gtk2/gtk/gtktreednd.c
2014-02-07 13:32:47 -05:00

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/* gtktreednd.c
* Copyright (C) 2001 Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library. If not, see <http://www.gnu.org/licenses/>.
*/
#include "config.h"
#include <string.h>
#include "gtktreednd.h"
#include "gtkintl.h"
/**
* SECTION:gtktreednd
* @Short_description: Interfaces for drag-and-drop support in GtkTreeView
* @Title: GtkTreeView drag-and-drop
*
* GTK+ supports Drag-and-Drop in tree views with a high-level and a low-level
* API.
*
* The low-level API consists of the GTK+ DND API, augmented by some treeview
* utility functions: gtk_tree_view_set_drag_dest_row(),
* gtk_tree_view_get_drag_dest_row(), gtk_tree_view_get_dest_row_at_pos(),
* gtk_tree_view_create_row_drag_icon(), gtk_tree_set_row_drag_data() and
* gtk_tree_get_row_drag_data(). This API leaves a lot of flexibility, but
* nothing is done automatically, and implementing advanced features like
* hover-to-open-rows or autoscrolling on top of this API is a lot of work.
*
* On the other hand, if you write to the high-level API, then all the
* bookkeeping of rows is done for you, as well as things like hover-to-open
* and auto-scroll, but your models have to implement the
* #GtkTreeDragSource and #GtkTreeDragDest interfaces.
*/
GType
gtk_tree_drag_source_get_type (void)
{
static GType our_type = 0;
if (!our_type)
{
const GTypeInfo our_info =
{
sizeof (GtkTreeDragSourceIface), /* class_size */
NULL, /* base_init */
NULL, /* base_finalize */
NULL,
NULL, /* class_finalize */
NULL, /* class_data */
0,
0, /* n_preallocs */
NULL
};
our_type = g_type_register_static (G_TYPE_INTERFACE,
I_("GtkTreeDragSource"),
&our_info, 0);
}
return our_type;
}
GType
gtk_tree_drag_dest_get_type (void)
{
static GType our_type = 0;
if (!our_type)
{
const GTypeInfo our_info =
{
sizeof (GtkTreeDragDestIface), /* class_size */
NULL, /* base_init */
NULL, /* base_finalize */
NULL,
NULL, /* class_finalize */
NULL, /* class_data */
0,
0, /* n_preallocs */
NULL
};
our_type = g_type_register_static (G_TYPE_INTERFACE, I_("GtkTreeDragDest"), &our_info, 0);
}
return our_type;
}
/**
* gtk_tree_drag_source_row_draggable:
* @drag_source: a #GtkTreeDragSource
* @path: row on which user is initiating a drag
*
* Asks the #GtkTreeDragSource whether a particular row can be used as
* the source of a DND operation. If the source doesnt implement
* this interface, the row is assumed draggable.
*
* Return value: %TRUE if the row can be dragged
**/
gboolean
gtk_tree_drag_source_row_draggable (GtkTreeDragSource *drag_source,
GtkTreePath *path)
{
GtkTreeDragSourceIface *iface = GTK_TREE_DRAG_SOURCE_GET_IFACE (drag_source);
g_return_val_if_fail (path != NULL, FALSE);
if (iface->row_draggable)
return (* iface->row_draggable) (drag_source, path);
else
return TRUE;
/* Returning TRUE if row_draggable is not implemented is a fallback.
Interface implementations such as GtkTreeStore and GtkListStore really should
implement row_draggable. */
}
/**
* gtk_tree_drag_source_drag_data_delete:
* @drag_source: a #GtkTreeDragSource
* @path: row that was being dragged
*
* Asks the #GtkTreeDragSource to delete the row at @path, because
* it was moved somewhere else via drag-and-drop. Returns %FALSE
* if the deletion fails because @path no longer exists, or for
* some model-specific reason. Should robustly handle a @path no
* longer found in the model!
*
* Return value: %TRUE if the row was successfully deleted
**/
gboolean
gtk_tree_drag_source_drag_data_delete (GtkTreeDragSource *drag_source,
GtkTreePath *path)
{
GtkTreeDragSourceIface *iface = GTK_TREE_DRAG_SOURCE_GET_IFACE (drag_source);
g_return_val_if_fail (iface->drag_data_delete != NULL, FALSE);
g_return_val_if_fail (path != NULL, FALSE);
return (* iface->drag_data_delete) (drag_source, path);
}
/**
* gtk_tree_drag_source_drag_data_get:
* @drag_source: a #GtkTreeDragSource
* @path: row that was dragged
* @selection_data: a #GtkSelectionData to fill with data
* from the dragged row
*
* Asks the #GtkTreeDragSource to fill in @selection_data with a
* representation of the row at @path. @selection_data->target gives
* the required type of the data. Should robustly handle a @path no
* longer found in the model!
*
* Return value: %TRUE if data of the required type was provided
**/
gboolean
gtk_tree_drag_source_drag_data_get (GtkTreeDragSource *drag_source,
GtkTreePath *path,
GtkSelectionData *selection_data)
{
GtkTreeDragSourceIface *iface = GTK_TREE_DRAG_SOURCE_GET_IFACE (drag_source);
g_return_val_if_fail (iface->drag_data_get != NULL, FALSE);
g_return_val_if_fail (path != NULL, FALSE);
g_return_val_if_fail (selection_data != NULL, FALSE);
return (* iface->drag_data_get) (drag_source, path, selection_data);
}
/**
* gtk_tree_drag_dest_drag_data_received:
* @drag_dest: a #GtkTreeDragDest
* @dest: row to drop in front of
* @selection_data: data to drop
*
* Asks the #GtkTreeDragDest to insert a row before the path @dest,
* deriving the contents of the row from @selection_data. If @dest is
* outside the tree so that inserting before it is impossible, %FALSE
* will be returned. Also, %FALSE may be returned if the new row is
* not created for some model-specific reason. Should robustly handle
* a @dest no longer found in the model!
*
* Return value: whether a new row was created before position @dest
**/
gboolean
gtk_tree_drag_dest_drag_data_received (GtkTreeDragDest *drag_dest,
GtkTreePath *dest,
GtkSelectionData *selection_data)
{
GtkTreeDragDestIface *iface = GTK_TREE_DRAG_DEST_GET_IFACE (drag_dest);
g_return_val_if_fail (iface->drag_data_received != NULL, FALSE);
g_return_val_if_fail (dest != NULL, FALSE);
g_return_val_if_fail (selection_data != NULL, FALSE);
return (* iface->drag_data_received) (drag_dest, dest, selection_data);
}
/**
* gtk_tree_drag_dest_row_drop_possible:
* @drag_dest: a #GtkTreeDragDest
* @dest_path: destination row
* @selection_data: the data being dragged
*
* Determines whether a drop is possible before the given @dest_path,
* at the same depth as @dest_path. i.e., can we drop the data in
* @selection_data at that location. @dest_path does not have to
* exist; the return value will almost certainly be %FALSE if the
* parent of @dest_path doesnt exist, though.
*
* Return value: %TRUE if a drop is possible before @dest_path
**/
gboolean
gtk_tree_drag_dest_row_drop_possible (GtkTreeDragDest *drag_dest,
GtkTreePath *dest_path,
GtkSelectionData *selection_data)
{
GtkTreeDragDestIface *iface = GTK_TREE_DRAG_DEST_GET_IFACE (drag_dest);
g_return_val_if_fail (iface->row_drop_possible != NULL, FALSE);
g_return_val_if_fail (selection_data != NULL, FALSE);
g_return_val_if_fail (dest_path != NULL, FALSE);
return (* iface->row_drop_possible) (drag_dest, dest_path, selection_data);
}
typedef struct _TreeRowData TreeRowData;
struct _TreeRowData
{
GtkTreeModel *model;
gchar path[4];
};
/**
* gtk_tree_set_row_drag_data:
* @selection_data: some #GtkSelectionData
* @tree_model: a #GtkTreeModel
* @path: a row in @tree_model
*
* Sets selection data of target type %GTK_TREE_MODEL_ROW. Normally used
* in a drag_data_get handler.
*
* Return value: %TRUE if the #GtkSelectionData had the proper target type to allow us to set a tree row
**/
gboolean
gtk_tree_set_row_drag_data (GtkSelectionData *selection_data,
GtkTreeModel *tree_model,
GtkTreePath *path)
{
TreeRowData *trd;
gchar *path_str;
gint len;
gint struct_size;
g_return_val_if_fail (selection_data != NULL, FALSE);
g_return_val_if_fail (GTK_IS_TREE_MODEL (tree_model), FALSE);
g_return_val_if_fail (path != NULL, FALSE);
if (gtk_selection_data_get_target (selection_data) != gdk_atom_intern_static_string ("GTK_TREE_MODEL_ROW"))
return FALSE;
path_str = gtk_tree_path_to_string (path);
len = strlen (path_str);
/* the old allocate-end-of-struct-to-hold-string trick */
struct_size = sizeof (TreeRowData) + len + 1 -
(sizeof (TreeRowData) - G_STRUCT_OFFSET (TreeRowData, path));
trd = g_malloc (struct_size);
strcpy (trd->path, path_str);
g_free (path_str);
trd->model = tree_model;
gtk_selection_data_set (selection_data,
gdk_atom_intern_static_string ("GTK_TREE_MODEL_ROW"),
8, /* bytes */
(void*)trd,
struct_size);
g_free (trd);
return TRUE;
}
/**
* gtk_tree_get_row_drag_data:
* @selection_data: a #GtkSelectionData
* @tree_model: (out): a #GtkTreeModel
* @path: (out): row in @tree_model
*
* Obtains a @tree_model and @path from selection data of target type
* %GTK_TREE_MODEL_ROW. Normally called from a drag_data_received handler.
* This function can only be used if @selection_data originates from the same
* process thats calling this function, because a pointer to the tree model
* is being passed around. If you arent in the same process, then you'll
* get memory corruption. In the #GtkTreeDragDest drag_data_received handler,
* you can assume that selection data of type %GTK_TREE_MODEL_ROW is
* in from the current process. The returned path must be freed with
* gtk_tree_path_free().
*
* Return value: %TRUE if @selection_data had target type %GTK_TREE_MODEL_ROW and
* is otherwise valid
**/
gboolean
gtk_tree_get_row_drag_data (GtkSelectionData *selection_data,
GtkTreeModel **tree_model,
GtkTreePath **path)
{
TreeRowData *trd;
g_return_val_if_fail (selection_data != NULL, FALSE);
if (tree_model)
*tree_model = NULL;
if (path)
*path = NULL;
if (gtk_selection_data_get_target (selection_data) != gdk_atom_intern_static_string ("GTK_TREE_MODEL_ROW"))
return FALSE;
if (gtk_selection_data_get_length (selection_data) < 0)
return FALSE;
trd = (void*) gtk_selection_data_get_data (selection_data);
if (tree_model)
*tree_model = trd->model;
if (path)
*path = gtk_tree_path_new_from_string (trd->path);
return TRUE;
}