From 47cac036c66c2bdc002d908457edc9b286d1454a Mon Sep 17 00:00:00 2001
From: Trevor Sayre <sayret@gmail.com>
Date: Wed, 6 Apr 2022 16:42:48 -0400
Subject: [PATCH] Add smooth pixel zooming

---
 web/_js/main.js | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/web/_js/main.js b/web/_js/main.js
index ba1e60bb..2420e4db 100644
--- a/web/_js/main.js
+++ b/web/_js/main.js
@@ -271,14 +271,23 @@ async function init(){
 		initialPinchZoom = zoom;
 		
 		lastPosition = [x, y];
-		
-		if(e.deltaY > 0){
 
-			zoom = zoom / 2;
-			
-		} else if(e.deltaY < 0){
-			
-			zoom = zoom * 2;
+		// Check if we are zooming by pixels
+		// https://developer.mozilla.org/en-US/docs/Web/API/WheelEvent/deltaMode
+		if (e.deltaMode === 0) {
+			// Scale the pixel delta by the current zoom factor
+			// We want to zoom faster when closer, and slower when further
+			// This creates a smoother experience
+			zoom -= e.deltaY * (0.001 * zoom);
+		} else {
+			if(e.deltaY > 0){
+	
+				zoom = zoom / 2;
+				
+			} else if(e.deltaY < 0){
+				
+				zoom = zoom * 2;
+			}
 		}
 
 		zoom = Math.max(minZoom, Math.min(maxZoom, zoom));