From 398693bc0797747eda967ee93a8fad74eb42b694 Mon Sep 17 00:00:00 2001
From: Daniel Barlow <dan@telent.net>
Date: Wed, 28 May 2025 18:50:12 +0100
Subject: [PATCH] hook the ui up to the overpass data

---
 pkgs/maps/main.fnl  | 57 +++++++++++++++++++----------------
 pkgs/maps/tiles.fnl | 73 ++++++++++++++++++++++++++++-----------------
 2 files changed, 76 insertions(+), 54 deletions(-)

diff --git a/pkgs/maps/main.fnl b/pkgs/maps/main.fnl
index 316d115..fc2cf33 100644
--- a/pkgs/maps/main.fnl
+++ b/pkgs/maps/main.fnl
@@ -1,12 +1,12 @@
 ; (local { : view } (require :fennel))
 (local { : fdopen } (require :posix.stdio))
 (local nmea (require :nmea))
+(local tiles (require :tiles))
 
 (import-macros { : define-tests : expect : expect= } :assert)
 
 (local {
         : Gtk
-        : OsmGpsMap
         : Gdk
         : Gio
         : GLib
@@ -52,20 +52,37 @@ label.readout {
 
 (local state-widgets { })
 
-(fn osm-widget []
-  (let [w
-        (doto (OsmGpsMap.Map {})
-          (tset :map-source  OsmGpsMap.MapSource_t.OPENSTREETMAP)
-          (: :set_center_and_zoom 52.595 -0.1 17)
-          (: :layer_add (OsmGpsMap.MapOsd {
-                                           :show_copyright true
-                                        ; :show_coordinates true
-                                           :show_scale true
-                                           }))
-          )]
-    (tset state-widgets :osm w)
-    w))
+(local
+ app-state {
+            :time-of-day 0
+            :elapsed-time 0
+            :speed 14
+            :lat 49
+            :lon 0
+            :course 22
+            }
+ )
 
+(fn osm-widget []
+  (let [height 256]
+    (Gtk.Label {
+                :width height :height height
+                :on_draw
+                (fn [self g]
+                  (print app-state.lat app-state.lon )
+                  (let [lines (tiles.polylines app-state.lat app-state.lon 17)]
+                    (g:set_source_rgb 0.2 0.2 0.4)
+                    (g:set_line_width 3)
+                    (each [_ line (ipairs lines)]
+                      (case line
+                        [[sx sy] & more]
+                        (do
+                          (g:move_to sx sy)
+                          (each [_ [x y] (ipairs more)]
+                            (g:line_to x y)))))
+                    (g:stroke)
+                    true))
+                })))
 
 (fn readout [name text]
   (let [w
@@ -89,18 +106,6 @@ label.readout {
 (expect= (hhmmss (+ 45 (* 60 12) (* 60 60 3))) "3:12:45")
 
 
-(local
- app-state {
-            :time-of-day 0
-            :elapsed-time 0
-            :speed 14
-            :lat 49
-            :lon 0
-            :course 22
-            }
- )
-
-
 (fn merge [table1 table2]
   (collect [k v (pairs table2) &into table1]
     k v))
diff --git a/pkgs/maps/tiles.fnl b/pkgs/maps/tiles.fnl
index 5325e85..79a444c 100644
--- a/pkgs/maps/tiles.fnl
+++ b/pkgs/maps/tiles.fnl
@@ -5,35 +5,8 @@
 (import-macros { : define-tests : expect : expect= : expect-near } :assert)
 (local { : view } (require :fennel))
 
+(local f% string.format)
 
-(local
- query
- (->
-  [
-   "[bbox:30.618338,-96.323712,30.591028,-96.330826]"
-   "[out:json]"
-   "[timeout:90];"
-   "("
-   "way ("
-   "30.626917110746,"
-   "-96.348809105664,"
-   "30.634468750236,"
-   "-96.339893442898"
-   ");"
-   ");"
-   "out ;"
-   ]
-  (table.concat "\n")))
-
-(let [r 
-       (req.new_from_uri
-        "https://overpass-api.de/api/interpreter")]
-  (tset r.headers ":method" "POST")
-  (r:set_body (dict_to_query { :data query }))
-  (let [(headers stream) (r:go)]
-    (print (view headers))
-    (print (view (json.decode (stream:get_body_as_string))))))
-      
 (fn sinh [x] (/ (- 1 (math.exp (* -2 x))) (* 2 (math.exp (- x)))))
 
 (expect (< (math.abs  (- (sinh 2) 3.626860407847)) 0.001))
@@ -69,3 +42,47 @@
   (expect= (math.floor x) 65343)
   (expect= (math.floor y) 43221))
 
+
+(fn overpass [lat lon]
+  (let [n (+ lat 0.01)
+        w (- lon 0.01)
+        s lat
+        e lon]
+    (->
+     [
+      "[out:json];"
+      (f% "way(%f,%f,%f,%f)['highway'];" s w n e)
+      "(._;>;);"
+      "out;"
+      ]
+     (table.concat  "\n"))))
+
+(fn canvas [elements offset-x offset-y]
+  (let [nodes {}
+        lines []]
+    (each [_ e (ipairs elements)]
+      (case e.type
+        :node (tset nodes e.id e)
+        :way
+        (table.insert
+         lines
+         (icollect [_ nd (ipairs e.nodes)]
+           (let [node (. nodes nd)
+                 (tx ty) (latlon->tile node.lat node.lon 17)]
+             ;;(print e.tags.name e.id e.name node.lat node.lon)
+             [ (* 256 (- tx offset-x)) (* 256  (- ty offset-y)) ])))))
+    lines))
+
+(fn polylines [lat long zoom]
+  (let [r
+        (req.new_from_uri
+         "https://overpass-api.de/api/interpreter")
+        query  { :data (overpass lat long zoom) }]
+    (tset r.headers ":method" "POST")
+    (r:set_body (dict_to_query query))
+    (let [(headers stream) (r:go)
+          (tx ty) (latlon->tile lat long zoom)
+          data (json.decode (stream:get_body_as_string))]
+      (canvas data.elements (math.floor tx) (math.floor ty)))))
+
+{ : polylines }