performResize method Null safety
protected">@protected
Updates the render objects size using only the constraints.
Do not call this function directly: call layout instead. This function is called by layout when there is actually work to be done by this render object during layout. The layout constraints provided by your parent are available via the constraints getter.
This function is called only if sizedByParent is true.
Subclasses that set sizedByParent to true should override this method to compute their size. Subclasses of RenderBox should consider overriding RenderBox.computeDryLayout instead.
Implementation
@protected
void performResize();