canvasdemo.java

人民邮电出版社的《J2ME手机开发入门》全部源代码

/*
 * CanvasDemo.java
 *
 * Created on 2005年4月26日, 上午11:48
 */

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;

/**
 *
 * @author  Liu Bin
 * @version
 */
public class CanvasDemo extends MIDlet implements CommandListener {
    private Display display;
    private MyCanvas can = null;
    
    //命令按钮
    private Command cmdFullScreen = new Command("全屏显示", Command.OK, 1);
    private Command cmdExit = new Command("退出", Command.STOP, 1);
    
    public CanvasDemo() {
        display = Display.getDisplay(this);
        can = new MyCanvas(this);
        can.addCommand(cmdFullScreen);
        can.addCommand(cmdExit);
        can.setCommandListener(this);
    }
    
    public void startApp() {
        display = Display.getDisplay(this);
        display.setCurrent(can);
    }
    
    public void pauseApp() {
    }
    
    public void destroyApp(boolean unconditional) {
        notifyDestroyed();
    }
    
    /**
     * 命令按钮事件
     */
    public void commandAction(Command c, Displayable d) {
        String label = c.getLabel();
        if (label.equals("退出")) {
            destroyApp(true);
        } 
        
        if (label.equals("全屏显示")) {
            can.setFullScreenMode(true);
            if (!can.hasPointerEvents()) {
                can.pointerValue = null;
                System.out.println("不支持指针事件");
            }
            can.removeCommand(cmdFullScreen);
            can.removeCommand(cmdExit);
            can.repaint();
        }
    }
    
    class MyCanvas extends Canvas {
        //保留屏幕的原始尺寸和全屏后的尺寸
        int oldW, oldH, newW, newH;
        //保留按键值
        String keyValue;
        //保留指针值
        String pointerValue;
        
        CanvasDemo parent = null;
        public MyCanvas(CanvasDemo parent) {
            super();
            this.parent = parent;
            oldW = getWidth();
            oldH = getHeight();
        }
        
        protected void paint(Graphics g) {
            //清除画布
            g.setColor(0xFFFFFF);
            g.fillRect(0, 0, getWidth(), getHeight());
            
            //在画布上输出信息
            g.setColor(0x000000);
            g.drawString("屏幕的原始大小为：" + oldW + "，" + oldH, 0, 0,
                    Graphics.TOP | Graphics.LEFT);
            
            g.drawString("全屏尺寸大小为：" + newW + "，" + newH, 0, 20,
                    Graphics.TOP | Graphics.LEFT);
            
            if (keyValue != null) {
                g.drawString("用户按键值为：" + keyValue, 0, 60,
                        Graphics.TOP | Graphics.LEFT);
            }
            
            if (pointerValue != null) {
                g.drawString(pointerValue, 0, 80,
                        Graphics.TOP | Graphics.LEFT);
            } else {
                g.drawString("该设备不支持指针", 0, 80,
                        Graphics.TOP | Graphics.LEFT);
            }
        }
        
        protected void keyPressed(int keyCode) {
            keyValue = String.valueOf(keyCode) + "   按键为：" + (char)keyCode +
                    "  键名为："  + getKeyName(keyCode);
            repaint();
        }
        
        protected void pointerPressed(int x,  int y) {
            pointerValue = "指针位置为：  " + x + "，" + y;
            repaint();
        }
        
        protected void sizeChanged(int w, int h) {
            newW = w;
            newH = h;
        }
    }
    
    
}