on_pre_update

zng_wgt

Function on_pre_update 

Source 
pub fn on_pre_update(
    child: impl IntoUiNode,
    handler: Handler<OnNodeOpArgs>,
) -> UiNode
Expand description

P Preview on_update event.

This property calls handler every time the UI updates, before the widget content updates. This means that the handler is raised before any on_init handler.

ยงHandlers

You can use one of the handler macros, hn! or hn_once!, to declare a handler closure. You must avoid using the async handlers as they cause an update every time the UI task advances from an await point causing another task to spawn.