6.5.1 转换屏幕坐标系方法

/×
原点坐标转换应用
×/
import javax.microedition.midlet.×;
import javax.microedition.lcdui.×;
public class canvasDemo5 extends MIDlet
{
Display display;
canvasTranslate canvastranslate;

   public canvasDemo5()
{
canvastranslate=new canvasTranslate();
display=Display.getDisplay(this);
}

   public void startApp()
{
display.setCurrent(canvastranslate);
}

   public void pauseApp(){}

   public void destroyApp(boolean unconditional){}

   class canvasTranslate extends Canvas 
{
int    gameaction=0;
int    x;
int    y;
boolean view;
Image  pictureImage;

      public canvasTranslate()
{
try{
pictureImage=Image.createImage("/picture.png");
}catch(Exception ex){}
}

public void keyPressed(int keyCode) 
{
gameaction=getGameAction(keyCode);
switch(gameaction)
{
case UP:
view=false;
repaint();                 
break;
case DOWN:
view=true;
//设置X, Y轴位移量
x=50;
y=60;
repaint();                 
break;
}
}
public void paint(Graphics g)
{ 
g.setColor(0xFFFFFF);
g.fillRect(0,0,getWidth(),getHeight());
g.setColor(0);
if(view)
{
　 //设置变换原点坐标，位移至(x,y) 
g.translate(x,y);
　 //取得X轴位移量
g.drawString("X轴位移"+String.valueOf(g.getTranslateX()), -10, -40, 
　Graphics.LEFT | Graphics.TOP);
　 //取得Y轴位移量
g.drawString("Y轴位移"+String.valueOf(g.getTranslateY()), -10, -20, 
　Graphics.LEFT | Graphics.TOP);
}
//保持图片都在原始点(0,0) 显示
g.drawImage(pictureImage, 0, 0, Graphics.LEFT | Graphics.TOP);
}
}
}