gi-gtk-3.0.26: Gtk bindings

Copyright Will Thompson Iñaki García Etxebarria and Jonas Platte LGPL-2.1 Iñaki García Etxebarria (garetxe@gmail.com) None Haskell2010

GI.Gtk.Objects.TreeModelFilter

Description

A 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 TreePath indicating the root node for the filter at construction time.

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

When using TreeModelFilter, it is important to realize that 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. 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 TreeModel documentation. (Note that e.g. 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 couting rule number 3 in the 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, 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, 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 'GI.Gtk.Objects.TreeModelFilter.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), 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 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.

Synopsis

# Exported types

newtype TreeModelFilter Source #

Memory-managed wrapper type.

Constructors

 TreeModelFilter (ManagedPtr TreeModelFilter)
Instances
 Source # Instance detailsDefined in GI.Gtk.Objects.TreeModelFilter Methods Source # Instance detailsDefined in GI.Gtk.Objects.TreeModelFilter Source # Instance detailsDefined in GI.Gtk.Objects.TreeModelFilter Source # Instance detailsDefined in GI.Gtk.Objects.TreeModelFilter Source # Instance detailsDefined in GI.Gtk.Objects.TreeModelFilter

class GObject o => IsTreeModelFilter o Source #

Type class for types which can be safely cast to TreeModelFilter, for instance with toTreeModelFilter.

Instances
 Source # Instance detailsDefined in GI.Gtk.Objects.TreeModelFilter Source # Instance detailsDefined in GI.Gtk.Objects.TreeModelFilter

toTreeModelFilter :: (MonadIO m, IsTreeModelFilter o) => o -> m TreeModelFilter Source #

Cast to TreeModelFilter, for types for which this is known to be safe. For general casts, use castTo.

A convenience alias for Nothing :: Maybe TreeModelFilter.

# Methods

## clearCache

Arguments

 :: (HasCallStack, MonadIO m, IsTreeModelFilter a) => a filter: A TreeModelFilter. -> m ()

This function should almost never be called. It clears the filter of any cached iterators that haven’t been reffed with treeModelRefNode. 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

## convertChildIterToIter

Arguments

 :: (HasCallStack, MonadIO m, IsTreeModelFilter a) => a filter: A TreeModelFilter. -> TreeIter childIter: A valid TreeIter pointing to a row on the child model. -> m (Bool, TreeIter) Returns: True, if filterIter was set, i.e. if childIter is a valid iterator pointing to a visible row in child model.

Sets filterIter to point to the row in filter that corresponds to the row pointed at by childIter. If filterIter was not set, False is returned.

Since: 2.4

## convertChildPathToPath

Arguments

 :: (HasCallStack, MonadIO m, IsTreeModelFilter a) => a filter: A TreeModelFilter. -> TreePath childPath: A TreePath to convert. -> m (Maybe TreePath) Returns: A newly allocated TreePath, or Nothing.

Converts childPath to a path relative to filter. That is, childPath points to a path in the child model. The rerturned path will point to the same row in the filtered model. If childPath isn’t a valid path on the child model or points to a row which is not visible in filter, then Nothing is returned.

Since: 2.4

## convertIterToChildIter

Arguments

 :: (HasCallStack, MonadIO m, IsTreeModelFilter a) => a filter: A TreeModelFilter. -> TreeIter filterIter: A valid TreeIter pointing to a row on filter. -> m TreeIter

Sets childIter to point to the row pointed to by filterIter.

Since: 2.4

## convertPathToChildPath

Arguments

 :: (HasCallStack, MonadIO m, IsTreeModelFilter a) => a filter: A TreeModelFilter. -> TreePath filterPath: A TreePath to convert. -> m (Maybe TreePath) Returns: A newly allocated TreePath, or Nothing.

Converts filterPath to a path on the child model of filter. That is, filterPath points to a location in filter. The returned path will point to the same location in the model not being filtered. If filterPath does not point to a location in the child model, Nothing is returned.

Since: 2.4

## getModel

Arguments

 :: (HasCallStack, MonadIO m, IsTreeModelFilter a) => a filter: A TreeModelFilter. -> m TreeModel Returns: A pointer to a TreeModel.

Returns a pointer to the child model of filter.

Since: 2.4

## refilter

Arguments

 :: (HasCallStack, MonadIO m, IsTreeModelFilter a) => a filter: A TreeModelFilter. -> m ()

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

## setVisibleColumn

Arguments

 :: (HasCallStack, MonadIO m, IsTreeModelFilter a) => a filter: A TreeModelFilter -> Int32 column: A gint which is the column containing the visible information -> m ()

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 treeModelFilterSetVisibleFunc or treeModelFilterSetVisibleColumn can only be called once for a given filter model.

Since: 2.4

## setVisibleFunc

Arguments

 :: (HasCallStack, MonadIO m, IsTreeModelFilter a) => a filter: A TreeModelFilter -> TreeModelFilterVisibleFunc func: A TreeModelFilterVisibleFunc, the visible function -> m ()

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 treeModelFilterRefilter 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.

### C code

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 treeModelFilterSetVisibleFunc or treeModelFilterSetVisibleColumn can only be called once for a given filter model.

Since: 2.4

# Properties

## childModel

No description available in the introspection data.

Construct a GValueConstruct with valid value for the “child-model” property. This is rarely needed directly, but it is used by new.

getTreeModelFilterChildModel :: (MonadIO m, IsTreeModelFilter o) => o -> m (Maybe TreeModel) Source #

Get the value of the “child-model” property. When overloading is enabled, this is equivalent to

get treeModelFilter #childModel


## virtualRoot

No description available in the introspection data.

Construct a GValueConstruct with valid value for the “virtual-root” property. This is rarely needed directly, but it is used by new.

getTreeModelFilterVirtualRoot :: (MonadIO m, IsTreeModelFilter o) => o -> m (Maybe TreePath) Source #

Get the value of the “virtual-root” property. When overloading is enabled, this is equivalent to

get treeModelFilter #virtualRoot