DragSource

gtk.drag_source.DragSource is an event controller to initiate Drag-And-Drop operations.

gtk.drag_source.DragSource can be set up with the necessary ingredients for a DND operation ahead of time. This includes the source for the data that is being transferred, in the form of a gdk.content_provider.ContentProvider, the desired action, and the icon to use during the drag operation. After setting it up, the drag source must be added to a widget as an event controller, using gtk.widget.Widget.addController.

static void
my_widget_init (MyWidget *self)
{
  GtkDragSource *drag_source = gtk_drag_source_new ();

  g_signal_connect (drag_source, "prepare", G_CALLBACK (on_drag_prepare), self);
  g_signal_connect (drag_source, "drag-begin", G_CALLBACK (on_drag_begin), self);

  gtk_widget_add_controller (GTK_WIDGET (self), GTK_EVENT_CONTROLLER (drag_source));
}

Setting up the content provider and icon ahead of time only makes sense when the data does not change. More commonly, you will want to set them up just in time. To do so, gtk.drag_source.DragSource has gtk.drag_source.DragSource.prepare and signal@Gtk.DragSource::drag-begin signals.

The ::prepare signal is emitted before a drag is started, and can be used to set the content provider and actions that the drag should be started with.

static GdkContentProvider *
on_drag_prepare (GtkDragSource *source,
                 double         x,
                 double         y,
                 MyWidget      *self)
{
  // This widget supports two types of content: GFile objects
  // and GdkPixbuf objects; GTK will handle the serialization
  // of these types automatically
  GFile *file = my_widget_get_file (self);
  GdkPixbuf *pixbuf = my_widget_get_pixbuf (self);

  return gdk_content_provider_new_union ((GdkContentProvider *[2]) {
      gdk_content_provider_new_typed (G_TYPE_FILE, file),
      gdk_content_provider_new_typed (GDK_TYPE_PIXBUF, pixbuf),
    }, 2);
}

The ::drag-begin signal is emitted after the gdk.drag.Drag object has been created, and can be used to set up the drag icon.

static void
on_drag_begin (GtkDragSource *source,
               GdkDrag       *drag,
               MyWidget      *self)
{
  // Set the widget as the drag icon
  GdkPaintable *paintable = gtk_widget_paintable_new (GTK_WIDGET (self));
  gtk_drag_source_set_icon (source, paintable, 0, 0);
  g_object_unref (paintable);
}

During the DND operation, gtk.drag_source.DragSource emits signals that can be used to obtain updates about the status of the operation, but it is not normally necessary to connect to any signals, except for one case: when the supported actions include gdk.types.DragAction.Move, you need to listen for the signal@Gtk.DragSource::drag-end signal and delete the data after it has been transferred.

class DragSource : GestureSingle {

this();

void dragCancel();

gdk.types.DragAction getActions();

gdk.content_provider.ContentProvider getContent();

gdk.drag.Drag getDrag();

void setActions(gdk.types.DragAction actions);

void setContent(gdk.content_provider.ContentProvider content);

void setIcon(gdk.paintable.Paintable paintable, int hotX, int hotY);

ulong connectDragBegin(T callback, Flag!"After" after);

ulong connectDragCancel(T callback, Flag!"After" after);

ulong connectDragEnd(T callback, Flag!"After" after);

ulong connectPrepare(T callback, Flag!"After" after);

}

Constructors

this this(): Creates a new gtk.drag_source.DragSource object.

Members

Functions

connectDragBegin ulong connectDragBegin(T callback, Flag!"After" after): Connect to DragBegin signal.
connectDragCancel ulong connectDragCancel(T callback, Flag!"After" after): Connect to DragCancel signal.
connectDragEnd ulong connectDragEnd(T callback, Flag!"After" after): Connect to DragEnd signal.
connectPrepare ulong connectPrepare(T callback, Flag!"After" after): Connect to Prepare signal.
dragCancel void dragCancel(): Cancels a currently ongoing drag operation.
getActions gdk.types.DragAction getActions(): Gets the actions that are currently set on the gtk.drag_source.DragSource.
getContent gdk.content_provider.ContentProvider getContent(): Gets the current content provider of a gtk.drag_source.DragSource.
getDrag gdk.drag.Drag getDrag(): Returns the underlying gdk.drag.Drag object for an ongoing drag.
setActions void setActions(gdk.types.DragAction actions): Sets the actions on the gtk.drag_source.DragSource.
setContent void setContent(gdk.content_provider.ContentProvider content): Sets a content provider on a gtk.drag_source.DragSource.
setIcon void setIcon(gdk.paintable.Paintable paintable, int hotX, int hotY): Sets a paintable to use as icon during DND operations.

Inherited Members

From GestureSingle

getButton uint getButton(): Returns the button number gesture listens for.
getCurrentButton uint getCurrentButton(): Returns the button number currently interacting with gesture, or 0 if there is none.
getCurrentSequence gdk.event_sequence.EventSequence getCurrentSequence(): Returns the event sequence currently interacting with gesture.
getExclusive bool getExclusive(): Gets whether a gesture is exclusive.
getTouchOnly bool getTouchOnly(): Returns true if the gesture is only triggered by touch events.
setButton void setButton(uint button): Sets the button number gesture listens to.
setExclusive void setExclusive(bool exclusive): Sets whether gesture is exclusive.
setTouchOnly void setTouchOnly(bool touchOnly): Sets whether to handle only touch events.

gtk drag_source classes

DragSource