From dfc2c4d23684b4dcce3e4d8a366e58040163ed51 Mon Sep 17 00:00:00 2001
From: Mustafa Taha Şahin <taha.sahin@metu.edu.tr>
Date: Thu, 1 Apr 2021 00:29:15 +0300
Subject: Limit zoom levels to integers for raster maps

---
 modern/src/map/Map.js | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

(limited to 'modern')

diff --git a/modern/src/map/Map.js b/modern/src/map/Map.js
index 8a43e97b..bbb1f5ce 100644
--- a/modern/src/map/Map.js
+++ b/modern/src/map/Map.js
@@ -35,7 +35,27 @@ const updateReadyValue = value => {
   readyListeners.forEach(listener => listener(value));
 };
 
+const onIdle = function () {
+  const zoom = Math.round(map.getZoom())
+  if (zoom !== map.getZoom()) {
+    map.zoomTo(zoom)
+  }
+};
+
+const isRasterMap = map => Object.values(map.getStyle().sources).some(e => e.type === 'raster');
+
+const setAllowedZoomLevels = map => {
+  if(isRasterMap(map)) {
+    map.scrollZoom.setWheelZoomRate(1);
+    map.on('idle', onIdle);
+  } else {
+    map.scrollZoom.setWheelZoomRate(1/450);
+    map.off('idle', onIdle);
+  }
+};
+
 const initMap = async () => {
+  setAllowedZoomLevels(map);
   const background = await loadImage('images/background.svg');
   await Promise.all(deviceCategories.map(async category => {
     if (!map.hasImage(category)) {
-- 
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