button.setForeground(new java.awt.Color(255, 0, 0)); button.addMouseListener(drag); button.addMouseMotionListener(drag); panel.add( button );        }        Jframe frame = new Jframe("SSCCE");        frame.setDefaultCloseOperation(Jframe.EXIT_ON_CLOSE);        frame.add( new JScrollPane(panel) );        frame.setLocationByPlatform( true );        frame.setSize(200, 400);        frame.setVisible( true );    }    public static void main(String[] args)    {        EventQueue.invokeLater(new Runnable()        { public void run() {     createAndShowGUI(); }        });    }}