ConstraintLayout.addConstraint

Adds a constraint to the layout manager.

The gtk.constraint.Constraint.source and gtk.constraint.Constraint.target properties of constraint can be:

• set to NULL to indicate that the constraint refers to the widget using layout
• set to the gtk.widget.Widget using layout
• set to a child of the gtk.widget.Widget using layout
• set to a gtk.constraint_guide.ConstraintGuide that is part of layout

The layout acquires the ownership of constraint after calling this function.