java 如何在swing中将面板另存为图像？

how to save panel as image in swing?

提问by Babu R

Hi i want to convert panel which contains components like label and buttons to image file.

嗨，我想将包含标签和按钮等组件的面板转换为图像文件。

I have done the following code. The image was saved. but the content of the panel not visible or saved. Can anyone tell me how to save the panel with its components.

我已经完成了以下代码。图像已保存。但面板的内容不可见或不保存。谁能告诉我如何保存面板及其组件。

Code:

代码：

package PanelToImage;

import java.awt.Color;
import java.awt.image.BufferedImage;
import java.io.File;
import javax.imageio.ImageIO;
import javax.swing.*;

public class sample extends JPanel {

public JPanel firstpanel;
public JPanel secondpanel;
JLabel label1, label2;
JButton button1, button2;

public sample() {
    firstpanel = new JPanel();
    firstpanel.setSize(400,300); 
    firstpanel.setBackground(Color.RED);
    secondpanel = new JPanel();
    secondpanel.setBackground(Color.GREEN);
    secondpanel.setSize(400,300); 

    label1 = new JLabel("label1");
    label2 = new JLabel("label2");
    button1 = new JButton("button1");
    button2 = new JButton("button2");

    firstpanel.add(label1);
    firstpanel.add(button1);

    secondpanel.add(label2);
    secondpanel.add(button2);

    saveImage(firstpanel);

    add(firstpanel);

    // add(secondpanel);
}

public static void main(String args[]) {

    JFrame frame = new JFrame();
    sample sam = new sample();
    frame.setContentPane(sam);
    frame.setVisible(true);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(400, 300);

}

private void saveImage(JPanel panel) {
    BufferedImage img = new BufferedImage(panel.getWidth(), panel.getHeight(), BufferedImage.TYPE_INT_RGB);
    panel.paint(img.getGraphics());
    try {
        ImageIO.write(img, "png", new File("E://Screen.png"));
        System.out.println("panel saved as image");

    } catch (Exception e) {
        System.out.println("panel not saved" + e.getMessage());
    }
}
}

回答by Alberto

Tthis code works for me (in the JFrame):

这段代码对我有用（在 中JFrame）：

Container c = getContentPane();
BufferedImage im = new BufferedImage(c.getWidth(), c.getHeight(), BufferedImage.TYPE_INT_ARGB);
c.paint(im.getGraphics());
ImageIO.write(im, "PNG", new File("shot.png"));

Maybe you have used custom panels. If true, try to add super.paint(g)at the beginning of the paintmethods of your panels.

也许您使用过自定义面板。如果为 true，请尝试super.paint(g)在paint面板方法的开头添加。

EDIT: You have to call saveImageafterdisplay the frame:

编辑：您必须saveImage在显示框架后调用：

public static void main(String args[]) {
    ...
    frame.setSize(400, 300);
    sam.saveImage(sam.firstpanel);
}

EDIT 2: This is the saved image (is little because the layout, but is the proof that it should work):

编辑 2：这是保存的图像（因为布局很少，但证明它应该可以工作）：

I called the saveImageas last call in the main, and used a file in the user dir (new File("Screen.png")) as nIcE cOwsaid.

我打电话给saveImage在最后一次通话main，并在用户目录使用的文件（new File("Screen.png")）为NICE牛说。

回答by nIcE cOw

Here try this example program, instead of using getGraphics()seems like you have to use createGraphics()for the BufferedImageyou are about to make.

这里尝试这个例子程序，而不是使用getGraphics()好像你必须使用createGraphics()对BufferedImage你即将作出。

import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import javax.imageio.ImageIO;
import javax.swing.*;

public class SnapshotExample
{
    private JPanel contentPane;

    private void displayGUI()
    {
        JFrame frame = new JFrame("Snapshot Example");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        contentPane = new JPanel();
        contentPane.setOpaque(true);
        contentPane.setBackground(Color.WHITE);
        JLabel label = new JLabel("This JLabel will display"
                        + " itself on the SNAPSHOT", JLabel.CENTER);
        contentPane.add(label);

        frame.setContentPane(contentPane);
        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);

        makePanelImage(contentPane);
    }

    private void makePanelImage(Component panel)
    {
        Dimension size = panel.getSize();
        BufferedImage image = new BufferedImage(
                    size.width, size.height 
                              , BufferedImage.TYPE_INT_RGB);
        Graphics2D g2 = image.createGraphics();
        panel.paint(g2);
        try
        {
            ImageIO.write(image, "png", new File("snapshot.png"));
            System.out.println("Panel saved as Image.");
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
    }

    public static void main(String... args)
    {
        SwingUtilities.invokeLater(new Runnable()
        {
            public void run()
            {           
                new SnapshotExample().displayGUI();
            }
        });
    }
}