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我正在尝试使用JPanel来设计此媒体播放应用程序的时间轴。为了提供关于时间线的当前视频帧的指示，我需要能够在TimeLinePanel类中的特定x坐标处绘制垂直线，其延伸JPanel。到目前为止，使用paint（）函数或覆盖paintComponent()的运气并不是很好。当我尝试使用我的NewJApplet（该类延伸JApplet）类中的paint（）函数时，将绘制垂直线，但我用作时间线的JPanel消失（边框不再可见）。另外，我听说使用paint()方法是不可取的。因此，我尝试在JPanel中覆盖paintComponent()方法，我尝试从NewJApplet调用paintComponent方法，但它并未使用垂直线更新timeLinePanel1。如何在JPanel中的特定位置绘制垂直线？
任何帮助，将不胜感激。
以下是我到目前为止的代码：
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package helloworld;
import java.awt.GridLayout;
import javax.swing.border.EmptyBorder;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
/**
*
* @author Justin
*/
public class NewJApplet extends javax.swing.JApplet {
/**
* Initializes the applet NewJApplet
*/
@Override
public void init() {
/* Set the Nimbus look and feel */
//<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
/* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
* For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
*/
try {
/*
for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}
* */
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException ex) {
java.util.logging.Logger.getLogger(NewJApplet.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(NewJApplet.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(NewJApplet.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(NewJApplet.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>
/* Create and display the applet */
try {
java.awt.EventQueue.invokeAndWait(new Runnable() {
public void run() {
initComponents();
timeLinePanel1.paintComponent(timeLinePanel1.getGraphics());
timeLinePanel1.repaint();
}
});
} catch (Exception ex) {
ex.printStackTrace();
}
}
/**
* This method is called from within the init() method to initialize the
* form. WARNING: Do NOT modify this code. The content of this method is
* always regenerated by the Form Editor.
*/
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
myPanel = new javax.swing.JPanel();
timeLinePanel1 = new helloworld.TimeLinePanel();
myPanel.setBackground(new java.awt.Color(51, 51, 51));
javax.swing.GroupLayout myPanelLayout = new javax.swing.GroupLayout(myPanel);
myPanel.setLayout(myPanelLayout);
myPanelLayout.setHorizontalGroup(
myPanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(myPanelLayout.createSequentialGroup()
.addContainerGap()
.addComponent(timeLinePanel1, javax.swing.GroupLayout.DEFAULT_SIZE, 600, Short.MAX_VALUE)
.addContainerGap())
);
myPanelLayout.setVerticalGroup(
myPanelLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, myPanelLayout.createSequentialGroup()
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(timeLinePanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap())
);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addComponent(myPanel, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addGap(0, 0, 0))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(myPanel, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
);
}// </editor-fold>
// Variables declaration - do not modify
private javax.swing.JPanel myPanel;
private helloworld.TimeLinePanel timeLinePanel1;
// End of variables declaration
}
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package helloworld;
import java.awt.GridLayout;
import javax.swing.border.EmptyBorder;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
/**
*
* @author Justin
*/
public class TimeLinePanel extends javax.swing.JPanel {
/**
* Creates new form TimeLinePanel
*/
public TimeLinePanel() {
initComponents();
}
@Override
protected void paintComponent(Graphics g) {
Rectangle r = new Rectangle(3, 0, 1, 25);
g.fillRect(25, 0, 1, 25);
}
/**
* This method is called from within the constructor to initialize the form.
* WARNING: Do NOT modify this code. The content of this method is always
* regenerated by the Form Editor.
*/
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
jPanel1 = new javax.swing.JPanel();
jPanel1.setBackground(new java.awt.Color(255, 255, 255));
jPanel1.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(0, 0, 0)));
javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
jPanel1.setLayout(jPanel1Layout);
jPanel1Layout.setHorizontalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 200, Short.MAX_VALUE)
);
jPanel1Layout.setVerticalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 25, Short.MAX_VALUE)
);
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(this);
this.setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
);
}// </editor-fold>
// Variables declaration - do not modify
private javax.swing.JPanel jPanel1;
// End of variables declaration
}
这是我所得到的，当我尝试运行小程序。理想情况下，我想在白色框（timeLinePanel1）的某个（x，y）坐标处绘制一条垂直线，例如（25,0）（如代码所示），以了解我可以如何继续在JPanel中绘制垂直线。
其他组件是否出现在时间线上？如果不是，则使用'BufferedImage'作为画布更简单，并将其显示在标签上。我猜想你看到的很多问题都与首选尺寸和布局有关。使用图像应该解决这些问题。 –