问题
Im working on a paint application written in java and running into a few (more) problems. I have a gui and a working program(kinda), my only problem is that the lines and graphics that the user draws are not saved(disappear after next one is drawn).
From a past question i learned that i will need to use a BufferedImage to store the drawings then paint that inside my paint class.
My questions are, Can anyone provide a basic explanation/example of how to use a bufferedimage to store and paint the drawing and if i need to, how will i pass the color and thickness of the drawn line into a stored array.
thats my whole class.
package javapaint;
import java.awt.*;
import javax.swing.*;
public class JavaPaintUI extends javax.swing.JFrame {
/** Creates new form JavaPaintUI */
public JavaPaintUI() {
initComponents();
}
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
buttonGroup1 = new javax.swing.ButtonGroup();
buttonGroup2 = new javax.swing.ButtonGroup();
jPanel4 = new javax.swing.JPanel();
jRadioButton9 = new javax.swing.JRadioButton();
jRadioButton10 = new javax.swing.JRadioButton();
jSlider2 = new javax.swing.JSlider();
jLabel1 = new javax.swing.JLabel();
jPanel2 = new Panel2();
jPanel3 = new javax.swing.JPanel();
jRadioButton3 = new javax.swing.JRadioButton();
jRadioButton4 = new javax.swing.JRadioButton();
jRadioButton5 = new javax.swing.JRadioButton();
jRadioButton6 = new javax.swing.JRadioButton();
jRadioButton7 = new javax.swing.JRadioButton();
jRadioButton8 = new javax.swing.JRadioButton();
jButton1 = new javax.swing.JButton();
jButton2 = new javax.swing.JButton();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
setTitle("JavaPaint ~ Nick R");
jPanel4.setBorder(javax.swing.BorderFactory.createTitledBorder("Tool"));
buttonGroup1.add(jRadioButton9);
jRadioButton9.setText("Pen");
jRadioButton9.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jRadioButton9ActionPerformed(evt);
}
});
buttonGroup1.add(jRadioButton10);
jRadioButton10.setText("Line");
jRadioButton10.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jRadioButton10ActionPerformed(evt);
}
});
jSlider2.setMajorTickSpacing(10);
jSlider2.setMaximum(51);
jSlider2.setMinimum(1);
jSlider2.setMinorTickSpacing(5);
jSlider2.setPaintTicks(true);
jSlider2.addChangeListener(new javax.swing.event.ChangeListener() {
public void stateChanged(javax.swing.event.ChangeEvent evt) {
jSlider2StateChanged(evt);
}
});
jLabel1.setText("Stroke Size (Radius)");
javax.swing.GroupLayout jPanel4Layout = new javax.swing.GroupLayout(jPanel4);
jPanel4.setLayout(jPanel4Layout);
jPanel4Layout.setHorizontalGroup(
jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel4Layout.createSequentialGroup()
.addContainerGap()
.addGroup(jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jRadioButton9)
.addComponent(jRadioButton10))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 51, Short.MAX_VALUE)
.addGroup(jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(jLabel1)
.addComponent(jSlider2, javax.swing.GroupLayout.PREFERRED_SIZE, 150, javax.swing.GroupLayout.PREFERRED_SIZE))
.addContainerGap())
);
jPanel4Layout.setVerticalGroup(
jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(jSlider2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addGroup(jPanel4Layout.createSequentialGroup()
.addGroup(jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jRadioButton9)
.addComponent(jLabel1))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addComponent(jRadioButton10)))
);
jPanel2.setBackground(new java.awt.Color(255, 255, 255));
jPanel2.setBorder(javax.swing.BorderFactory.createBevelBorder(javax.swing.border.BevelBorder.RAISED));
jPanel2.addMouseListener(new java.awt.event.MouseAdapter() {
public void mousePressed(java.awt.event.MouseEvent evt) {
jPanel2MousePressed(evt);
}
public void mouseReleased(java.awt.event.MouseEvent evt) {
jPanel2MouseReleased(evt);
}
});
jPanel2.addMouseMotionListener(new java.awt.event.MouseMotionAdapter() {
public void mouseDragged(java.awt.event.MouseEvent evt) {
jPanel2MouseDragged(evt);
}
});
javax.swing.GroupLayout jPanel2Layout = new javax.swing.GroupLayout(jPanel2);
jPanel2.setLayout(jPanel2Layout);
jPanel2Layout.setHorizontalGroup(
jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 596, Short.MAX_VALUE)
);
jPanel2Layout.setVerticalGroup(
jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 357, Short.MAX_VALUE)
);
jPanel3.setBorder(javax.swing.BorderFactory.createTitledBorder("Color"));
buttonGroup2.add(jRadioButton3);
jRadioButton3.setText("Red");
jRadioButton3.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jRadioButton3ActionPerformed(evt);
}
});
buttonGroup2.add(jRadioButton4);
jRadioButton4.setText("Black");
jRadioButton4.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jRadioButton4ActionPerformed(evt);
}
});
buttonGroup2.add(jRadioButton5);
jRadioButton5.setText("Gray");
jRadioButton5.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jRadioButton5ActionPerformed(evt);
}
});
buttonGroup2.add(jRadioButton6);
jRadioButton6.setText("Green");
jRadioButton6.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jRadioButton6ActionPerformed(evt);
}
});
buttonGroup2.add(jRadioButton7);
jRadioButton7.setText("White");
jRadioButton7.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jRadioButton7ActionPerformed(evt);
}
});
buttonGroup2.add(jRadioButton8);
jRadioButton8.setText("Blue");
jRadioButton8.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jRadioButton8ActionPerformed(evt);
}
});
javax.swing.GroupLayout jPanel3Layout = new javax.swing.GroupLayout(jPanel3);
jPanel3.setLayout(jPanel3Layout);
jPanel3Layout.setHorizontalGroup(
jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(jPanel3Layout.createSequentialGroup()
.addContainerGap()
.addGroup(jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addComponent(jRadioButton3, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jRadioButton4, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, 66, Short.MAX_VALUE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jRadioButton5, javax.swing.GroupLayout.DEFAULT_SIZE, 55, Short.MAX_VALUE)
.addComponent(jRadioButton6, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING, false)
.addComponent(jRadioButton8, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jRadioButton7, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
.addContainerGap())
);
jPanel3Layout.setVerticalGroup(
jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel3Layout.createSequentialGroup()
.addGroup(jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jRadioButton4)
.addComponent(jRadioButton5)
.addComponent(jRadioButton7))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 3, Short.MAX_VALUE)
.addGroup(jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
.addComponent(jRadioButton3)
.addComponent(jRadioButton6)
.addComponent(jRadioButton8)))
);
jButton1.setText("Clear");
jButton1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton1ActionPerformed(evt);
}
});
jButton2.setText("About");
jButton2.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton2ActionPerformed(evt);
}
});
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jPanel2, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addGroup(layout.createSequentialGroup()
.addComponent(jPanel4, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
.addComponent(jPanel3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jButton2, javax.swing.GroupLayout.DEFAULT_SIZE, 112, Short.MAX_VALUE)
.addComponent(jButton1, javax.swing.GroupLayout.DEFAULT_SIZE, 112, Short.MAX_VALUE))))
.addContainerGap())
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
.addGroup(layout.createSequentialGroup()
.addGap(4, 4, 4)
.addComponent(jButton1, javax.swing.GroupLayout.PREFERRED_SIZE, 30, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jButton2, javax.swing.GroupLayout.PREFERRED_SIZE, 28, javax.swing.GroupLayout.PREFERRED_SIZE))
.addComponent(jPanel4, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jPanel3, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jPanel2, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addContainerGap())
);
pack();
}// </editor-fold>
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
System.out.println("You cleared the canvas.");
}
private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {
JOptionPane.showMessageDialog(null, "JavaPaint is a simple java based painting application."
+ " Nick R 5/22/2011", "About", JOptionPane.INFORMATION_MESSAGE);
}
int currentX, currentY, oldX, oldY;
private void jPanel2MouseDragged(java.awt.event.MouseEvent evt) {
currentX = evt.getX();
currentY = evt.getY();
repaint();
if (tool == 1) {
oldX = currentX;
oldY = currentY;
System.out.println("Using pen at " + currentX + ", " + currentY);
}
}
private void jPanel2MousePressed(java.awt.event.MouseEvent evt) {
oldX = evt.getX();
oldY = evt.getY();
if (tool == 2) {
currentX = oldX;
currentY = oldY;
}
}
//Tool Selection//
int tool = 0;
private void jRadioButton9ActionPerformed(java.awt.event.ActionEvent evt) {
tool = 1;
System.out.println("Using the pen tool.");
}
private void jRadioButton10ActionPerformed(java.awt.event.ActionEvent evt) {
tool = 2;
System.out.println("Using the line tool.");
}
//Slider Properties//
double value = 5;
private void jSlider2StateChanged(javax.swing.event.ChangeEvent evt) {
value = jSlider2.getValue();
System.out.println(value);
}
//COLOR CODE//
int color = 1;
private void jRadioButton4ActionPerformed(java.awt.event.ActionEvent evt) {
color = 1; // Black
}
private void jRadioButton5ActionPerformed(java.awt.event.ActionEvent evt) {
color = 2; // Grey
}
private void jRadioButton7ActionPerformed(java.awt.event.ActionEvent evt) {
color = 3; // White
}
private void jRadioButton3ActionPerformed(java.awt.event.ActionEvent evt) {
color = 4; // Red
}
private void jRadioButton6ActionPerformed(java.awt.event.ActionEvent evt) {
color = 5; // Green
}
private void jRadioButton8ActionPerformed(java.awt.event.ActionEvent evt) {
color = 6; // Blue
}
//mouse released//
private void jPanel2MouseReleased(java.awt.event.MouseEvent evt) {
currentX = evt.getX();
currentY = evt.getY();
if (tool == 2) {
System.out.println("line from " + oldX +", "+ oldY + " to " + currentX + ", " + currentY);
}
}
//set ui visible//
public static void main(String args[]) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new JavaPaintUI().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.ButtonGroup buttonGroup1;
private javax.swing.ButtonGroup buttonGroup2;
private javax.swing.JButton jButton1;
private javax.swing.JButton jButton2;
private javax.swing.JLabel jLabel1;
public javax.swing.JPanel jPanel2;
private javax.swing.JPanel jPanel3;
private javax.swing.JPanel jPanel4;
private javax.swing.JRadioButton jRadioButton10;
private javax.swing.JRadioButton jRadioButton3;
private javax.swing.JRadioButton jRadioButton4;
private javax.swing.JRadioButton jRadioButton5;
private javax.swing.JRadioButton jRadioButton6;
private javax.swing.JRadioButton jRadioButton7;
private javax.swing.JRadioButton jRadioButton8;
private javax.swing.JRadioButton jRadioButton9;
public javax.swing.JSlider jSlider2;
// End of variables declaration
class Panel2 extends JPanel {
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON);
if(color==1)
g2.setPaint( Color.black );
else if(color==2)
g2.setPaint( Color.gray);
else if(color==3)
g2.setPaint( Color.white );
else if(color==4)
g2.setPaint( Color.red );
else if(color==5)
g2.setPaint( Color.green );
else if(color==6)
g2.setPaint( Color.blue );
if (tool == 1) {
g2.fillOval(currentX - ((int) value / 2), currentY - ((int) value / 2), (int) value, (int) value);
} else if (tool == 2) {
g2.setStroke(new BasicStroke((float) value, BasicStroke.CAP_ROUND,BasicStroke.JOIN_ROUND));
g2.drawLine(oldX, oldY, currentX, currentY);
g2.setStroke(new BasicStroke(1.0f));
}
}
}
}
Thanks ahead!
回答1:
OK - here are a ..few changes.
import java.awt.*;
import java.awt.image.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;
import javax.swing.event.*;
public class JavaPaintUI extends JFrame {
private BufferedImage canvas;
/** Creates new form JavaPaintUI */
public JavaPaintUI() {
initComponents();
}
//this was moved from the overriden paintComponent()
// instead it update the canvas BufferedImage and calls repaint()
public void updateCanvas() {
Graphics2D g2d = canvas.createGraphics();
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setPaint( getColor() );
if (tool == 1) {
g2d.fillOval(currentX - ((int) value / 2), currentY - ((int) value / 2), (int) value, (int) value);
} else if (tool == 2) {
g2d.setStroke(new BasicStroke((float) value, BasicStroke.CAP_ROUND,BasicStroke.JOIN_ROUND));
g2d.drawLine(oldX, oldY, currentX, currentY);
g2d.setStroke(new BasicStroke(1.0f));
}
repaint();
}
// used in both the updateCanvas and 'clear' method.
private Color getColor() {
Color c = null;
if(color==1)
c = Color.black;
else if(color==2)
c = Color.gray;
else if(color==3)
c = Color.white;
else if(color==4)
c = Color.red;
else if(color==5)
c = Color.green;
else if(color==6)
c = Color.blue;
return c;
}
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
canvas = new BufferedImage(600,400,BufferedImage.TYPE_INT_RGB);
buttonGroup1 = new ButtonGroup();
buttonGroup2 = new ButtonGroup();
jPanel4 = new JPanel();
jRadioButton9 = new JRadioButton();
jRadioButton10 = new JRadioButton();
jSlider2 = new JSlider();
jLabel1 = new JLabel();
jPanel2 = new JPanel(new GridBagLayout());
JLabel canvasLabel = new JLabel(new ImageIcon(canvas));
jPanel2.add(canvasLabel, null);
jPanel3 = new JPanel();
jRadioButton3 = new JRadioButton();
jRadioButton4 = new JRadioButton();
jRadioButton5 = new JRadioButton();
jRadioButton6 = new JRadioButton();
jRadioButton7 = new JRadioButton();
jRadioButton8 = new JRadioButton();
jButton1 = new JButton();
jButton2 = new JButton();
setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
setTitle("JavaPaint ~ Nick R");
jPanel4.setBorder(BorderFactory.createTitledBorder("Tool"));
buttonGroup1.add(jRadioButton9);
jRadioButton9.setText("Pen");
jRadioButton9.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
jRadioButton9ActionPerformed(evt);
}
});
buttonGroup1.add(jRadioButton10);
jRadioButton10.setText("Line");
jRadioButton10.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
jRadioButton10ActionPerformed(evt);
}
});
jSlider2.setMajorTickSpacing(10);
jSlider2.setMaximum(51);
jSlider2.setMinimum(1);
jSlider2.setMinorTickSpacing(5);
jSlider2.setPaintTicks(true);
jSlider2.addChangeListener(new ChangeListener() {
public void stateChanged(ChangeEvent evt) {
jSlider2StateChanged(evt);
}
});
jLabel1.setText("Stroke Size (Radius)");
GroupLayout jPanel4Layout = new GroupLayout(jPanel4);
jPanel4.setLayout(jPanel4Layout);
jPanel4Layout.setHorizontalGroup(
jPanel4Layout.createParallelGroup(GroupLayout.Alignment.LEADING)
.addGroup(jPanel4Layout.createSequentialGroup()
.addContainerGap()
.addGroup(jPanel4Layout.createParallelGroup(GroupLayout.Alignment.LEADING)
.addComponent(jRadioButton9)
.addComponent(jRadioButton10))
.addPreferredGap(LayoutStyle.ComponentPlacement.RELATED, 51, Short.MAX_VALUE)
.addGroup(jPanel4Layout.createParallelGroup(GroupLayout.Alignment.TRAILING)
.addComponent(jLabel1)
.addComponent(jSlider2, GroupLayout.PREFERRED_SIZE, 150, GroupLayout.PREFERRED_SIZE))
.addContainerGap())
);
jPanel4Layout.setVerticalGroup(
jPanel4Layout.createParallelGroup(GroupLayout.Alignment.LEADING)
.addGroup(jPanel4Layout.createParallelGroup(GroupLayout.Alignment.TRAILING)
.addComponent(jSlider2, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
.addGroup(jPanel4Layout.createSequentialGroup()
.addGroup(jPanel4Layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
.addComponent(jRadioButton9)
.addComponent(jLabel1))
.addPreferredGap(LayoutStyle.ComponentPlacement.UNRELATED)
.addComponent(jRadioButton10)))
);
jPanel2.setBackground(new Color(128, 40, 128));
jPanel2.setBorder(BorderFactory.createBevelBorder(BevelBorder.RAISED));
// add the listeners to the label that contains the canvas buffered image
canvasLabel.addMouseListener(new MouseAdapter() {
public void mousePressed(MouseEvent evt) {
jPanel2MousePressed(evt);
}
public void mouseReleased(MouseEvent evt) {
jPanel2MouseReleased(evt);
}
});
canvasLabel.addMouseMotionListener(new MouseMotionAdapter() {
public void mouseDragged(MouseEvent evt) {
jPanel2MouseDragged(evt);
}
});
// this part of the code was not helping.
// either layout a container or custom paint it.
// only attempt both if you are very confident of what you are doing.
/*
GroupLayout jPanel2Layout = new GroupLayout(jPanel2);
jPanel2.setLayout(jPanel2Layout);
jPanel2Layout.setHorizontalGroup(
jPanel2Layout.createParallelGroup(GroupLayout.Alignment.LEADING)
.addGap(0, 596, Short.MAX_VALUE)
);
jPanel2Layout.setVerticalGroup(
jPanel2Layout.createParallelGroup(GroupLayout.Alignment.LEADING)
.addGap(0, 357, Short.MAX_VALUE)
);
*/
jPanel3.setBorder(BorderFactory.createTitledBorder("Color"));
buttonGroup2.add(jRadioButton3);
jRadioButton3.setText("Red");
jRadioButton3.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
jRadioButton3ActionPerformed(evt);
}
});
buttonGroup2.add(jRadioButton4);
jRadioButton4.setText("Black");
jRadioButton4.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
jRadioButton4ActionPerformed(evt);
}
});
buttonGroup2.add(jRadioButton5);
jRadioButton5.setText("Gray");
jRadioButton5.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
jRadioButton5ActionPerformed(evt);
}
});
buttonGroup2.add(jRadioButton6);
jRadioButton6.setText("Green");
jRadioButton6.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
jRadioButton6ActionPerformed(evt);
}
});
buttonGroup2.add(jRadioButton7);
jRadioButton7.setText("White");
jRadioButton7.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
jRadioButton7ActionPerformed(evt);
}
});
buttonGroup2.add(jRadioButton8);
jRadioButton8.setText("Blue");
jRadioButton8.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
jRadioButton8ActionPerformed(evt);
}
});
GroupLayout jPanel3Layout = new GroupLayout(jPanel3);
jPanel3.setLayout(jPanel3Layout);
jPanel3Layout.setHorizontalGroup(
jPanel3Layout.createParallelGroup(GroupLayout.Alignment.LEADING)
.addGroup(jPanel3Layout.createSequentialGroup()
.addContainerGap()
.addGroup(jPanel3Layout.createParallelGroup(GroupLayout.Alignment.LEADING, false)
.addComponent(jRadioButton3, GroupLayout.Alignment.TRAILING, GroupLayout.DEFAULT_SIZE, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jRadioButton4, GroupLayout.Alignment.TRAILING, GroupLayout.DEFAULT_SIZE, 66, Short.MAX_VALUE))
.addPreferredGap(LayoutStyle.ComponentPlacement.RELATED)
.addGroup(jPanel3Layout.createParallelGroup(GroupLayout.Alignment.LEADING)
.addComponent(jRadioButton5, GroupLayout.DEFAULT_SIZE, 55, Short.MAX_VALUE)
.addComponent(jRadioButton6, GroupLayout.DEFAULT_SIZE, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
.addPreferredGap(LayoutStyle.ComponentPlacement.RELATED)
.addGroup(jPanel3Layout.createParallelGroup(GroupLayout.Alignment.TRAILING, false)
.addComponent(jRadioButton8, GroupLayout.DEFAULT_SIZE, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jRadioButton7, GroupLayout.DEFAULT_SIZE, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
.addContainerGap())
);
jPanel3Layout.setVerticalGroup(
jPanel3Layout.createParallelGroup(GroupLayout.Alignment.LEADING)
.addGroup(GroupLayout.Alignment.TRAILING, jPanel3Layout.createSequentialGroup()
.addGroup(jPanel3Layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
.addComponent(jRadioButton4)
.addComponent(jRadioButton5)
.addComponent(jRadioButton7))
.addPreferredGap(LayoutStyle.ComponentPlacement.RELATED, 3, Short.MAX_VALUE)
.addGroup(jPanel3Layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
.addComponent(jRadioButton3)
.addComponent(jRadioButton6)
.addComponent(jRadioButton8)))
);
jButton1.setText("Clear");
jButton1.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
jButton1ActionPerformed(evt);
}
});
jButton2.setText("About");
jButton2.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
jButton2ActionPerformed(evt);
}
});
GroupLayout layout = new GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addGroup(layout.createParallelGroup(GroupLayout.Alignment.LEADING)
.addComponent(jPanel2, GroupLayout.Alignment.TRAILING, GroupLayout.DEFAULT_SIZE, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addGroup(layout.createSequentialGroup()
.addComponent(jPanel4, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
.addPreferredGap(LayoutStyle.ComponentPlacement.UNRELATED)
.addComponent(jPanel3, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE)
.addPreferredGap(LayoutStyle.ComponentPlacement.RELATED)
.addGroup(layout.createParallelGroup(GroupLayout.Alignment.LEADING)
.addComponent(jButton2, GroupLayout.DEFAULT_SIZE, 112, Short.MAX_VALUE)
.addComponent(jButton1, GroupLayout.DEFAULT_SIZE, 112, Short.MAX_VALUE))))
.addContainerGap())
);
layout.setVerticalGroup(
layout.createParallelGroup(GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(GroupLayout.Alignment.LEADING, false)
.addGroup(layout.createSequentialGroup()
.addGap(4, 4, 4)
.addComponent(jButton1, GroupLayout.PREFERRED_SIZE, 30, GroupLayout.PREFERRED_SIZE)
.addPreferredGap(LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jButton2, GroupLayout.PREFERRED_SIZE, 28, GroupLayout.PREFERRED_SIZE))
.addComponent(jPanel4, GroupLayout.DEFAULT_SIZE, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jPanel3, GroupLayout.DEFAULT_SIZE, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
.addPreferredGap(LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jPanel2, GroupLayout.DEFAULT_SIZE, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addContainerGap())
);
pack();
}// </editor-fold>
// clear the canvas using the currently selected color.
private void jButton1ActionPerformed(ActionEvent evt) {
System.out.println("You cleared the canvas.");
Graphics g = canvas.getGraphics();
g.setColor( getColor() );
g.fillRect(0,0,canvas.getWidth(),canvas.getHeight());
repaint();
}
private void jButton2ActionPerformed(ActionEvent evt) {
JOptionPane.showMessageDialog(null, "JavaPaint is a simple java based painting application."
+ " Nick R 5/22/2011", "About", JOptionPane.INFORMATION_MESSAGE);
}
int currentX, currentY, oldX, oldY;
private void jPanel2MouseDragged(MouseEvent evt) {
currentX = evt.getX();
currentY = evt.getY();
updateCanvas();
if (tool == 1) {
oldX = currentX;
oldY = currentY;
System.out.println("Using pen at " + currentX + ", " + currentY);
}
}
private void jPanel2MousePressed(MouseEvent evt) {
oldX = evt.getX();
oldY = evt.getY();
if (tool == 2) {
currentX = oldX;
currentY = oldY;
}
}
//Tool Selection//
int tool = 0;
private void jRadioButton9ActionPerformed(ActionEvent evt) {
tool = 1;
System.out.println("Using the pen tool.");
}
private void jRadioButton10ActionPerformed(ActionEvent evt) {
tool = 2;
System.out.println("Using the line tool.");
}
//Slider Properties//
double value = 5;
private void jSlider2StateChanged(ChangeEvent evt) {
value = jSlider2.getValue();
System.out.println(value);
}
//COLOR CODE//
int color = 1;
private void jRadioButton4ActionPerformed(ActionEvent evt) {
color = 1; // Black
}
private void jRadioButton5ActionPerformed(ActionEvent evt) {
color = 2; // Grey
}
private void jRadioButton7ActionPerformed(ActionEvent evt) {
color = 3; // White
}
private void jRadioButton3ActionPerformed(ActionEvent evt) {
color = 4; // Red
}
private void jRadioButton6ActionPerformed(ActionEvent evt) {
color = 5; // Green
}
private void jRadioButton8ActionPerformed(ActionEvent evt) {
color = 6; // Blue
}
//mouse released//
private void jPanel2MouseReleased(MouseEvent evt) {
currentX = evt.getX();
currentY = evt.getY();
if (tool == 2) {
System.out.println("line from " + oldX +", "+ oldY + " to " + currentX + ", " + currentY);
}
}
//set ui visible//
public static void main(String args[]) {
EventQueue.invokeLater(new Runnable() {
public void run() {
new JavaPaintUI().setVisible(true);
}
});
}
// Variables declaration - do not modify
private ButtonGroup buttonGroup1;
private ButtonGroup buttonGroup2;
private JButton jButton1;
private JButton jButton2;
private JLabel jLabel1;
public JPanel jPanel2;
private JPanel jPanel3;
private JPanel jPanel4;
private JRadioButton jRadioButton10;
private JRadioButton jRadioButton3;
private JRadioButton jRadioButton4;
private JRadioButton jRadioButton5;
private JRadioButton jRadioButton6;
private JRadioButton jRadioButton7;
private JRadioButton jRadioButton8;
private JRadioButton jRadioButton9;
public JSlider jSlider2;
// End of variables declaration
}
Screen shot
回答2:
Drawing into a buffer is just like drawing in a paintComponent(Graphics g). The difference is that you:
1) first create the buffer from any component (e.g. a Panel):
Image image = panel.createImage(width, height);
2) get the graphics context for the image:
Graphics g = image.getGraphics();
3) finally when done drawing into the buffer:
g.dispose();
Later, to draw the image onto your component:
void paintComponent(Graphics g) {
g.drawImage(image, x_offset, y_offset, null);
}
来源：https://stackoverflow.com/questions/6132988/painting-in-a-bufferedimage-inside-swing