HTML5 Canvas 画钟表

2022-10-16 08:34:39
画钟表是2D画图的老生常谈，我也不能免俗弄了一个。代码如下：
<!DOCTYPE html>
<html lang="utf-8">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<head>
     <title>钟表</title>
    </head>

     <body onload="draw()">
        <canvas id="myCanvus" width="200px" height="200px" style="border:1px dashed black;">
            出现文字表示你的浏览器不支持HTML5
        </canvas>
     </body>
</html>
<script type="text/javascript">
<!--
function draw(){
    var canvas=document.getElementById('myCanvus');
    canvas.width=200;
    canvas.height=200;    

    context=canvas.getContext('2d');
    context.translate(100,100);

    clock=new Clock(100);
    clock.init();

    animate();
};

var context;
var clock;

function animate(){
    context.clearRect(-100,-100,200,200);// 清屏

    clock.paintBg(context);
    clock.paintScale(context);
    clock.paintNumbers(context);
    clock.paintPointers(context);

    if(true){
        // 让浏览器自行决定帧速率
        window.requestAnimationFrame(animate);
    }
}

// 钟表类
function Clock(radius){
    this.radius=radius;
    this.img;

    this.init=function(){
        this.img=new Image();
        this.img.src="clock7.jpg";
    }

    // 画背景
    this.paintBg=function(ctx){
        ctx.drawImage(this.img,66,50,880,880,-100,-100,200,200);
    };

    // 画刻度
    this.paintScale=function(ctx){
        for(var i=0;i<60;i++){
            var degree=i*6;
            var x=this.radius*Math.cos(getRad(degree));
            var y=this.radius*Math.sin(getRad(degree));

            ctx.strokeStyle = "black";
            ctx.fillStyle="black";
            ctx.beginPath();

            if((i % 5)==0){
                ctx.arc(x,y,1.5,0,Math.PI*2,false);
            }else{
                //ctx.arc(x,y,0.5,0,Math.PI*2,false);
            }            

            ctx.closePath();
            ctx.fill();
        }
    };

    // 画数字
    this.paintNumbers=function(ctx){
        ctx.font="bold 16px 宋体";
        ctx.fillStyle="Red";        

        ctx.fillText("XII",-12,-80);
        ctx.fillText("VI",-8,93);
        ctx.fillText("IX",-94,5);
        ctx.fillText("III",68,5);
    };

    // 画指针
    this.paintPointers=function(ctx){
        var date = new Date();
        var hour=date.getHours();
        var minute=date.getMinutes();
        var second=date.getSeconds();

        ctx.font="bold 6px 宋体";
        ctx.fillStyle="navy";
        ctx.fillText(hour+":"+minute+":"+second,12,-50);

        var angleS=second*6;
        var angleM=minute*6;
        var angleH=hour*30+angleM/360*30;

        context.save();
        context.rotate(getRad(-90));

        var x,y;

        context.lineWidth=0.5;
        x=(this.radius-2)*Math.cos(getRad(angleS));
        y=(this.radius-2)*Math.sin(getRad(angleS));
        ctx.strokeStyle = "black";
        ctx.beginPath();
        ctx.moveTo(-x/3, -y/3);
        ctx.lineTo(x,y);
        ctx.stroke();
        ctx.closePath();

        context.lineWidth=1.5;
        x=(this.radius-8)*Math.cos(getRad(angleM));
        y=(this.radius-8)*Math.sin(getRad(angleM));
        ctx.strokeStyle = "yellow";
        ctx.beginPath();
        ctx.moveTo(0, 0);
        ctx.lineTo(x,y);
        ctx.stroke();
        ctx.closePath();

        context.lineWidth=2;
        x=(this.radius-25)*Math.cos(getRad(angleH));
        y=(this.radius-25)*Math.sin(getRad(angleH));
        ctx.strokeStyle = "maroon";
        ctx.beginPath();
        ctx.moveTo(0, 0);
        ctx.lineTo(x,y);
        ctx.stroke();
        ctx.closePath();

        context.restore();

        ctx.fillStyle="black";
        ctx.arc(0,0,2.5,0,Math.PI*2,false);
        ctx.fill();
    };
}

//  常规函数:角度得到弧度
function getRad(degree){
    return degree/180*Math.PI;
}

//  常规函数:得到颜色
function getColor(index){
    if(index==0){
        return "green";
    }else if(index==1){
        return "silver";
    }else if(index==2){
        return "lime";
    }else if(index==3){
        return "gray";
    }else if(index==4){
        return "white";
    }else if(index==5){
        return "yellow";
    }else if(index==6){
        return "maroon";
    }else if(index==7){
        return "navy";
    }else if(index==8){
        return "red";
    }else if(index==9){
        return "blue";
    }else if(index==10){
        return "purple";
    }else if(index==11){
        return "teal";
    }else if(index==12){
        return "fuchsia";
    }else if(index==13){
        return "aqua";
    }else if(index==14){
        return "black";
    }
}

//-->
</script>
完整代码从这里下载：https://files.cnblogs.com/files/xiandedanteng/clock.rar
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