First, add automatic detection of toolkit DPI scaling options. For now, this
is, in order,
* Check the GDK_SCALE option under GTK+ (users can set this to force the scaling)
* Check the value from WX's GetContentScalingFactor(). This will start to work
correctly from WX 3.1 and GTK+ 3.10.
Then, add a user-settable override in the main prefs panel, next to the icon
scaling. This is independent of the icon scaling options.
DPI handling is performed in a standalone class, so they can be shared between
the prefs UI and the OpenGL backend easily. Also means Cairo could use the same
interface in future.
Also adjust the OpenGL grid drawing code to use the computed scale factor,
which avoids over-thick grids in scaled environments (the user can manually
thicken the grid if wanted).
Fixes: lp:1797308
* https://bugs.launchpad.net/kicad/+bug/1797308
Cherry-pick of: 567bdd9b9 (master)
Cairo supports antialiasing when rendering but can be slow when set to
sub-pixel mode. This bumps the minimum version of Cairo to 1.12
(available in 14.04 LTS as well as mingw) to support three antialias
settings (fast, good, best) that offer speed/appearance tradeoffs.
This can provide a higher-quality eeschema render as it works on a
per-element basis as opposed to the OpenGL per-screen antialias.
Split antialiasing options out from display options. Move
antialiasing to common. Duplicate the rest of display options
for Eeschema.
Implement OnSelectGrid and hookup GAL canvas refresh to
SetPresetGrid.
Add Grid Settings... to View menu and move Show Grid from
preferences to View Menu to match Pcbnew.
John Beard
Wayne Stambaugh
Seth Hillbrand
jean-pierre charras
Jeff Young
José Jorge Enríquez