Use SDF sprites to render icon halos (#128)

Uses maplibre/martin#1492

Unfortunately, SDF sprites cannot be layered right below each image,
they have to be in their own layer below the icons.

Symbols with outline:


![image](https://github.com/user-attachments/assets/da290ed7-441a-4c88-881a-88ee845d3acf)

Hovering on rail lines in their native color:


![image](https://github.com/user-attachments/assets/79556b75-e6ab-4c37-95d6-87c9d22264ab)

Railway direction including hover:


![image](https://github.com/user-attachments/assets/fe071904-2e9d-450f-8f63-e0613c8ac515)

docker-compose.yml

@@ -44,7 +44,7 @@ services:
       - OSM2PGSQL_DATAFILE
 
   martin-cp:
-    image: ghcr.io/maplibre/martin
+    image: ghcr.io/maplibre/martin:main
     depends_on:
       db:
         condition: service_healthy

features/signals_railway_signals.yaml

@@ -826,9 +826,18 @@ signals_railway_signals:
 
     - description: Blockkennzeichen
       country: DE
-      # TODO match width and height
-      # WHEN ref_width <= 4 AND ref_height <= 2 THEN CONCAT('de/blockkennzeichen-', ref_width, 'x', ref_height)
-      icon: { default: 'de/blockkennzeichen' }
+      icon:
+        match: 'ref_multiline'
+        cases:
+          - { regex: '^([^\n]{4}\n[^\n]{1,4})|([^\n]{1,4}\n[^\n]{4})$', value: 'de/blockkennzeichen-4x2' }
+          - { regex: '^[^\n]{4}$', value: 'de/blockkennzeichen-4x1' }
+          - { regex: '^([^\n]{3}\n[^\n]{1,3})|([^\n]{1,3}\n[^\n]{3})$', value: 'de/blockkennzeichen-3x2' }
+          - { regex: '^[^\n]{3}$', value: 'de/blockkennzeichen-3x1' }
+          - { regex: '^([^\n]{2}\n[^\n]{1,2})|([^\n]{1,2}\n[^\n]{2})$', value: 'de/blockkennzeichen-2x2' }
+          - { regex: '^[^\n]{2}$', value: 'de/blockkennzeichen-2x1' }
+          - { regex: '^[^\n]\n[^\n]$', value: 'de/blockkennzeichen-1x2' }
+          - { regex: '^[^\n]$', value: 'de/blockkennzeichen-1x1' }
+        default: 'de/blockkennzeichen'
       tags:
         - { tag: 'railway:signal:train_protection', value: 'DE-ESO:blockkennzeichen' }
 

import/openrailwaymap.lua

@@ -169,8 +169,6 @@ local signals = osm2pgsql.define_table({
     { column = 'deactivated', type = 'boolean' },
     { column = 'ref', type = 'text' },
     { column = 'ref_multiline', type = 'text' },
-    { column = 'ref_width', type = 'smallint' },
-    { column = 'ref_height', type = 'smallint' },
     { column = 'signal_direction', type = 'text' },
     {% for tag in signals_railway_signals.tags %}
     { column = '{% tag %}', type = 'text' },
@@ -429,11 +427,6 @@ function osm2pgsql.process_node(object)
       tags['railway:signal:speed_limit:deactivated']
     ) == 'yes'
     local ref_multiline, newline_count = (tags.ref or ''):gsub(' ', '\n')
-    local ref_height = newline_count + 1
-    local ref_width = 0
-    for part in string.gmatch(tags.ref or '', '[^ ]+') do
-      ref_width = math.max(ref_width, part:len())
-    end
 
     signals:insert({
       way = object:as_point(),
@@ -442,8 +435,6 @@ function osm2pgsql.process_node(object)
       deactivated = deactivated,
       ref = tags.ref,
       ref_multiline = ref_multiline ~= '' and ref_multiline or nil,
-      ref_height = ref_multiline ~= '' and ref_height or nil,
-      ref_width = ref_multiline ~= '' and ref_width or nil,
       signal_direction = tags['railway:signal:direction'],
       {% for tag in signals_railway_signals.tags %}
       ["{% tag %}"] = tags['{% tag %}'],

martin-static.Dockerfile

@@ -1,7 +1,7 @@
-FROM ghcr.io/maplibre/martin
+FROM ghcr.io/maplibre/martin:main
 
 COPY martin /config
 COPY symbols /symbols
 COPY tiles /tiles
 
-CMD ["/tiles", "--listen-addresses", "[::]:3000", "--sprite", "/symbols", "--font", "/config/fonts"]
+CMD ["/tiles", "--listen-addresses", "[::]:3000", "--sprite", "/symbols", "--font", "/config/fonts"]

martin.Dockerfile

@@ -1,6 +1,6 @@
-FROM ghcr.io/maplibre/martin
+FROM ghcr.io/maplibre/martin:main
 
 COPY martin /config
 COPY symbols /symbols
 
-CMD ["--config", "/config/configuration.yml", "--sprite", "/symbols", "--font", "/config/fonts"]
+CMD ["--config", "/config/configuration.yml", "--sprite", "/symbols", "--font", "/config/fonts"]