mycanvas.java

J2ME 无线通信技术应用开发源代码

// 程序名MyCanvas.java
// 测试把不变图象转换为可变图象
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import java.util.Random;

public class MyCanvas extends Canvas {
  private UI_Low8 midlet;
  private Image source;
  private Graphics g;

  public MyCanvas( UI_Low8 midlet ){
    this.midlet = midlet;
    System.out.println(isDoubleBuffered());
  } 
 
  protected void paint( Graphics g ){
    //刷新整个屏幕为黑色，然后绘制这个可变图象，位置为画布正中央。
    g.setColor(0x000000);
    g.fillRect( 0, 0, getWidth(), getHeight());

    try {
      source = Image.createImage("/Duke.png");
    } catch (java.io.IOException e) {
      midlet.exit();
    }
    //生成一个和源图象大小一样的可变图象
    Image copy = Image.createImage(source.getWidth(), source.getHeight());
    Graphics g1 = copy.getGraphics();
    g1.drawImage(source, 0, 0, g1.TOP | g1.LEFT);//把源图象拷贝进这个可变图象
    g1.setColor(0x0000FF);
    g1.fillArc(g1.getClipWidth()/2-10, g1.getClipHeight()/2-10,20,20,0,360);
    g.drawImage(copy, getWidth()/2, getHeight()/2,g.VCENTER | g.HCENTER );
  }
}