Interface SelectionModel<T extends GObject>

All Superinterfaces:
Collection<T>, Iterable<T>, List<T>, ListModel<T>, ListModelJavaList<T>, Proxy, SequencedCollection<T>
All Known Implementing Classes:
MultiSelection, NoSelection, SelectionModel.SelectionModel$Impl, SingleSelection, ViewStackPages
@Generated("org.javagi.JavaGI") public interface SelectionModel<T extends GObject> extends Proxy, ListModel<T>

An interface that adds 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 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 isSelected(int). When the selected state of one or more items changes, the model will emit the Gtk.SelectionModel::selection-changed signal by calling the selectionChanged(int, int) 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 Gio.ListModel::items-changed signal are selected or not is up to the implementation.

Note that items added via Gio.ListModel::items-changed may already be selected and no Gtk.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.

  • Method Details

    • getType

      static @Nullable Type getType()
      Get the GType of the SelectionModel class.
      Returns:
      the GType

    • getSelection

      default Bitset getSelection()

      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 isSelected(int) or if you are only interested in a few, consider getSelectionInRange(int, int).

      Returns:
      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.

    • getSelectionInRange

      default Bitset getSelectionInRange(int position, int nItems)

      Gets the set of selected items in a range.

      This function is an optimization for getSelection() when you are only interested in part of the model's selected state. A common use case is in response to the Gtk.SelectionModel::selection-changed signal.

      Parameters:
      position - start of the queried range
      nItems - number of items in the queried range
      Returns:
      A GtkBitset that matches the selection state for the given range with all other values being undefined. The bitset must not be modified.

    • isSelected

      default boolean isSelected(int position)
      Checks if the given item is selected.
      Parameters:
      position - the position of the item to query
      Returns:
      true if the item is selected

    • selectAll

      default boolean selectAll()
      Requests to select all items in the model.
      Returns:
      true if this action was supported and no fallback should be tried. This does not mean that all items are now selected.

    • selectItem

      default boolean selectItem(int position, boolean unselectRest)
      Requests to select an item in the model.
      Parameters:
      position - the position of the item to select
      unselectRest - whether previously selected items should be unselected
      Returns:
      true if this action was supported and no fallback should be tried. This does not mean the item was selected.

    • selectRange

      default boolean selectRange(int position, int nItems, boolean unselectRest)
      Requests to select a range of items in the model.
      Parameters:
      position - the first item to select
      nItems - the number of items to select
      unselectRest - whether previously selected items should be unselected
      Returns:
      true if this action was supported and no fallback should be tried. This does not mean the range was selected.

    • selectionChanged

      default void selectionChanged(int position, int nItems)

      Helper function for implementations of GtkSelectionModel.

      Call this when the selection changes to emit the Gtk.SelectionModel::selection-changed signal.

      Parameters:
      position - the first changed item
      nItems - the number of changed items

    • setSelection

      default boolean setSelection(Bitset selected, Bitset mask)

      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 - bitmask specifying if items should be selected or unselected
      mask - bitmask specifying which items should be updated
      Returns:
      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.

    • unselectAll

      default boolean unselectAll()
      Requests to unselect all items in the model.
      Returns:
      true if this action was supported and no fallback should be tried. This does not mean that all items are now unselected.

    • unselectItem

      default boolean unselectItem(int position)
      Requests to unselect an item in the model.
      Parameters:
      position - the position of the item to unselect
      Returns:
      true if this action was supported and no fallback should be tried. This does not mean the item was unselected.

    • unselectRange

      default boolean unselectRange(int position, int nItems)
      Requests to unselect a range of items in the model.
      Parameters:
      position - the first item to unselect
      nItems - the number of items to unselect
      Returns:
      true if this action was supported and no fallback should be tried. This does not mean the range was unselected.

    • onSelectionChanged

      default SignalConnection<SelectionModel.SelectionChangedCallback> onSelectionChanged(SelectionModel.SelectionChangedCallback handler)

      Emitted when the selection state of some of the items in model changes.

      Note that this signal does not specify the new selection state of the items, they need to be queried manually. It is also not necessary for a model to change the selection state of any of the items in the selection model, though it would be rather useless to emit such a signal.

      Parameters:
      handler - the signal handler
      Returns:
      a signal handler ID to keep track of the signal connection
      See Also:

    • emitSelectionChanged

      default void emitSelectionChanged(int position, int nItems)
      Emits the "selection-changed" signal. See onSelectionChanged(SelectionModel.SelectionChangedCallback).