Module: Gtk::SelectionModel

Defined in:
(unknown)

Overview

GtkSelectionModel is an interface that add support for selection to list models.

This support is then used by widgets using list models to add the ability
to select and unselect various items.

GTK provides default implementations of the most common selection modes such
as [classGtk.SingleSelection], so you will only need to implement this
interface if you want detailed control about how selections should be handled.

A GtkSelectionModel supports a single boolean per item indicating if an item is
selected or not. This can be queried via [methodGtk.SelectionModel.is_selected].
When the selected state of one or more items changes, the model will emit the
[signalGtk.SelectionModel::selection-changed] signal by calling the
[methodGtk.SelectionModel.selection_changed] function. The positions given
in that signal may have their selection state changed, though that is not a
requirement. If new items added to the model via the
[signalGio.ListModel::items-changed] signal are selected or not is up to the
implementation.

Note that items added via [signalGio.ListModel::items-changed] may already
be selected and no [signalGtk.SelectionModel::selection-changed] will be
emitted for them. So to track which items are selected, it is necessary to
listen to both signals.

Additionally, the interface can expose functionality to select and unselect
items. If these functions are implemented, GTK's list widgets will allow users
to select and unselect items. However, GtkSelectionModels are free to only
implement them partially or not at all. In that case the widgets will not
support the unimplemented operations.

When selecting or unselecting is supported by a model, the return values of
the selection functions do not indicate if selection or unselection happened.
They are only meant to indicate complete failure, like when this mode of
selecting is not supported by the model.

Selections may happen asynchronously, so the only reliable way to find out
when an item was selected is to listen to the signals that indicate selection.

Instance Method Summary collapse

Instance Method Details

#get_selection_in_range(position, n_items) ⇒ Gtk::Bitset

Gets the set of selected items in a range.

This function is an optimization for
[methodGtk.SelectionModel.get_selection] when you are only
interested in part of the model's selected state. A common use
case is in response to the [signalGtk.SelectionModel::selection-changed]
signal.

Parameters:

  • position (Integer) —

    start of the queried range

  • n_items (Integer) —

    number of items in the queried range

Returns:

  • (Gtk::Bitset) —

    A GtkBitset that matches the selection state
    for the given range with all other values being undefined.
    The bitset must not be modified.

#is_selected(position) ⇒ Boolean

Checks if the given item is selected.

Parameters:

  • position (Integer) —

    the position of the item to query

Returns:

  • (Boolean) —

    true if the item is selected

#select_all ⇒ Boolean

Requests to select all items in the model.

Returns:

  • (Boolean) —

    true if this action was supported and no fallback should be
    tried. This does not mean that all items are now selected.

#select_item(position, unselect_rest) ⇒ Boolean

Requests to select an item in the model.

Parameters:

  • position (Integer) —

    the position of the item to select

  • unselect_rest (Boolean) —

    whether previously selected items should be unselected

Returns:

  • (Boolean) —

    true if this action was supported and no fallback should be
    tried. This does not mean the item was selected.

#select_range(position, n_items, unselect_rest) ⇒ Boolean

Requests to select a range of items in the model.

Parameters:

  • position (Integer) —

    the first item to select

  • n_items (Integer) —

    the number of items to select

  • unselect_rest (Boolean) —

    whether previously selected items should be unselected

Returns:

  • (Boolean) —

    true if this action was supported and no fallback should be
    tried. This does not mean the range was selected.

#selection ⇒ Gtk::Bitset

Gets the set containing all currently selected items in the model.

This function may be slow, so if you are only interested in single item,
consider using [methodGtk.SelectionModel.is_selected] or if you are only
interested in a few, consider [methodGtk.SelectionModel.get_selection_in_range].

Returns:

  • (Gtk::Bitset) —

    a GtkBitset containing all the values currently
    selected in model. If no items are selected, the bitset is empty.
    The bitset must not be modified.

#selection_changed(position, n_items) ⇒ nil

Helper function for implementations of GtkSelectionModel.

Call this when the selection changes to emit the
[signalGtk.SelectionModel::selection-changed] signal.

Parameters:

  • position (Integer) —

    the first changed item

  • n_items (Integer) —

    the number of changed items

Returns:

  • (nil)

#set_selection(selected, mask) ⇒ Boolean

Make selection changes.

This is the most advanced selection updating method that allows
the most fine-grained control over selection changes. If you can,
you should try the simpler versions, as implementations are more
likely to implement support for those.

Requests that the selection state of all positions set in mask
be updated to the respective value in the selected bitmask.

In pseudocode, it would look something like this:

for (i = 0; i < n_items; i++)
  {
    // don't change values not in the mask
    if (!gtk_bitset_contains (mask, i))
      continue;

    if (gtk_bitset_contains (selected, i))
      select_item (i);
    else
      unselect_item (i);
  }

gtk_selection_model_selection_changed (model,
                                       first_changed_item,
                                       n_changed_items);

mask and selected must not be modified. They may refer to the
same bitset, which would mean that every item in the set should
be selected.

Parameters:

  • selected (Gtk::Bitset) —

    bitmask specifying if items should be selected or unselected

  • mask (Gtk::Bitset) —

    bitmask specifying which items should be updated

Returns:

  • (Boolean) —

    true if this action was supported and no fallback should be
    tried. This does not mean that all items were updated according
    to the inputs.

#unselect_all ⇒ Boolean

Requests to unselect all items in the model.

Returns:

  • (Boolean) —

    true if this action was supported and no fallback should be
    tried. This does not mean that all items are now unselected.

#unselect_item(position) ⇒ Boolean

Requests to unselect an item in the model.

Parameters:

  • position (Integer) —

    the position of the item to unselect

Returns:

  • (Boolean) —

    true if this action was supported and no fallback should be
    tried. This does not mean the item was unselected.

#unselect_range(position, n_items) ⇒ Boolean

Requests to unselect a range of items in the model.

Parameters:

  • position (Integer) —

    the first item to unselect

  • n_items (Integer) —

    the number of items to unselect

Returns:

  • (Boolean) —

    true if this action was supported and no fallback should be
    tried. This does not mean the range was unselected.