Fix alt zoom (#424)

packages/core/src/hooks/useZoomEvents.ts

@@ -34,6 +34,8 @@ export function useZoomEvents<T extends HTMLElement>(zoom: number, ref: React.Re
   useGesture(
     {
       onWheel: ({ delta, event: e }) => {
+        e.preventDefault()
+
         if (e.altKey && e.buttons === 0) {
           const point = inputs.pointer?.point ?? [bounds.width / 2, bounds.height / 2]
 
@@ -43,8 +45,6 @@ export function useZoomEvents<T extends HTMLElement>(zoom: number, ref: React.Re
           return
         }
 
-        e.preventDefault()
-
         if (inputs.isPinching) return
 
         if (Vec.isEqual(delta, [0, 0])) return

packages/tldraw/src/state/TldrawApp.ts

@@ -2665,7 +2665,7 @@ export class TldrawApp extends StateManager<TDSnapshot> {
         ? info.delta[2] / 100
         : info.delta[2] / 2
 
-    this.zoomBy(delta, info.delta)
+    this.zoomBy(delta, this.centerPoint)
     this.onPointerMove(info, e as unknown as React.PointerEvent)
   }