Adds DPI configuration (#660)

Adds a new DPI configuration, especially useful for HiDPI displays. This changes the scaling factor for fonts as displayed by Pango. It defaults to 96.0 which corresponds to an average screen and is the default in [Cairo](https://hackage.haskell.org/package/pango-0.13.5.0/docs/Graphics-Rendering-Pango-Cairo.html#v:cairoFontMapGetDefault). It's also possible to supply a zero or negative value to use the default scaling factor, but I felt setting the default to 96.0 makes it more explicit.

It also adds a matching command line option.

I haven't tested it too thoroughly, but in my limited use it appears to be working as intended.

One thing this does not do is scale XBM and XPM bitmap files which I'm unsure how to do or if that should even be our concern (instead leaving it up to the user to supply appropriate bitmaps).

Co-authored-by: Jonathan Grochowski <jon@grocho.net>
Reviewed-on: https://codeberg.org/xmobar/xmobar/pulls/660
Co-authored-by: jgrocho <codeberg@jon.grocho.net>
Co-committed-by: jgrocho <codeberg@jon.grocho.net>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/Xmobar/App/Config.hs b/src/Xmobar/App/Config.hs
index a284973..5c2f362 100644
--- a/src/Xmobar/App/Config.hs
+++ b/src/Xmobar/App/Config.hs
@@ -67,6 +67,7 @@ defaultConfig =
            , signal = SignalChan Nothing
            , textOutput = False
            , textOutputFormat = Plain
+           , dpi = 96.0
            }
 
 -- | Return the path to the xmobar data directory.  This directory is