package com.zking.diypointtouch;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Handler;
import android.os.Message;
import android.view.MotionEvent;
import android.view.View;
/**
* Created by Administrator on 2017/7/9 0009.
*/
public class Practice extends View{
//画笔
private Paint mpaint;
//定义圆线的宽度
private int mstroken;
//圆心
private int cx;
private int cy;
//半径
private int cr;
//发送消息
private static final int FLUSH=0;
public Practice(Context context) {
super(context);
init();
}
private void init(){
//初始化画笔
mpaint=new Paint();
//抗锯齿
mpaint.setAntiAlias(true);
//设置颜色
mpaint.setColor(Color.BLACK);
//设置圆线的宽度
mpaint.setStrokeWidth(mstroken);
//设置圆的透明度
mpaint.setAlpha(255);
//初始值
mstroken=0;
cr=0;
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawCircle(cx,cy,cr,mpaint);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
// 判断手势按下和抬起
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
cx = (int) event.getX();
cy = (int) event.getY();
break;
}
// 初始化
init();
// 发送
handler.sendEmptyMessage(FLUSH);
return true;
}
private void flush(){
cr+=10;//每次都加十
mstroken=cr/4;//圆线的粗细
mpaint.setStrokeWidth(mstroken);//重新设置
int nextAlpha=mpaint.getAlpha()-20;//每次减20
if(nextAlpha<0){//避免透明度为负
nextAlpha=0;
}
mpaint.setAlpha(nextAlpha);
}
private Handler handler=new Handler(){
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case FLUSH:
flush();
invalidate();//重新绘制
if (mpaint.getAlpha() != 0) {
//每100ms刷新一次
handler.sendEmptyMessageDelayed(FLUSH, 100);
}
break;
}
}
};
}
