improve road name labelling

- print each name only once
- enlarge text size
- print white rectangle underneath label

pkgs/maps/default.nix

@@ -31,8 +31,8 @@ let
     src = fetchFromGitHub {
       owner = "lgi-devs";
       repo = "lgi";
-      rev = "e06ad94c8a1c84e3cdb80cee293450a280dfcbc7";
-      hash = "sha256-VYr/DV1FAyzPe6p6Quc1nmsHup23IAMfz532rL167Q4=";
+      rev = "a412921fad445bcfc05a21148722a92ecb93ad06";
+      hash = "sha256-kZBpH5gcaCNU134Wn6JXAkFELzmiphc1PeCtmN9cagc=";
     };
   };
   rxi-json = callPackage ../rxi-json { lua = lua5_3; };

pkgs/maps/main.fnl

@@ -155,6 +155,7 @@ label.readout {
      (* tile-size (- y bounds.min.y))
      angle)))
 
+(var map-surface nil)
 
 (fn cairo-the-map [window]
   (let [{ : lat : lon : zoom } app-state
@@ -173,7 +174,8 @@ label.readout {
            cairo.Content.COLOR
            (* tile-size num-tiles-x)
            (* tile-size num-tiles-y))
-          g (cairo.Context.create map-surface)]
+          g (cairo.Context.create map-surface)
+          seen-roads {}]
 
       (g:set_source_rgb 0.7 0.8 0.8)
       (g:rectangle 0 0 (* tile-size num-tiles-x) (* tile-size num-tiles-y))
@@ -187,11 +189,25 @@ label.readout {
       (cairo-roads-path g lines bounds)
 
       (g:set_source_rgb 0.2 0.2 0.2)
-      (g:set_font_size (- road-width 3))
+      (g:set_font_size (+ road-width 1))
       (each [_ line (pairs lines)]
         (case line.name
-          n (let [(x y angle) (label-coords line bounds)]
-              (when (and x y)
+          n (let [(x y angle) (label-coords line bounds)
+                  ext  (g:text_extents n)
+                  w ext.width
+                  h ext.height]
+              (when (and x y (not (. seen-roads n)))
+                (tset seen-roads n true)
+
+                (g:save)
+                (g:set_line_width h)
+                (g:set_source_rgb 1 1 1)
+                (g:move_to (- x 1) (- y 1))
+                (g:rotate angle)
+                (g:rel_line_to (+ w 1) 0)
+                (g:stroke)
+                (g:restore)
+
                 (g:save)
                 (g:move_to x y)
                 (g:rotate angle)