GtkTreeView drag-and-drop

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

## Functions

gboolean | gtk_tree_drag_source_drag_data_delete ()
gboolean | gtk_tree_drag_source_drag_data_get ()
gboolean | gtk_tree_drag_source_row_draggable ()
gboolean | gtk_tree_drag_dest_drag_data_received ()
gboolean | gtk_tree_drag_dest_row_drop_possible ()
gboolean | gtk_tree_set_row_drag_data ()
gboolean | gtk_tree_get_row_drag_data ()

## Types and Values

| GtkTreeDragSource
struct | GtkTreeDragSourceIface
| GtkTreeDragDest
struct | GtkTreeDragDestIface

## Object Hierarchy

        GInterface
        ├── GtkTreeDragDest
        ╰── GtkTreeDragSource

## Known Implementations

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

GtkTreeDragDest is implemented by GtkListStore and GtkTreeStore.

## Includes

    #include <gtk/gtk.h>

## 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.

## Functions

### 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!

#### Parameters

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!

#### Parameters

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.

#### Parameters

drag_source | a GtkTreeDragSource |
path | row on which user is initiating a drag |

#### Returns

`TRUE` if the row can be dragged

### 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!

#### Parameters

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.

#### Parameters

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.

#### Parameters

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()`.

#### Parameters

selection_data | a GtkSelectionData |
tree_model | a GtkTreeModel. | [nullable][optional][transfer none][out]
path | row in `tree_model` . | [nullable][optional][out]

#### Returns

`TRUE` if `selection_data` had target type `GTK_TREE_MODEL_ROW` and is otherwise valid

## Types and Values

### GtkTreeDragSource

    typedef struct _GtkTreeDragSource GtkTreeDragSource;

### struct GtkTreeDragSourceIface

    struct GtkTreeDragSourceIface {
      /* 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);
    };

#### Members

`row_draggable` () | Asks the GtkTreeDragSource whether a particular row can be used as the source of a DND operation. |
`drag_data_get` () | Asks the GtkTreeDragSource to fill in selection_data with a representation of the row at path. |
`drag_data_delete` () | Asks the GtkTreeDragSource to delete the row at path, because it was moved somewhere else via drag-and-drop. |

### GtkTreeDragDest

    typedef struct _GtkTreeDragDest GtkTreeDragDest;

### struct GtkTreeDragDestIface

    struct GtkTreeDragDestIface {
      /* 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);
    };

#### Members

`drag_data_received` () | Asks the GtkTreeDragDest to insert a row before the path dest, deriving the contents of the row from selection_data. |
`row_drop_possible` () | Determines whether a drop is possible before the given dest_path, at the same depth as dest_path. |