Function
GtkTreeIterCompareFunc
Declaration
int
(* GtkTreeIterCompareFunc) (
  GtkTreeModel* model,
  GtkTreeIter* a,
  GtkTreeIter* b,
  gpointer user_data
)
Description [src]
A GtkTreeIterCompareFunc should return a negative integer, zero, or a positive
integer if a sorts before b, a sorts with b, or a sorts after b
respectively.
If two iters compare as equal, their order in the sorted model
is undefined. In order to ensure that the GtkTreeSortable behaves as
expected, the GtkTreeIterCompareFunc must define a partial order on
the model, i.e. it must be reflexive, antisymmetric and transitive.
For example, if model is a product catalogue, then a compare function
for the “price” column could be one which returns
price_of(a) - price_of(b).
Parameters
- model
- 
            Type: GtkTreeModelThe GtkTreeModelthe comparison is within.The data is owned by the caller of the function. 
- a
- 
            Type: GtkTreeIterA GtkTreeIterinmodel.The data is owned by the caller of the function. 
- b
- 
            Type: GtkTreeIterAnother GtkTreeIterinmodel.The data is owned by the caller of the function. 
- user_data
- 
            Type: gpointerData passed when the compare func is assigned e.g. by gtk_tree_sortable_set_sort_func()The argument can be NULL.The data is owned by the caller of the function.