Java 将 Graphics2D 转换为 Image 或 BufferedImage
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Convert a Graphics2D to an Image or BufferedImage
提问by caarlos0
I have a little problem here.
我这里有一个小问题。
I have an applet, where user can "draw" inside it. To do that, I use the java.awt.Graphics2D. But, how can I do to save the user draw image as a JPEG image, or at least, convert it to a BufferedImage or something? I don't know how to do that.
我有一个小程序，用户可以在其中“绘图”。为此，我使用 java.awt.Graphics2D。但是，我该如何将用户绘制的图像保存为 JPEG 图像，或者至少将其转换为 BufferedImage 或其他什么？我不知道该怎么做。
Thanks.
谢谢。
采纳答案by caarlos0
I do it that way, and works very well:
我就是这样做的，而且效果很好：
BufferedImage awtImage = new BufferedImage(drawPanel.getWidth(), drawPanel.getHeight(), BufferedImage.TYPE_INT_RGB);
Graphics g = awtImage.getGraphics();
drawPanel.printAll(g);
try
{
String caminhoImagem = System.getProperty("user.home") + "\temps\assinatura.jpg";
FileOutputStream fos = new FileOutputStream(caminhoImagem);
JPEGImageEncoderImpl j = new JPEGImageEncoderImpl(fos);
j.encode(awtImage);
fos.close();
} catch(e) {..... }
That's all :) Thanks everyone :)
就是这样 :) 谢谢大家 :)
回答by Hovercraft Full Of Eels
Have them draw directly in a BufferedImage by way of it's Graphics2D object which you can get via getGraphics(). Then use ImageIO.write(...)to output the image to whatever file type you desire (and that's supported). The ImageIO API should help you with this: ImageIO API.
让它们通过可以通过 getGraphics() 获得的 Graphics2D 对象直接在 BufferedImage 中绘制。然后用于ImageIO.write(...)将图像输出到您想要的任何文件类型（并且支持）。ImageIO API 应该可以帮助您解决这个问题：ImageIO API。
The other issue you'll have is where are they supposed to save the image once it has been drawn? On their own computer? If so and this is an applet program, then the applet will need to be "signed" in order for it to have the permission to write to disk. If you're unsure on this, check out Google, this article, or you may wish to write a new question for this issue alone.
您将遇到的另一个问题是，一旦绘制图像，他们应该在哪里保存图像？在自己的电脑上？如果是这样并且这是一个小程序程序，那么小程序将需要“签名”以便它具有写入磁盘的权限。如果您对此不确定，请查看 Google、这篇文章，或者您可能希望单独针对这个问题写一个新问题。
Edit 1: code example
For example:
编辑 1：代码示例
例如：
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.swing.*;
import javax.swing.filechooser.FileNameExtensionFilter;
@SuppressWarnings("serial")
public class DrawAndSaveImage extends JPanel {
private static final int BI_WIDTH = 600;
private static final int BI_HEIGHT = BI_WIDTH;
private static final Color LABEL_DRAW_COLOR = new Color(180, 180, 255);
private static final Stroke LABEL_DRAW_STROKE = new BasicStroke(1);
private static final Stroke BIMAGE_DRAW_STROKE = new BasicStroke(4);
private static final int COLOR_DIV = 5;
private BufferedImage bImage = new BufferedImage(BI_WIDTH, BI_HEIGHT,
BufferedImage.TYPE_INT_RGB);
private List<Point> pointList = new ArrayList<Point>();
private JLabel imageLabel;
private List<Color> colorList = new ArrayList<Color>();
private Random random = new Random();
public DrawAndSaveImage() {
Graphics2D g2d = bImage.createGraphics();
g2d.setBackground(Color.white);
g2d.clearRect(0, 0, BI_WIDTH, BI_HEIGHT);
g2d.dispose();
for (int r = 0; r < COLOR_DIV; r++) {
for (int g = 0; g < COLOR_DIV; g++) {
for (int b = 0; b < COLOR_DIV; b++) {
Color c = new Color((r * 255) / COLOR_DIV,
(g * 255) / COLOR_DIV, (b * 255) / COLOR_DIV);
colorList.add(c);
}
}
}
imageLabel = new JLabel(new ImageIcon(bImage)) {
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
paintInLabel(g);
}
};
MyMouseAdapter myMouseAdapter = new MyMouseAdapter();
imageLabel.addMouseListener(myMouseAdapter);
imageLabel.addMouseMotionListener(myMouseAdapter);
imageLabel.setBorder(BorderFactory.createEtchedBorder());
JButton saveImageBtn = new JButton("Save Image");
saveImageBtn.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
saveImageActionPerformed();
}
});
JButton clearImageBtn = new JButton("Clear Image");
clearImageBtn.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
Graphics2D g2 = bImage.createGraphics();
g2.setBackground(Color.white);
g2.clearRect(0, 0, BI_WIDTH, BI_HEIGHT);
g2.dispose();
imageLabel.repaint();
}
});
JPanel btnPanel = new JPanel();
btnPanel.add(saveImageBtn);
btnPanel.add(clearImageBtn);
setLayout(new BorderLayout());
add(imageLabel, BorderLayout.CENTER);
add(btnPanel, BorderLayout.SOUTH);
}
private void saveImageActionPerformed() {
JFileChooser filechooser = new JFileChooser();
FileNameExtensionFilter filter = new FileNameExtensionFilter(
"JPG Images", "jpg");
filechooser.setFileFilter(filter);
int result = filechooser.showSaveDialog(this);
if (result == JFileChooser.APPROVE_OPTION) {
File saveFile = filechooser.getSelectedFile();
try {
ImageIO.write(bImage, "jpg", saveFile);
} catch (IOException e) {
e.printStackTrace();
}
}
}
private void paintInLabel(Graphics g) {
Graphics2D g2d = (Graphics2D) g;
g2d.setColor(LABEL_DRAW_COLOR);
g2d.setStroke(LABEL_DRAW_STROKE);
if (pointList.size() < 2) {
return;
}
for (int i = 1; i < pointList.size(); i++) {
int x1 = pointList.get(i - 1).x;
int y1 = pointList.get(i - 1).y;
int x2 = pointList.get(i).x;
int y2 = pointList.get(i).y;
g2d.drawLine(x1, y1, x2, y2);
}
}
private class MyMouseAdapter extends MouseAdapter {
@Override
public void mousePressed(MouseEvent e) {
pointList.add(e.getPoint());
imageLabel.repaint();
}
@Override
public void mouseReleased(MouseEvent e) {
Graphics2D g2d = bImage.createGraphics();
g2d.setColor(colorList.get(random.nextInt(colorList.size())));
g2d.setStroke(BIMAGE_DRAW_STROKE);
if (pointList.size() >= 2) {
for (int i = 1; i < pointList.size(); i++) {
int x1 = pointList.get(i - 1).x;
int y1 = pointList.get(i - 1).y;
int x2 = pointList.get(i).x;
int y2 = pointList.get(i).y;
g2d.drawLine(x1, y1, x2, y2);
}
}
g2d.dispose();
pointList.clear();
imageLabel.repaint();
}
@Override
public void mouseDragged(MouseEvent e) {
pointList.add(e.getPoint());
imageLabel.repaint();
}
}
private static void createAndShowUI() {
JFrame frame = new JFrame("DrawAndSaveImage");
frame.getContentPane().add(new DrawAndSaveImage());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
createAndShowUI();
}
});
}
}
回答by c00kiemon5ter
Use the drawImagemethod provided by Graphics2Dand write it using ImageIO
使用drawImage提供的方法Graphics2D并使用ImageIO
BufferedImage img;
g2dObject.drawImage(img, null, 0, 0);
ImageIO.write(img, "JPEG", new File("foo.jpg"));
回答by camickr
Use the "drawOnImage" example from Custom Painting Approaches. Then to create the image of the panel you can use the Screen Imageclass.
使用自定义绘画方法中的“drawOnImage”示例。然后要创建面板的图像，您可以使用Screen Image类。
回答by Muskovets
If you'd like to draw JComponent's image onto BufferedImage (JApplet extends JComponent):
如果您想将 JComponent 的图像绘制到 BufferedImage 上（JApplet 扩展 JComponent）：
JComponent whatToDraw = ...;
BufferedImage img = new BufferedImage(whatToDraw.getWidth(),
whatToDraw.getHeight(), BufferedImage.TYPE_INT_RGB);
whatToDraw.printAll(img.getGraphics());
And to write its data to JPEG file:
并将其数据写入 JPEG 文件：
ImageIO.write(img, "jpg", new File("something.jpg"));
