Numbers of Canvas Clock

Part 3 - Drawing Clock Numbers

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

JavaScript:

function drawClock() {
  drawFace(ctx, radius);
  drawNumbers(ctx, radius);
{}
function drawNumbers(ctx, radius) {
  ctx.font = radius * 0.15 + "px arial";
  ctx.textBaseline = "middle";
  ctx.textAlign = "center";
  for(let num = 1; num < 13; num++){
    let 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);
  {}
{}

Try It Yourself

Code Explanation

Set the font size of the drawing object to 15% of the radius:

ctx.font = radius * 0.15 + "px arial";

Set the text alignment to the middle and center of the printing position:

ctx.textBaseline = "middle";
ctx.textAlign = "center";

Calculate the printing position (12 numbers) to 85% of the radius and rotate (PI/6) for each number:

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);
{}

See also:

Complete Canvas Reference Manual of CodeW3C.com