TransformApplet
Resources: saturnVoyager.jpg

import javax.swing.*;
import java.awt.*;
import java.awt.image.*;
import javax.swing.event.*;
import java.awt.geom.*;

/** Demonstrate an affine transform of an image. **/
public class TransformApplet extends JApplet
                          implements ChangeListener {

  BufferedImage fSrcImage, fDstImage;
  ImageIcon fDstIcon;
  JLabel fShxLabel, fShyLabel;
  JSlider fShxSlider,fShySlider;
  double fShxFactor = 0.0;
  double fShyFactor = 0.0;

  /**
    * Build the interface with the source and filter output image
    * displayed side by side.
   **/
  public void init () {

    setLayout (new BorderLayout ());

    fSrcImage = getBufImage ("saturnVoyager.jpg");
    if (fSrcImage == null) {
        System.out.println ("Error in reading image file!");
        return;
    }

    JPanel control_panel = new JPanel(new GridLayout (2,1));
    control_panel.add (fShxLabel =
                       new JLabel ("shx 0 ",SwingConstants.RIGHT) );
    control_panel.add (fShxSlider =
                       new JSlider (Adjustable.HORIZONTAL, 0, 10, 0));
    fShxSlider.addChangeListener (this);

    control_panel.add (fShyLabel =
                       new JLabel ("shy 0 ",SwingConstants.RIGHT) );
    control_panel.add (fShySlider =
                       new JSlider (Adjustable.HORIZONTAL, 0, 10, 0));
    fShySlider.addChangeListener (this);

    // Transform image with default settings.
    transformFilter();

    // Use ImageIcon objects to hold the two images
    ImageIcon src_icon = new ImageIcon (fSrcImage);
    fDstIcon = new ImageIcon (fDstImage);

    // Put the icons on labels
    JLabel src_display = new JLabel (src_icon);
    JLabel dst_display = new JLabel (fDstIcon);

    // And then display the labels on the scroll panes
    JScrollPane src_pane = new JScrollPane (src_display);
    JScrollPane dst_pane = new JScrollPane (dst_display);

    // Use a JSplitPane to show the source and destination
    // images side by side.
    JSplitPane split_pane =
      new JSplitPane (JSplitPane.HORIZONTAL_SPLIT,
                      true, src_pane, dst_pane);

    split_pane.setResizeWeight (0.5);
    split_pane.setContinuousLayout (true);

    // Add the DrawingPanel to the contentPane.
    add (split_pane, BorderLayout.CENTER);
    add (control_panel, BorderLayout.SOUTH);

  } // init

  /**
    * This class implements ChangeListener for the
    * slider. So the ChangeEvents come here when the
    * slider is moved.
   **/
  public void stateChanged (ChangeEvent evt) {

    // Use the label to show the numerical value of the slider.
    fShxLabel.setText ("shx " + fShxSlider.getValue ());

    // Get the values from the slider and set a new scale factor.
    fShxFactor = fShxSlider.getValue ();

    // Use the label to show the numerical value of the slider.
    fShyLabel.setText ("shy " + fShySlider.getValue ());

    // Get the values from the slider and set a new scale factor.
    fShyFactor = fShySlider.getValue ();

    // Transform the image.
    transformFilter();

    // Reset the destination images with the modified version.
    fDstIcon.setImage(fDstImage);

    // Repaint to show the modified image.
    repaint ();

  } // stateChanged

  /** Create the filter to execute an affine transform amd
    * apply it to the source image.
   **/
  void transformFilter () {

    // Some extreme combinations of filters can result in
    // invalid operations so catch the resulting exceptions
    // and reset images to the default.
    try {
      AffineTransform shearer =
        AffineTransform.getShearInstance (fShxFactor, fShyFactor);
      AffineTransformOp shear_op =
        new AffineTransformOp (shearer, null);
      fDstImage = shear_op.filter (fSrcImage, null);
    }
    catch (Exception e) {
      System.out.println("Shearing exception = " + e);
      // Reset back to default
      AffineTransform shearer =
        AffineTransform.getShearInstance (0.0, 0.0);
      AffineTransformOp shear_op =
        new AffineTransformOp (shearer, null);
      fDstImage = shear_op.filter (fSrcImage, null);
    }
  } // transformFilter

  /**
    *  Download the image file and convert to a
    *  BufferedImage object.
   **/
  BufferedImage getBufImage (String image_name){

    // Get the image
    Image img = getImage (getCodeBase(), image_name);

    // and use a MediaTracker to load it before converting it to
    // a BufferedImage.
    try {
      MediaTracker tracker = new MediaTracker (this);
      tracker.addImage (img,0);
      tracker.waitForID (0);
    } catch (InterruptedException e) { return null; }

    int width = img.getWidth (this);
    int height= img.getHeight (this);

    BufferedImage buffered_image =
      new BufferedImage (width, height, BufferedImage.TYPE_INT_RGB);
    Graphics2D g2 = buffered_image.createGraphics ();
    g2.drawImage (img,0 ,0, null);

    return buffered_image;

  } // getBufImage

} // class TransformApplet

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