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GtkTreeView drag-and-drop

GtkTreeView drag-and-drop — Interfaces for drag-and-drop support in GtkTreeView

Synopsis


#include <gtk/gtk.h>


            GtkTreeDragSource;
            GtkTreeDragSourceIface;
gboolean    gtk_tree_drag_source_drag_data_delete
                                            (GtkTreeDragSource *drag_source,
                                             GtkTreePath *path);
gboolean    gtk_tree_drag_source_drag_data_get
                                            (GtkTreeDragSource *drag_source,
                                             GtkTreePath *path,
                                             GtkSelectionData *selection_data);
gboolean    gtk_tree_drag_source_row_draggable
                                            (GtkTreeDragSource *drag_source,
                                             GtkTreePath *path);
            GtkTreeDragDest;
            GtkTreeDragDestIface;
gboolean    gtk_tree_drag_dest_drag_data_received
                                            (GtkTreeDragDest *drag_dest,
                                             GtkTreePath *dest,
                                             GtkSelectionData *selection_data);
gboolean    gtk_tree_drag_dest_row_drop_possible
                                            (GtkTreeDragDest *drag_dest,
                                             GtkTreePath *dest_path,
                                             GtkSelectionData *selection_data);
gboolean    gtk_tree_set_row_drag_data      (GtkSelectionData *selection_data,
                                             GtkTreeModel *tree_model,
                                             GtkTreePath *path);
gboolean    gtk_tree_get_row_drag_data      (GtkSelectionData *selection_data,
                                             GtkTreeModel **tree_model,
                                             GtkTreePath **path);


Object Hierarchy


  GInterface
   +----GtkTreeDragSource

  GInterface
   +----GtkTreeDragDest

Known Implementations

GtkTreeDragSource is implemented by GtkTreeModelSort, GtkTreeStore, GtkListStore and GtkTreeModelFilter.

GtkTreeDragDest is implemented by GtkTreeStore and GtkListStore.

Description

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.

Details

GtkTreeDragSource

typedef struct _GtkTreeDragSource GtkTreeDragSource;


GtkTreeDragSourceIface

typedef struct {
  GTypeInterface g_iface;

  /* VTable - not signals */

  gboolean     (* row_draggable)        (GtkTreeDragSource   *drag_source,
                                         GtkTreePath         *path);

  gboolean     (* drag_data_get)        (GtkTreeDragSource   *drag_source,
                                         GtkTreePath         *path,
                                         GtkSelectionData    *selection_data);

  gboolean     (* drag_data_delete)     (GtkTreeDragSource *drag_source,
                                         GtkTreePath       *path);
} GtkTreeDragSourceIface;


gtk_tree_drag_source_drag_data_delete ()

gboolean    gtk_tree_drag_source_drag_data_delete
                                            (GtkTreeDragSource *drag_source,
                                             GtkTreePath *path);

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!

drag_source : a GtkTreeDragSource
path : row that was being dragged
Returns : TRUE if the row was successfully deleted

gtk_tree_drag_source_drag_data_get ()

gboolean    gtk_tree_drag_source_drag_data_get
                                            (GtkTreeDragSource *drag_source,
                                             GtkTreePath *path,
                                             GtkSelectionData *selection_data);

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!

drag_source : a GtkTreeDragSource
path : row that was dragged
selection_data : a GtkSelectionData to fill with data from the dragged row
Returns : TRUE if data of the required type was provided

gtk_tree_drag_source_row_draggable ()

gboolean    gtk_tree_drag_source_row_draggable
                                            (GtkTreeDragSource *drag_source,
                                             GtkTreePath *path);

Asks the GtkTreeDragSource whether a particular row can be used as the source of a DND operation. If the source doesn't implement this interface, the row is assumed draggable.

drag_source : a GtkTreeDragSource
path : row on which user is initiating a drag
Returns : TRUE if the row can be dragged

GtkTreeDragDest

typedef struct _GtkTreeDragDest GtkTreeDragDest;


GtkTreeDragDestIface

typedef struct {
  GTypeInterface g_iface;

  /* VTable - not signals */

  gboolean     (* drag_data_received) (GtkTreeDragDest   *drag_dest,
                                       GtkTreePath       *dest,
                                       GtkSelectionData  *selection_data);

  gboolean     (* row_drop_possible)  (GtkTreeDragDest   *drag_dest,
                                       GtkTreePath       *dest_path,
				       GtkSelectionData  *selection_data);
} GtkTreeDragDestIface;


gtk_tree_drag_dest_drag_data_received ()

gboolean    gtk_tree_drag_dest_drag_data_received
                                            (GtkTreeDragDest *drag_dest,
                                             GtkTreePath *dest,
                                             GtkSelectionData *selection_data);

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!

drag_dest : a GtkTreeDragDest
dest : row to drop in front of
selection_data : data to drop
Returns : whether a new row was created before position dest

gtk_tree_drag_dest_row_drop_possible ()

gboolean    gtk_tree_drag_dest_row_drop_possible
                                            (GtkTreeDragDest *drag_dest,
                                             GtkTreePath *dest_path,
                                             GtkSelectionData *selection_data);

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 doesn't exist, though.

drag_dest : a GtkTreeDragDest
dest_path : destination row
selection_data : the data being dragged
Returns : TRUE if a drop is possible before dest_path

gtk_tree_set_row_drag_data ()

gboolean    gtk_tree_set_row_drag_data      (GtkSelectionData *selection_data,
                                             GtkTreeModel *tree_model,
                                             GtkTreePath *path);

Sets selection data of target type GTK_TREE_MODEL_ROW. Normally used in a drag_data_get handler.

selection_data : some GtkSelectionData
tree_model : a GtkTreeModel
path : a row in tree_model
Returns : TRUE if the GtkSelectionData had the proper target type to allow us to set a tree row

gtk_tree_get_row_drag_data ()

gboolean    gtk_tree_get_row_drag_data      (GtkSelectionData *selection_data,
                                             GtkTreeModel **tree_model,
                                             GtkTreePath **path);

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 that's calling this function, because a pointer to the tree model is being passed around. If you aren't 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().

selection_data : a GtkSelectionData
tree_model : a GtkTreeModel
path : row in tree_model
Returns : TRUE if selection_data had target type GTK_TREE_MODEL_ROW and is otherwise valid