Jpanel在重绘时调整大小

Question

我在下面的代码中执行了缩放操作。窗体中的两个滑块是缩放仿射变换的 X 和 Y 参数。我在这里的问题是，当我更改滑块时，图像正在缩放，如何动态调整绘制此图像的 jpanel 的大小。

/*
     * To change this template, choose Tools | Templates
     * and open the template in the editor.
     */
    package newpackage;

    import java.awt.Graphics;
    import java.awt.Image;
    import java.awt.geom.AffineTransform;
    import java.awt.image.AffineTransformOp;
    import java.awt.image.BufferedImage;
    import java.io.File;
    import java.io.IOException;
    import java.util.logging.Level;
    import java.util.logging.Logger;
    import javax.imageio.ImageIO;

    /**
     *
     * @author ABC
     */
    public class Swon extends javax.swing.JFrame {

        final BufferedImage img;
        /**
         * Creates new form Swon
         */
        public Swon() throws IOException{
           BufferedImage im=ImageIO.read(new File("C:/Users/ABC/Desktop/I-RIX2012_Final_logo_out.jpg"));
           this.img=new BufferedImage(im.getWidth(),im.getWidth(),BufferedImage.TYPE_BYTE_GRAY);
           this.img.getGraphics().drawImage(im, 0, 0, null);
            initComponents();
        }

        /**
         * This method is called from within the constructor to initialize the form.
         * WARNING: Do NOT modify this code. The content of this method is always
         * regenerated by the Form Editor.
         */
        @SuppressWarnings("unchecked")
        // <editor-fold defaultstate="collapsed" desc="Generated Code">
        private void initComponents() {

            jPanel1 = new javax.swing.JPanel(){

                // @Override

                //    public void paint(Graphics g)
                //    {
                    //        super.paint(g);
                    //        g.drawImage(img.getScaledInstance(this.getWidth(), this.getHeight(), Image.SCALE_FAST),0,0,null);
                    //    }

            };
            jSlider1 = new javax.swing.JSlider();
            jSlider2 = new javax.swing.JSlider();

            setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

            jPanel1.setBorder(new javax.swing.border.SoftBevelBorder(javax.swing.border.BevelBorder.RAISED));
            jPanel1.addComponentListener(new java.awt.event.ComponentAdapter() {
                public void componentResized(java.awt.event.ComponentEvent evt) {
                    jPanel1ComponentResized(evt);
                }
            });

            javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
            jPanel1.setLayout(jPanel1Layout);
            jPanel1Layout.setHorizontalGroup(
                jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGap(0, 268, Short.MAX_VALUE)
            );
            jPanel1Layout.setVerticalGroup(
                jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGap(0, 209, Short.MAX_VALUE)
            );

            jSlider1.setMaximum(5);
            jSlider1.setValue(1);
            jSlider1.addChangeListener(new javax.swing.event.ChangeListener() {
                public void stateChanged(javax.swing.event.ChangeEvent evt) {
                    jSlider1StateChanged(evt);
                }
            });

            jSlider2.setMaximum(5);
            jSlider2.setValue(1);
            jSlider2.addChangeListener(new javax.swing.event.ChangeListener() {
                public void stateChanged(javax.swing.event.ChangeEvent evt) {
                    jSlider2StateChanged(evt);
                }
            });

            javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
            getContentPane().setLayout(layout);
            layout.setHorizontalGroup(
                layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(layout.createSequentialGroup()
                    .addGap(45, 45, 45)
                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                        .addComponent(jSlider2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addComponent(jSlider1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
                    .addContainerGap(242, Short.MAX_VALUE))
            );
            layout.setVerticalGroup(
                layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(layout.createSequentialGroup()
                    .addGap(36, 36, 36)
                    .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                    .addGap(33, 33, 33)
                    .addComponent(jSlider1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                    .addComponent(jSlider2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addContainerGap(38, Short.MAX_VALUE))
            );

            pack();
        }// </editor-fold>

        private void jPanel1ComponentResized(java.awt.event.ComponentEvent evt) {
            // TODO add your handling code here:
          //  AffineTransform f=new AffineTransform();

        }

        private void jSlider1StateChanged(javax.swing.event.ChangeEvent evt) {
            // TODO add your handling code here:

                        AffineTransform scale = AffineTransform.getScaleInstance(jSlider1.getValue(),jSlider2.getValue());       
                    AffineTransformOp op3 = new AffineTransformOp(scale, AffineTransformOp.TYPE_BILINEAR);
                    BufferedImage scaling = new BufferedImage(this.img.getHeight(), this.img.getWidth(), this.img.getType());
                    BufferedImage img1=op3.filter(this.img, scaling);
                    jPanel1.getGraphics().drawImage(img1.getScaledInstance(jPanel1.getWidth(), jPanel1.getHeight(), Image.SCALE_FAST), 0, 0, null);
        }

        private void jSlider2StateChanged(javax.swing.event.ChangeEvent evt) {
            // TODO add your handling code here:
             AffineTransform scale = AffineTransform.getScaleInstance(jSlider1.getValue(),jSlider2.getValue());       
                    AffineTransformOp op3 = new AffineTransformOp(scale, AffineTransformOp.TYPE_BILINEAR);
                    BufferedImage scaling = new BufferedImage(this.img.getHeight(), this.img.getWidth(), this.img.getType());
                    BufferedImage img1=op3.filter(this.img, scaling);
                    jPanel1.getGraphics().drawImage(img1.getScaledInstance(jPanel1.getWidth(), jPanel1.getHeight(), Image.SCALE_FAST), 0, 0, null);
        }

        /**
         * @param args the command line arguments
         */
        public static void main(String args[]) {
            /* Set the Nimbus look and feel */
            //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
            /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
             * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
             */
            try {
                for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                    if ("Nimbus".equals(info.getName())) {
                        javax.swing.UIManager.setLookAndFeel(info.getClassName());
                        break;
                    }
                }
            } catch (ClassNotFoundException ex) {
                java.util.logging.Logger.getLogger(Swon.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
            } catch (InstantiationException ex) {
                java.util.logging.Logger.getLogger(Swon.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
            } catch (IllegalAccessException ex) {
                java.util.logging.Logger.getLogger(Swon.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
            } catch (javax.swing.UnsupportedLookAndFeelException ex) {
                java.util.logging.Logger.getLogger(Swon.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
            }
            //</editor-fold>

            /* Create and display the form */
            java.awt.EventQueue.invokeLater(new Runnable() {
                public void run() {
                    try {
                        new Swon().setVisible(true);
                    } catch (IOException ex) {
                        Logger.getLogger(Swon.class.getName()).log(Level.SEVERE, null, ex);
                    }
                }
            });
        }
        // Variables declaration - do not modify
        public javax.swing.JPanel jPanel1;
        private javax.swing.JSlider jSlider1;
        private javax.swing.JSlider jSlider2;
        // End of variables declaration
    }

Answer 1

好吧，首先，不要这样做.img.getGraphics（）.drawImage（im， 0， 0， null），当面板被重新绘制时，图像不会更新。您需要重写 JComponent 的 paintComponent 方法（首选 JPanel）并以适当的比例重新绘制图像。

其次，您需要将图像面板放置在能够实际关心面板大小的布局上（例如 GridBagLayout）。为此，请重写 getPreferredSize 方法并返回缩放图像的大小...

public class ResizableImagePane {

    public static void main(String[] args) {
        new ResizableImagePane();
    }

    public ResizableImagePane() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException ex) {
                } catch (InstantiationException ex) {
                } catch (IllegalAccessException ex) {
                } catch (UnsupportedLookAndFeelException ex) {
                }

                JFrame frame = new JFrame();
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new ScalerPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    protected class ScalerPane extends JPanel {
        private JSlider slider;
        private ImagePane imagePane;
        public ScalerPane() {

            setLayout(new GridBagLayout());
            GridBagConstraints gbc = new GridBagConstraints();

            gbc.gridx = 0;
            gbc.gridy = 0;

            imagePane = new ImagePane();

            add(imagePane, gbc);

            gbc.gridy = 1;
            gbc.weightx = 0;
            gbc.weighty = 0;
            gbc.fill = GridBagConstraints.HORIZONTAL;

            slider = new JSlider();
            slider.setMinimum(1);
            slider.setMaximum(100);
            gbc.weightx = 1;
            gbc.weighty = 1;
            gbc.anchor = GridBagConstraints.SOUTH;
            gbc.fill = GridBagConstraints.HORIZONTAL;
            add(slider, gbc);

            slider.addChangeListener(new ChangeListener() {
                @Override
                public void stateChanged(ChangeEvent ce) {
                    imagePane.setZoom(slider.getValue() / 100f);
                }
            });
            slider.setValue(100);
        }
    }

    protected class ImagePane extends JPanel {
        private BufferedImage background;
        private Image scaled;
        private float zoom;
        public ImagePane() {
            try {
                background = ImageIO.read(new File("path/to/your/image"));
            } catch (IOException ex) {
                ex.printStackTrace();
            }

            setZoom(1f);
            setBorder(new LineBorder(Color.RED));
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(scaled.getWidth(this), scaled.getHeight(this));
        }

        public void setZoom(float zoom) {
            this.zoom = zoom;
            int width = Math.round(background.getWidth() * zoom);
            scaled = background.getScaledInstance(width, -1, Image.SCALE_SMOOTH);

            invalidate();
            revalidate();
            repaint();
        }

        public float getZoom() {
            return zoom;
        }

        @Override
        protected void paintComponent(Graphics grphcs) {
            super.paintComponent(grphcs);

            int x = (getWidth() - scaled.getWidth(this)) / 2;
            int y = (getHeight() - scaled.getHeight(this)) / 2;

            grphcs.drawImage(scaled, x, y, this);
        }
    }
}