From 1a8396a3faa460952f94bdac497f4e76c7496024 Mon Sep 17 00:00:00 2001
From: Stefan Peters <stefandesu@exo.pm>
Date: Wed, 31 Jul 2024 09:42:47 +0200
Subject: [PATCH] MapView: Support multiple locations in one map (#38)

---
 src/client/components/MapView.vue | 48 +++++++++++++++++++++++++------
 src/client/views/ItemView.vue     |  6 ++--
 2 files changed, 42 insertions(+), 12 deletions(-)

diff --git a/src/client/components/MapView.vue b/src/client/components/MapView.vue
index 7ea2b30..77dd0b8 100644
--- a/src/client/components/MapView.vue
+++ b/src/client/components/MapView.vue
@@ -1,25 +1,55 @@
 <script setup>
 const props = defineProps({
-  location: Object,
+  locations: Array,
 })
 
 import "leaflet/dist/leaflet.css"
 import { LMap, LTileLayer, LGeoJson } from "@vue-leaflet/vue-leaflet"
+import { watch } from "vue"
 
-const geojsonLayerReady = (layer) => {
-  layer._map?.fitBounds(layer.getBounds())
-  if (props.location.type === "Point") {
-    layer._map?.setZoom(15)
+const initialBounds = {
+  _northEast: {
+    lat: -90,
+    lng: -180,
+  },
+  _southWest: {
+    lat: 90,
+    lng: 180,
+  },
+}
+let bounds, count
+watch(() => props.locations, () => {
+  bounds = initialBounds
+  count = 0
+}, { immediate: true })
+
+const geojsonLayerReady = (layer, location) => {
+  count += 1
+  const layerBounds = layer.getBounds()
+  // Track all locations and fit the view so that all of them are visible
+  bounds._northEast.lat = Math.max(bounds._northEast.lat, layerBounds._northEast.lat)
+  bounds._northEast.lng = Math.max(bounds._northEast.lng, layerBounds._northEast.lng)
+  bounds._southWest.lat = Math.min(bounds._southWest.lat, layerBounds._southWest.lat)
+  bounds._southWest.lng = Math.min(bounds._southWest.lng, layerBounds._southWest.lng)
+  if (count >= props.locations.length) {
+    layer._map?.fitBounds([
+      [bounds._northEast.lat, bounds._northEast.lng],
+      [bounds._southWest.lat, bounds._southWest.lng],
+    ])
+    // A single point gets zoom level 15 (TODO: 15 seems to far zoomed in.)
+    if (count === 1 && location.type === "Point") {
+      layer._map?.setZoom(15)
+    }
   }
 }
 </script>
 
 <template>
   <div style="height: 300px">
-    <!-- For some reason, we need zoom and center, even though we are providing bounds -->
+    <!-- Initial zoom and center will be overridden when GeoJSON layer is ready -->
     <l-map
       :zoom="1"
-      :center="[47.2, 12]"
+      :center="[47, 12]"
       :use-global-leaflet="false">
       <l-tile-layer
         url="https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png"
@@ -27,8 +57,10 @@ const geojsonLayerReady = (layer) => {
         name="OpenStreetMap"
         attribution="&copy; <a href='http://www.openstreetmap.org/copyright'>OpenStreetMap</a>" />
       <l-geo-json 
+        v-for="(location, index) in locations"
+        :key="index"
         :geojson="location"
-        @ready="geojsonLayerReady" />
+        @ready="geojsonLayerReady($event, location)" />
     </l-map>
   </div>
 </template>
diff --git a/src/client/views/ItemView.vue b/src/client/views/ItemView.vue
index f0994e5..d18c9da 100644
--- a/src/client/views/ItemView.vue
+++ b/src/client/views/ItemView.vue
@@ -226,14 +226,12 @@ const topConcepts = computed(() => {
             </li>
           </ul>
         </div>
-        <!-- TODO: Show all locations in one map? Needs test case. -->
         <div
           v-if="concept?.location?.length"
           title="Map">
           <MapView
-            v-for="(location, index) in concept.location"
-            :key="`${uri}-${index}`"
-            :location="location" />
+            :key="`${uri}`"
+            :locations="Array.isArray(concept.location) ? concept.location : [concept.location]" />
         </div>
         <div style="margin: 0 0 10px;">
           <b>Linked Data:</b>