import java.util.Random;
import Android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceHolder.Callback;
import android.view.SurfaceView;
import android.view.Window;
import android.view.WindowManager;
public class BallActivity extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//设置全屏
requestWindowFeature(Window.FEATURE_NO_TITLE);
this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(new BallSurfaceView(this));
}
class BallSurfaceView extends SurfaceView implements Callback,Runnable{
private int screenW;//屏幕宽度
private int screenH;//屏幕高度
private Paint paint;//定义画笔
private float cx = 50;//圆点默认X坐标
private float cy = 50;//圆点默认Y坐标
private int radius = 20;
//定义颜色数组
private int colorArray[] = {Color.BLACK,Color.BLACK,Color.GREEN,Color.YELLOW, Color.RED};
private int paintColor = colorArray[0]; //定义画笔默认颜色
private Canvas canvas = null; //定义画布
private Thread th = null;//定义线程
private SurfaceHolder sfh = null;
public BallSurfaceView(Context context){
super(context);
/*备注1:在此处获取屏幕高、宽值为0,以为此时view还未被创建,
* 在接口Callback的surfaceCreated方法中view才被创建
*/
/*screenW = getWidth();
screenH = getHeight();*/
//初始化画笔
initPaint();
sfh = getHolder();
sfh.addCallback(this);
th = new Thread(this);
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
//获取屏幕宽度
screenW = getWidth();
//获取屏幕高度
screenH = getHeight();
//启动绘图线程
th.start();
}
private void initPaint(){
paint = new Paint();
//设置消除锯齿
paint.setAntiAlias(true);
//设置画笔颜色
paint.setColor(paintColor);
}
@Override
public void run() {
while(true){
try{
myDraw();
Thread.sleep(100);
}catch(InterruptedException e){
e.printStackTrace();
}
}
}
/*备注2:切记,在自定SurfaceView中定义的myDraw方法,自定义View(继承自View的子类)中的onDraw方法
* 完全是两码事:
* 1)自定义View(继承自View的子类)中的onDraw方法是重写父类的onDraw方法,在调用postInvalidate后会自动回调该onDraw()方法。
* 2)此处的myDraw方法需要手动调用,所以此处故意将方法命名为myDraw,突出为该方法是自己写的,非重写父类的方法 。
*
*/
//重写onDraw方法实现绘图操作
protected void myDraw() {
//获取canvas实例
canvas = sfh.lockCanvas();
//将屏幕设置为白色
canvas.drawColor(Color.WHITE);
//修正圆点坐标
revise();
//随机设置画笔颜色
setPaintRandomColor();
//绘制小圆作为小球
canvas.drawCircle(cx, cy, radius, paint);
//将画好的画布提交
sfh.unlockCanvasAndPost(canvas);
}
//为画笔设置随机颜色
private void setPaintRandomColor(){
Random rand = new Random();
int randomIndex = rand.nextInt(colorArray.length);
paint.setColor(colorArray[randomIndex]);
}
//修正圆点坐标
private void revise(){
if(cx <= radius){
cx = radius;
}else if(cx >= (screenW-radius)){
cx = screenW-radius;
}
if(cy <= radius){
cy = radius;
}else if(cy >= (screenH-radius)){
cy = screenH-radius;
}
}
@Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
// 按下
cx = (int) event.getX();
cy = (int) event.getY();
break;
case MotionEvent.ACTION_MOVE:
// 移动
cx = (int) event.getX();
cy = (int) event.getY();
break;
case MotionEvent.ACTION_UP:
// 抬起
cx = (int) event.getX();
cy = (int) event.getY();
break;
}
/*
* 备注1:次处一定要将return super.onTouchEvent(event)修改为return true,原因是:
* 1)父类的onTouchEvent(event)方法可能没有做任何处理,但是返回了false。
* 2)一旦返回false,在该方法中再也不会收到MotionEvent.ACTION_MOVE及MotionEvent.ACTION_UP事件。
*/
//return super.onTouchEvent(event);
return true;
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
}
}
}