Java 在重画图像后,如何继续在其上绘制?
我的程序旨在让用户在BuffereImage上绘制,并打开/保存要绘制的文件。打开保存的BuffereImage后,无法继续在其上绘制。下面是我的代码。如果您有任何其他关于代码迁移或简化的建议,我们将不胜感激Java 在重画图像后,如何继续在其上绘制?,java,swing,jpanel,bufferedimage,paintcomponent,Java,Swing,Jpanel,Bufferedimage,Paintcomponent,我的程序旨在让用户在BuffereImage上绘制,并打开/保存要绘制的文件。打开保存的BuffereImage后,无法继续在其上绘制。下面是我的代码。如果您有任何其他关于代码迁移或简化的建议,我们将不胜感激 import javax.imageio.ImageIO; import javax.swing.*; import java.awt.*; import java.awt.event.*; import java.awt.image.BufferedImage; import java.
import javax.imageio.ImageIO;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
public class MySmallPaint extends JPanel implements MouseListener, MouseMotionListener, ActionListener{
private int myX = -10, myY = -10;
private int radius = 5;
BufferedImage img = new BufferedImage(1000, 1000, BufferedImage.TYPE_INT_ARGB);
Graphics2D g2d = img.createGraphics();
private JPanel bucket = new JPanel(new GridLayout(7, 2));
private JPanel northPanel = new JPanel(new GridBagLayout());
private JButton[] buttons = new JButton[11];
private Color[] colorList = {Color.RED, Color.BLUE, Color.ORANGE, Color.CYAN, Color.YELLOW, Color.GREEN,
Color.WHITE, Color.MAGENTA, Color.GRAY, Color.PINK, Color.BLACK};
private Color currentColor = Color.BLACK;
private String[] pencilSize = {"1", "5", "10", "15", "20"};
private JComboBox sizeList = new JComboBox(pencilSize);
private JLabel thickness = new JLabel("Thickness");
private JButton clear = new JButton("Clear");
private JButton save = new JButton("Save");
private JButton open = new JButton("Open");
JFileChooser fc = new JFileChooser();
public MySmallPaint(){
super();
setImage();
setLayout(new BorderLayout());
addMouseListener(this);
addMouseMotionListener(this);
sizeList.setEditable(true);
for(int i = 0; i < buttons.length; i++){
buttons[i] = new JButton();
buttons[i].setBackground(colorList[i]);
buttons[i].addActionListener(this);
bucket.add(buttons[i]);
}
northPanel.add(thickness);
northPanel.add(sizeList);
sizeList.addActionListener(this);
northPanel.add(open);
open.addActionListener(this);
northPanel.add(save);
save.addActionListener(this);
northPanel.add(clear);
clear.addActionListener(this);
add(bucket, BorderLayout.WEST);
add(northPanel, BorderLayout.NORTH);
}
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@覆盖
已执行的公共无效操作(操作事件e){
对象源=e.getSource();
对于(int i=0;i
在读取新的BuffereImage后,需要更新Graphics2D对象。否则,你仍在试图画旧的(现在已经消失的)图像。@AlexMarkenzon:我同意:我认为这根本没有帮助。但是试着在ImageIO.read(…)
之后调用它,你可能会有更好的结果。是的,我回头看时注意到了这一点。在读取后移动它是有效的。谢谢不客气。你在我的评论发布之前删除了你的评论。如果他们帮助你解决你的问题,考虑一下这个问题(并且回答前面的问题)。
public void paintComponent(Graphics g){
super.paintComponents(g);
g2d.setColor(currentColor);
g2d.fillOval(myX - radius, myY - radius, 2 * radius, 2 * radius);
if(img != null)
g.drawImage(img, 0, 0, null);
}
@Override
public void actionPerformed(ActionEvent e) {
Object source = e.getSource();
for(int i = 0; i < buttons.length; i++)
if(source == buttons[i])
currentColor = colorList[i];
//Clears the panel
if(source == clear){
setImage();
}
//Changes radius
else if(source == sizeList)
radius = Integer.parseInt((String) sizeList.getSelectedItem());
//open a file
if(source == open){
int returnValue = fc.showOpenDialog(null);
if (returnValue == fc.APPROVE_OPTION) {
File sf = fc.getSelectedFile();
try {
img = ImageIO.read(sf);
repaint();
}
catch (IOException e2) {
e2.printStackTrace();
}
}
}
//save a file
else if(source == save){
fc.setDialogTitle("Specify a file to save");
int userSelection = fc.showSaveDialog(northPanel);
if (userSelection == JFileChooser.APPROVE_OPTION) {
File fileToSave = fc.getSelectedFile();
try{
ImageIO.write(img, "png", new File("pic.png"));
repaint();
} catch (Exception e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
}
}
}
@Override
public void mouseDragged(MouseEvent e) {
// TODO Auto-generated method stub
myX = e.getX();
myY = e.getY();
repaint();
}
@Override
public void mouseMoved(MouseEvent arg0) {
// TODO Auto-generated method stub
}
@Override
public void mouseClicked(MouseEvent e) {
myX = e.getX();
myY = e.getY();
repaint();
}
@Override
public void mouseEntered(MouseEvent arg0) {
// TODO Auto-generated method stub
}
@Override
public void mouseExited(MouseEvent arg0) {
// TODO Auto-generated method stub
}
@Override
public void mousePressed(MouseEvent arg0) {
// TODO Auto-generated method stub
}
@Override
public void mouseReleased(MouseEvent arg0) {
// TODO Auto-generated method stub
}
public void setImage (){
g2d.setColor(Color.WHITE);
g2d.fillRect(0, 0, img.getWidth(), img.getHeight());
g2d.dispose();
g2d = img.createGraphics();
}
public static void main(String[] args){
JFrame f = new JFrame("Swing Paint Demo");
f.setBackground(Color.WHITE);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(new MySmallPaint());
f.setVisible(true);
f.setResizable(false);
f.setSize(1000,1000);
}
}