How can i get my custom control width

Hello,

I just starting SAPui5 and i developped my custom control which contains FixFlex component (and others layout inside this FixFlex).

Problem is that i have to know the width of the FixFlex container during OnAfterRendering method of my custom control. And i can't get the width, it seems the DOM is'nt really ready during this method. What can i do ?

Thanks,

Rick