gtk2/gtk/gtkselectionmodel.c
Matthias Clasen 53a9b7f6c0 selection model: Further documentation tweaks
Reword this to use plain language instead of throwing
arond reentrancy and ordering.
2020-06-03 07:51:29 -04:00

389 lines
13 KiB
C

/*
* Copyright © 2018 Benjamin Otte
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see <http://www.gnu.org/licenses/>.
*
* Authors: Benjamin Otte <otte@gnome.org>
*/
#include "config.h"
#include "gtkselectionmodel.h"
#include "gtkintl.h"
#include "gtkmarshalers.h"
/**
* SECTION:gtkselectionmodel
* @Title: GtkSelectionModel
* @Short_description: An extension of the list model interface that handles selections
* @See_also: #GListModel, #GtkSingleSelection
*
* #GtkSelectionModel is an interface that extends the #GListModel interface by adding
* support for selections. 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 mode common selection modes such as
* #GtkSingleSelection, 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 gtk_selection_model_is_selected(). When the selected
* state of one or more items changes, the model will emit the
* #GtkSelectionModel::selection-changed signal by calling the
* gtk_selection_model_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 #GListModel::items-changed signal are selected
* or not is up to the implementation.
*
* Note that items added via #GListModel::items-changed may already be selected
* and no #GtkSelectionModel::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.
*/
G_DEFINE_INTERFACE (GtkSelectionModel, gtk_selection_model, G_TYPE_LIST_MODEL)
enum {
SELECTION_CHANGED,
LAST_SIGNAL
};
static guint signals[LAST_SIGNAL] = { 0 };
static gboolean
gtk_selection_model_default_is_selected (GtkSelectionModel *model,
guint position)
{
return FALSE;
}
static gboolean
gtk_selection_model_default_select_item (GtkSelectionModel *model,
guint position,
gboolean exclusive)
{
return FALSE;
}
static gboolean
gtk_selection_model_default_unselect_item (GtkSelectionModel *model,
guint position)
{
return FALSE;
}
static gboolean
gtk_selection_model_default_select_range (GtkSelectionModel *model,
guint position,
guint n_items,
gboolean exclusive)
{
return FALSE;
}
static gboolean
gtk_selection_model_default_unselect_range (GtkSelectionModel *model,
guint position,
guint n_items)
{
return FALSE;
}
static gboolean
gtk_selection_model_default_select_all (GtkSelectionModel *model)
{
return gtk_selection_model_select_range (model, 0, g_list_model_get_n_items (G_LIST_MODEL (model)), FALSE);
}
static gboolean
gtk_selection_model_default_unselect_all (GtkSelectionModel *model)
{
return gtk_selection_model_unselect_range (model, 0, g_list_model_get_n_items (G_LIST_MODEL (model)));
}
static void
gtk_selection_model_default_query_range (GtkSelectionModel *model,
guint position,
guint *start_range,
guint *n_items,
gboolean *selected)
{
*start_range = position;
if (position >= g_list_model_get_n_items (G_LIST_MODEL (model)))
{
*n_items = 0;
*selected = FALSE;
}
else
{
*n_items = 1;
*selected = gtk_selection_model_is_selected (model, position);
}
}
static void
gtk_selection_model_default_init (GtkSelectionModelInterface *iface)
{
iface->is_selected = gtk_selection_model_default_is_selected;
iface->select_item = gtk_selection_model_default_select_item;
iface->unselect_item = gtk_selection_model_default_unselect_item;
iface->select_range = gtk_selection_model_default_select_range;
iface->unselect_range = gtk_selection_model_default_unselect_range;
iface->select_all = gtk_selection_model_default_select_all;
iface->unselect_all = gtk_selection_model_default_unselect_all;
iface->query_range = gtk_selection_model_default_query_range;
/**
* GtkSelectionModel::selection-changed
* @model: a #GtkSelectionModel
* @position: The first item that may have changed
* @n_items: number of items with changes
*
* 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.
*/
signals[SELECTION_CHANGED] =
g_signal_new ("selection-changed",
GTK_TYPE_SELECTION_MODEL,
G_SIGNAL_RUN_LAST,
0,
NULL, NULL,
_gtk_marshal_VOID__UINT_UINT,
G_TYPE_NONE, 2, G_TYPE_UINT, G_TYPE_UINT);
g_signal_set_va_marshaller (signals[SELECTION_CHANGED],
GTK_TYPE_SELECTION_MODEL,
_gtk_marshal_VOID__UINT_UINTv);
}
/**
* gtk_selection_model_is_selected:
* @model: a #GtkSelectionModel
* @position: the position of the item to query
*
* Checks if the given item is selected.
*
* Returns: %TRUE if the item is selected
**/
gboolean
gtk_selection_model_is_selected (GtkSelectionModel *model,
guint position)
{
GtkSelectionModelInterface *iface;
g_return_val_if_fail (GTK_IS_SELECTION_MODEL (model), 0);
iface = GTK_SELECTION_MODEL_GET_IFACE (model);
return iface->is_selected (model, position);
}
/**
* gtk_selection_model_select_item:
* @model: a #GtkSelectionModel
* @position: the position of the item to select
* @exclusive: whether previously selected items should be unselected
*
* Requests to select an item in the model.
*/
gboolean
gtk_selection_model_select_item (GtkSelectionModel *model,
guint position,
gboolean exclusive)
{
GtkSelectionModelInterface *iface;
g_return_val_if_fail (GTK_IS_SELECTION_MODEL (model), 0);
iface = GTK_SELECTION_MODEL_GET_IFACE (model);
return iface->select_item (model, position, exclusive);
}
/**
* gtk_selection_model_unselect_item:
* @model: a #GtkSelectionModel
* @position: the position of the item to unselect
*
* Requests to unselect an item in the model.
*/
gboolean
gtk_selection_model_unselect_item (GtkSelectionModel *model,
guint position)
{
GtkSelectionModelInterface *iface;
g_return_val_if_fail (GTK_IS_SELECTION_MODEL (model), 0);
iface = GTK_SELECTION_MODEL_GET_IFACE (model);
return iface->unselect_item (model, position);
}
/**
* gtk_selection_model_select_range:
* @model: a #GtkSelectionModel
* @position: the first item to select
* @n_items: the number of items to select
* @exclusive: whether previously selected items should be unselected
*
* Requests to select a range of items in the model.
*/
gboolean
gtk_selection_model_select_range (GtkSelectionModel *model,
guint position,
guint n_items,
gboolean exclusive)
{
GtkSelectionModelInterface *iface;
g_return_val_if_fail (GTK_IS_SELECTION_MODEL (model), 0);
iface = GTK_SELECTION_MODEL_GET_IFACE (model);
return iface->select_range (model, position, n_items, exclusive);
}
/**
* gtk_selection_model_unselect_range:
* @model: a #GtkSelectionModel
* @position: the first item to unselect
* @n_items: the number of items to unselect
*
* Requests to unselect a range of items in the model.
*/
gboolean
gtk_selection_model_unselect_range (GtkSelectionModel *model,
guint position,
guint n_items)
{
GtkSelectionModelInterface *iface;
g_return_val_if_fail (GTK_IS_SELECTION_MODEL (model), 0);
iface = GTK_SELECTION_MODEL_GET_IFACE (model);
return iface->unselect_range (model, position, n_items);
}
/**
* gtk_selection_model_select_all:
* @model: a #GtkSelectionModel
*
* Requests to select all items in the model.
*/
gboolean
gtk_selection_model_select_all (GtkSelectionModel *model)
{
GtkSelectionModelInterface *iface;
g_return_val_if_fail (GTK_IS_SELECTION_MODEL (model), 0);
iface = GTK_SELECTION_MODEL_GET_IFACE (model);
return iface->select_all (model);
}
/**
* gtk_selection_model_unselect_all:
* @model: a #GtkSelectionModel
*
* Requests to unselect all items in the model.
*/
gboolean
gtk_selection_model_unselect_all (GtkSelectionModel *model)
{
GtkSelectionModelInterface *iface;
g_return_val_if_fail (GTK_IS_SELECTION_MODEL (model), 0);
iface = GTK_SELECTION_MODEL_GET_IFACE (model);
return iface->unselect_all (model);
}
/**
* gtk_selection_model_query_range:
* @model: a #GtkSelectionModel
* @position: the position inside the range
* @start_range: (out): returns the position of the first element of the range
* @n_items: (out): returns the size of the range
* @selected: (out): returns whether items in @range are selected
*
* This function allows to query the selection status of multiple elements at once.
* It is passed a position and returns a range of elements of uniform selection status.
*
* If @position is greater than the number of items in @model, @n_items is set to 0.
* Otherwise the returned range is guaranteed to include the passed-in position, so
* @n_items will be >= 1.
*
* Positions directly adjacent to the returned range may have the same selection
* status as the returned range.
*
* This is an optimization function to make iterating over a model faster when few
* items are selected. However, it is valid behavior for implementations to use a
* naive implementation that only ever returns a single element.
*/
void
gtk_selection_model_query_range (GtkSelectionModel *model,
guint position,
guint *start_range,
guint *n_items,
gboolean *selected)
{
GtkSelectionModelInterface *iface;
g_return_if_fail (GTK_IS_SELECTION_MODEL (model));
g_return_if_fail (start_range != NULL);
g_return_if_fail (n_items != NULL);
g_return_if_fail (selected != NULL);
iface = GTK_SELECTION_MODEL_GET_IFACE (model);
return iface->query_range (model, position, start_range, n_items, selected);
}
/**
* gtk_selection_model_selection_changed:
* @model: a #GtkSelectionModel
* @position: the first changed item
* @n_items: the number of changed items
*
* Helper function for implementations of #GtkSelectionModel.
* Call this when a the selection changes to emit the ::selection-changed
* signal.
*/
void
gtk_selection_model_selection_changed (GtkSelectionModel *model,
guint position,
guint n_items)
{
g_return_if_fail (GTK_IS_SELECTION_MODEL (model));
g_return_if_fail (n_items > 0);
g_return_if_fail (position + n_items <= g_list_model_get_n_items (G_LIST_MODEL (model)));
g_signal_emit (model, signals[SELECTION_CHANGED], 0, position, n_items);
}