bug#50958: 27.2; Very blurry svg rendering on Retina screen

[Carlos Pita]

Hi Alan,

> I think docview uses external applications to render the files to png
> and it has its own setting for DPI (doc-view-resolution), which on a
> hi-dpi screen is a bit low.
>
> IIRC docview is a bit strange because you don't set the dpi to the
> screen's dpi, the actual value you want to use depends on various
> factors, like how large your window is and whether you zoom in on the
> image or not.

Wouldn't it make sense to set the default resolution to a value more
appropriate to the screen resolution then? I understand that someone
may want to change it for zooming for example, but OOTB seems quite
broken in a HiDPI screen and the average user (even the average emacs
user) probably doesn't understand a lot about scaling factors, not to
say about the existence of doc-view-resolution. Maybe now that there
is frame-scale-factor in emacs 28 it could be used to set the default
resolution for docview?

Best regards,
Carlos