Class

Gtk.TreeModelFilter

Description [src]

class Gtk.TreeModelFilter : GObject.Object {
  parent: GObject
}

A GtkTreeModel which hides parts of an underlying tree model

A GtkTreeModelFilter is a tree model which wraps another tree model, and can do the following things:

  • Filter specific rows, based on data from a “visible column”, a column storing booleans indicating whether the row should be filtered or not, or based on the return value of a “visible function”, which gets a model, iter and user_data and returns a boolean indicating whether the row should be filtered or not.

  • Modify the “appearance” of the model, using a modify function. This is extremely powerful and allows for just changing some values and also for creating a completely different model based on the given child model.

  • Set a different root node, also known as a “virtual root”. You can pass in a GtkTreePath indicating the root node for the filter at construction time.

The basic API is similar to GtkTreeModelSort. For an example on its usage, see the section on GtkTreeModelSort.

When using GtkTreeModelFilter, it is important to realize that GtkTreeModelFilter maintains an internal cache of all nodes which are visible in its clients. The cache is likely to be a subtree of the tree exposed by the child model. GtkTreeModelFilter will not cache the entire child model when unnecessary to not compromise the caching mechanism that is exposed by the reference counting scheme. If the child model implements reference counting, unnecessary signals may not be emitted because of reference counting rule 3, see the GtkTreeModel documentation. (Note that e.g. GtkTreeStore does not implement reference counting and will always emit all signals, even when the receiving node is not visible).

Because of this, limitations for possible visible functions do apply. In general, visible functions should only use data or properties from the node for which the visibility state must be determined, its siblings or its parents. Usually, having a dependency on the state of any child node is not possible, unless references are taken on these explicitly. When no such reference exists, no signals may be received for these child nodes (see reference counting rule number 3 in the GtkTreeModel section).

Determining the visibility state of a given node based on the state of its child nodes is a frequently occurring use case. Therefore, GtkTreeModelFilter explicitly supports this. For example, when a node does not have any children, you might not want the node to be visible. As soon as the first row is added to the node’s child level (or the last row removed), the node’s visibility should be updated.

This introduces a dependency from the node on its child nodes. In order to accommodate this, GtkTreeModelFilter must make sure the necessary signals are received from the child model. This is achieved by building, for all nodes which are exposed as visible nodes to GtkTreeModelFilters clients, the child level (if any) and take a reference on the first node in this level. Furthermore, for every row-inserted, row-changed or row-deleted signal (also these which were not handled because the node was not cached), GtkTreeModelFilter will check if the visibility state of any parent node has changed.

Beware, however, that this explicit support is limited to these two cases. For example, if you want a node to be visible only if two nodes in a child’s child level (2 levels deeper) are visible, you are on your own. In this case, either rely on GtkTreeStore to emit all signals because it does not implement reference counting, or for models that do implement reference counting, obtain references on these child levels yourself.

Hierarchy

Hierarchy for Gtk.TreeModelFilter

Ancestors

  • GObject

Instance methods

gtk_tree_model_filter_clear_cache

This function should almost never be called. It clears the filter of any cached iterators that haven’t been reffed with gtk_tree_model_ref_node(). This might be useful if the child model being filtered is static (and doesn’t change often) and there has been a lot of unreffed access to nodes. As a side effect of this function, all unreffed iters will be invalid.

gtk_tree_model_filter_convert_child_iter_to_iter

Sets filter_iter to point to the row in filter that corresponds to the row pointed at by child_iter. If filter_iter was not set, FALSE is returned.

gtk_tree_model_filter_convert_child_path_to_path

Converts child_path to a path relative to filter. That is, child_path points to a path in the child model. The rerturned path will point to the same row in the filtered model. If child_path isn’t a valid path on the child model or points to a row which is not visible in filter, then NULL is returned.

gtk_tree_model_filter_convert_iter_to_child_iter

Sets child_iter to point to the row pointed to by filter_iter.

gtk_tree_model_filter_convert_path_to_child_path

Converts filter_path to a path on the child model of filter. That is, filter_path points to a location in filter. The returned path will point to the same location in the model not being filtered. If filter_path does not point to a location in the child model, NULL is returned.

gtk_tree_model_filter_get_model

Returns a pointer to the child model of filter.

gtk_tree_model_filter_refilter

Emits ::row_changed for each row in the child model, which causes the filter to re-evaluate whether a row is visible or not.

gtk_tree_model_filter_set_modify_func

With the n_columns and types parameters, you give an array of column types for this model (which will be exposed to the parent model/view). The func, data and destroy parameters are for specifying the modify function. The modify function will get called for each data access, the goal of the modify function is to return the data which should be displayed at the location specified using the parameters of the modify function.

gtk_tree_model_filter_set_visible_column

Sets column of the child_model to be the column where filter should look for visibility information. columns should be a column of type G_TYPE_BOOLEAN, where TRUE means that a row is visible, and FALSE if not.

gtk_tree_model_filter_set_visible_func

Sets the visible function used when filtering the filter to be func. The function should return TRUE if the given row should be visible and FALSE otherwise.

Methods inherited from GtkTreeDragSource (3)
gtk_tree_drag_source_drag_data_delete

Asks the GtkTreeDragSource to delete the row at path, because it was moved somewhere else via drag-and-drop. Returns FALSE if the deletion fails because path no longer exists, or for some model-specific reason. Should robustly handle a path no longer found in the model!

gtk_tree_drag_source_drag_data_get

Asks the GtkTreeDragSource to return a GdkContentProvider representing the row at path. Should robustly handle a path no longer found in the model!

gtk_tree_drag_source_row_draggable

Asks the GtkTreeDragSource whether a particular row can be used as the source of a DND operation. If the source doesn’t implement this interface, the row is assumed draggable.

Methods inherited from GtkTreeModel (28)

Properties

Gtk.TreeModelFilter:child-model
No description available.
Gtk.TreeModelFilter:virtual-root
No description available.

Class structure

struct GtkTreeModelFilterClass {
  GObjectClass parent_class;
  gboolean (* visible) (
    GtkTreeModelFilter* self,
    GtkTreeModel* child_model,
    GtkTreeIter* iter
  );
  void (* modify) (
    GtkTreeModelFilter* self,
    GtkTreeModel* child_model,
    GtkTreeIter* iter,
    GValue* value,
    int column
  );
  
}
Class members
parent_class
GObjectClass
  No description available.
visible
gboolean (* visible) (
    GtkTreeModelFilter* self,
    GtkTreeModel* child_model,
    GtkTreeIter* iter
  )
  No description available.
modify
void (* modify) (
    GtkTreeModelFilter* self,
    GtkTreeModel* child_model,
    GtkTreeIter* iter,
    GValue* value,
    int column
  )
  No description available.

Virtual methods

Gtk.TreeModelFilterClass.modify
No description available.
Gtk.TreeModelFilterClass.visible
No description available.