From 933e958d46257890b5c97f375bab797b4a3131cc Mon Sep 17 00:00:00 2001
From: easbar <easbar.mail@posteo.net>
Date: Thu, 20 May 2021 07:08:34 +0200
Subject: [PATCH] Better solution

---
 src/map/Map.tsx | 38 +++++++++++++++++++-------------------
 1 file changed, 19 insertions(+), 19 deletions(-)

diff --git a/src/map/Map.tsx b/src/map/Map.tsx
index 4828a99f..65de43e1 100644
--- a/src/map/Map.tsx
+++ b/src/map/Map.tsx
@@ -1,7 +1,7 @@
 import { QueryPoint } from '@/stores/QueryStore'
 import React, { useEffect, useRef, useState } from 'react'
 import styles from '@/map/Map.module.css'
-import Mapbox from '@/map/Mapbox'
+import Mapbox, { ViewPort } from '@/map/Mapbox'
 import Dispatcher from '@/stores/Dispatcher'
 import { MapIsLoaded } from '@/actions/Actions'
 import { Bbox, Path } from '@/api/graphhopper'
@@ -18,39 +18,39 @@ type MapProps = {
 export default function({ selectedPath, paths, queryPoints, bbox, mapStyle }: MapProps) {
     const mapContainerRef: React.RefObject<HTMLDivElement> = useRef(null)
     const [map, setMap] = useState<Mapbox | null>(null)
-    // we need to keep track of the latest bbox so it is available in the onMapReady callback by the time the Mapbox
-    // instance is loaded
-    const prevBbox = useRef<Bbox>()
-    useEffect(() => {
-        prevBbox.current = bbox
-    }, [bbox])
+    const prevViewPort = useRef<ViewPort | null>(null)
+    prevViewPort.current = null
 
     useEffect(() => {
-        // as long as we re-create the Mapbox instance when changing the mapStyle we need to make sure the viewport
-        // state is preserved
-        const prevViewPort = map?.getViewPort()
-        if (map) map.remove()
+        if (map) {
+            map.remove()
+            // save the current view port so we can set it after re-creating the Mapbox instance when we change mapStyle
+            prevViewPort.current = map.getViewPort()
+        }
 
         const mapWrapper = new Mapbox(
             mapContainerRef.current!,
             mapStyle,
             () => {
                 setMap(mapWrapper)
-                if (!prevViewPort)
-                    mapWrapper.fitBounds(prevBbox.current!)
                 Dispatcher.dispatch(new MapIsLoaded())
             }
         )
-        if (prevViewPort)
-            mapWrapper.setViewPort(prevViewPort)
+        if (prevViewPort.current)
+            mapWrapper.setViewPort(prevViewPort.current)
         return () => map?.remove()
-    }, [mapStyle, prevBbox])
+    }, [mapStyle])
     useEffect(() => map?.drawPaths(paths, selectedPath), [paths, selectedPath, map])
     useEffect(() => map?.showPathDetails(selectedPath), [selectedPath, map])
     useEffect(() => map?.drawMarkers(queryPoints), [queryPoints, map])
-    // no dependency on map here, because in case changed the viewport manually we do not want to go back to the bbox
-    // after a style change onMapReady
-    useEffect(() => map?.fitBounds(bbox), [bbox])
+    useEffect(() => {
+        // previous view port takes precedence if it was set. for example when we just changed the mapStyle we do
+        // not want to go back to the bbox
+        if (prevViewPort.current)
+            map?.setViewPort(prevViewPort.current)
+        else
+            map?.fitBounds(bbox)
+    }, [bbox, map, prevViewPort])
 
     return <div className={styles.map} ref={mapContainerRef} />
 }