单点触控

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//**********************************************************DrawView类
/
package com.example.diandianchukong;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 dell on 2017/9/1. */public class DrawView extends View {    public float currentX = 40;    public float currentY = 50;    Paint p = new Paint();    public DrawView(Context context) {        super(context);    }    public DrawView(Context context, @Nullable AttributeSet attrs) {        super(context, attrs);    }    @Override    protected void onDraw(Canvas canvas) {        super.onDraw(canvas);        p.setColor(Color.BLUE);        canvas.drawCircle(currentX, currentY, 15, p);    }    @Override    public boolean onTouchEvent(MotionEvent event) {        currentY = event.getY();        currentX = event.getX();        invalidate();        return true;    }}


/****************************************************************MainActivity 类
/
package com.example.diandianchukong;import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.widget.LinearLayout;public class MainActivity extends AppCompatActivity {    private DrawView drawView;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);//        drawView = (DrawView) findViewById(R.id.drawview);        LinearLayout root = (LinearLayout) findViewById(R.id.root);        final DrawView drawView = new DrawView(this);        drawView.setMinimumWidth(300);        drawView.setMinimumHeight(500);        root.addView(drawView);    }}

/***********************************************************************layout类/
<?xml version="1.0" encoding="utf-8"?><LinearLayout 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:id="@+id/root"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical"    tools:context="com.example.diandianchukong.MainActivity"></LinearLayout>
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