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Gnome::Gtk4::R-TreeModel

Gnome::Gtk4::R-TreeModel

Description

The tree interface used by GtkTreeView

The Gnome::Gtk4::R-TreeModel interface defines a generic tree interface for use by the Gnome::Gtk4::TreeView widget. It is an abstract interface, and is designed to be usable with any appropriate data structure. The programmer just has to implement this interface on their own data type for it to be viewable by a Gnome::Gtk4::TreeView widget.

The model is represented as a hierarchical tree of strongly-typed, columned data. In other words, the model can be seen as a tree where every node has different values depending on which column is being queried. The type of data found in a column is determined by using the GType system (ie. G_TYPE_INT, GTK_TYPE_BUTTON, G_TYPE_POINTER, etc). The types are homogeneous per column across all nodes. It is important to note that this interface only provides a way of examining a model and observing changes. The implementation of each individual model decides how and if changes are made.

In order to make life simpler for programmers who do not need to write their own specialized model, two generic models are provided — the Gnome::Gtk4::TreeStore and the Gnome::Gtk4::ListStore. To use these, the developer simply pushes data into these models as necessary. These models provide the data structure as well as all appropriate tree interfaces. As a result, implementing drag and drop, sorting, and storing data is trivial. For the vast majority of trees and lists, these two models are sufficient.

Models are accessed on a node/column level of granularity. One can query for the value of a model at a certain node and a certain column on that node. There are two structures used to reference a particular node in a model. They are the Gnome::Gtk4::N-TreePath and the Gnome::Gtk4::N-TreeIter (“iter” is short for iterator). Most of the interface consists of operations on a Gnome::Gtk4::N-TreeIter .

A path is essentially a potential node. It is a location on a model that may or may not actually correspond to a node on a specific model. A Gnome::Gtk4::N-TreePath can be converted into either an array of unsigned integers or a string. The string form is a list of numbers separated by a colon. Each number refers to the offset at that level. Thus, the path 0 refers to the root node and the path 2:4` refers to the fifth child of the third node.

By contrast, a Gnome::Gtk4::N-TreeIter is a reference to a specific node on a specific model. It is a generic struct with an integer and three generic pointers. These are filled in by the model in a model-specific way. One can convert a path to an iterator by calling .get-iter(). These iterators are the primary way of accessing a model and are similar to the iterators used by Gnome::Gtk4::TextBuffer. They are generally statically allocated on the stack and only used for a short time. The model interface defines a set of operations using them for navigating the model.

It is expected that models fill in the iterator with private data. For example, the Gnome::Gtk4::ListStore model, which is internally a simple linked list, stores a list node in one of the pointers. The Gnome::Gtk4::R-TreeModelSort stores an array and an offset in two of the pointers. Additionally, there is an integer field. This field is generally filled with a unique stamp per model. This stamp is for catching errors resulting from using invalid iterators with a model.

The lifecycle of an iterator can be a little confusing at first. Iterators are expected to always be valid for as long as the model is unchanged (and doesn’t emit a signal). The model is considered to own all outstanding iterators and nothing needs to be done to free them from the user’s point of view. Additionally, some models guarantee that an iterator is valid for as long as the node it refers to is valid (most notably the Gnome::Gtk4::TreeStore and Gnome::Gtk4::ListStore). Although generally uninteresting, as one always has to allow for the case where iterators do not persist beyond a signal, some very important performance enhancements were made in the sort model. As a result, the GTK_TREE_MODEL_ITERS_PERSIST flag was added to indicate this behavior.

To help show some common operation of a model, some examples are provided. The first example shows three ways of getting the iter at the location 3:2:5`. While the first method shown is easier, the second is much more common, as you often get paths from callbacks.

Acquiring a Gnome::Gtk4::N-TreeIter

This second example shows a quick way of iterating through a list and getting a string and an integer from each row. The populate_model() function used below is not shown, as it is specific to the Gnome::Gtk4::ListStore. For information on how to write such a function, see the Gnome::Gtk4::ListStore documentation.

Reading data from a Gnome::Gtk4::R-TreeModel

The Gnome::Gtk4::R-TreeModel interface contains two methods for reference counting: .ref-node() and .unref-node(). These two methods are optional to implement. The reference counting is meant as a way for views to let models know when nodes are being displayed. Gnome::Gtk4::TreeView will take a reference on a node when it is visible, which means the node is either in the toplevel or expanded. Being displayed does not mean that the node is currently directly visible to the user in the viewport. Based on this reference counting scheme a caching model, for example, can decide whether or not to cache a node based on the reference count. A file-system based model would not want to keep the entire file hierarchy in memory, but just the folders that are currently expanded in every current view.

When working with reference counting, the following rules must be taken into account:

  • Never take a reference on a node without owning a reference on its parent. This means that all parent nodes of a referenced node must be referenced as well.

  • Outstanding references on a deleted node are not released. This is not possible because the node has already been deleted by the time the row-deleted signal is received.

  • Models are not obligated to emit a signal on rows of which none of its siblings are referenced. To phrase this differently, signals are only required for levels in which nodes are referenced. For the root level however, signals must be emitted at all times (however the root level is always referenced when any view is attached).

Methods

filter-new

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

Creates a new Gnome::Gtk4::R-TreeModel, with $child-model as the child_model and $root as the virtual root.

method filter-new ( N-Object $root --> N-Object )
  • $root; A Gnome::Gtk4::N-TreePath

Return value; A new Gnome::Gtk4::R-TreeModel..

foreach

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

Calls $func on each node in model in a depth-first fashion.

If $func returns True, then the tree ceases to be walked, and .foreach() returns.

method foreach ( &func, gpointer $user-data )
  • &func; a function to be called on each row. Tthe function must be specified with following signature; :( N-Object $model, N-Object $path, N-Object $iter, gpointer $data -- gboolean )>.

  • $user-data; user data to passed to $func.

get This function is not yet available

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

Gets the value of one or more cells in the row referenced by $iter.

The variable argument list should contain integer column numbers, each column number followed by a place to store the value being retrieved. The list is terminated by a -1. For example, to get a value from column 0 with type G_TYPE_STRING, you would write: gtk_tree_model_get (model, iter, 0, &place_string_here, -1)`, where place_string_here is a #gchararray to be filled with the string.

Returned values with type G_TYPE_OBJECT have to be unreferenced, values with type G_TYPE_STRING or G_TYPE_BOXED have to be freed. Other values are passed by value.

method get ( N-Object $iter, … )
  • $iter; a row in $tree-model

  • …; …. Note that each argument must be specified as a type followed by its value!

get-column-type

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

Returns the type of the column.

method get-column-type ( Int() $index --> GType )
  • $index; the column index.

Return value; the type of the column.

get-flags This function is not yet available

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

Returns a set of flags supported by this interface.

The flags are a bitwise combination of Gnome::Gtk4::R-TreeModelFlags. The flags supported should not change during the lifetime of the $tree-model.

method get-flags (--> UInt )

Return value; the flags supported by this interface.

get-iter

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

Sets $iter to a valid iterator pointing to $path.

If $path does not exist, $iter is set to an invalid iterator and False is returned.

method get-iter ( N-Object $iter, N-Object $path --> Bool )
  • $iter; the uninitialized Gnome::Gtk4::N-TreeIter

  • $path; the Gnome::Gtk4::N-TreePath

Return value; True, if $iter was set.

get-iter-first

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

Initializes $iter with the first iterator in the tree (the one at the path "0").

Returns False if the tree is empty, True otherwise.

method get-iter-first ( N-Object $iter --> Bool )
  • $iter; the uninitialized Gnome::Gtk4::N-TreeIter

Return value; True, if $iter was set.

get-iter-from-string

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

Sets $iter to a valid iterator pointing to $path-string, if it exists.

Otherwise, $iter is left invalid and False is returned.

method get-iter-from-string ( N-Object $iter, Str $path-string --> Bool )
  • $iter; an uninitialized Gnome::Gtk4::N-TreeIter

  • $path-string; a string representation of a Gnome::Gtk4::N-TreePath.

Return value; True, if $iter was set.

get-n-columns

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

Returns the number of columns supported by $tree-model.

method get-n-columns (--> Int )

Return value; the number of columns.

get-path

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

Returns a newly-created Gnome::Gtk4::N-TreePath referenced by $iter.

This path should be freed with gtk_tree_path_free().

method get-path ( N-Object $iter --> N-Object )
  • $iter; the Gnome::Gtk4::N-TreeIter

Return value; a newly-created Gnome::Gtk4::N-TreePath.

get-string-from-iter

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

Generates a string representation of the iter.

This string is a “:” separated list of numbers. For example, “4:10:0:3” would be an acceptable return value for this string.

method get-string-from-iter ( N-Object $iter --> Str )
  • $iter; a Gnome::Gtk4::N-TreeIter

Return value; a newly-allocated string.

get-valist This function is not yet available

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

Gets the value of one or more cells in the row referenced by $iter.

See .get(), this version takes a va_list for language bindings to use.

method get-valist ( N-Object $iter, … )
  • $iter; a row in $tree-model

  • var-args; va_list of column/return location pairs. Note that each argument must be specified as a type followed by its value!

get-value

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

Initializes and sets $value to that at $column.

When done with $value, g_value_unset() needs to be called to free any allocated memory.

method get-value ( N-Object $iter, Int() $column, N-Object $value )
  • $iter; the Gnome::Gtk4::N-TreeIter

  • $column; the column to lookup the value at.

  • $value; an empty Gnome::GObject::N-Value to set

iter-children

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

Sets $iter to point to the first child of $parent.

If $parent has no children, False is returned and $iter is set to be invalid. $parent will remain a valid node after this function has been called.

If $parent is undefined returns the first node, equivalent to gtk_tree_model_get_iter_first (tree_model, iter);`

method iter-children ( N-Object $iter, N-Object $parent --> Bool )
  • $iter; the new Gnome::Gtk4::N-TreeIter to be set to the child

  • $parent; the Gnome::Gtk4::N-TreeIter

Return value; True, if $iter has been set to the first child.

iter-has-child

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

Returns True if $iter has children, False otherwise.

method iter-has-child ( N-Object $iter --> Bool )
  • $iter; the Gnome::Gtk4::N-TreeIter to test for children

Return value; True if $iter has children.

iter-n-children

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

Returns the number of children that $iter has.

As a special case, if $iter is undefined, then the number of toplevel nodes is returned.

method iter-n-children ( N-Object $iter --> Int )
  • $iter; the Gnome::Gtk4::N-TreeIter

Return value; the number of children of $iter.

iter-next

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

Sets $iter to point to the node following it at the current level.

If there is no next $iter, False is returned and $iter is set to be invalid.

method iter-next ( N-Object $iter --> Bool )
  • $iter; the Gnome::Gtk4::N-TreeIter

Return value; True if $iter has been changed to the next node.

iter-nth-child

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

Sets $iter to be the child of $parent, using the given index.

The first index is 0. If $n is too big, or $parent has no children, $iter is set to an invalid iterator and False is returned. $parent will remain a valid node after this function has been called. As a special case, if $parent is undefined, then the $n-th root node is set.

method iter-nth-child ( N-Object $iter, N-Object $parent, Int() $n --> Bool )
  • $iter; the Gnome::Gtk4::N-TreeIter to set to the nth child

  • $parent; the Gnome::Gtk4::N-TreeIter to get the child from

  • $n; the index of the desired child.

Return value; True, if $parent has an $n-th child.

iter-parent

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

Sets $iter to be the parent of $child.

If $child is at the toplevel, and doesn’t have a parent, then $iter is set to an invalid iterator and False is returned. $child will remain a valid node after this function has been called. $iter will be initialized before the lookup is performed, so $child and $iter cannot point to the same memory location.

method iter-parent ( N-Object $iter, N-Object $child --> Bool )
  • $iter; the new Gnome::Gtk4::N-TreeIter to set to the parent

  • $child; the Gnome::Gtk4::N-TreeIter

Return value; True, if $iter is set to the parent of $child.

iter-previous

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

Sets $iter to point to the previous node at the current level.

If there is no previous $iter, False is returned and $iter is set to be invalid.

method iter-previous ( N-Object $iter --> Bool )
  • $iter; the Gnome::Gtk4::N-TreeIter

Return value; True if $iter has been changed to the previous node.

ref-node

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

Lets the tree ref the node.

This is an optional method for models to implement. To be more specific, models may ignore this call as it exists primarily for performance reasons.

This function is primarily meant as a way for views to let caching models know when nodes are being displayed (and hence, whether or not to cache that node). Being displayed means a node is in an expanded branch, regardless of whether the node is currently visible in the viewport. For example, a file-system based model would not want to keep the entire file-hierarchy in memory, just the sections that are currently being displayed by every current view.

A model should be expected to be able to get an iter independent of its reffed state.

method ref-node ( N-Object $iter )
  • $iter; the Gnome::Gtk4::N-TreeIter

row-changed

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

Emits the row-changed signal on $tree-model.

See row-changed.

method row-changed ( N-Object $path, N-Object $iter )
  • $path; a Gnome::Gtk4::N-TreePath pointing to the changed row

  • $iter; a valid Gnome::Gtk4::N-TreeIter pointing to the changed row

row-deleted

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

Emits the row-deleted signal on $tree-model.

See row-deleted.

This should be called by models after a row has been removed. The location pointed to by $path should be the location that the row previously was at. It may not be a valid location anymore.

Nodes that are deleted are not unreffed, this means that any outstanding references on the deleted node should not be released.

method row-deleted ( N-Object $path )
  • $path; a Gnome::Gtk4::N-TreePath pointing to the previous location of the deleted row

row-has-child-toggled

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

Emits the row-has-child-toggled signal on $tree-model.

See row-has-child-toggled.

This should be called by models after the child state of a node changes.

method row-has-child-toggled ( N-Object $path, N-Object $iter )
  • $path; a Gnome::Gtk4::N-TreePath pointing to the changed row

  • $iter; a valid Gnome::Gtk4::N-TreeIter pointing to the changed row

row-inserted

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

Emits the row-inserted signal on $tree-model.

See row-inserted.

method row-inserted ( N-Object $path, N-Object $iter )
  • $path; a Gnome::Gtk4::N-TreePath pointing to the inserted row

  • $iter; a valid Gnome::Gtk4::N-TreeIter pointing to the inserted row

rows-reordered

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

Emits the rows-reordered signal on $tree-model.

See rows-reordered.

This should be called by models when their rows have been reordered.

method rows-reordered ( N-Object $path, N-Object $iter, Array[Int] $new-order )
  • $path; a Gnome::Gtk4::N-TreePath pointing to the tree node whose children have been reordered

  • $iter; a valid Gnome::Gtk4::N-TreeIter pointing to the node whose children have been reordered, or undefined if the depth of $path is 0

  • $new-order; an array of integers mapping the current position of each child to its old position before the re-ordering, i.e. $new-order`[newpos] = oldpos`.

rows-reordered-with-length

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

Emits the rows-reordered signal on $tree-model.

See rows-reordered.

This should be called by models when their rows have been reordered.

method rows-reordered-with-length ( N-Object $path, N-Object $iter, Array[Int] $new-order, Int() $length )
  • $path; a Gnome::Gtk4::N-TreePath pointing to the tree node whose children have been reordered

  • $iter; a valid Gnome::Gtk4::N-TreeIter pointing to the node whose children have been reordered, or undefined if the depth of $path is 0

  • $new-order; an array of integers mapping the current position of each child to its old position before the re-ordering, i.e. $new-order`[newpos] = oldpos`.

  • $length; length of $new-order array.

unref-node

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

Lets the tree unref the node.

This is an optional method for models to implement. To be more specific, models may ignore this call as it exists primarily for performance reasons. For more information on what this means, see .ref-node().

Please note that nodes that are deleted are not unreffed.

method unref-node ( N-Object $iter )
  • $iter; the Gnome::Gtk4::N-TreeIter

Signals

row-changed

This signal is emitted when a row in the model has changed.

method handler (
  N-Object $path,
  N-Object $iter,
  Int :$_handle_id,
  N-GObject :$_native-object,
  Gnome::Gtk4::TreeModel :$_widget,
  *C<user>-options
)
  • $path; a Gnome::Gtk4::N-TreePath identifying the changed row.

  • $iter; a valid Gnome::Gtk4::N-TreeIter pointing to the changed row.

  • $_handle_id; The registered event handler id.

  • $_native-object; The native object provided by the Raku object which registered this event. This a native Gnome::Gtk4::TreeModel object.

  • $_widget; The object which registered the signal. User code may have left the object going out of scope.

  • user-options; A list of named arguments provided at the .register-signal() method from Gnome::GObject::Object.

row-deleted

This signal is emitted when a row has been deleted.

Note that no iterator is passed to the signal handler, since the row is already deleted.

This should be called by models after a row has been removed. The location pointed to by $path should be the location that the row previously was at. It may not be a valid location anymore.

method handler (
  N-Object $path,
  Int :$_handle_id,
  N-GObject :$_native-object,
  Gnome::Gtk4::TreeModel :$_widget,
  *C<user>-options
)
  • $path; a Gnome::Gtk4::N-TreePath identifying the row.

  • $_handle_id; The registered event handler id.

  • $_native-object; The native object provided by the Raku object which registered this event. This a native Gnome::Gtk4::TreeModel object.

  • $_widget; The object which registered the signal. User code may have left the object going out of scope.

  • user-options; A list of named arguments provided at the .register-signal() method from Gnome::GObject::Object.

row-has-child-toggled

This signal is emitted when a row has gotten the first child row or lost its last child row.

method handler (
  N-Object $path,
  N-Object $iter,
  Int :$_handle_id,
  N-GObject :$_native-object,
  Gnome::Gtk4::TreeModel :$_widget,
  *C<user>-options
)
  • $path; a Gnome::Gtk4::N-TreePath identifying the row.

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

  • $_handle_id; The registered event handler id.

  • $_native-object; The native object provided by the Raku object which registered this event. This a native Gnome::Gtk4::TreeModel object.

  • $_widget; The object which registered the signal. User code may have left the object going out of scope.

  • user-options; A list of named arguments provided at the .register-signal() method from Gnome::GObject::Object.

row-inserted

This signal is emitted when a new row has been inserted in the model.

Note that the row may still be empty at this point, since it is a common pattern to first insert an empty row, and then fill it with the desired values.

method handler (
  N-Object $path,
  N-Object $iter,
  Int :$_handle_id,
  N-GObject :$_native-object,
  Gnome::Gtk4::TreeModel :$_widget,
  *C<user>-options
)
  • $path; a Gnome::Gtk4::N-TreePath identifying the new row.

  • $iter; a valid Gnome::Gtk4::N-TreeIter pointing to the new row.

  • $_handle_id; The registered event handler id.

  • $_native-object; The native object provided by the Raku object which registered this event. This a native Gnome::Gtk4::TreeModel object.

  • $_widget; The object which registered the signal. User code may have left the object going out of scope.

  • user-options; A list of named arguments provided at the .register-signal() method from Gnome::GObject::Object.

rows-reordered

This signal is emitted when the children of a node in the Gnome::Gtk4::R-TreeModel have been reordered.

Note that this signal is not emitted when rows are reordered by DND, since this is implemented by removing and then reinserting the row.

method handler (
  N-Object $path,
  N-Object $iter,
  gpointer $new-order,
  Int :$_handle_id,
  N-GObject :$_native-object,
  Gnome::Gtk4::TreeModel :$_widget,
  *C<user>-options
)
  • $path; a Gnome::Gtk4::N-TreePath identifying the tree node whose children have been reordered.

  • $iter; a valid Gnome::Gtk4::N-TreeIter pointing to the node whose children have been reordered, or undefined if the depth of $path is 0.

  • $new-order; an array of integers mapping the current position of each child to its old position before the re-ordering, i.e. $new-order`[newpos] = oldpos`.

  • $_handle_id; The registered event handler id.

  • $_native-object; The native object provided by the Raku object which registered this event. This a native Gnome::Gtk4::TreeModel object.

  • $_widget; The object which registered the signal. User code may have left the object going out of scope.

  • user-options; A list of named arguments provided at the .register-signal() method from Gnome::GObject::Object.