html5 text manipulation

I'm trying to write a piece of software to grab strings and pack them in and ordered layout, like in the image below

I think that to achieve that result the first step I'd take would be being able to calculate the size of a single string in the canvas in order to modify the font-size to fit the desired width.

so, i开发者_如何学Pythonf any1's got a solution to some built-in function, or a way to perform it so that I can code it myself that would be nice (very nice).

thanks in advance

k

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If you decide to do it without CANVAS, this might come in useful: how to calculate a letter's width: http://jsfiddle.net/rudiedirkx/sCUac/ in a specific font with a specific size.

edit
Or a sentence's width.