onMetricsChanged property

VoidCallback? onMetricsChanged

A callback that is invoked whenever the devicePixelRatio, physicalSize, padding, viewInsets, PlatformDispatcher.views, or systemGestureInsets values change.

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.

When using the Flutter framework, the MediaQuery widget exposes much of these metrics. Using MediaQuery.of to obtain them allows the framework to automatically rebuild widgets that depend on them, without having to manage the onMetricsChanged callback.

See PlatformDispatcher.onMetricsChanged for more information.

Implementation

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

Implementation

set onMetricsChanged(VoidCallback? callback) {
  platformDispatcher.onMetricsChanged = callback;
}