coodinate_canvas.java

J2ME下的图形编程实例,包括简单图形的绘制,以及一个打老鼠的游戏实现.可为学习参考.

package ch05;

import javax.microedition.lcdui.*;
import javax.microedition.lcdui.game.*;

public class Coodinate_Canvas
    extends GameCanvas {

  //声明一个代表屏幕宽度的int型属性变量
  private int width;

  //声明一个代表屏幕高度的int型属性变量
  private int height;

  //声明一个代表坐标原点X轴移动的变量
  private int x = 0;

  //声明一个代表坐标原点Y轴移动的变量
  private int y = 0;

  //获取绘制上下文
  Graphics g = getGraphics();

  //构造器
  Coodinate_Canvas() {
    //支持键盘事件
    super(false);
    //获取屏幕宽度和高度
    width = getWidth();
    height = getHeight();
    render(g);
  }

  /*
   3.实现绘制
   */
  private void render(Graphics g) {
    g.setColor(0xffffff);
    g.fillRect(0, 0, width, height);
    g.setColor(0x000000);
    g.drawString("坐标原点(0,0)", 0, 0, Graphics.LEFT | Graphics.TOP);
    g.drawString("坐标原点绝对坐标值：" + g.getTranslateX() + "," + g.getTranslateY(), 0,
                 height - g.getTranslateY(), Graphics.LEFT | Graphics.TOP);
    System.out.println("坐标原点绝对坐标值：" + g.getTranslateX() + "," + g.getTranslateY());

  }

  /*
   4.响应按键事件
   */
  protected void keyPressed(int keyCode) {
    int keyState = getKeyStates();
    if ( (keyState & LEFT_PRESSED) != 0) {
      g.translate( -10, 0);
    }
    if ( (keyState & RIGHT_PRESSED) != 0) {
      g.translate(10, 0);
    }
    if ( (keyState & UP_PRESSED) != 0) {
      g.translate(0, -10);
    }
    if ( (keyState & DOWN_PRESSED) != 0) {
      g.translate(0, 10);
    }
    render(g);
  }
}