Package ch.bailu.gtk.gtk

Class DragSource

java.lang.Object
ch.bailu.gtk.type.Type
ch.bailu.gtk.type.Pointer
ch.bailu.gtk.gobject.Object
ch.bailu.gtk.gtk.EventController
ch.bailu.gtk.gtk.Gesture
ch.bailu.gtk.gtk.GestureSingle
ch.bailu.gtk.gtk.DragSource
All Implemented Interfaces:
PointerInterface
public class DragSource extends GestureSingle
`GtkDragSource` is an event controller to initiate Drag-And-Drop operations.

`GtkDragSource` 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 [class@Gdk.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
[method@Gtk.Widget.add_controller].

```c
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, `GtkDragSource` has
[signal@Gtk.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.

```c
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 `GdkDrag` object has
been created, and can be used to set up the drag icon.

```c
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, `GtkDragSource` 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_ACTION_MOVE, you need to listen for the
[signal@Gtk.DragSource::drag-end] signal and delete the
data after it has been transferred.

https://docs.gtk.org/gtk4/class.DragSource.html

  • Field Details

  • Constructor Details

    • DragSource

      public DragSource(PointerContainer pointer)

    • DragSource

      public DragSource()
      Creates a new `GtkDragSource` object.

  • Method Details

    • getClassHandler

      public static ClassHandler getClassHandler()

    • dragCancel

      public void dragCancel()
      Cancels a currently ongoing drag operation.

    • getActions

      public int getActions()
      Gets the actions that are currently set on the `GtkDragSource`.
      Returns:
      the actions set on @source

    • getContent

      public ContentProvider getContent()
      Gets the current content provider of a `GtkDragSource`.
      Returns:
      the `GdkContentProvider` of @source

    • getDrag

      public Drag getDrag()
      Returns the underlying `GdkDrag` object for an ongoing drag.
      Returns:
      the `GdkDrag` of the current drag operation

    • setActions

      public void setActions(int actions)
      Sets the actions on the `GtkDragSource`.

      During a DND operation, the actions are offered to potential
      drop targets. If @actions include %GDK_ACTION_MOVE, you need
      to listen to the [signal@Gtk.DragSource::drag-end] signal and
      handle @delete_data being %TRUE.

      This function can be called before a drag is started,
      or in a handler for the [signal@Gtk.DragSource::prepare] signal.
      Parameters:
      actions - the actions to offer

    • setContent

      public void setContent(@Nullable ContentProvider content)
      Sets a content provider on a `GtkDragSource`.

      When the data is requested in the cause of a DND operation,
      it will be obtained from the content provider.

      This function can be called before a drag is started,
      or in a handler for the [signal@Gtk.DragSource::prepare] signal.

      You may consider setting the content provider back to
      %NULL in a [signal@Gtk.DragSource::drag-end] signal handler.
      Parameters:
      content - a `GdkContentProvider`

    • setIcon

      public void setIcon(@Nullable Paintable paintable, int hot_x, int hot_y)
      Sets a paintable to use as icon during DND operations.

      The hotspot coordinates determine the point on the icon
      that gets aligned with the hotspot of the cursor.

      If @paintable is %NULL, a default icon is used.

      This function can be called before a drag is started, or in
      a [signal@Gtk.DragSource::prepare] or
      [signal@Gtk.DragSource::drag-begin] signal handler.
      Parameters:
      paintable - the `GdkPaintable` to use as icon
      hot_x - the hotspot X coordinate on the icon
      hot_y - the hotspot Y coordinate on the icon

    • onDragBegin

      public SignalHandler onDragBegin(DragSource.OnDragBegin signal)
      Connect to signal "drag-begin".
      See DragSource.OnDragBegin.onDragBegin(ch.bailu.gtk.gdk.Drag) for signal description.
      Field SIGNAL_ON_DRAG_BEGIN contains original signal name and can be used as resource reference.
      Parameters:
      signal - callback function (lambda).
      Returns:
      SignalHandler. Can be used to disconnect signal and to release callback function.

    • onDragCancel

      public SignalHandler onDragCancel(DragSource.OnDragCancel signal)
      Connect to signal "drag-cancel".
      See DragSource.OnDragCancel.onDragCancel(ch.bailu.gtk.gdk.Drag, int) for signal description.
      Field SIGNAL_ON_DRAG_CANCEL contains original signal name and can be used as resource reference.
      Parameters:
      signal - callback function (lambda).
      Returns:
      SignalHandler. Can be used to disconnect signal and to release callback function.

    • onDragEnd

      public SignalHandler onDragEnd(DragSource.OnDragEnd signal)
      Connect to signal "drag-end".
      See DragSource.OnDragEnd.onDragEnd(ch.bailu.gtk.gdk.Drag, boolean) for signal description.
      Field SIGNAL_ON_DRAG_END contains original signal name and can be used as resource reference.
      Parameters:
      signal - callback function (lambda).
      Returns:
      SignalHandler. Can be used to disconnect signal and to release callback function.

    • onPrepare

      public SignalHandler onPrepare(DragSource.OnPrepare signal)
      Connect to signal "prepare".
      See DragSource.OnPrepare.onPrepare(double, double) for signal description.
      Field SIGNAL_ON_PREPARE contains original signal name and can be used as resource reference.
      Parameters:
      signal - callback function (lambda).
      Returns:
      SignalHandler. Can be used to disconnect signal and to release callback function.

    • getTypeID

      public static long getTypeID()

    • getParentTypeID

      public static long getParentTypeID()

    • getTypeSize

      public static TypeSystem.TypeSize getTypeSize()

    • getParentTypeSize

      public static TypeSystem.TypeSize getParentTypeSize()

    • getInstanceSize

      public static int getInstanceSize()