自定义view 小球的移动

自定义View 继承View

package com.mrli.rk03;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.support.annotation.Nullable;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

/**
 * Created by MRli on 2017/11/2.
 */

public class MyView extends View {
    public int currentX = 100;
    public int currentY = 100;
    Context context;
    //创建画笔
    Paint p  = new Paint();

    public MyView(Context context) {
        super(context);
    }

    public MyView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    public MyView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        //设置画笔的颜色
        p.setColor(Color.RED);
        //绘制一个小球
        //参数分别是：圆心坐标，半径，所使用的画笔
        canvas.drawCircle(currentX,currentY,45,p);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {

        this.currentX = (int) event.getX(); //触摸座标X
        this.currentY = (int) event.getY(); //触摸座标Y
        this.invalidate();
        // 自己处理触摸事件
        return true;
    }

}

在xml文件中引入

<com.mrli.rk03.MyView
        android:layout_width="wrap_content"
        android:id="@+id/circle"
        android:layout_height="wrap_content" />