From 2a86a2bfde28e5a979897582755d875c4a656bcb Mon Sep 17 00:00:00 2001
From: Daniel Barlow <dan@telent.net>
Date: Thu, 29 May 2025 21:13:19 +0100
Subject: [PATCH] use register-widget more, fewer arrow widget repaints

---
 pkgs/maps/main.fnl | 51 +++++++++++++++++++++++-----------------------
 1 file changed, 26 insertions(+), 25 deletions(-)

diff --git a/pkgs/maps/main.fnl b/pkgs/maps/main.fnl
index e349eab..73f19d4 100644
--- a/pkgs/maps/main.fnl
+++ b/pkgs/maps/main.fnl
@@ -126,12 +126,11 @@ label.readout {
                      })))
 
 (fn readout [name text]
-  (let [w
-        (doto (Gtk.Label {:label text : name})
-          (-> (: :get_style_context)
-              (: :add_class :readout)))]
-    (tset state-widgets name w)
-    w))
+  (register-widget
+   name
+   (doto (Gtk.Label {:label text : name})
+     (-> (: :get_style_context)
+         (: :add_class :readout)))))
 
 (local knot-in-m-s
        (/ 1852 ; metres in nautical mile
@@ -157,6 +156,7 @@ label.readout {
       :speed (widget:set_label
               (string.format "%.1f km/h" (* app-state.speed 3.6)))
       :osm (: (widget:get_window) :invalidate_rect nil)
+      :arrow (: (widget:get_window) :invalidate_rect nil)
       :time (widget:set_label
              (hhmmss (+ utc-offset app-state.time-of-day)))
       )))
@@ -174,25 +174,26 @@ label.readout {
     (: :add (readout :speed "0"))))
 
 (fn arrow []
-  (let [height 40
-        w (Gtk.Label {
-                       :halign Gtk.Align.CENTER
-                       :valign Gtk.Align.CENTER
-                       :width height :height height
-                       :on_draw
-                       (fn [self g]
-                         (g:set_source_rgb 0.4 0.0 0.1)
-                         (g:translate (// height 2) (// height 2))
-                         (g:rotate (/ (* -2  app-state.course math.pi) 360) )
-                         (g:translate (// height -2) (// height -2))
-                         (g:set_line_width 4)
-                         (g:move_to 10 height)
-                         (g:line_to (// height 2) 0)
-                         (g:line_to (- height 10) height)
-                         (g:fill)
-                         true)
-                       })]
-    w))
+  (let [height 40]
+    (register-widget
+     :arrow
+     (Gtk.Label {
+                 :halign Gtk.Align.CENTER
+                 :valign Gtk.Align.CENTER
+                 :width height :height height
+                 :on_draw
+                 (fn [self g]
+                   (g:set_source_rgb 0.4 0.0 0.1)
+                   (g:translate (// height 2) (// height 2))
+                   (g:rotate (/ (* -2  app-state.course math.pi) 360) )
+                   (g:translate (// height -2) (// height -2))
+                   (g:set_line_width 4)
+                   (g:move_to 10 height)
+                   (g:line_to (// height 2) 0)
+                   (g:line_to (- height 10) height)
+                   (g:fill)
+                   true)
+                 }))))
 
 
 (local socket-path (or (. arg 1) "/var/run/gnss-share.sock"))