将图像加载到小程序中的 JPanel

Question

基于此线程：Java: Load image from file, edit and add to JPanel 我试图将 na 图像加载到 JPanel 但它没有绘制它，所以这是交易，正如建议的那样，我创建了一个名为 JImageComponent 的新类文件，它从 JComponent 扩展，如下所示：

package in.co.sneh;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import javax.swing.JComponent;
private BufferedImage img;
    public class JImageComponent  extends JComponent
{
    public JImageComponent (BufferedImage bi)
{
    img = bi;
}

@Override
public void paintComponent(Graphics g)
{
    g.drawImage(img, 0, 0, this);
}
}

然后在小程序表单类中，当我点击 loadPicture 按钮时，执行的操作如下所示：

JFileChooser chooser = new JFileChooser();
    chooser.setFileSelectionMode(JFileChooser.FILES_AND_DIRECTORIES);
   int retVal = chooser.showDialog(AppletForm.this, "Attach");
    if (retVal == JFileChooser.APPROVE_OPTION) {
        picFile = chooser.getSelectedFile();
        try {

            image = ImageIO.read(picFile);
            JImageComponent jcomp = new JImageComponent(image);
            Graphics2D g = image.createGraphics();
            jcomp.paintComponents(g);
            // Draw here on the graphics
            //g.dispose();
            g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, 
            RenderingHints.VALUE_ANTIALIAS_ON);
            jPanel6.add(jcomp);
            System.out.println("Testing" + picFile);



        } catch (IOException e) {

            e.printStackTrace();
        }

对我来说一切都准备好了，但是在文件资源管理器中选择图像时图像没有显示，有人可以帮我吗？ 提前致谢， 罗慕洛·罗梅罗

Answer 1

向容器中添加新组件后，需要调用

jPanel6.revalidate();
jPanel6.repaint();

Applet 也无法从本地文件系统加载资源，除非它们被签名。

注意： 虽然有一个JImageComponent 会更好，但JLabel 组件已经提供了使用setIcon 切换图像的功能。

Answer 2

这是一个简单的小程序代码，可以帮助您编辑图像......

you can try it

/*Arpana*/

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridLayout;
import java.awt.Image;
import java.awt.MediaTracker;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.image.BufferedImage;
import java.awt.image.ConvolveOp;
import java.awt.image.Kernel;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.border.TitledBorder;

public class ConvolveApp extends JFrame {
  CPanel displayPanel;

  JButton sharpenButton, blurringButton, edButton, resetButton;

  public ConvolveApp() {
    super();
    Container container = getContentPane();

    displayPanel = new CPanel();
    container.add(displayPanel);

    JPanel panel = new JPanel();
    panel.setLayout(new GridLayout(2, 2));
    panel
        .setBorder(new TitledBorder(
            "Click a Button to Perform the Associated Operation and Reset..."));

    sharpenButton = new JButton("Sharpen");
    sharpenButton.addActionListener(new ButtonListener());
    blurringButton = new JButton("Blur");
    blurringButton.addActionListener(new ButtonListener());
    edButton = new JButton("Edge Detect");
    edButton.addActionListener(new ButtonListener());
    resetButton = new JButton("Reset");
    resetButton.addActionListener(new ButtonListener());

    panel.add(sharpenButton);
    panel.add(blurringButton);
    panel.add(edButton);
    panel.add(resetButton);

    container.add(BorderLayout.SOUTH, panel);

    addWindowListener(new WindowAdapter() {
      public void windowClosing(WindowEvent e) {
        System.exit(0);
      }
    });
     //setSize(100,100);
    setSize(displayPanel.getWidth()+50, displayPanel.getHeight() );
    setVisible(true); 
  }
  public static void main(String arg[]) {
    new ConvolveApp();
  }

  class ButtonListener implements ActionListener {
    public void actionPerformed(ActionEvent e) {
      JButton button = (JButton) e.getSource();

      if (button.equals(sharpenButton)) {
        displayPanel.sharpen();
        displayPanel.repaint();
      } else if (button.equals(blurringButton)) {
        displayPanel.blur();
        displayPanel.repaint();
      } else if (button.equals(edButton)) {
        displayPanel.edgeDetect();
        displayPanel.repaint();
      } else if (button.equals(resetButton)) {
        displayPanel.reset();
        displayPanel.repaint();
      }
    }
  }
}

class CPanel extends JLabel {
  Image displayImage;

  BufferedImage biSrc;

  BufferedImage biDest; // Destination image is mandetory.

  BufferedImage bi; // Only an additional reference.

  Graphics2D big;

  CPanel() {
    setBackground(Color.black);
    loadImage();
    setSize(displayImage.getWidth(this), displayImage.getWidth(this)); 
    createBufferedImages();
    bi = biSrc;
  }

  public void loadImage() {
    displayImage = Toolkit.getDefaultToolkit().getImage("Desert.jpg");
    MediaTracker mt = new MediaTracker(this);
    mt.addImage(displayImage, 1);
    try {
      mt.waitForAll();
    } catch (Exception e) {
      System.out.println("Exception while loading.");
    }
    if (displayImage.getWidth(this) == -1) {
      System.out.println("No jpg file");
      System.exit(0);
    }
  }

  public void createBufferedImages() {
    biSrc = new BufferedImage(displayImage.getWidth(this), displayImage
        .getHeight(this), BufferedImage.TYPE_INT_RGB);

    big = biSrc.createGraphics();
    big.drawImage(displayImage, 0, 0, this);

    biDest = new BufferedImage(displayImage.getWidth(this), displayImage
        .getHeight(this), BufferedImage.TYPE_INT_RGB);
  }

  public void sharpen() {
    float data[] = { -1.0f, -1.0f, -1.0f, -1.0f, 9.0f, -1.0f, -1.0f, -1.0f,
        -1.0f };
    Kernel kernel = new Kernel(3, 3, data);
    ConvolveOp convolve = new ConvolveOp(kernel, ConvolveOp.EDGE_NO_OP,
        null);
    convolve.filter(biSrc, biDest);
    bi = biDest;
  }

  public void blur() {
    float data[] = { 0.0625f, 0.125f, 0.0625f, 0.125f, 0.25f, 0.125f,
        0.0625f, 0.125f, 0.0625f };
    Kernel kernel = new Kernel(3, 3, data);
    ConvolveOp convolve = new ConvolveOp(kernel, ConvolveOp.EDGE_NO_OP,
        null);
    convolve.filter(biSrc, biDest);
    bi = biDest;
  }

    public void edgeDetect() {
    float data[] = { 1.0f, 0.0f, -1.0f, 1.0f, 0.0f, -1.0f, 1.0f, 0.0f,
        -1.0f };

    Kernel kernel = new Kernel(3, 3, data);
    ConvolveOp convolve = new ConvolveOp(kernel, ConvolveOp.EDGE_NO_OP,
        null);
    convolve.filter(biSrc, biDest);

    bi = biDest;
  }

  public void reset() {
    big.setColor(Color.black);
    big.clearRect(0, 0, bi.getWidth(this), bi.getHeight(this));
    big.drawImage(displayImage, 0, 0, this);
    bi = biSrc;
  }

  public void update(Graphics g) {
    g.clearRect(0, 0, getWidth(), getHeight());
    paintComponent(g);
  }

  public void paintComponent(Graphics g) {
    super.paintComponent(g);
    Graphics2D g2D = (Graphics2D) g;

    g2D.drawImage(bi, 0, 0, this);
  }
}