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);
}
