add compass rose

pkgs/maps/main.fnl

@@ -339,6 +339,7 @@ label.readout {
                 (string.format "%.1f km/h" (* app-state.speed 3.6)))
         :osm (: (widget:get_window) :invalidate_rect nil)
         :arrow (: (widget:get_window) :invalidate_rect nil)
+        :rose (: (widget:get_window) :invalidate_rect nil)
         :time (widget:set_label
                (hhmmss (+ utc-offset app-state.time-of-day)))
         ))))
@@ -378,6 +379,48 @@ label.readout {
                    true)
                  }))))
 
+(fn deg->rad [degrees]
+  (* math.pi (/ degrees 180)))
+
+(fn rose []
+  (let [height 60]
+    (register-widget
+     :rose
+     (Gtk.Label {
+                 :halign Gtk.Align.START
+                 :valign Gtk.Align.START
+                 :width height :height height
+                 :on_draw
+                 (fn [self g]
+                   (g:save)
+                   (g:set_line_width 1)
+                   (g:set_source_rgb 0.4 0.0 0.1)
+                   (g:arc (// height 2) (// height 2)  15
+                          0 (* 2 math.pi))
+                   (g:stroke)
+                   
+                   (g:translate (// height 2) (// height 2))
+                   (g:rotate (- (deg->rad app-state.orientation.actual)))
+                   (g:translate (// height -2) (// height -2))
+                   
+                   (g:set_line_width 2)
+                   (g:move_to (// height 2) height)
+                   (g:line_to (// height 2) 0)
+
+                   (g:move_to 10 20)
+                   (g:line_to (// height 2) 0)
+                   (g:line_to (- height 10) 20)
+                   (g:stroke)
+                   
+                   (g:set_source_rgb 1 1 0)
+                   (g:move_to  (// height -2) (// height -2))
+                   (g:text_path "N")
+                   (g:fill)
+
+                   (g:restore)
+                   true)
+                 }))))
+
 
 (local socket-path (or (. arg 1) "/var/run/gnss-share.sock"))
 
@@ -434,6 +477,7 @@ label.readout {
    (: :add (osm-widget))
    (: :add_overlay (readouts))
    (: :add_overlay (arrow))
+   (: :add_overlay (rose))
    ))
 
 (window:show_all)