Description

A Gnome::Gtk4::R-TreeModel which hides parts of an underlying tree model

A Gnome::Gtk4::TreeModelFilter 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 Gnome::Gtk4::N-TreePath indicating the root node for the filter at construction time.

The basic API is similar to Gnome::Gtk4::TreeModelSort. For an example on its usage, see the section on Gnome::Gtk4::TreeModelSort.

When using Gnome::Gtk4::TreeModelFilter, it is important to realize that Gnome::Gtk4::TreeModelFilter 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. Gnome::Gtk4::TreeModelFilter 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 Gnome::Gtk4::R-TreeModel documentation. (Note that e.g. Gnome::Gtk4::TreeStore 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 Gnome::Gtk4::R-TreeModel section).

Determining the visibility state of a given node based on the state of its child nodes is a frequently occurring use case. Therefore, Gnome::Gtk4::TreeModelFilter 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, Gnome::Gtk4::TreeModelFilter 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 Gnome::Gtk4::TreeModelFilter'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), Gnome::Gtk4::TreeModelFilter 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 Gnome::Gtk4::TreeStore 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.

Class initialization

Note: The native version of this class is deprecated in gtk4-lib() since version 4.10

new

:native-object

Create an object using a native object from elsewhere. See also Gnome::N::TopLevelSupportClass.

multi method new ( N-Object :$native-object! )

Methods

clear-cache

Note: The native version of this routine is deprecated in gtk4-lib() since version 4.10

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.

method clear-cache ( )

convert-child-iter-to-iter

Note: The native version of this routine is deprecated in gtk4-lib() since version 4.10

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.

method convert-child-iter-to-iter ( N-Object $filter-iter, N-Object $child-iter --> Bool )

• $filter-iter; An uninitialized Gnome::Gtk4::N-TreeIter

• $child-iter; A valid Gnome::Gtk4::N-TreeIter pointing to a row on the child model.

Return value; True, if $filter-iter was set, i.e. if $child-iter is a valid iterator pointing to a visible row in child model..

convert-child-path-to-path

Note: The native version of this routine is deprecated in gtk4-lib() since version 4.10

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 undefined is returned.

method convert-child-path-to-path ( N-Object $child-path --> N-Object )

• $child-path; A Gnome::Gtk4::N-TreePath to convert.

Return value; A newly allocated Gnome::Gtk4::N-TreePath.

convert-iter-to-child-iter

Note: The native version of this routine is deprecated in gtk4-lib() since version 4.10

Sets $child-iter to point to the row pointed to by $filter-iter.

method convert-iter-to-child-iter ( N-Object $child-iter, N-Object $filter-iter )

• $child-iter; An uninitialized Gnome::Gtk4::N-TreeIter

• $filter-iter; A valid Gnome::Gtk4::N-TreeIter pointing to a row on $filter.

convert-path-to-child-path

Note: The native version of this routine is deprecated in gtk4-lib() since version 4.10

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, undefined is returned.

method convert-path-to-child-path ( N-Object $filter-path --> N-Object )

• $filter-path; A Gnome::Gtk4::N-TreePath to convert.

Return value; A newly allocated Gnome::Gtk4::N-TreePath.

get-model

Note: The native version of this routine is deprecated in gtk4-lib() since version 4.10

Returns a pointer to the child model of $filter.

method get-model (--> N-Object )

Return value; A pointer to a Gnome::Gtk4::R-TreeModel.

refilter

Note: The native version of this routine is deprecated in gtk4-lib() since version 4.10

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

method refilter ( )

set-modify-func This function is not yet available

Note: The native version of this routine is deprecated in gtk4-lib() since version 4.10

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 .set-modify-func() can only be called once for a given filter model.

method set-modify-func ( Int() $n-columns, …, &func, gpointer $data, … )

• $n-columns; The number of columns in the filter model..

• types; The Gnome::GObject::TreeModelFilters of the columns.. Note that each argument must be specified as a type followed by its value!

• &func; A Gnome::Gtk4::T-treemodelfilter. Tthe function must be specified with following signature; :( N-Object $model, N-Object $iter, N-Object $value, gint $column, gpointer $data ).

• $data; User data to pass to the modify function.

• destroy; Destroy notifier of $data. Note that each argument must be specified as a type followed by its value!

set-visible-column

Note: The native version of this routine is deprecated in gtk4-lib() since version 4.10

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 .set-visible-func() or .set-visible-column() can only be called once for a given filter model.

method set-visible-column ( Int() $column )

• $column; A int which is the column containing the visible information.

set-visible-func This function is not yet available

Note: The native version of this routine is deprecated in gtk4-lib() since version 4.10

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 .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.

Note that .set-visible-func() or .set-visible-column() can only be called once for a given filter model.

method set-visible-func ( &func, gpointer $data, … )

• &func; A Gnome::Gtk4::T-treemodelfilter, the visible function. Tthe function must be specified with following signature; :( N-Object $model, N-Object $iter, gpointer $data -- gboolean )>.

• $data; User data to pass to the visible function.

• destroy; Destroy notifier of $data. Note that each argument must be specified as a type followed by its value!