自定义View绘制时钟

package com.example.a04_clockview.clockview;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.util.AttributeSet;import android.view.View;import java.util.Calendar;/** * Created by yujie on 2017/12/1. */public class ClockView extends View{    private int width;    private int height;    private Paint mPaintLine;    private Paint mPaintCircle;    private Paint mPaintHour;    private Paint mPaintMinute;    private Paint mPaintSec;    private Paint mPaintText;    private Calendar mCalendar;    public static final int NEED_INVALIDATE = 0X23;    //每隔一秒，在handler中调用一次重新绘制方法    private Handler handler = new Handler(){        @Override        public void handleMessage(Message msg) {            switch (msg.what){                case NEED_INVALIDATE:                    mCalendar = Calendar.getInstance();                    invalidate();//告诉UI主线程重新绘制                    handler.sendEmptyMessageDelayed(NEED_INVALIDATE,1000);                    break;                default:                    break;            }        }    };    public ClockView(Context context) {        super(context);    }    public ClockView(Context context, AttributeSet attrs) {        super(context, attrs);        mCalendar = Calendar.getInstance();        mPaintLine = new Paint();        mPaintLine.setColor(Color.BLUE);        mPaintLine.setStrokeWidth(10);        mPaintCircle = new Paint();        mPaintCircle.setColor(Color.GREEN);//设置颜色        mPaintCircle.setStrokeWidth(10);//设置线宽        mPaintCircle.setAntiAlias(true);//设置是否抗锯齿        mPaintCircle.setStyle(Paint.Style.STROKE);//设置绘制风格        mPaintText = new Paint();        mPaintText.setColor(Color.BLUE);        mPaintText.setStrokeWidth(10);        mPaintText.setTextAlign(Paint.Align.CENTER);        mPaintText.setTextSize(40);        mPaintHour = new Paint();        mPaintHour.setStrokeWidth(20);        mPaintHour.setColor(Color.BLUE);        mPaintMinute = new Paint();        mPaintMinute.setStrokeWidth(15);        mPaintMinute.setColor(Color.BLUE);        mPaintSec = new Paint();        mPaintSec.setStrokeWidth(10);        mPaintSec.setColor(Color.BLUE);        handler.sendEmptyMessage(NEED_INVALIDATE);//向handler发送一个消息，让它开启重绘    }    @Override    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {        super.onMeasure(widthMeasureSpec, heightMeasureSpec);        width = getDefaultSize(getSuggestedMinimumWidth(), widthMeasureSpec);        height = getDefaultSize(getSuggestedMinimumHeight(), heightMeasureSpec);        setMeasuredDimension(width, height);    }    @Override    protected void onDraw(Canvas canvas) {        super.onDraw(canvas);        int circleRadius = 300;        //画出大圆        canvas.drawCircle(width / 2, height / 2, circleRadius, mPaintCircle);        //画出圆中心        canvas.drawCircle(width / 2, height / 2, 20, mPaintCircle);        //依次旋转画布，画出每个刻度和对应数字        for (int i = 1; i <= 12; i++) {            canvas.save();//保存当前画布            canvas.rotate(360/12*i,width/2,height/2);            //左起：起始位置x坐标，起始位置y坐标，终止位置x坐标，终止位置y坐标，画笔(一个Paint对象)            canvas.drawLine(width / 2, height / 2 - circleRadius, width / 2, height / 2 - circleRadius + 30, mPaintCircle);            //左起：文本内容，起始位置x坐标，起始位置y坐标，画笔            canvas.drawText(""+i, width / 2, height / 2 - circleRadius + 70, mPaintText);            canvas.restore();//        }        int minute = mCalendar.get(Calendar.MINUTE);//得到当前分钟数        int hour = mCalendar.get(Calendar.HOUR);//得到当前小时数        int sec = mCalendar.get(Calendar.SECOND);//得到当前秒数        float minuteDegree = minute/60f*360;//得到分针旋转的角度        canvas.save();        canvas.rotate(minuteDegree, width / 2, height / 2);        canvas.drawLine(width / 2, height / 2 - 250, width / 2, height / 2 + 40, mPaintMinute);        canvas.restore();        float hourDegree = (hour*60+minute)/12f/60*360;//得到时钟旋转的角度        canvas.save();        canvas.rotate(hourDegree, width / 2, height / 2);        canvas.drawLine(width / 2, height / 2 - 200, width / 2, height / 2 + 30, mPaintHour);        canvas.restore();        float secDegree = sec/60f*360;//得到秒针旋转的角度        canvas.save();        canvas.rotate(secDegree,width/2,height/2);        canvas.drawLine(width/2,height/2-300,width/2,height/2+40,mPaintSec);        canvas.restore();    }}