picture.java

Java样例程序集合：2D

/*
 * Picture.java is used by the 1.4
 * TrackFocusDemo.java and DragPictureDemo.java examples.
 */
import javax.swing.InputMap;
import javax.swing.KeyStroke;
import javax.swing.Action;
import javax.swing.JComponent;
import javax.accessibility.Accessible;

import java.beans.*; 
import java.awt.*;
import java.awt.event.*;


class Picture extends JComponent
                       implements MouseListener,
                                  FocusListener,
                                  Accessible {
    Image image;

    public Picture(Image image) {

        this.image = image;
        setFocusable(true);
        addMouseListener(this);
        addFocusListener(this);
    }

    public void mouseClicked(MouseEvent e) {
        //Since the user clicked on us, let's get focus!
        requestFocusInWindow();
    }

    public void mouseEntered(MouseEvent e) { }
    public void mouseExited(MouseEvent e) { }
    public void mousePressed(MouseEvent e) { }
    public void mouseReleased(MouseEvent e) { }

    public void focusGained(FocusEvent e) {
        //Draw the component with a red border
        //indicating that it has focus.
        this.repaint();
    }

    public void focusLost(FocusEvent e) {
        //Draw the component with a black border
        //indicating that it doesn't have focus.
        this.repaint();
    }

    protected void paintComponent(Graphics graphics) {
        Graphics g = graphics.create();

        //Draw in our entire space, even if isOpaque is false.
        g.setColor(Color.WHITE);
        g.fillRect(0, 0, image == null ? 125 : image.getWidth(this),
                         image == null ? 125 : image.getHeight(this));

        if (image != null) {
            //Draw image at its natural size of 125x125.
            g.drawImage(image, 0, 0, this);
        }

        //Add a border, red if picture currently has focus
        if (isFocusOwner()) {
            g.setColor(Color.RED);
        } else {
            g.setColor(Color.BLACK);
        }
        g.drawRect(0, 0, image == null ? 125 : image.getWidth(this),
                         image == null ? 125 : image.getHeight(this));
        g.dispose();
    }
}