imageprocessor.java

learning java的源代码。书中每个实例都有相关的代码example。

//file: ImageProcessor.java
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.awt.image.*;
import javax.swing.*;

public class ImageProcessor extends JComponent {
  private BufferedImage source, destination;
  private JComboBox options;

  public ImageProcessor(BufferedImage image) {
    source = destination = image;
    setBackground(Color.white);
    setLayout(new BorderLayout(  ));
    // create a panel to hold the combo box
    JPanel controls = new JPanel(  );
    // create the combo box with the names of the area operators
    options = new JComboBox(
      new String[] { "[source]", "brighten",
          "darken", "rotate", "scale" }
    );
    // perform some processing when the selection changes
    options.addItemListener(new ItemListener(  ) {
      public void itemStateChanged(ItemEvent ie) {
        // retrieve the selection option from the combo box
        String option = (String)options.getSelectedItem(  );
        // process the image according to the selected option
        BufferedImageOp op = null;
        if (option.equals("[source]"))
          destination = source;
        else if (option.equals("brighten"))
          op = new RescaleOp(1.5f, 0, null);
        else if (option.equals("darken"))
          op = new RescaleOp(.5f, 0, null);
        else if (option.equals("rotate"))
          op = new AffineTransformOp(
              AffineTransform.getRotateInstance(Math.PI / 6), null);
        else if (option.equals("scale"))
          op = new AffineTransformOp(
              AffineTransform.getScaleInstance(.5, .5), null);
        if (op != null) destination = op.filter(source, null);
        repaint(  );
      }
    });
    controls.add(options);
    add(controls, BorderLayout.SOUTH);
  }

  public void paintComponent(Graphics g) {
    int imageWidth = destination.getWidth(  );
    int imageHeight = destination.getHeight(  );
    int width = getSize(  ).width;
    int height = getSize(  ).height;
    g.drawImage(destination,
        (width - imageWidth) / 2, (height - imageHeight) / 2, null);
  }

  public static void main(String[] args) {
    String filename = args[0];
    // load the image
    Image i = Toolkit.getDefaultToolkit(  ).getImage(filename);
    Component c = new Component(  ) {};
    MediaTracker tracker = new MediaTracker(c);
    tracker.addImage(i, 0);
    try { tracker.waitForID(0); }
    catch (InterruptedException ie) {}

    // draw the Image into a BufferedImage
    int w = i.getWidth(null), h = i.getHeight(null);
    BufferedImage bi = new BufferedImage(w, h,
        BufferedImage.TYPE_INT_RGB);
    Graphics2D imageGraphics = bi.createGraphics(  );
    imageGraphics.drawImage(i, 0, 0, null);

    // create a frame window
    JFrame f = new JFrame("ImageProcessor");
    f.addWindowListener(new WindowAdapter(  ) {
      public void windowClosing(WindowEvent e) { System.exit(0); }
    });
    Container content = f.getContentPane(  );
    content.setLayout(new BorderLayout(  ));
    content.add(new ImageProcessor(bi));
    f.setSize(bi.getWidth(), bi.getHeight(  ));
    f.setLocation(100, 100);
    f.setVisible(true);
  }
}