onSystemFontFamilyChanged property Null safety

VoidCallback? onSystemFontFamilyChanged

A callback that is invoked whenever systemFontFamily changes value.

Accessing this value returns the value contained in the PlatformDispatcher singleton, so instead of getting it from here, you should consider getting it from WidgetsBinding.instance.platformDispatcher instead (or, when WidgetsBinding isn't available, from PlatformDispatcher.instance). The reason this value forwards to the PlatformDispatcher is to provide convenience for applications that only use a single main window.

The framework invokes this callback in the same zone in which the callback was set.

See also:


VoidCallback? get onSystemFontFamilyChanged => platformDispatcher.onSystemFontFamilyChanged;
void onSystemFontFamilyChanged=(VoidCallback? callback)


set onSystemFontFamilyChanged(VoidCallback? callback) {
  platformDispatcher.onSystemFontFamilyChanged = callback;