Added onInit and useInitialized hooks

packages/svelte/src/lib/container/EdgeRenderer/EdgeRenderer.svelte

@@ -1,6 +1,7 @@
 <script lang="ts">
   import { onMount } from 'svelte';
   import { EdgeWrapper } from '$lib/components/EdgeWrapper';
+  import { CallOnMount } from '$lib/components/CallOnMount';
   import { MarkerDefinition } from '$lib/container/EdgeRenderer/MarkerDefinition';
   import { useStore } from '$lib/store';
   import type { DefaultEdgeOptions } from '$lib/types';
@@ -10,6 +11,7 @@
   const {
     elementsSelectable,
     visibleEdges,
+    edgesInitialized,
     edges: { setDefaultOptions }
   } = useStore();
 
@@ -29,7 +31,6 @@
       edge.selectable ||
       ($elementsSelectable && typeof edge.selectable === 'undefined')
     )}
-
     <EdgeWrapper
       id={edge.id}
       source={edge.source}
@@ -61,4 +62,15 @@
       on:edgecontextmenu
     />
   {/each}
+
+  {#if $visibleEdges.length > 0}
+    <CallOnMount
+      onMount={() => {
+        $edgesInitialized = true;
+      }}
+      onDestroy={() => {
+        $edgesInitialized = false;
+      }}
+    />
+  {/if}
 </div>

packages/svelte/src/lib/container/SvelteFlow/SvelteFlow.svelte

@@ -77,6 +77,7 @@
   export let onconnectstart: $$Props['onconnectstart'] = undefined;
   export let onconnectend: $$Props['onconnectend'] = undefined;
   export let onbeforedelete: $$Props['onbeforedelete'] = undefined;
+  export let oninit: $$Props['oninit'] = undefined;
 
   export let defaultMarkerColor = '#b1b1b7';
 
@@ -130,6 +131,16 @@
     }
   }
 
+  // Call oninit once when flow is intialized
+  const { initialized } = store;
+  let onInitCalled = false;
+  $: {
+    if (!onInitCalled && $initialized) {
+      oninit?.();
+      onInitCalled = true;
+    }
+  }
+
   // this updates the store for simple changes
   // where the prop names equals the store name
   $: {

packages/svelte/src/lib/container/SvelteFlow/types.ts

@@ -333,4 +333,6 @@ export type SvelteFlowProps = DOMAttributes<HTMLDivElement> & {
   onconnectstart?: OnConnectStart;
   /** When a user stops dragging a connection line, this event gets fired. */
   onconnectend?: OnConnectEnd;
+  /** This handler gets called when the flow is finished initializing */
+  oninit?: () => void;
 };

packages/svelte/src/lib/container/Zoom/Zoom.svelte

@@ -4,6 +4,7 @@
   import { useStore } from '$lib/store';
   import zoom from '$lib/actions/zoom';
   import type { ZoomProps } from './types';
+  import { onMount } from 'svelte';
 
   type $$Props = ZoomProps;
 
@@ -29,12 +30,17 @@
     translateExtent,
     lib,
     panActivationKeyPressed,
-    zoomActivationKeyPressed
+    zoomActivationKeyPressed,
+    viewportInitialized
   } = useStore();
 
   $: viewPort = initialViewport || { x: 0, y: 0, zoom: 1 };
   $: _panOnDrag = $panActivationKeyPressed || panOnDrag;
   $: _panOnScroll = $panActivationKeyPressed || panOnScroll;
+
+  onMount(() => {
+    $viewportInitialized = true;
+  });
 </script>
 
 <div