fix: Fix centering element on init (#2445)

Co-authored-by: Andrés Rivera <andres@MBP.local>
Co-authored-by: Lipis <lipiridis@gmail.com>
Co-authored-by: dwelle <luzar.david@gmail.com>

src/tests/scroll.test.tsx

@@ -0,0 +1,48 @@
+import React from "react";
+import { render, waitFor } from "./test-utils";
+import Excalidraw from "../packages/excalidraw/index";
+import { API } from "./helpers/api";
+
+const { h } = window;
+
+describe("appState", () => {
+  it("scroll-to-center on init works with non-zero offsets", async () => {
+    const WIDTH = 600;
+    const HEIGHT = 700;
+    const OFFSET_LEFT = 200;
+    const OFFSET_TOP = 100;
+
+    const ELEM_WIDTH = 100;
+    const ELEM_HEIGHT = 60;
+
+    await render(
+      <Excalidraw
+        width={WIDTH}
+        height={HEIGHT}
+        offsetLeft={OFFSET_LEFT}
+        offsetTop={OFFSET_TOP}
+        initialData={{
+          elements: [
+            API.createElement({
+              type: "rectangle",
+              id: "A",
+              width: ELEM_WIDTH,
+              height: ELEM_HEIGHT,
+            }),
+          ],
+        }}
+      />,
+    );
+
+    await waitFor(() => {
+      expect(h.state.width).toBe(WIDTH);
+      expect(h.state.height).toBe(HEIGHT);
+      expect(h.state.offsetLeft).toBe(OFFSET_LEFT);
+      expect(h.state.offsetTop).toBe(OFFSET_TOP);
+
+      // assert scroll is in center
+      expect(h.state.scrollX).toBe(WIDTH / 2 - ELEM_WIDTH / 2);
+      expect(h.state.scrollY).toBe(HEIGHT / 2 - ELEM_HEIGHT / 2);
+    });
+  });
+});