Interfacing Raku to Gnome GTK+

Gnome::Gtk3::TreeModel

The tree interface used by Gnome::Gtk3::TreeView

Description

The Gnome::Gtk3::TreeModel interface defines a generic tree interface for use by the Gnome::Gtk3::TreeView widget. It is an abstract interface, and is designed to be usable with any appropriate data structure.

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

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::Gtk3::TreeStore and the Gnome::Gtk3::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::Gtk3::TreePath-struct and the Gnome::Gtk3::TreeIter-struct (“iter” is short for iterator). Most of the interface consists of operations on a Gnome::Gtk3::TreeIter-struct.

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. The Gnome::Gtk3::TreePath-struct 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::Gtk3::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 gtk_tree_model_get_iter(). These iterators are the primary way of accessing a model and are similar to the iterators used by Gnome::Gtk3::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::Gtk3::ListStore model, which is internally a simple linked list, stores a list node in one of the pointers. The Gnome::Gtk3::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::Gtk3::TreeStore and Gnome::Gtk3::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::Gtk3::TreeIter

# A ListStore with two columns, an integer and a string
my Gnome::Gtk3::ListStore $ls .= new(:field-types( G_TYPE_INT, G_TYPE_STRING));

# Filling a ListStore needs also an iterator. This on points to the end.
my Gnome::Gtk3::TreeIter $iter = $ls.gtk-list-store-append;
$ls.gtk-list-store-set( $iter, 0, 1001, 1, 'first entry');
$iter = $ls.gtk-list-store-append;
$ls.gtk-list-store-set( $iter, 0, 2002, 1, 'second entry');

# Get the iterator from a string. A ListStore has simple paths.
$iter = $ls.get_iter_from_string("1");

# Get the iterator from a path
my Gnome::Gtk3::TreePath $path .= new(:string('0'));
$iter = $ls.get-iter($path);
$path.clear-tree-path;

See Also

Gnome::Gtk3::TreeView, Gnome::Gtk3::TreeStore, Gnome::Gtk3::ListStore,

Synopsis

Declaration

unit role Gnome::Gtk3::TreeModel;

Uml Diagram

Types

enum GtkTreeModelFlags

These flags indicate various properties of a Gnome::Gtk3::TreeModel.

They are returned by gtk_tree_model_get_flags(), and must be static for the lifetime of the object. A more complete description of GTK_TREE_MODEL_ITERS_PERSIST can be found in the overview of this section.

  • GTK_TREE_MODEL_ITERS_PERSIST: iterators survive all signals emitted by the tree

  • GTK_TREE_MODEL_LIST_ONLY: the model is a list only, and never has children

Methods

[gtk_] tree_row_reference_new

Creates a row reference based on $path.

This reference will keep pointing to the node pointed to by $path, so long as it exists. Any changes that occur on $model are propagated, and the path is updated appropriately. If $path isn’t a valid path in $model, then Any is returned.

Returns: a newly allocated Gnome::Gtk3::TreeRowReference, or Any

method gtk_tree_row_reference_new (
  N-GtkTreePath $path --> N-GtkTreeRowReference
)
  • N-GtkTreePath $path; a valid Gnome::Gtk3::TreePath-struct to monitor

[[gtk_] tree_model_] get_flags

Returns a set of flags supported by this interface.

The flags are a bitwise combination of enum values of GtkTreeModelFlags. The flags supported should not change during the lifetime of the tree_model.

Returns: the flags supported by this interface

method gtk_tree_model_get_flags ( --> GtkTreeModelFlags  )

[[gtk_] tree_model_] get_n_columns

Returns the number of columns supported by tree_model.

method gtk_tree_model_get_n_columns ( --> Int  )

[[gtk_] tree_model_] get_column_type

Returns the type of the column.

method gtk_tree_model_get_column_type ( Int $index --> UInt )
  • Int $index; the column index

[[gtk_] tree_model_] get_iter

Returns a valid iterator pointing to $path. If $path does not exist, an invalid iterator is returned. Test with .tree-iter-is-valid() to see if the iterator is ok.

method gtk_tree_model_get_iter (
  Gnome::Gtk3::TreePath $path
  --> Gnome::Gtk3::TreeIter
)
  • Gnome::Gtk3::TreePath $path; The path to point the iterator to.

[[gtk_] tree_model_] get_iter_from_string

Returns a valid iterator pointing to $path_string, if it exists. Otherwise, an invalid iterator is returned. Test with .tree-iter-is-valid() to see if the iterator is ok.

method gtk_tree_model_get_iter_from_string (
  Str $path_string
  --> N-GtkTreeIter
)
  • Str $path_string; a string representation of a Gnome::Gtk3::TreePath-struct

[[gtk_] tree_model_] get_string_from_iter

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.

Returns: a newly-allocated string.

Since: 2.2

method gtk_tree_model_get_string_from_iter ( N-GtkTreeIter $iter --> Str  )
  • N-GtkTreeIter $iter; a Gnome::Gtk3::TreeIter-struct

[[gtk_] tree_model_] get_iter_first

Initializes iter with the first iterator in the tree (the one at the path “0”). Returns an invalid iterator if the tree is empty.

method gtk_tree_model_get_iter_first ( --> Gnome::Gtk3::TreeIter  )

[[gtk_] tree_model_] get_path

Returns a newly-created Gnome::Gtk3::TreePath referenced by $iter.

This path should be freed with .clear-tree-path().

method gtk_tree_model_get_path (
  Gnome::Gtk3::TreeIter $iter
  --> Gnome::Gtk3::TreePath
)
  • Gnome::Gtk3::TreeIter $iter; the iterator

[[gtk_] tree_model_] get_value

Returns an array of values found at the $iter and $columns.

When done with each value, .clear-object() needs to be called to free any allocated memory.

method gtk_tree_model_get_value (
  Gnome::Gtk3::TreeIter $iter, Int $column, ...
  --> Array[Gnome::GObject::Value]
)

  • Gnome::Gtk3::TreeIter $iter; the iterator

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

  • N-GObject $value; (out) (transfer none): an empty GValue to set

[[gtk_] tree_model_] iter_previous

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

If there is no previous iter, 0 is returned and iter is set to be invalid.

Returns: 1 if iter has been changed to the previous node

Since: 3.0

method gtk_tree_model_iter_previous ( N-GtkTreeIter $iter --> Int  )
  • N-GtkTreeIter $iter; (in): the Gnome::Gtk3::TreeIter-struct

[[gtk_] tree_model_] iter_next

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

If there is no next iter, 0 is returned and iter is set to be invalid.

Returns: 1 if iter has been changed to the next node

method gtk_tree_model_iter_next ( N-GtkTreeIter $iter --> Int  )
  • N-GtkTreeIter $iter; (in): the Gnome::Gtk3::TreeIter-struct

[[gtk_] tree_model_] iter_children

Returns an iterator to point to the first child of $parent. Gnome::Gtk3::ListStore does not have children but a Gnome::Gtk3::TreeStore does.

If $parent has no children, an invalid iterator is returned. $parent will remain a valid node after this function has been called.

method gtk_tree_model_iter_children (
  Gnome::Gtk3::TreeIter $parent
  --> Gnome::Gtk3::TreeIter
)
  • Gnome::Gtk3::TreeIter $parent; an iterator pointing to a parent.

[[gtk_] tree_model_] iter_has_child

Returns 1 if $iter has children, 0 otherwise.

method gtk_tree_model_iter_has_child (
  Gnome::Gtk3::TreeIter $iter
  --> Int
)
  • Gnome::Gtk3::TreeIter $iter; iterator to test for children

[[gtk_] tree_model_] iter_n_children

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 gtk_tree_model_iter_n_children (
  Gnome::Gtk3::TreeIter $iter?
  --> Int
)
  • Gnome::Gtk3::TreeIter $iter; the iterator

[[gtk_] tree_model_] iter_nth_child

Returns an iterator 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, the returned iterator is invalid. $parent will remain a valid node after this function has been called. As a special case, if $parent is undefined, then the iterator is set to the $n-th root node is set.

method gtk_tree_model_iter_nth_child (
  Gnome::Gtk3::TreeIter $parent, Int $n
  --> Gnome::Gtk3::TreeIter
)

  • Gnome::Gtk3::TreeIter $parent; the parent iterator to get the child from, or Any.

  • Int $n; the index of the desired child

[[gtk_] tree_model_] iter_parent

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 0 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.

Returns: 1, if iter is set to the parent of child

method gtk_tree_model_iter_parent ( N-GtkTreeIter $iter, N-GtkTreeIter $child --> Int  )

  • N-GtkTreeIter $iter; (out): the new Gnome::Gtk3::TreeIter-struct to set to the parent

  • N-GtkTreeIter $child; the Gnome::Gtk3::TreeIter-struct

foreach

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

If func returns 1, then the tree ceases to be walked, and foreach() returns.

method foreach (
  $function-object, Str $function-name, *%user-options
)

  • $function-object; an object where the function is defined

  • $function-name; the name of the function which is called

  • %user-options; named arguments which will be provided to the callback

The function signature is

method f (
  N-GObject $n-store,
  Gnome::Gtk3::TreePath $path,
  Gnome::Gtk3::TreeIter $iter,
  *%user-options
  --> Bool
)

The value in $n-store is a native object and cannot be created into a Raku object here because it is not known if this is a ListStore or a TreeStore object.

An example

my Gnome::Gtk3::ListStore $ls;
my Gnome::Gtk3::TreeIter $iter;

# specify column types
$ls .= new(:field-types( G_TYPE_INT, G_TYPE_STRING));

# fill some rows
$iter = $ls.gtk-list-store-append;
$ls.gtk-list-store-set( $iter, 0, 1001, 1, 'some text');
$iter = $ls.gtk-list-store-append;
$ls.gtk-list-store-set( $iter, 0, 2002, 1, 'a bit more');

# define class for handler
class X {
  method row-loop (
    N-GObject $n-store,
    Gnome::Gtk3::TreePath $path,
    Gnome::Gtk3::TreeIter $iter
    --> Bool
  ) {
    # get values for this iterator
    my Gnome::Gtk3::ListStore $store .= new(:native-object($n-store));
    my Array[Gnome::GObject::Value] $va = $store.get-value( $iter, 0);

    # do something with this row ...

    my Int $value = $va[0].get-int;
    $va[0].clear-object;

    if $value of col 0 != 1001 {
      # let the search continue
      False
    }

    # value of col 0 == 1001
    else {
      # stop walking to the next row
      True
    }
  }
}

$ls.foreach( X.new, 'row-loop');

[[gtk_] tree_model_] row_changed

Emits the row-changed signal on the tree model.

method gtk_tree_model_row_changed (
  Gnome::Gtk3::TreePath $path,
  Gnome::Gtk3::TreeIter $iter
)

  • Gnome::Gtk3::TreePath $path; a path pointing to the changed row

  • Gnome::Gtk3::TreeIter $iter; an iterator pointing to the changed row

[[gtk_] tree_model_] row_inserted

Emits the row-inserted signal on the tree model.

method gtk_tree_model_row_inserted (
  Gnome::Gtk3::TreePath $path,
  Gnome::Gtk3::TreeIter $iter
)

  • Gnome::Gtk3::TreePath $path; a path pointing to the changed row

  • Gnome::Gtk3::TreeIter $iter; an iterator pointing to the changed row

[[gtk_] tree_model_] row_has_child_toggled

Emits the row-has-child-toggled signal on tree_model. This should be called by models after the child state of a node changes.

method gtk_tree_model_row_has_child_toggled ( N-GtkTreePath $path, N-GtkTreeIter $iter )

  • N-GtkTreePath $path; a Gnome::Gtk3::TreePath-struct pointing to the changed row

  • N-GtkTreeIter $iter; a valid Gnome::Gtk3::TreeIter-struct pointing to the changed row

[[gtk_] tree_model_] row_deleted

Emits the row-deleted signal on tree_model.

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 gtk_tree_model_row_deleted ( N-GtkTreePath $path )
  • N-GtkTreePath $path; a Gnome::Gtk3::TreePath-struct pointing to the previous location of the deleted row

[[gtk_] tree_model_] rows_reordered

Emits the rows-reordered signal on tree_model.

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

method gtk_tree_model_rows_reordered ( N-GtkTreePath $path, N-GtkTreeIter $iter, Int $new_order )

  • N-GtkTreePath $path; a Gnome::Gtk3::TreePath-struct pointing to the tree node whose children have been reordered

  • N-GtkTreeIter $iter; a valid Gnome::Gtk3::TreeIter-struct pointing to the node whose children have been reordered, or Any if the depth of path is 0

  • Int $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

[[gtk_] tree_model_] rows_reordered_with_length

Emits the rows-reordered signal on tree_model.

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

Since: 3.10

method gtk_tree_model_rows_reordered_with_length ( N-GtkTreePath $path, N-GtkTreeIter $iter, Int $new_order, Int $length )

  • N-GtkTreePath $path; a Gnome::Gtk3::TreePath-struct pointing to the tree node whose children have been reordered

  • N-GtkTreeIter $iter; (allow-none): a valid Gnome::Gtk3::TreeIter-struct pointing to the node whose children have been reordered, or Any if the depth of path is 0

  • Int $new_order; (array length=length): 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

  • Int $length; length of new_order array

Signals

There are two ways to connect to a signal. The first option you have is to use register-signal() from Gnome::GObject::Object. The second option is to use g_signal_connect_object() directly from Gnome::GObject::Signal.

First method

The positional arguments of the signal handler are all obligatory as well as their types. The named attributes :$widget and user data are optional.

# handler method
method mouse-event ( N-GdkEvent $event, :$widget ) { ... }

# connect a signal on window object
my Gnome::Gtk3::Window $w .= new( ... );
$w.register-signal( self, 'mouse-event', 'button-press-event');

Second method

my Gnome::Gtk3::Window $w .= new( ... );
my Callable $handler = sub (
  N-GObject $native, N-GdkEvent $event, OpaquePointer $data
) {
  ...
}

$w.connect-object( 'button-press-event', $handler);

Also here, the types of positional arguments in the signal handler are important. This is because both methods register-signal() and g_signal_connect_object() are using the signatures of the handler routines to setup the native call interface.

Supported signals

row-changed

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

method handler (
  N-GObject $path,
  N-GtkTreeIter $iter,
  Int :$_handler_id,
  Gnome::GObject::Object :_widget($tree_model),
  *%user-options
);

  • Gnome::Gtk3::TreeModel $tree_model; the model on which the signal is emitted

  • N-GObject $path; a native Gnome::Gtk3::TreePath identifying the changed row

  • N-GtkTreeIter $iter; a native Gnome::Gtk3::TreeIter pointing to the changed row

row-deleted

This signal is emitted when a row in the model is deleted.

method handler (
  N-GObject $path,
  Int :$_handler_id,
  Gnome::GObject::Object :_widget($tree_model),
  *%user-options
);

  • Gnome::Gtk3::TreeModel $tree_model; the model on which the signal is emitted.

  • N-GObject $path; a native Gnome::Gtk3::TreePath identifying where the deleted row has been at. This path may not be a valid location anymore.

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-GObject $path,
  N-GtkTreeIter $iter,
  Int :$_handler_id,
  Gnome::GObject::Object :_widget($tree_model),
  *%user-options
);

  • Gnome::Gtk3::TreeModel $tree_model; the model on which the signal is emitted

  • $path; a native Gnome::Gtk3::TreePath identifying the new row

  • $iter; a native Gnome::Gtk3::TreeIter pointing to the new row

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-GObject $path,
  N-GtkTreeIter $iter,
  Int :$_handler_id,
  Gnome::GObject::Object :_widget($tree_model),
  *%user-options
);

  • Gnome::Gtk3::TreeModel $tree_model; the model on which the signal is emitted

  • $path; a native Gnome::Gtk3::TreePath identifying the new row

  • $iter; a native Gnome::Gtk3::TreeIter pointing to the new row

rows-reordered

This signal is emitted when the children of a node in the GtkTreeModel 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-GObject $path,
  N-GtkTreeIter $iter,
  CArray[int32] $new-order,
  Int :$_handler_id,
  Gnome::GObject::Object :_widget($tree_model),
  *%user-options
);

  • Gnome::Gtk3::TreeModel $tree_model; the model on which the signal is emitted

  • $path; a native Gnome::Gtk3::TreePath identifying the new row

  • $iter; a native Gnome::Gtk3::TreeIter pointing to the new row

  • $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.