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Canvas Clock Numbers


Part III - Draw 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) {
  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);
  }
}
Try it Yourself »


Example Explained

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 the center of the print position:

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

Calculate the print position (for 12 numbers) to 85% of the radius, rotated (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);
}