Re: [PATCH] avoid hard-coded assumptions in image scaling

[Lars Ingebrigtsen <larsi@gnus.org>]

"James N. V. Cash" <james.nvc@gmail.com> writes:

> In image-compute-scaling-factor in images.el, it currently hard-codes
> the assumption that the average character width is 10 pixels. Since
> `frame-char-width` gives this information though, it seems like it's less
> error-prone to use that function instead of assuming.

[...]

> +      ;; We should scale all images according to how wide they are.
> +      ;; But don't scale images down.
> +      (if (< width (frame-char-width))
>            1
> -        (/ (float width) 10))))
> +        (/ (float width) (frame-char-width)))))

The point of the heuristic here is that we want to scale images up on
HiDPI screens, so the current code gives me a scaling factor of 2.3.
(I've got a 14" 4K screen.)

(frame-char-width)
=> 23

With your patch, it'll return 1, of course, which is exactly the
opposite of what we want.

(The function could just have used (frame-char-width) divided by ten, I
guess, instead of computing it itself.)

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no