Re: What is the proper way to scale fringe-bitmaps for high-DPI displays?

["Clément Pit-Claudel" <cpitclaudel@gmail.com>]

On 2019-03-20 23:32, Eli Zaretskii wrote:
>> Cc: emacs-devel@gnu.org
>> From: Clément Pit-Claudel <cpitclaudel@gmail.com>
>> Date: Wed, 20 Mar 2019 17:17:16 -0400
>>
>>>> Oh, so Emacs' C code would scale the bitmaps? I expected the Lisp code would do that.
>>>
>>> Fringes are displayed in C.  Doing this in Lisp will produce
>>> flickering, I'm afraid.
>>
>> I thought the C code would read the scaling factor and set the bitmap accordingly just once, when creating overlays or applying text properties.
> 
> But you were saying that a frame can move from a high-DPI terminal to
> a low-DPI one, which seems to mean we cannot compute that just once.

True, but I wouldn't be too unhappy if switching from high to low DPI (or vice versa) didn't work so well.  I also don't know if it's actually possible to have different-DPI displays on GNU/Linux systems.

> And besides, there are fringe bitmaps that we display regardless of
> any overlays and text properties (e.g., truncation and continuation
> indicators), which are displayed directly from C.

Good point.