SelectionModel

class SelectionModel(*args, **kwargs)

Implementations: MultiSelection, NoSelection, SingleSelection

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 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 is_selected. When the selected state of one or more items changes, the model will emit the selection_changed signal by calling the 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 items_changed signal are selected or not is up to the implementation.

Note that items added via items_changed may already be selected and no 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, GtkSelectionModel’s 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.

Methods

class SelectionModel

get_selection() → 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 is_selected or if you are only interested in a few, consider get_selection_in_range.

get_selection_in_range(position: int, n_items: int) → Bitset

Gets the set of selected items in a range.

This function is an optimization for get_selection when you are only interested in part of the model’s selected state. A common use case is in response to the selection_changed signal.

Parameters:

position – start of the queried range
n_items – number of items in the queried range

is_selected(position: int) → bool

Checks if the given item is selected.

Parameters:: position – the position of the item to query

select_all() → bool: Requests to select all items in the model.

select_item(position: int, unselect_rest: bool) → bool

Requests to select an item in the model.

Parameters:

position – the position of the item to select
unselect_rest – whether previously selected items should be unselected

select_range(position: int, n_items: int, unselect_rest: bool) → bool

Requests to select a range of items in the model.

Parameters:

position – the first item to select
n_items – the number of items to select
unselect_rest – whether previously selected items should be unselected

selection_changed(position: int, n_items: int) → None

Helper function for implementations of GtkSelectionModel.

Call this when the selection changes to emit the selection_changed signal.

Parameters:

position – the first changed item
n_items – the number of changed items

set_selection(selected: Bitset, mask: Bitset) → bool

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

unselect_all() → bool: Requests to unselect all items in the model.

unselect_item(position: int) → bool

Requests to unselect an item in the model.

Parameters:: position – the position of the item to unselect

unselect_range(position: int, n_items: int) → bool

Requests to unselect a range of items in the model.

Parameters:

position – the first item to unselect
n_items – the number of items to unselect

Signals

class SelectionModel.signals

selection_changed(position: int, n_items: int) → None

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:

position – The first item that may have changed
n_items – number of items with changes

Virtual Methods

class SelectionModel

do_get_selection_in_range(position: int, n_items: int) → Bitset

Gets the set of selected items in a range.

This function is an optimization for get_selection when you are only interested in part of the model’s selected state. A common use case is in response to the selection_changed signal.

Parameters:

position – start of the queried range
n_items – number of items in the queried range

do_is_selected(position: int) → bool

Checks if the given item is selected.

Parameters:: position – the position of the item to query

do_select_all() → bool: Requests to select all items in the model.

do_select_item(position: int, unselect_rest: bool) → bool

Requests to select an item in the model.

Parameters:

position – the position of the item to select
unselect_rest – whether previously selected items should be unselected

do_select_range(position: int, n_items: int, unselect_rest: bool) → bool

Requests to select a range of items in the model.

Parameters:

position – the first item to select
n_items – the number of items to select
unselect_rest – whether previously selected items should be unselected

do_set_selection(selected: Bitset, mask: Bitset) → bool

Make selection changes.

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

do_unselect_all() → bool: Requests to unselect all items in the model.

do_unselect_item(position: int) → bool

Requests to unselect an item in the model.

Parameters:: position – the position of the item to unselect

do_unselect_range(position: int, n_items: int) → bool

Requests to unselect a range of items in the model.

Parameters:

position – the first item to unselect
n_items – the number of items to unselect