倒计时

package com.example.monizk.view;

import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Handler;
import android.os.Message;
import android.support.annotation.Nullable;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;
import android.widget.Toast;

import com.example.monizk.R;


/**
 * Created by 小薇 on 2018/7/8.
 */

public class AdTimeViewPager extends View {
   private Handler handler=new Handler(){
       @Override
       public void handleMessage(Message msg) {
           super.handleMessage(msg);
           if(msg.what==0){
               if(time>1){
                   time--;
                   //重新初始化第二个画布，将以前画的数字消除
                   //重新画
                   draw();
                   //更新界面
                   //调用ondraw
                   invalidate();
                   handler.sendEmptyMessageDelayed(0,1000);
               }else{
                   Toast.makeText(getContext(),"跳转成功",Toast.LENGTH_SHORT).show();
               }
           }
       }
   };
    private int height;
    private int width;
    private Canvas mcanvas;
    private Bitmap mbitmap;
    private Paint mpaint;
    private int time;
    public AdTimeViewPager(Context context) {
        super(context);
    }

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

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

    @SuppressLint("DrawAllocation")
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        //设置第一支画笔
        Paint paint = new Paint();
        //设置画笔颜色
        paint.setColor(Color.RED);
        paint.setAntiAlias(true);
        //设置透明度
        paint.setAlpha(240);
        //获取背景图片资源
        Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.mipmap.dd);
        Log.i("aaa",bitmap.toString());
        //将背景图片画到屏幕上
        canvas.drawBitmap(bitmap,0,0,paint);
        //根据屏幕确定圆的位值，不是根据控件的大小
        width = getWidth()-380;
        height = 80;
        //圆的半径
        float radius=60;

        Log.i("bbbb",getHeight()+"...."+getWidth());

        //画圆
        canvas.drawCircle(width,height,radius,paint);
        //将第二层的画布画到屏幕上
        canvas.drawBitmap(mbitmap,0,0,null);

        //初始化显示数字，如果将这行注释掉，就不会显示5s这个数字
//        mcanvas.drawText(time+"s",width-30,height*10,mpaint);
    }
    public void init(int i){
        if(i<3){
            time=3;
        }else{
            time=i;
        }
        //设置第二支画笔
        mpaint = new Paint();
        //设置文字颜色大小
        mpaint.setTextSize(80);
        mpaint.setColor(Color.BLACK);
        draw();
         handler.sendEmptyMessageDelayed(0,1000);
    }
    /*
    * 初始化mbitmap和mcanvas
    * 并且画上倒计时数字
    * 这里画的东西都是画到了第二层画布上
    */
    private void draw(){
        mbitmap = Bitmap.createBitmap(getLayoutParams().width, getLayoutParams().height, Bitmap.Config.ARGB_8888);
        //初始化第二个画布，将所有的东西画到mbitmap上
        mcanvas = new Canvas(mbitmap);
        //将数字画到第二个画布上
        mcanvas.drawText(time+"s",width-30,height+10,mpaint);
    }


}