From fef52f812a3ba2d845c473e8ab5e617537c89fd3 Mon Sep 17 00:00:00 2001
From: Daniel Barlow <dan@telent.net>
Date: Mon, 2 Jun 2025 13:33:51 +0100
Subject: [PATCH] add on-completion callback to tile fetcher, invalidate
 map-surface

---
 pkgs/maps/main.fnl  | 7 +++++--
 pkgs/maps/tiles.fnl | 3 ++-
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/pkgs/maps/main.fnl b/pkgs/maps/main.fnl
index 097c80c..e57bef0 100644
--- a/pkgs/maps/main.fnl
+++ b/pkgs/maps/main.fnl
@@ -150,6 +150,8 @@ label.readout {
          (* tile-size (- ny bounds.min.y))
          (+ math.pi angle)))))
 
+(var map-surface nil)
+
 (fn cairo-the-map [window]
   (let [{ : lat : lon : zoom } app-state
         { : num-tiles-x : num-tiles-y &as bounds } (map-bounds lat lon zoom)
@@ -158,7 +160,9 @@ label.readout {
 
     (for [x bounds.min.x bounds.max.x]
       (for [y bounds.min.y bounds.max.y]
-        (merge lines (tiles.polylines cq x y zoom))))
+        (merge lines (tiles.polylines cq x y zoom
+                                      #(set map-surface nil)
+                                      ))))
 
     (let [map-surface
           (window:create_similar_surface
@@ -203,7 +207,6 @@ label.readout {
 
       map-surface)))
 
-(var map-surface nil)
 
 (fn on-osm-draw [widget g]
   (when (not map-surface)
diff --git a/pkgs/maps/tiles.fnl b/pkgs/maps/tiles.fnl
index b3cb152..7defc3e 100644
--- a/pkgs/maps/tiles.fnl
+++ b/pkgs/maps/tiles.fnl
@@ -109,7 +109,7 @@
 ;; we'd like to have a way for completed background fetch to signal
 ;; so that the map can be redrawn
 
-(fn polylines [cq x y zoom]
+(fn polylines [cq x y zoom cb]
   (let [k (..  x "_" y "_" zoom)
         pathname (.. "/tmp/tiles/" k ".json")]
     (if (file-exists? pathname)
@@ -129,6 +129,7 @@
                            (cqueues.sleep (math.random 2 6))))
                        (print "got " k)
                        (f:write json)
+                       (cb)
                        true)))
           [] ; return no lines for now
           ))))