布局
<com.lll.day03.BallView
android:id="@+id/ballView2"
android:layout_width=“match_parent”
android:layout_height=“wrap_content” />
BallView页面
package com.lll.day03;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
public class BallView extends View {
private Paint mRectPaint;
private float cx = 200f;
private float cy = 200f;
public BallView(Context context) {
super(context);
init();
}
public BallView(Context context,AttributeSet attrs) {
super(context, attrs);
init();
}
public BallView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init();
}
private void init() {
//创建画笔
mRectPaint = new Paint();
//设置画笔颜色
mRectPaint.setColor(Color.GREEN);
mRectPaint.setStrokeWidth(3);
//设置画笔的样式
mRectPaint.setStyle(Paint.Style.FILL);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
// Path path = new Path();
canvas.drawCircle(cx,cy,50,mRectPaint);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
//第一种简单方法
// cx = event.getX();
// cy = event.getY();
// this.invalidate();
//第二种判断
switch (event.getAction()){
case MotionEvent.ACTION_DOWN:
cx = event.getX();
cy = event.getY();
break;
case MotionEvent.ACTION_MOVE:
cx = event.getX();
cy = event.getY();
break;
case MotionEvent.ACTION_UP:
cx = event.getX();
cy = event.getY();
break;
}
this.invalidate();
return true;
}
}
MainActivity页面
package com.lll.day03;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
}