Canvas Clock Hands

Part IV – Draw Clock Hands

The clock needs hands. Create a JavaScript function to draw clock hands:

Example

function drawClock() {
  drawFace(ctx, radius);
  drawNumbers(ctx, radius);
  drawTime(ctx, radius);
}

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); }

Result


Example Explained

Use Date to get hour, minute, second:

var now = new Date();
var hour = now.getHours();
var minute = now.getMinutes();
var second = now.getSeconds();

Calculate the angle of the hour hand, and draw it a length (50% of radius), and a width (7% of radius):

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);

Use the same technique for minutes and seconds.

The drawHand() routine does not need an explanation. It just draws a line with a given length and width.

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3D Effect

Portal scene

UI Design