colorpan.java

这个是Java的swing相关的典型的源码

import java.awt.Graphics;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.image.BufferedImage;

import javax.swing.JComponent;
import javax.swing.JFrame;

public class ColorPan extends JComponent {
  BufferedImage image;

  public void initialize() {
  	
  	// Returns the size of this component in the form of 
  	// a Dimension object. The height field of the Dimension object 
  	// contains this component's height, and the width field of 
  	// the Dimension object contains this component's width. 
  	
    int width = getSize().width;
    int height = getSize().height;
    int[] data = new int[width * height];
    int index = 0;
    int blue = 128;
    
    for (int i = 0; i < height; i++) {
      int red = (i * 255) / (height - 1);
      for (int j = 0; j < width; j++) {
        int green = (j * 255) / (width - 1);
        data[index++] = (red << 16) | (green << 8) | blue;
      }
    }

	// Constructs a BufferedImage of one of the predefined image types.
	// The ColorSpace for the image is the default sRGB space. 
    image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
    
    // Sets an array of integer pixels in the default RGB color model 
    // (TYPE_INT_ARGB) and default sRGB color space, into a portion of the image data.
    image.setRGB(0, 0, width, height, data, 0, width);
  }

  public void paint(Graphics g) {
    if (image == null)
      initialize();
   
    g.drawImage(image, 0, 0, this);
  }

  public static void main(String[] args) {
    JFrame f = new JFrame("ColorPan");
    f.getContentPane().add(new ColorPan());
    f.setSize(300, 300);
    f.setLocation(100, 100);
    f.addWindowListener(new WindowAdapter() {
      public void windowClosing(WindowEvent e) {
        System.exit(0);
      }
    });
    f.setVisible(true);
  }
}