html5 Canvas Clock

HTML5 canvas example of drawing clocks, refer to other people's examples, organize and complete, with detailed comments

Reference: http://www.html5tricks.com/demo/html5-canvas-circle-clock/index.html

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width">
  <title>JS Bin</title>
</head>
<body>
<canvas id="myCanvas" width="400" height="400" style="border:5px solid #888;background-color:#edf;"></canvas>
</body>
</html>

	var c = document.getElementById('myCanvas').getContext('2d');
	function clock(){
		// clear the canvas
		c.clearRect(0,0,400,400);
		var data = new Date();
		var sec =data.getSeconds();
		var min = data.getMinutes ();
		var hour=data.getHours();
        var year=data.getFullYear();
        var month=data.getMonth()+1;
        var day =data.getDate();

		//Save the current state of the environment
		c.save();
		//Remap the (0,0) position on the canvas
		c.translate(200,200);
		//Rotate the current drawing (rotate 1/4 of the circular path counterclockwise)
		c.rotate(-2*Math.PI/4);

		//minute tick (draw 60 tick marks)
		for(var i=0;i<60;i++){
			c.beginPath();
			c.strokeStyle = "#f00";
			c.lineWidth = 5;
			c.moveTo (110.0);
			c.lineTo(120,0);
			c.stroke();
			//Draw a clock tick mark every 6deg (circular path rotated 1/60 clockwise)
			c.rotate(2*Math.PI/60);
			c.closePath();
		}

		//Clock tick marks (draw 12 tick marks)
		for(var i=0;i<12;i++){
			c.beginPath();
			c.strokeStyle = "#000";
			c.lineWidth = 8;
			c.moveTo (100.0);
			c.lineTo(120,0);
			c.stroke();
			//Draw a clock tick mark every 30deg (circular path rotated 1/12 clockwise)
			c.rotate(2*Math.PI/12);
			c.closePath();
		}

		c.rotate(-1);
		//Clock tick numbers (draw 12 tick numbers)
		for(var i=0;i<12;i++){
			c.beginPath();
			c.strokeStyle = "blue";
			c.lineWidth = 2 ;
            c.strokeText(i+1,0,90);
			// draw a clock tick every 30deg
			c.rotate(2*Math.PI/12);
			c.closePath();
		}
		c.rotate(1);

		//time display
		c.rotate(2*Math.PI/4);
        c.font="30px Song";
        c.strokeText(year+"-"+month+"-"+day+" "+hour+":"+min+":"+sec,-130,180);
		c.rotate(-2*Math.PI/4);
		
		//outer dial
		c.beginPath();
		c.strokeStyle = "pink";
		c.lineWidth = 12 ;
		// draw circle
		c.arc(0,0,135,0,Math.PI*2);
		c.stroke();
		c.closePath();

		// draw the hour hand
		hour = hour>12?hour-12:hour;
		c.beginPath();
		//Save the current state of the environment
		c.save();
		//Rotate the current clock clockwise to point to the arc path formed
		c.rotate(2*Math.PI/12*hour+2*Math.PI/12/60*min+2*Math.PI/12/3600*sec);
		c.strokeStyle = "yellowgreen";
		c.lineWidth = 4;
		c.moveTo (-20.0);
		c.lineTo(50,0);
		c.stroke();
		//Return the previously saved path state and attributes
		c.restore();
		c.closePath();

		// draw the minute hand
		c.beginPath();
		//Save the current state of the environment
		c.save();
		//Rotate the current minute hand clockwise to point to the arc path formed
		c.rotate(2*Math.PI/60*min+2*Math.PI/60/60*sec);
		c.strokeStyle = "springgreen";
		c.lineWidth = 3;
		c.moveTo (-30.0);
		c.lineTo(70,0);
		c.stroke();
		//Return the previously saved path state and attributes
		c.restore();
		c.closePath();

		// draw the second hand
		c.beginPath();
		//Save the current state of the environment
		c.save();
		//Rotate the current second hand clockwise to point to the arc path formed
		c.rotate(2*Math.PI/60*sec);
		c.strokeStyle = "red";
		c.lineWidth = 2 ;
		c.moveTo (-40.0);
		c.lineTo(120,0);
		c.stroke();
		//Return the previously saved path state and attributes
		c.restore();
		c.closePath();

		c.restore();
	}
	clock();
	setInterval(clock,1000);

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