【备忘】Android模拟小球自由落体（SurfaceView）

package com.example.sft;

import java.util.ArrayList;
import java.util.List;
import java.util.Random;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.RadialGradient;
import android.graphics.Shader;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;

public class TestSurfaceView extends SurfaceView implements SurfaceHolder.Callback{

private Paint cp;
private List<KCircle> KCList;
private Random r;

public TestSurfaceView(Context context, AttributeSet attrs) {
super(context, attrs);
// TODO Auto-generated constructor stub
getHolder().addCallback(this);
cp=new Paint();
cp.setColor(Color.BLACK);
KCList=new ArrayList<KCircle>();
r=new Random();
}

@Override
public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3) {
// TODO Auto-generated method stub

}

private int getRandomColor(){
return r.nextInt()%0xff000000;
}
@Override
public void surfaceCreated(SurfaceHolder arg0) {
// TODO Auto-generated method stub

}

/**
*
*/
public void run(){
new MyThread().start();
}

@Override
public void surfaceDestroyed(SurfaceHolder arg0) {
// TODO Auto-generated method stub

}

@Override
public boolean onTouchEvent(MotionEvent event) {
// TODO Auto-generated method stub
if (event.getAction() != MotionEvent.ACTION_DOWN &&
event.getAction() != MotionEvent.ACTION_MOVE) {
return false;
}
KCList.add(new KCircle(getRandomColor(),(int)event.getX(),(int)event.getY()));
return true;
}

class MyThread extends Thread{
@Override
public void run() {
// TODO Auto-generated method stub
while(true){
Canvas c=getHolder().lockCanvas();
c.drawPaint(cp);
for(int i=0;i<KCList.size();i++){
KCList.get(i).moveAndDraw(c);
if(KCList.get(i).y>getHeight()){
KCList.remove(i);
}
}

try {
sleep(15);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

getHolder().unlockCanvasAndPost(c);
}

}
}

}

package com.example.sft;

import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.RadialGradient;
import android.graphics.Shader;

public class KCircle {

private int color;
public int x;
public int y;
private Paint p;
private int radius;
int v;
int a;

public KCircle(int color){
this.color=color;
x=0;
y=0;
v=0;
a=2;
radius=25;
p=new Paint();
p.setColor(color);
RadialGradient rg=new RadialGradient(x+10, y-10, 25,color+(0xffffffff-color)/2, color, Shader.TileMode.CLAMP);

p.setShader(rg);
p.setAntiAlias(true);
}

public KCircle(int colcr,int x,int y){
this(colcr);
this.x=x;
this.y=y;
}

public void moveAndDraw(Canvas c){
y+=v;
v+=a;
draw(c);
}

public void moveTo(int x,int y){
this.x=x;
this.y=y;
}

public void draw(Canvas c){
RadialGradient rg=new RadialGradient(x+10, y-10, 25,0xffdddddd, color, Shader.TileMode.CLAMP);
p.setShader(rg);
c.drawCircle(x, y, radius, p);

}

}