Re: Pixel-based display functions

[Lars Ingebrigtsen]

Eli Zaretskii <address@hidden> writes:

>> From: Lars Ingebrigtsen <address@hidden>
>> Date: Wed, 28 Jan 2015 14:27:17 +1100
>> 
>> shr needs three functions to be kind-of fast to work:
>> 
>> 1) A pixel equivalent of `current-column'
>
> You already have it:
>
>   (car (nth 2 (posn-at-point)))

Isn't that one of those functions that says what redisplay has already
computed?  So it's kinda useless.

(with-temp-buffer
  (insert (propertize "hello" 'face 'variable-pitch))
  (car (nth 2 (posn-at-point))))
=> nil

>> 2) A pixel equivalent of `move-to-column' (which will be imprecise, of
>> course, but that's OK)
>
> You already have it (albeit not necessarily where you'd look ;-):
>
>   (vertical-motion (cons (/ PIXELS (frame-char-width)) 0))

Is that another one of those that only work after redisplay?

>> 3) A pixel equivalent of `string-width'
>
> Didn't we just go through using font-get-glyphs for that?

Yes, and it's too slow to use.

-- 
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  bloggy blog http://lars.ingebrigtsen.no/