Memoize fontkit.fk_shape

[akinsho]

fixes #115, memoizes the fn in a similar way as the getTexture function

[bryphe]

There's one gotcha with our built-in memoization - it only supports single argument functions.

This means, with the current implementation, we'd actually only be memoizing the 'font' parameter. To speed up this code-path, we'll need to cache the tuple of (font, text).

So I think we'd need to update our memoize function to take in a pair of (font, text) - that's why we have the somewhat awkward syntax in our other memoized functions:

revery/src/UI/FontRenderer.re

Line 14 in 7b8ccf7

let _getTexture = ((font: Fontkit.fk_face, codepoint: int)) => {

let _getTexture = ((font: Fontkit.fk_face, codepoint: int)) => {
...
}


let _memoizedGetTexture = Memoize.make(_getTexture);
let getTexture = (font: Fontkit.fk_face, codepoint: int) =>
  _memoizedGetTexture((font, codepoint));

Note the extra ( and ) in the _getTexture and the way we call _memoizedGetTexture. The _getTexture is actually taking a single argument of (font, codepoint), and the getTexture is converting its arguments to a tuple to send them into _memoizedGetTexture.

Let me know if you have any questions!

[bryphe]

Thanks for the PR, @Akin909 ! Left a comment around the memoization strategy - I think we'll need a tweak to get the full benefit of memoization in this scenario.

[bryphe]

Looks good to me! Thanks for fixing this, @Akin909 🎉