1 跟随手指移动的球

 1 package ui;
 2 
 3 import android.content.Context;
 4 import android.graphics.Canvas;
 5 import android.graphics.Color;
 6 import android.graphics.Paint;
 7 import android.util.AttributeSet;
 8 import android.view.MotionEvent;
 9 import android.view.View;
10 
11 /**
12  * Created by Administrator on 2016/4/3.
13  */
14 public class MoveCircle extends View{
15     public MoveCircle(Context context) {
16         super(context);
17     }
18 
19     public MoveCircle(Context context, AttributeSet attrs) {
20         super(context, attrs);
21     }
22 
23     public MoveCircle(Context context, AttributeSet attrs, int defStyleAttr) {
24         super(context, attrs, defStyleAttr);
25     }
26 
27     float currentX = 50.0f;
28     float currentY = 50.0f;
29 
30     @Override
31     protected void onDraw(Canvas canvas) {
32         super.onDraw(canvas);
33         Paint paint = new Paint();
34         paint.setColor(Color.RED);
35         canvas.drawCircle(currentX,currentY,10,paint);
36     }
37 
38     @Override
39     public boolean onTouchEvent(MotionEvent event) {
40         super.onTouchEvent(event);
41         currentX = event.getX();
42         currentY = event.getY();
43         //重绘
44         invalidate();
45         return  true;
46 
47     }
48 }

1 <ui.MoveCircle
2        android:id="@+id/circle"
3        android:layout_width="wrap_content"
4        android:layout_height="wrap_content"
5        android:minHeight="100dp"
6        android:minWidth="100dp"
7        />