analog-clock.html

<!DOCTYPE html>
<html lang="en">
  <!--
      File:  analog-clock.html
      From:  <https://www.w3schools.com/graphics/canvas_clock.asp>
      From:  https://www.w3schools.com/graphics/canvas_clock_start.asp
      Note:  This is an example given by W3 Schools for using the <canvas> 
             HTML element - the Canvas Clock example is give in sections, 
	     there.  This is the complete canvas clock example code in 
	     a single file from the final page of the example given at
	     <https://www.w3schools.com/graphics/tryit.asp?filename=trycanvas_clock_start>
	     The example at W3 Schools starts with 	     
    -->
  <head>
    <title>Analog Clock</title>
    <style>
      body {
	  padding:10px;
	  background-color:#212121;
	  color:silver;
	  text-align:center;
      }
      canvas {
	  margin-left:auto;
	  margin-right:auto;
	  opacity:0.8;
	  border: 7px cyan;
	  box-shadow: 5px 5px 5px 5px white,
		      -5px -5px 5px 5px white,
		      5px -5px 5px 5px white,
		      -5px 5px 5px 5px white 
	  ;
      }
    </style>
  </head>
  <body>
    <canvas id="canvas" width="400" height="400"
	    style="background-color:#333"></canvas>
    
    <script>
      var canvas = document.getElementById("canvas");
      var ctx = canvas.getContext("2d");
      var radius = canvas.height / 2;
      ctx.translate(radius, radius);
      radius = radius * 0.90
      setInterval(drawClock, 1000);
      drawClock();
      
      function drawClock() {
	  drawFace(ctx, radius);
	  drawNumbers(ctx, radius);
	  drawTime(ctx, radius);
      }

      function drawFace(ctx, radius) {
	  var grad;
	  ctx.beginPath();
	  ctx.arc(0, 0, radius, 0, 2*Math.PI);
	  ctx.fillStyle = 'white';
	  ctx.fill();
	  grad = ctx.createRadialGradient(0,0,radius*0.95, 0,0,radius*1.05);
	  grad.addColorStop(0, '#333');
	  grad.addColorStop(0.5, 'white');
	  grad.addColorStop(1, '#333');
	  ctx.strokeStyle = grad;
	  ctx.lineWidth = radius*0.1;
	  ctx.stroke();
	  ctx.beginPath();
	  ctx.arc(0, 0, radius*0.1, 0, 2*Math.PI);
	  ctx.fillStyle = '#333';
	  ctx.fill();
      }

      function drawNumbers(ctx, radius) {
	  var ang;
	  var num;
	  ctx.font = radius*0.15 + "px arial";
	  ctx.textBaseline="middle";
	  ctx.textAlign="center";
	  for(num = 1; num < 13; num++){
	      ang = num * Math.PI / 6;
	      ctx.rotate(ang);
	      ctx.translate(0, -radius*0.85);
	      ctx.rotate(-ang);
	      ctx.fillText(num.toString(), 0, 0);
	      ctx.rotate(ang);
	      ctx.translate(0, radius*0.85);
	      ctx.rotate(-ang);
	  }
      }

      function drawTime(ctx, radius){
	  var now = new Date();
	  var hour = now.getHours();
	  var minute = now.getMinutes();
	  var second = now.getSeconds();
	  //hour
	  hour=hour%12;
	  hour=(hour*Math.PI/6)+
	      (minute*Math.PI/(6*60))+
	      (second*Math.PI/(360*60));
	  drawHand(ctx, hour, radius*0.5, radius*0.07);
	  //minute
	  minute=(minute*Math.PI/30)+(second*Math.PI/(30*60));
	  drawHand(ctx, minute, radius*0.8, radius*0.07);
	  // second
	  second=(second*Math.PI/30);
	  drawHand(ctx, second, radius*0.9, radius*0.02);
      }

      function drawHand(ctx, pos, length, width) {
	  ctx.beginPath();
	  ctx.lineWidth = width;
	  ctx.lineCap = "round";
	  ctx.moveTo(0,0);
	  ctx.rotate(pos);
	  ctx.lineTo(0, -length);
	  ctx.stroke();
	  ctx.rotate(-pos);
      }
    </script>

  </body>
</html>