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

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

On 2019-03-20 13:32, Eli Zaretskii wrote:
>> From: Clément Pit-Claudel <cpitclaudel@gmail.com>
>> Date: Wed, 20 Mar 2019 10:55:43 -0400
>>
>> Users on Flycheck are complaining about poor readability of our fringe bitmaps on high-DPI monitors, as the bitmaps look tiny on such screens.  An easy fix is to double the size of the bitmap, but it leaves users of low-DPI monitors in the cold.  A trickier fix would be to dynamically detect the current monitor's density, and pick the appropriate bitmap accordingly, but I'm not entirely sure how to do detect these high-DPI monitors:
>>
>> - x-display-monitor-attributes-list seems OK, but looks more complex than what we need (based on looking at the C code) — is it OK to call it repeatedly to figure out the current monitor's density for a given frame?
> 
> That'd be very inelegant, IMO.
> 
> Instead, I think when a frame is created, we should record its
> high-DPI state in the frame structure, or maybe in the frame's
> parameters, and then use that when we prepare the fringe bitmaps for
> display.

In addition to my previous message, I should add that other parts of Emacs would likely benefit from this as well, since we have code (see cb73c70180f57f3fb99fae3aaefbacf0a61cea3f) that computes DPI values in gamegrid.el.

Cheers,
Clément.