在手动调整窗口大小之前,swing Java窗口无法正确重新绘制
我使用了一个非常基本的设置,一个扩展了JPanel
的类,我将它添加到了JFrame
import java.awt.*;
import javax.swing.*;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import java.awt.event.*;
import java.awt.geom.RoundRectangle2D;
import java.awt.image.*;
import java.io.*;
import javax.imageio.ImageIO;
public class PinTestMCVE extends JPanel implements ActionListener{
BufferedImage loadedImage;
JButton calcButton;
public static void main(String[] args) {
new PinTestMCVE();
}
public PinTestMCVE() {
loadedImage = getTestImage();
JPanel toolbarPanel = new JPanel();
calcButton = new JButton("calcButton...");
toolbarPanel.add(calcButton);
calcButton.addActionListener(this);
JFrame jf = new JFrame();
jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jf.getContentPane().setLayout(new BorderLayout());
jf.getContentPane().add(toolbarPanel, BorderLayout.NORTH);
jf.getContentPane().add(this, BorderLayout.CENTER);
jf.setSize(1250, 950);
jf.setVisible(true);
}
public void paintComponent(Graphics g) {
g.drawImage(loadedImage, 0, 0, this);
}
public void actionPerformed(ActionEvent e) {
System.out.println("ActionEvent " + e.getActionCommand());
if(e.getSource().equals(calcButton)){
this.repaint();
}
}
//Please ignore the inner workings of this
public static BufferedImage getTestImage(){
BufferedImage image = new BufferedImage(500, 500, BufferedImage.TYPE_INT_RGB);
Graphics2D g2d = image.createGraphics();
g2d.setPaint(Color.GRAY);
g2d.fillRect ( 0, 0, image.getWidth(), image.getHeight() );
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setPaint(Color.gray);
int x = 5;
int y = 7;
GradientPaint redtowhite = new GradientPaint(x, y, Color.red, 200, y, Color.blue);
g2d.setPaint(redtowhite);
g2d.fill(new RoundRectangle2D.Double(x, y, 200, 200, 10, 10));
return image;
}
}
所发生的事情是,最初窗口是正确绘制的,但一旦调用paintComponent
,在新绘制的图像下方就可以看到一条旧图像(与工具栏面板的高度相同)——类似于从扑克牌组中伸出的扑克牌。但是,如果我手动调整窗口的大小,比如拖动边框,背景会像应该的那样变灰
发生了什么,我该如何解决
# 1 楼答案
如here所述,在调用} 以指定合适的初始
setVisible()
之前需要pack()
帧。您可以重写^{Dimension
。还考虑使用^ {< CD5> }。另见Initial Threads