add mouse scroll to zoom functionality

2025-08-11 21:59:53 +00:00
parent dbe17805e0
commit 2b942893c0
2 changed files with 59 additions and 42 deletions
@@ -208,8 +208,9 @@ class LazyCanvasController with ChangeNotifier {
  }

  /// Increment or decrement the scale by an additive delta value.
-  void updateScalebyDelta(double delta) {
-    final focalPoint = Offset(canvasSize.width / 2, canvasSize.height / 2);
+  void updateScalebyDelta(double delta, {Offset? focalPoint}) {
+    // added focalPoint param
+    focalPoint ??= Offset(canvasSize.width / 2, canvasSize.height / 2);
    final newScale = _scale + delta;
    _gsTopLeftOffset = newGsTopLeftOnScaling(_gsTopLeftOffset, focalPoint, _scale, newScale);
    _scale = newScale;