gtk2/docs/reference/gtk/tmpl/gtkdnd.sgml

<!-- ##### SECTION Title ##### -->
Drag and Drop

<!-- ##### SECTION Short_Description ##### -->
Functions for controlling drag and drop handling.

<!-- ##### SECTION Long_Description ##### -->
<para>
GTK+ has a rich set of functions for doing inter-process
communication via the drag-and-drop metaphore. GTK+
can do drag and drop (DND) via multiple protocols.
The currently supported protocols are the Xdnd and
Motif protocols.

As well as the functions listed here, applications
may need to use some facilities provided for
<link linkend="gtk-Selections">Selections</link>.
Also, the Drag and Drop API makes use of signals
in the #GtkWidget class.
</para>

<!-- ##### SECTION See_Also ##### -->
<para>

</para>

<!-- ##### ENUM GtkDestDefaults ##### -->
<para>
The #GtkDestfaults enumeration specifies the various
types of action that will be taken on behalf
of the user for a drag destination site.
</para>
<informaltable pgwide=1 frame="none" role="enum">
<tgroup cols="2"><colspec colwidth="2*"><colspec colwidth="8*">
<tbody>

<row>
<entry><symbol>GTK_DEST_DEFAULT_MOTION</symbol></entry>
<entry>
   If set for a widget, GTK+, during a drag over this
   widget will check if the drag matches this widget's
   list of possible targets and actions.
   GTK+ will then call gtk_drag_status() as appropriate.
</entry>
</row>

<row>
<entry><symbol>GTK_DEST_DEFAULT_HIGHLIGHT</symbol></entry>
<entry>
   If set for a widget, GTK+ will draw a highlight on
   this widget as long as a drag is over this widget
   and the wiget drag format and action is accetable.</entry>
</row>

<row>
<entry><symbol>GTK_DEST_DEFAULT_DROP</symbol></entry>
<entry>
   If set for a widget, when a drop occurs, GTK+ will
   will check if the drag matches this widget's
   list of possible targets and actions. If so, 
   GTK+ will call gtk_drag_data_get() on behalf 
   of the widget. Whether or not the drop is succesful,
   GTK+ will call gtk_drag_finish(). If the action
   was a move, then if the drag was succesful, then
   %TRUE will be passed for the @delete parameter
   to gtk_drag_finish().
</entry>
</row>

<row>
<entry><symbol>GTK_DEST_DEFAULT_ALL</symbol></entry>
<entry>
   If set, specifies that all default actions should
   be taken.
</entry>
</row>

</tbody></tgroup></informaltable>

@GTK_DEST_DEFAULT_MOTION: 
@GTK_DEST_DEFAULT_HIGHLIGHT: 
@GTK_DEST_DEFAULT_DROP: 
@GTK_DEST_DEFAULT_ALL: 

<!-- ##### ENUM GtkTargetFlags ##### -->
<para>
The #GtkTargetFlags enumeration is used to specifies
constraints on an entry in a GtkTargetTable. 
</para>
<variablelist>
 <varlistentry><term> %GTK_TARGET_SAME_APP </term>
 <listitem>
   <para>
   If this is set, the target will only be selected
   for drags within a single application.
   </para>
 </listitem>
 </varlistentry>
 <varlistentry><term> %GTK_TARGET_SAME_WIDGET </term>
 <listitem>
   <para>
   If this is set, the target will only be selected
   for drags within a single widget.
   </para>
 </listitem>
 </varlistentry>
</variablelist>

@GTK_TARGET_SAME_APP: 
@GTK_TARGET_SAME_WIDGET: 

<!-- ##### FUNCTION gtk_drag_dest_set ##### -->
<para>
Set a widget as a potential drop destination.
</para>

@widget: a widget
@flags: the flags that specify what actions GTK+ should take
 on behalf of a widget for drops onto that widget. The @targets
 and @actions fields only are used if %GTK_DEST_DEFAULT_MOTION
 or %GTK_DEST_DEFAULT_DROP are given.
@targets: a pointer to an array of #GtkTargetEntry indicating
 the drop types that this widget will accept.
@n_targets: the number of entries in @targets.
@actions: a bitmask of possible actions for a drop onto this
 widget.


<!-- ##### FUNCTION gtk_drag_dest_set_proxy ##### -->
<para>
Set this widget as a proxy for drops to another window.
</para>

@widget: a #GtkWidget
@proxy_window: the window to which to forward drag events
@protocol: the drag protocol which the @proxy_window accepts
           (You can use gdk_drag_get_protocol() to determine this)
@use_coordinates: If true, send the same coordinates to the
                  destination, because it is a embedded 
                  subwindow.


<!-- ##### FUNCTION gtk_drag_dest_unset ##### -->
<para>
Clear information about a drop destination set with
gtk_drag_dest_set(). The widget will no longer receive
notification of drags.
</para>

@widget: a #GtkWidget


<!-- ##### FUNCTION gtk_drag_finish ##### -->
<para>
Inform the drag source that the drop is finished, and
that the data of the drag will no longer be required.
</para>

@context: the drag context.
@success: a flag indicating whether the drop was succesful
@del: a flag indicating whether the source should delete the
      original data. (This should be %TRUE for a move)
@time: the timestamp from the "drag_data_drop" signal.


<!-- ##### FUNCTION gtk_drag_get_data ##### -->
<para>
Get the data associated with a drag. When the data
is received or the retrieval fails, GTK+ will emit a 
"drag_data_received" signal. Failure of the retrieval
is indicated by the length field of the @selection_data
signal parameter being negative. However, when gtk_drag_get_data() 
is called implicitely because the %GTK_DRAG_DEFAULT_DROP was set, 
then the widget will not receive notification of failed
drops.
</para>

@widget: the widget that will receive the "drag_data_received"
 signal.
@context: the drag context
@target: the target (form of the data) to retrieve.
@time: a timestamp for retrieving the data. This will
       generally be the time received in a "drag_data_motion"
       or "drag_data_drop" signal.


<!-- ##### FUNCTION gtk_drag_get_source_widget ##### -->
<para>
Determine the source widget for a drag.
</para>

@context: a (destination side) drag context.
@Returns: if the drag is occurring within a single application,
          a pointer to the source widget. Otherwise, NULL.


<!-- ##### FUNCTION gtk_drag_highlight ##### -->
<para>
Draw a highlight around a widget. This will attach
handlers to  "expose_event" and "draw", so the highlight
will continue to be displayed until gtk_drag_unhighlight
is called.
</para>

@widget: a widget to highlight


<!-- ##### FUNCTION gtk_drag_unhighlight ##### -->
<para>
Remove a highlight set by gtk_drag_highlight() from
a widget.
is called.
</para>

@widget: a widget to remove the highlight from.


<!-- ##### FUNCTION gtk_drag_begin ##### -->
<para>
Initiate a drag on the source side. The function
only needs to be used when the application is
starting drags itself, and is not needed when
gtk_drag_source_set() is used.
</para>

@widget: the source widget.
@targets: The targets (data formats) in which the
 source can provide the data.
@actions: A bitmask of the allowed drag actions for this
          drag.
@button: The button the user clicked to start the drag.
@event: The event that triggered the start of the
        drag. Usually
@Returns: The context for this drag.


<!-- ##### FUNCTION gtk_drag_set_icon_widget ##### -->
<para>
Change the icon for a widget to a given widget. GTK+
will not destroy the icon, so if you don't want
it to persist, you should connect to the "drag_end" 
signal and destroy it yourself.
</para>

@context: the context for a drag. (This must be called 
          with a  context for the source side of a drag)
@widget: A toplevel window to use as an icon.
@hot_x: The X offset within @widget of the hotspot.
@hot_y: The Y offset within @widget of the hotspot.


<!-- ##### FUNCTION gtk_drag_set_icon_pixmap ##### -->
<para>
Sets a given pixmap as the icon for a given drag.
GTK+ retains a reference count for the arguments, and 
will release them when they are no longer needed.
</para>

@context: the context for a drag. (This must be called 
          with a  context for the source side of a drag)
@colormap: the colormap of the icon
@pixmap: the image data for the icon
@mask: the transparency mask for an image.
@hot_x: The X offset within @widget of the hotspot.
@hot_y: The Y offset within @widget of the hotspot.


<!-- ##### FUNCTION gtk_drag_set_icon_default ##### -->
<para>
Set the icon for a particular drag to the default
icon.
</para>

@context: the context for a drag. (This must be called 
          with a  context for the source side of a drag)


<!-- ##### FUNCTION gtk_drag_set_default_icon ##### -->
<para>
Change the default drag icon. GTK+ retains a reference count for the
arguments, and will release them when they are no longer needed.
</para>

@colormap: the colormap of the icon
@pixmap: the image data for the icon
@mask: the transparency mask for an image.
@hot_x: The X offset within @widget of the hotspot.
@hot_y: The Y offset within @widget of the hotspot.


<!-- ##### FUNCTION gtk_drag_source_set ##### -->
<para>
Sets up a widget so that GTK+ will start a drag
operation when the user clicks and drags on the
widget. The widget must have a window.
</para>

@widget: a #GtkWidget
@start_button_mask: the bitmask of buttons that can start the drag
@targets: the table of targets that the drag will support
@n_targets: the number of items in @targets
@actions: the bitmask of possible actions for a drag from this
 widget.


<!-- ##### FUNCTION gtk_drag_source_set_icon ##### -->
<para>
Sets the icon that will be used for drags from a 
particular widget. GTK+ retains a reference count
for the arguments, and will release them when
they are no longer needed.
</para>

@widget: a #GtkWidget
@colormap: the colormap of the icon
@pixmap: the image data for the icon
@mask: the transparency mask for an image.


<!-- ##### FUNCTION gtk_drag_source_unset ##### -->
<para>
Undo the effects of gtk_drag_source_set().
</para>

@widget: a #GtkWidget


<!-- ##### FUNCTION gtk_drag_source_handle_event ##### -->
<para>
Internal function.
</para>

@widget: 
@event: 


<!-- ##### FUNCTION gtk_drag_dest_handle_event ##### -->
<para>
Internal function.
</para>

@toplevel: 
@event: