Package org.gnome.gtk

Class DropTarget

java.lang.Object
io.github.jwharm.javagi.base.ProxyInstance
org.gnome.gobject.TypeInstance
org.gnome.gobject.GObject
org.gnome.gtk.EventController
org.gnome.gtk.DropTarget
All Implemented Interfaces:
Proxy
@Generated("io.github.jwharm.JavaGI") public class DropTarget extends EventController
GtkDropTarget is an event controller to receive Drag-and-Drop operations.

The most basic way to use a GtkDropTarget to receive drops on a widget is to create it via DropTarget(org.gnome.glib.Type, org.gnome.gdk.DragAction...), passing in the GType of the data you want to receive and connect to the Gtk.DropTarget::drop signal to receive the data: 

static gboolean
 on_drop (GtkDropTarget *target,
          const GValue  *value,
          double         x,
          double         y,
          gpointer       data)
 {
   MyWidget *self = data;

   // Call the appropriate setter depending on the type of data
   // that we received
   if (G_VALUE_HOLDS (value, G_TYPE_FILE))
     my_widget_set_file (self, g_value_get_object (value));
   else if (G_VALUE_HOLDS (value, GDK_TYPE_PIXBUF))
     my_widget_set_pixbuf (self, g_value_get_object (value));
   else
     return FALSE;

   return TRUE;
 }

 static void
 my_widget_init (MyWidget *self)
 {
   GtkDropTarget *target =
     gtk_drop_target_new (G_TYPE_INVALID, GDK_ACTION_COPY);

   // This widget accepts two types of drop types: GFile objects
   // and GdkPixbuf objects
   gtk_drop_target_set_gtypes (target, (GType [2]) {
     G_TYPE_FILE,
     GDK_TYPE_PIXBUF,
   }, 2);

   g_signal_connect (target, "drop", G_CALLBACK (on_drop), self);
   gtk_widget_add_controller (GTK_WIDGET (self), GTK_EVENT_CONTROLLER (target));
 }

GtkDropTarget supports more options, such as:

  • rejecting potential drops via the Gtk.DropTarget::accept signal and the reject() function to let other drop targets handle the drop
  • tracking an ongoing drag operation before the drop via the Gtk.DropTarget::enter, Gtk.DropTarget::motion and Gtk.DropTarget::leave signals
  • configuring how to receive data by setting the Gtk.DropTarget:preload property and listening for its availability via the Gtk.DropTarget:value property

However, GtkDropTarget is ultimately modeled in a synchronous way and only supports data transferred via GType. If you want full control over an ongoing drop, the DropTargetAsync object gives you this ability.

While a pointer is dragged over the drop target's widget and the drop has not been rejected, that widget will receive the StateFlags.DROP_ACTIVE state, which can be used to style the widget.

If you are not interested in receiving the drop, but just want to update UI state during a Drag-and-Drop operation (e.g. switching tabs), you can use DropControllerMotion.