圆移动

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xml布局

<?xml version="1.0" encoding="utf-8"?><RelativeLayout    android:id="@+id/ra"    xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:app="http://schemas.android.com/apk/res-auto"    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"    android:layout_height="match_parent" tools:context="com.example.ballviewdemo.MainActivity"><com.example.ballviewdemo.Myclass    android:id="@+id/ball"    android:layout_width="wrap_content"    android:layout_height="wrap_content" /></RelativeLayout>

class

package com.example.ballviewdemo;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;/** * author:Created by WangZhiQiang on 2017/11/30. */public class Myclass extends View {    private float x = 20;    private float y = 20;    private float radio = 188;    //画笔    private Paint a = new Paint();Context context;    public Myclass(Context context) {        super(context);        this.context=context;        init();    }    public Myclass(Context context, @Nullable AttributeSet attrs) {        super(context, attrs);        this.context=context;        init();    }    public Myclass(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        this.context=context;        init();    }    private void init() {        a.setColor(Color.RED);    }    @Override    protected void onDraw(Canvas canvas) {        super.onDraw(canvas);        a.setAntiAlias(true);        canvas.drawCircle(x, y, radio, a);    }    @Override    public boolean onTouchEvent(MotionEvent event) {    this.x=(float) event.getX();     this.y= (float) event.getY();        invalidate();        return true;    }}

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