Re: "Fix" sag scaling for hidpi

[Robert Pluim]

>>>>> On Sat, 06 Feb 2021 12:35:41 +0100, Lars Ingebrigtsen <larsi@gnus.org> 
>>>>> said:

    Lars> Eli Zaretskii <eliz@gnu.org> writes:
    >> If someone explains what are the "logical" and "physical" pixel sizes,
    >> I could try figuring out what that means for the MS-Windows case.

    Lars> Physical pixel size is what you'd think -- it's one actual pixel on 
the
    Lars> screen.  (If the monitor is 1280 × 1024, you have (* 1280 1024) =>
    Lars> 1310720 physical pixels.)

    Lars> "Logical" pixels was something that was introduced when people started
    Lars> making high-resolution screens.  In a 2x HiDPI scenario, the OS will
    Lars> report that the 1280 × 1024 is really a 640 x 512 screen, but if you
    Lars> give it an image that's 640x512 to display, it'll scale it up, using
    Lars> four physical pixels per logical pixel, and this will be blurry.

    Lars> So you give it a 1280x1024 image if it's a logical 640x512 2x screen 
if
    Lars> you don't want blurriness.  :-/

Or you use a scalable image format, or you donʼt specify the
dimensions, and let the toolkit work it out.

    Lars> (Of course, with fonts you avoid the blurriness, because it'll just
    Lars> render the fonts to whatever the physical pixels are.)

Font glyphs are just (small) scalable images :-)

Robert