Method

GtkWidgetdrag_dest_set

Declaration [src]

void
gtk_drag_dest_set (
  GtkWidget* widget,
  GtkDestDefaults flags,
  const GtkTargetEntry* targets,
  gint n_targets,
  GdkDragAction actions
)

Description [src]

Sets a widget as a potential drop destination, and adds default behaviors.

The default behaviors listed in flags have an effect similar to installing default handlers for the widget’s drag-and-drop signals (GtkWidget::drag-motion, GtkWidget::drag-drop, …). They all exist for convenience. When passing #GTK_DEST_DEFAULT_ALL for instance it is sufficient to connect to the widget’s GtkWidget::drag-data-received signal to get primitive, but consistent drag-and-drop support.

Things become more complicated when you try to preview the dragged data, as described in the documentation for GtkWidget::drag-motion. The default behaviors described by flags make some assumptions, that can conflict with your own signal handlers. For instance #GTK_DEST_DEFAULT_DROP causes invokations of gdk_drag_status() in the context of GtkWidget::drag-motion, and invokations of gtk_drag_finish() in GtkWidget::drag-data-received. Especially the later is dramatic, when your own GtkWidget::drag-motion handler calls gtk_drag_get_data() to inspect the dragged data.

There’s no way to set a default action here, you can use the GtkWidget::drag-motion callback for that. Here’s an example which selects the action to use depending on whether the control key is pressed or not:

static void
drag_motion (GtkWidget *widget,
             GdkDragContext *context,
             gint x,
             gint y,
             guint time)
{
  GdkModifierType mask;

  gdk_window_get_pointer (gtk_widget_get_window (widget),
                          NULL, NULL, &mask);
  if (mask & GDK_CONTROL_MASK)
    gdk_drag_status (context, GDK_ACTION_COPY, time);
  else
    gdk_drag_status (context, GDK_ACTION_MOVE, time);
}

Parameters

flags GtkDestDefaults
 

Which types of default drag behavior to use.

targets An array of GtkTargetEntry
 

A pointer to an array of GtkTargetEntrys indicating the drop types that this widget will accept, or NULL. Later you can access the list with gtk_drag_dest_get_target_list() and gtk_drag_dest_find_target().

 The argument can be NULL.
 The length of the array is specified in the n_targets argument.
 The data is owned by the caller of the function.
n_targets gint
 

The number of entries in targets.

actions GdkDragAction
 

A bitmask of possible actions for a drop onto this widget.