Use HTML 5 to create a simple clock effect-H5 Tutorial-php.cn

Use HTML 5 to create a simple clock effect

王林

Release： 2021-03-04 11:21:05

forward

3682 people have browsed it

Use HTML 5 to create a simple clock effect

Let’s take a look at the final effect first:

Use HTML 5 to create a simple clock effect

It looks like a very simple clock effect, but the specific implementation code still contains acquired some key knowledge.

The following is the specific implementation code:

(Tip: Pay special attention to the use of fillText drawhand and the calculation of the angle)

<%-- 
    Document   : 时钟
    Created on : 2016-5-19, 9:49:29
    Author     : Administrator
--%>
 
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>JSP Page</title>
    </head>
    <style>
        canvas{
            border: 1px solid black;
        }
    </style>
    <script>
        (function(){
            //cavas元素对象
            var canvas=null;
            //canvas的3d上下文
            var ctx=null;
            //cavan的尺寸
            var cw=0;
            var ch=0;
            /**
             * 页面导入时的事件处理
             */
            window.addEventListener("load",function(){
                canvas=document.getElementById("sample");
                ctx=canvas.getContext("2d");
                cw=parseInt(canvas.width);
                ch=parseInt(canvas.height);
                
                ctx.translate(cw/2, ch/2);
            
                //绘制时钟
                draw_watch();
            },false);  
 
        
            /**
             * 绘制时钟
             */
            function draw_watch(){
                //清空Canvas
                ctx.clearRect(-cw/2,-ch/2,cw,ch);
                //计算针的最大长度
                var len=Math.min(cw, ch)/2;
                //绘制刻度盘
                var tlen=len*0.85;
                ctx.font="14px &#39;Arial&#39;";
                ctx.fillStyle="black";
                ctx.textAlign="center";
                ctx.textBaseLine="middle";
            
                for(var i=0; i<12; i++){
                    var tag1=Math.PI*2*(3-i)/12;
                    var tx=tlen * Math.cos(tag1);
                    var ty=-tlen * Math.sin(tag1);
                    ctx.fillText(i,tx,ty);
                }
                //获取当前的时分秒
                var d=new Date();
                var h=d.getHours();
                var m=d.getMinutes();
                var s=d.getSeconds();
                if(h >12 ){
                    h=h-12;
                }
            
                //绘制时针
                var angle1 = Math.PI * 2 *(3 - (h+ m/60))/12;
                var length1=len * 0.5;
                var width1=5;
                var color1="#000000";
                drawhand(angle1,length1,width1,color1);
            
                //绘制分针
                var angle2 = Math.PI * 2 *(15 - (m+ s/60))/60;
                var length2=len * 0.7;
                var width2=3;
                var color2="#555555";
                drawhand(angle2,length2,width2,color2);
            
                //绘制秒针
                var angle3 = Math.PI * 2 *(15 - s)/60;
                var length3=len * 0.8;
                var width3=1;
                var color3="#aa0000";
                drawhand(angle3,length3,width3,color3);
            
                //设置timer
                setTimeout(draw_watch,1000);
            }
            /**
             * 针绘制函数
             */
        
            function drawhand(angle,len,width,color){
                //计算针端的坐标
                var x=len*Math.cos(angle);
                var y=-len * Math.sin(angle);
                //绘制针
                ctx.strokeStyle=color;
                ctx.lineWidth=width;
                ctx.lineCap="round";
                ctx.beginPath();
                ctx.moveTo(0,0);
                ctx.lineTo(x,y);
                ctx.stroke();
            
            }
        })();
    </script>
    <body>
        <canvas id="sample" width="150" height="150"></canvas>
    </body>
</html>

Copy after login

Related recommendations: html5 tutorial

The above is the detailed content of Use HTML 5 to create a simple clock effect. For more information, please follow other related articles on the PHP Chinese website!