java - Jpanel中的放大缩小功能

Question

我必须向 JPanel 添加 Zoom In and Zoom Out 功能，它包含 JLabel 和 ImageIcon 等组件>.

我想用它们的组件适本地Zoom JPanel 我尝试使用以下代码片段，但它无法正常工作。

JPanel 具有null 布局，它本身位于Applet 中。 我不确定为什么它因为 Applet 或其他原因而无法正常工作!!

cPanel 是我的 JPanel，它包含 JLabel

在 Zoom Button 上单击以下代码片段， 它在按钮点击后显示闪烁屏幕作为原始

Graphics g = cPanel.getGraphics();
Graphics2D g2d = (Graphics2D) g;
AffineTransform savedXForm = g2d.getTransform();
g2d.scale(1.0, 1.0);
g2d.setColor(Color.red);
super.paint(g);
g2d.setTransform(savedXForm);
cPanel.validate();
cPanel.repaint();

Answer 1

您可以查看此链接: http://blog.sodhanalibrary.com/2015/04/zoom-in-and-zoom-out-image-using-mouse_9.html#.Vz6iG-QXV0w

引用源码(这里使用MouseWheelListener实现):

import java.awt.EventQueue;
import javax.imageio.ImageIO;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JScrollPane;
import java.awt.BorderLayout;
import javax.swing.JPanel;
import com.mortennobel.imagescaling.ResampleOp;
import java.awt.event.MouseWheelListener;
import java.awt.event.MouseWheelEvent;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

public class ImageZoom {

    private JFrame frmImageZoomIn;
    private static final String inputImage = "C:\\my-pfl-pic.jpg"; // give image path here
    private JLabel label = null; 
    private double zoom = 1.0;  // zoom factor
    private BufferedImage image = null;
    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    ImageZoom window = new ImageZoom();
                    window.frmImageZoomIn.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the application.
     * @throws IOException 
     */
    public ImageZoom() throws IOException {
        initialize();
    }

    /**
     * Initialize the contents of the frame.
     * @throws IOException 
     */
    private void initialize() throws IOException {
        frmImageZoomIn = new JFrame();
        frmImageZoomIn.setTitle("Image Zoom In and Zoom Out");
        frmImageZoomIn.setBounds(100, 100, 450, 300);
        frmImageZoomIn.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JScrollPane scrollPane = new JScrollPane();
        frmImageZoomIn.getContentPane().add(scrollPane, BorderLayout.CENTER);

        image = ImageIO.read(new File(inputImage));

        JPanel panel = new JPanel();
        panel.setLayout(new BorderLayout());

        // display image as icon 
        Icon imageIcon = new ImageIcon(inputImage);
        label = new JLabel( imageIcon );
        panel.add(label, BorderLayout.CENTER);

        panel.addMouseWheelListener(new MouseWheelListener() {
            public void mouseWheelMoved(MouseWheelEvent e) {
                int notches = e.getWheelRotation();
                double temp = zoom - (notches * 0.2);
                // minimum zoom factor is 1.0
                temp = Math.max(temp, 1.0);
                if (temp != zoom) {
                    zoom = temp;
                    resizeImage();
                }
            }
        });
        scrollPane.setViewportView(panel);
    }

    public void resizeImage() {
           System.out.println(zoom);
           ResampleOp  resampleOp = new ResampleOp((int)(image.getWidth()*zoom), (int)(image.getHeight()*zoom));
               BufferedImage resizedIcon = resampleOp.filter(image, null);
           Icon imageIcon = new ImageIcon(resizedIcon);
           label.setIcon(imageIcon);
        }


}