android学习3跟随手指的小球

public class DrawView extends View{

public float currentX = 40;

public float currentY = 50;

//定义、并创建画笔

Paint p = new Paint();

public DrawView(Context context) {

super(context);

}

public DrawView(Context context,AttributeSet set){

super(context,set);

}

@Override

protected void onDraw(Canvas canvas) {

super.onDraw(canvas);

//设置画笔的颜色

p.setColor(Color.RED);

//绘制一个小圆（作为小球）

canvas.drawCircle(currentX, currentY, 15, p);

}

//为该组建的触碰事件重写事件处理方法

@Override

public boolean onTouchEvent(MotionEvent event) {

//修改currentX,currentY两个属性

currentX = event.getX();

currentY = event.getY();

//通知当前组建重绘自己

invalidate();

//返回true表明该处理方法已经处理该事件

return true;

}

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

////获取布局文件中的LinearLayout容器

//LinearLayout root = (LinearLayout) findViewById(R.id.root);

////创建DrawView组建

//final DrawView draw = new DrawView(this);

////设置自定义组件的最多宽度、高度

//draw.setMinimumWidth(300);

//draw.setMinimumHeight(500);

//root.addView(draw);

}

来自：疯狂android