Question

我有2个JInternalFrame，每个都包含一个JPanel。一个JPanel（源）更新其GUI和一些数据以响应鼠标事件。另一个JPanel（目标）接收指示数据已更改的事件并相应地更新其外观。

如果源面板与目标面板重叠，则目标面板中的重绘会在源面板中触发重新绘制。此外，即使源面板遮挡了对目标面板所需的更改，目标面板仍会重新绘制，并仍然在源面板中触发重新绘制。

在我的真实应用程序中，这会产生性能问题，因为多个面板在鼠标拖动时触发重新绘制，并且源面板具有要显示的复杂图像。

如何阻止目标面板更新在源面板中触发重绘？

我尝试的事情：

为重绘提供参数，这意味着只重绘目标面板的非重叠位可以解决问题，但在我的情况下，我不知道目标面板的哪一位是可见的（我试过getVisibleRect和getClipBounds但他们只返回整个面板尺寸）。在我的实际应用程序中，整个目标面板都会更新，而不仅仅是其中的一部分，因此我也无法通过这种方式限制重绘。

基于现有的InternalFrameDemo创建了一个最小示例：同样的问题，请参阅下面的代码。该示例有2个面板，如我所述，单击源面板（标记为文档1）在该位置绘制一个红色框，并更新DataModel对象，该对象触发目标面板拾取的事件（标记为Document） 2），在其自身的相同位置绘制一个红色框。在源paintComponent方法中设置断点，可以看到有2个更新，一个来自SourcePanel重绘，另一个来自TargetPanel重绘。

public class InternalFrameDemo extends JFrame
                       implements ActionListener {
 JDesktopPane desktop;
 DataModel model = new DataModel();

public InternalFrameDemo() {
super("InternalFrameDemo");

//Make the big window be indented 50 pixels from each edge
//of the screen.
int inset = 50;
Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
setBounds(inset, inset,
          screenSize.width  - inset*2,
          screenSize.height - inset*2);

//Set up the GUI.
desktop = new JDesktopPane(); //a specialized layered pane
MyInternalFrame frame1 = createFrame(); //create first "window"
MyInternalFrame frame2 = createFrame();
setContentPane(desktop);

SourcePanel sp = new SourcePanel(model);
frame1.add(sp);
TargetPanel tp = new TargetPanel(model);
frame2.add(tp);

//Make dragging a little faster but perhaps uglier.
desktop.setDragMode(JDesktopPane.OUTLINE_DRAG_MODE);
}

public void actionPerformed(ActionEvent e) {
}

//Create a new internal frame.
protected MyInternalFrame createFrame() {
    MyInternalFrame frame = new MyInternalFrame();
    frame.setVisible(true); //necessary as of 1.3
    frame.setOpaque(true);


desktop.add(frame);
    try {
        frame.setSelected(true);
    } catch (java.beans.PropertyVetoException e) {}
    return frame;
}

//Quit the application.
protected void quit() {
    System.exit(0);
}

/**
 * Create the GUI and show it.  For thread safety,
 * this method should be invoked from the
 * event-dispatching thread.
 */
private static void createAndShowGUI() {
   //Create and set up the window.
    InternalFrameDemo frame = new InternalFrameDemo();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    //Display the window.
    frame.setVisible(true);
}

public static void main(String[] args) {
    //Schedule a job for the event-dispatching thread:
    //creating and showing this application's GUI.
    javax.swing.SwingUtilities.invokeLater(new Runnable() {
        public void run() {
            createAndShowGUI();
        }
    });
}
}

    package components;

    import javax.swing.JInternalFrame;

    /* Used by InternalFrameDemo.java. */
    public class MyInternalFrame extends JInternalFrame {
    static int openFrameCount = 0;
    static final int xOffset = 30, yOffset = 30;

    public MyInternalFrame() {
        super("Document #" + (++openFrameCount), 
              true, //resizable
              true, //closable
              true, //maximizable
              true);//iconifiable

        setSize(300,300);
        setLocation(xOffset*openFrameCount, yOffset*openFrameCount);
    }
}

package components;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class SourcePanel extends JPanel {

    int boxX, boxY;
    int boxWidth = 10;
    int boxHeight = 10;

    public SourcePanel(DataModel data) {

        addMouseListener(new MouseAdapter()
        {
          @Override
          public void mousePressed(MouseEvent evt)
          {
            if (!SwingUtilities.isRightMouseButton(evt))
            {
              boxX = evt.getX();
              boxY = evt.getY();
              data.update(boxX,boxY);
              repaint();
            }
          }
        });
    }

    @Override
    public void paintComponent(Graphics g)
    {
        super.paintComponent(g);
        g.setColor(Color.RED);
        int x = Math.min(boxX, this.getWidth()-boxWidth);
        int y = Math.min(boxY,  this.getHeight()-boxHeight);
        g.drawRect(x, y, boxWidth, boxHeight);
        g.drawRect(x + 1, y + 1, boxWidth - 2, boxHeight - 2);
    }
}

package components;

import java.awt.Color;
import java.awt.Graphics;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;

import javax.swing.JPanel;

public class TargetPanel extends JPanel implements PropertyChangeListener {

    int boxX, boxY;
    int boxWidth = 10;
    int boxHeight = 10;

    public TargetPanel(DataModel data) {
        data.addPropertyChangeListener(this);
    }

    @Override
    public void propertyChange(PropertyChangeEvent evt)
    {
      //draw something in response to the data change
      boxX = ((int[])evt.getNewValue())[0];
      boxY = ((int[])evt.getNewValue())[1];
      repaint();
    }

    @Override
    public void paintComponent(Graphics g)
    {
        super.paintComponent(g);
        g.setColor(Color.BLUE);
        g.fillRect(0, 0, getWidth(), getHeight());
        g.setColor(Color.RED);
        int x = Math.min(boxX, this.getWidth()-boxWidth);
        int y = Math.min(boxY,  this.getHeight()-boxHeight);
        g.fillRect(x, y, boxWidth, boxHeight);
    }
}

package components;

import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;

public class DataModel {

    int datax = 10;
    int datay = 10;

    public DataModel()
    {
    }

    public void update(int x, int y)
    {
        int[] olddata = new int[]{datax,datay};
        datax = x;
        datay = y;
        int[] newdata = new int[]{datax,datay};
        changeSupport.firePropertyChange("DataChange", olddata, newdata);
    }

    protected PropertyChangeSupport changeSupport = new PropertyChangeSupport(
              this);

    public void addPropertyChangeListener(PropertyChangeListener listener)
    {
        changeSupport.addPropertyChangeListener(listener);
    }

    public void removePropertyChangeListener(PropertyChangeListener listener)
    {
        changeSupport.removePropertyChangeListener(listener);
    }

}

/*
 * Copyright (c) 1995, 2008, Oracle and/or its affiliates. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
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 *
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 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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 */

Answer 1

您可以缓存鼠标更改并按间隔或鼠标跟踪结束。

最容易的是尝试推迟重画。

@Override
public void propertyChange(PropertyChangeEvent evt)
{
  //draw something in response to the data change
  boxX = ((int[])evt.getNewValue())[0];
  boxY = ((int[])evt.getNewValue())[1];
  repaint(200L);
}

实际上在几次调用repaint(200L);之后重新粉刷。（因为我的感觉，我已经选择了高五分之一的值。）

如何防止JInternalFrame重新绘制重叠的JInternalFrame

1 个答案: