Re: HiDPI and zoom levels interpolation

[Felix Riemann <friemann gnome org>]

Hi,

Am Mittwoch, den 26.10.2016, 13:03 +0400 schrieb François Guerraz:
> Hello,
>
> In tracking down bug #770266, I read parts of the code.
>
> After reading eog-scroll-view.c:1409, I wonder if the following is
> correct:
>
>       if(!DOUBLE_EQUAL(priv->zoom, 1.0) && priv->force_unfiltered)
>       {
>               interp_type = CAIRO_FILTER_NEAREST;
>               _set_hq_redraw_timeout(view);
>       }
>
> Surely "1.0" should be replaced by the inverse of the UI scale
> factor,
> same for the hardcoded "1.0" value in is_zoomed_in().
>
> What do you think?

I think the 1.0 is correct as priv->zoom is a purely internal zoom
factor for eog. So if the image is shown at 100% zoom the factor should
be 1.0. If you need additional scaling due to having a HiDPI screen eog
currently expects GTK and cairo to handle this. Is your image too small
on 100% zoom?

If we need to change something in eog for HiDPI to work correctly,
things will become difficult as I don't have such a screen.

Regards,

Felix