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GtkTreeModelFilterGtkTreeModelFilter — A GtkTreeModel which hides parts of an underlying tree model |
Functions
Properties
| GtkTreeModel * | child-model | Read / Write / Construct Only |
| GtkTreePath * | virtual-root | Read / Write / Construct Only |
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 |
|
data |
user data given to |
[closure] |
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 |
||
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 |
[out caller-allocates] |
column |
the column whose display value is determined |
|
data |
user data given to |
[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.
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.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 |
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 |
||
func |
A GtkTreeModelFilterVisibleFunc, the visible function |
|
data |
User data to pass to the visible function, or |
[allow-none] |
destroy |
Destroy notifier of |
[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
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.
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
.
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 |
||
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 |
||
child_iter |
An uninitialized GtkTreeIter. |
[out] |
filter_iter |
A valid GtkTreeIter pointing to a row on |
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.
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.
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.
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.
Since 2.4
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