Owlkettle

AfterBuild Hook

The afterBuild-hook runs once after initial values (default-values or values propagated from the Widget) have been assigned to the WidgetState.

They are useful if any processing on the initial data that is passed in must happen. Example are validating data, inferring data from passed in data, or fetching other data based on what was passed in. In renderables they are also useful to update the GTK widget once with data from the initial WidgetState.

It should be noted that unlike build hooks, afterBuild hooks are not inherited by any child-widget. For more information, see the build hooks section.

Let's return to our earlier renderable example and write it so that the parent-widget can decide what text the MyRenderable should display:

import owlkettle
import owlkettle/bindings/gtk
import std/json

renderable MyRenderable:
  text: string

  hooks:
    beforeBuild:
      echo state.repr
      state.internalWidget = gtk_label_new("")

    afterBuild:
      gtk_label_set_text(state.internalWidget, state.text.cstring)

viewable App:
  discard

method view(app: AppState): Widget =
  result = gui:
    Window:
      MyRenderable(text = "Defined by App")

when not defined(owlkettleNimiDocs):
  brew(gui(App()))

Note: The value of the Label is set only once during build-time and never updated afterwards! If you want this section to be updated when the input from the parent-widget changes, you may want to look into property hooks.