Update view.js

lutzroeder · Jul 7, 2023 · 52da31a · 52da31a
1 parent 48e383b
commit 52da31a
Showing 1 changed file with 9 additions and 7 deletions.
diff --git a/source/view.js b/source/view.js
@@ -417,13 +417,15 @@ view.View = class {
             const pointerMoveHandler = (e) => {
                 e.preventDefault();
                 e.stopImmediatePropagation();
-                const dx = e.clientX - this._mousePosition.x;
-                const dy = e.clientY - this._mousePosition.y;
-                this._mousePosition.moved = dx * dx + dy * dy > 0;
-                if (this._mousePosition.moved) {
-                    const container = this._element('graph');
-                    container.scrollTop = this._mousePosition.top - dy;
-                    container.scrollLeft = this._mousePosition.left - dx;
+                if (this._mousePosition) {
+                    const dx = e.clientX - this._mousePosition.x;
+                    const dy = e.clientY - this._mousePosition.y;
+                    this._mousePosition.moved = dx * dx + dy * dy > 0;
+                    if (this._mousePosition.moved) {
+                        const container = this._element('graph');
+                        container.scrollTop = this._mousePosition.top - dy;
+                        container.scrollLeft = this._mousePosition.left - dx;
+                    }
                 }
             };
             const pointerUpHandler = (e) => {