GtkTreeModelFilter: GTK+ 3 Reference Manual

GtkTreeModelFilter

GtkTreeModelFilter — A GtkTreeModel which hides parts of an underlying tree model

Properties

GtkTreeModel *	child-model	Read / Write / Construct Only
GtkTreePath *	virtual-root	Read / Write / Construct Only

Types and Values

struct

GtkTreeModelFilter

Object Hierarchy

    GObject
    ╰── GtkTreeModelFilter

Implemented Interfaces

GtkTreeModelFilter implements GtkTreeModel and GtkTreeDragSource.

Includes

#include <gtk/gtk.h>

Description

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 couting 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 GtkTreeModelFilter's 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.

Functions

GtkTreeModelFilterVisibleFunc ()

gboolean
(*GtkTreeModelFilterVisibleFunc) (GtkTreeModel *model,
                                  GtkTreeIter *iter,
                                  gpointer data);

A function which decides whether the row indicated by iter is visible.

Parameters

model	the child model of the GtkTreeModelFilter
iter	a GtkTreeIter pointing to the row in `model` whose visibility is determined
data	user data given to `gtk_tree_model_filter_set_visible_func()`.	[closure]

Returns

Whether the row indicated by iter is visible.

GtkTreeModelFilterModifyFunc ()

void
(*GtkTreeModelFilterModifyFunc) (GtkTreeModel *model,
                                 GtkTreeIter *iter,
                                 GValue *value,
                                 gint column,
                                 gpointer data);

A function which calculates display values from raw values in the model. It must fill value with the display value for the column column in the row indicated by iter .

Since this function is called for each data access, it’s not a particularly efficient operation.

Parameters

model	the GtkTreeModelFilter
iter	a GtkTreeIter pointing to the row whose display values are determined
value	A GValue which is already initialized for with the correct type for the column `column` .	[out caller-allocates]
column	the column whose display value is determined
data	user data given to `gtk_tree_model_filter_set_modify_func()`.	[closure]

gtk_tree_model_filter_new ()

GtkTreeModel *
gtk_tree_model_filter_new (GtkTreeModel *child_model,
                           GtkTreePath *root);

Creates a new GtkTreeModel, with child_model as the child_model and root as the virtual root.

Parameters

child_model	A GtkTreeModel.
root	A GtkTreePath or `NULL`.	[allow-none]

Returns

A new GtkTreeModel.

[transfer full]

Since: 2.4

gtk_tree_model_filter_set_visible_func ()

void
gtk_tree_model_filter_set_visible_func
                               (GtkTreeModelFilter *filter,
                                GtkTreeModelFilterVisibleFunc func,
                                gpointer data,
                                GDestroyNotify destroy);

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.

If the condition calculated by the function changes over time (e.g. because it depends on some global parameters), you must call gtk_tree_model_filter_refilter() to keep the visibility information of the model up-to-date.

Note that func is called whenever a row is inserted, when it may still be empty. The visible function should therefore take special care of empty rows, like in the example below.

static gboolean
visible_func (GtkTreeModel *model,
              GtkTreeIter  *iter,
              gpointer      data)
{
  // Visible if row is non-empty and first column is “HI”
  gchar *str;
  gboolean visible = FALSE;

  gtk_tree_model_get (model, iter, 0, &str, -1);
  if (str && strcmp (str, "HI") == 0)
    visible = TRUE;
  g_free (str);

  return visible;
}

Note that gtk_tree_model_filter_set_visible_func() or gtk_tree_model_filter_set_visible_column() can only be called once for a given filter model.

Parameters

filter	A GtkTreeModelFilter
func	A GtkTreeModelFilterVisibleFunc, the visible function
data	User data to pass to the visible function, or `NULL`.	[allow-none]
destroy	Destroy notifier of `data` , or `NULL`.	[allow-none]

Since: 2.4

gtk_tree_model_filter_set_modify_func ()

void
gtk_tree_model_filter_set_modify_func (GtkTreeModelFilter *filter,
                                       gint n_columns,
                                       GType *types,
                                       GtkTreeModelFilterModifyFunc func,
                                       gpointer data,
                                       GDestroyNotify destroy);

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.

Note that gtk_tree_model_filter_set_modify_func() can only be called once for a given filter model.

Parameters

filter	A GtkTreeModelFilter.
n_columns	The number of columns in the filter model.
types	The GTypes of the columns.	[array length=n_columns]
func	A GtkTreeModelFilterModifyFunc
data	User data to pass to the modify function, or `NULL`.	[allow-none]
destroy	Destroy notifier of `data` , or `NULL`.	[allow-none]

Since: 2.4

gtk_tree_model_filter_set_visible_column ()

void
gtk_tree_model_filter_set_visible_column
                               (GtkTreeModelFilter *filter,
                                gint 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.

Note that gtk_tree_model_filter_set_visible_func() or gtk_tree_model_filter_set_visible_column() can only be called once for a given filter model.

Parameters

filter	A GtkTreeModelFilter
column	A gint which is the column containing the visible information

Since: 2.4

gtk_tree_model_filter_get_model ()

GtkTreeModel *
gtk_tree_model_filter_get_model (GtkTreeModelFilter *filter);

Returns a pointer to the child model of filter .

Parameters

filter

A GtkTreeModelFilter.

Returns

A pointer to a GtkTreeModel.

[transfer none]

Since: 2.4

gtk_tree_model_filter_convert_child_iter_to_iter ()

gboolean
gtk_tree_model_filter_convert_child_iter_to_iter
                               (GtkTreeModelFilter *filter,
                                GtkTreeIter *filter_iter,
                                GtkTreeIter *child_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.

Parameters

filter	A GtkTreeModelFilter.
filter_iter	An uninitialized GtkTreeIter.	[out]
child_iter	A valid GtkTreeIter pointing to a row on the child model.

Returns

TRUE, if filter_iter was set, i.e. if child_iter is a valid iterator pointing to a visible row in child model.

Since: 2.4

gtk_tree_model_filter_convert_iter_to_child_iter ()

void
gtk_tree_model_filter_convert_iter_to_child_iter
                               (GtkTreeModelFilter *filter,
                                GtkTreeIter *child_iter,
                                GtkTreeIter *filter_iter);

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

Parameters

filter	A GtkTreeModelFilter.
child_iter	An uninitialized GtkTreeIter.	[out]
filter_iter	A valid GtkTreeIter pointing to a row on `filter` .

Since: 2.4

gtk_tree_model_filter_convert_child_path_to_path ()

GtkTreePath *
gtk_tree_model_filter_convert_child_path_to_path
                               (GtkTreeModelFilter *filter,
                                GtkTreePath *child_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.

Parameters

filter	A GtkTreeModelFilter.
child_path	A GtkTreePath to convert.

Returns

A newly allocated GtkTreePath, or NULL.

[nullable][transfer full]

Since: 2.4

gtk_tree_model_filter_convert_path_to_child_path ()

GtkTreePath *
gtk_tree_model_filter_convert_path_to_child_path
                               (GtkTreeModelFilter *filter,
                                GtkTreePath *filter_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.

Parameters

filter	A GtkTreeModelFilter.
filter_path	A GtkTreePath to convert.

Returns

A newly allocated GtkTreePath, or NULL.

[nullable][transfer full]

Since: 2.4

gtk_tree_model_filter_refilter ()

void
gtk_tree_model_filter_refilter (GtkTreeModelFilter *filter);

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

Parameters

filter

A GtkTreeModelFilter.

Since: 2.4

gtk_tree_model_filter_clear_cache ()

void
gtk_tree_model_filter_clear_cache (GtkTreeModelFilter *filter);

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.

Parameters

filter

A GtkTreeModelFilter.

Since: 2.4

Types and Values

struct GtkTreeModelFilter

struct GtkTreeModelFilter;

Property Details

The `“child-model”` property

  “child-model”              GtkTreeModel *

The model for the filtermodel to filter.

Flags: Read / Write / Construct Only

The `“virtual-root”` property

  “virtual-root”             GtkTreePath *

The virtual root (relative to the child model) for this filtermodel.

Flags: Read / Write / Construct Only

gboolean	(*GtkTreeModelFilterVisibleFunc) ()
void	(*GtkTreeModelFilterModifyFunc) ()
GtkTreeModel *	gtk_tree_model_filter_new ()
void	gtk_tree_model_filter_set_visible_func ()
void	gtk_tree_model_filter_set_modify_func ()
void	gtk_tree_model_filter_set_visible_column ()
GtkTreeModel *	gtk_tree_model_filter_get_model ()
gboolean	gtk_tree_model_filter_convert_child_iter_to_iter ()
void	gtk_tree_model_filter_convert_iter_to_child_iter ()
GtkTreePath *	gtk_tree_model_filter_convert_child_path_to_path ()
GtkTreePath *	gtk_tree_model_filter_convert_path_to_child_path ()
void	gtk_tree_model_filter_refilter ()
void	gtk_tree_model_filter_clear_cache ()