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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);
}