Center (proportional font) text in an HTML5 canvas

Question

I would like to be able to center single lines of text within rectangular areas I can calculate. The one thing I have expected to do in 2D geometry on a canvas is to center

Answer 1

You can do this by using measureText

var canvas = document.getElementById("canvas"),
    ctx = canvas.getContext("2d")

canvas.width = 400;
canvas.height = 200;

ctx.fillStyle = "#003300";
ctx.font = '20px san-serif';

var textString = "Hello look at me!!!",
    textWidth = ctx.measureText(textString ).width;


ctx.fillText(textString , (canvas.width/2) - (textWidth / 2), 100);

Live Demo

More elaborate demo