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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 [classGdk.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 [methodGtk.Widget.add_controller].

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 [signalGtk.DragSource::prepare] and [signalGtk.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 GdkDrag 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, 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 [signalGtk.DragSource::drag-end] signal and delete the data after it has been transferred.

Hierarchy

Index

Constructors

Properties

actions: Gdk.DragAction

The actions that are supported by drag operations from the source.

Note that you must handle the [signalGtk.DragSource::drag-end] signal if the actions include %GDK_ACTION_MOVE.

button: number

Mouse button number to listen to, or 0 to listen for any button.

The data that is offered by drag operations from this source.

exclusive: boolean

Whether the gesture is exclusive.

Exclusive gestures only listen to pointer and pointer emulated events.

g_type_instance: TypeInstance
n_points: number

The number of touch points that trigger recognition on this gesture.

name: string

The name for this controller, typically used for debugging purposes.

propagation_limit: PropagationLimit

The limit for which events this controller will handle.

propagation_phase: Gtk.PropagationPhase

The propagation phase at which this controller will handle events.

touch_only: boolean

Whether the gesture handles only touch events.

widget: Gtk.Widget

The widget receiving the GdkEvents that the controller will handle.

$gtype: GType<DragSource>
name: string

Methods

  • Creates a binding between source_property on source and target_property on target.

    Whenever the source_property is changed the target_property is updated using the same value. For instance:

      g_object_bind_property (action, "active", widget, "sensitive", 0);
    

    Will result in the "sensitive" property of the widget #GObject instance to be updated with the same value of the "active" property of the action #GObject instance.

    If flags contains %G_BINDING_BIDIRECTIONAL then the binding will be mutual: if target_property on target changes then the source_property on source will be updated as well.

    The binding will automatically be removed when either the source or the target instances are finalized. To remove the binding without affecting the source and the target you can just call g_object_unref() on the returned #GBinding instance.

    Removing the binding by calling g_object_unref() on it must only be done if the binding, source and target are only used from a single thread and it is clear that both source and target outlive the binding. Especially it is not safe to rely on this if the binding, source or target can be finalized from different threads. Keep another reference to the binding and use g_binding_unbind() instead to be on the safe side.

    A #GObject can have multiple bindings.

    Parameters

    • source_property: string

      the property on source to bind

    • target: GObject.Object

      the target #GObject

    • target_property: string

      the property on target to bind

    • flags: BindingFlags

      flags to pass to #GBinding

    Returns Binding

  • Creates a binding between source_property on source and target_property on target, allowing you to set the transformation functions to be used by the binding.

    This function is the language bindings friendly version of g_object_bind_property_full(), using #GClosures instead of function pointers.

    Parameters

    • source_property: string

      the property on source to bind

    • target: GObject.Object

      the target #GObject

    • target_property: string

      the property on target to bind

    • flags: BindingFlags

      flags to pass to #GBinding

    • transform_to: TClosure<any, any>

      a #GClosure wrapping the transformation function from the source to the target, or %NULL to use the default

    • transform_from: TClosure<any, any>

      a #GClosure wrapping the transformation function from the target to the source, or %NULL to use the default

    Returns Binding

  • disconnect(id: number): void
  • drag_cancel(): void
  • emit(sigName: "drag-begin", drag: Drag, ...args: any[]): void
  • emit(sigName: "drag-cancel", drag: Drag, reason: Gdk.DragCancelReason, ...args: any[]): void
  • emit(sigName: "drag-end", drag: Drag, delete_data: boolean, ...args: any[]): void
  • emit(sigName: "prepare", x: number, y: number, ...args: any[]): void
  • emit(sigName: "notify::actions", ...args: any[]): void
  • emit(sigName: "notify::content", ...args: any[]): void
  • emit(sigName: "notify::button", ...args: any[]): void
  • emit(sigName: "notify::exclusive", ...args: any[]): void
  • emit(sigName: "notify::touch-only", ...args: any[]): void
  • emit(sigName: "notify::n-points", ...args: any[]): void
  • emit(sigName: "notify::name", ...args: any[]): void
  • emit(sigName: "notify::propagation-limit", ...args: any[]): void
  • emit(sigName: "notify::propagation-phase", ...args: any[]): void
  • emit(sigName: "notify::widget", ...args: any[]): void
  • emit(sigName: string, ...args: any[]): void
  • force_floating(): void
  • This function is intended for #GObject implementations to re-enforce a [floating][floating-ref] object reference. Doing this is seldom required: all #GInitiallyUnowneds are created with a floating reference which usually just needs to be sunken by calling g_object_ref_sink().

    Returns void

  • freeze_notify(): void
  • Increases the freeze count on object. If the freeze count is non-zero, the emission of "notify" signals on object is stopped. The signals are queued until the freeze count is decreased to zero. Duplicate notifications are squashed so that at most one #GObject::notify signal is emitted for each property modified while the object is frozen.

    This is necessary for accessors that modify multiple properties to prevent premature notification while the object is still being modified.

    Returns void

  • If there are touch sequences being currently handled by gesture, returns %TRUE and fills in rect with the bounding box containing all active touches.

    Otherwise, %FALSE will be returned.

    Note: This function will yield unexpected results on touchpad gestures. Since there is no correlation between physical and pixel distances, these will look as if constrained in an infinitely small area, rect width and height will thus be 0 regardless of the number of touchpoints.

    Returns [boolean, Gdk.Rectangle]

  • get_bounding_box_center(): [boolean, number, number]
  • If there are touch sequences being currently handled by gesture, returns %TRUE and fills in x and y with the center of the bounding box containing all active touches.

    Otherwise, %FALSE will be returned.

    Returns [boolean, number, number]

  • get_button(): number
  • get_current_button(): number
  • get_current_event_time(): number
  • get_data(key?: string): object
  • get_exclusive(): boolean
  • get_name(): string
  • If sequence is currently being interpreted by gesture, returns %TRUE and fills in x and y with the last coordinates stored for that event sequence.

    The coordinates are always relative to the widget allocation.

    Parameters

    Returns [boolean, number, number]

  • get_property(property_name?: string, value?: any): void
  • Gets a property of an object.

    The value can be:

    • an empty #GValue initialized by %G_VALUE_INIT, which will be automatically initialized with the expected type of the property (since GLib 2.60)
    • a #GValue initialized with the expected type of the property
    • a #GValue initialized with a type to which the expected type of the property can be transformed

    In general, a copy is made of the property contents and the caller is responsible for freeing the memory by calling g_value_unset().

    Note that g_object_get_property() is really intended for language bindings, g_object_get() is much more convenient for C programming.

    Parameters

    • Optional property_name: string

      the name of the property to get

    • Optional value: any

      return location for the property value

    Returns void

  • get_qdata(quark: number): object
  • get_touch_only(): boolean
  • getv(names: string[], values: any[]): void
  • Gets n_properties properties for an object. Obtained properties will be set to values. All properties must be valid. Warnings will be emitted and undefined behaviour may result if invalid properties are passed in.

    Parameters

    • names: string[]

      the names of each property to get

    • values: any[]

      the values of each property to get

    Returns void

  • Adds gesture to the same group than group_gesture.

    Gestures are by default isolated in their own groups.

    Both gestures must have been added to the same widget before they can be grouped.

    When gestures are grouped, the state of GdkEventSequences is kept in sync for all of those, so calling [methodGtk.Gesture.set_sequence_state], on one will transfer the same value to the others.

    Groups also perform an "implicit grabbing" of sequences, if a GdkEventSequence state is set to %GTK_EVENT_SEQUENCE_CLAIMED on one group, every other gesture group attached to the same GtkWidget will switch the state for that sequence to %GTK_EVENT_SEQUENCE_DENIED.

    Parameters

    Returns void

  • is_active(): boolean
  • is_floating(): boolean
  • is_recognized(): boolean
  • notify(property_name: string): void
  • Emits a "notify" signal for the property property_name on object.

    When possible, eg. when signaling a property change from within the class that registered the property, you should use g_object_notify_by_pspec() instead.

    Note that emission of the notify signal may be blocked with g_object_freeze_notify(). In this case, the signal emissions are queued and will be emitted (in reverse order) when g_object_thaw_notify() is called.

    Parameters

    • property_name: string

      the name of a property installed on the class of object.

    Returns void

  • Emits a "notify" signal for the property specified by pspec on object.

    This function omits the property name lookup, hence it is faster than g_object_notify().

    One way to avoid using g_object_notify() from within the class that registered the properties, and using g_object_notify_by_pspec() instead, is to store the GParamSpec used with g_object_class_install_property() inside a static array, e.g.:

      enum
    {
    PROP_0,
    PROP_FOO,
    PROP_LAST
    };

    static GParamSpec *properties[PROP_LAST];

    static void
    my_object_class_init (MyObjectClass *klass)
    {
    properties[PROP_FOO] = g_param_spec_int ("foo", "Foo", "The foo",
    0, 100,
    50,
    G_PARAM_READWRITE);
    g_object_class_install_property (gobject_class,
    PROP_FOO,
    properties[PROP_FOO]);
    }

    and then notify a change on the "foo" property with:

      g_object_notify_by_pspec (self, properties[PROP_FOO]);
    

    Parameters

    • pspec: ParamSpec

      the #GParamSpec of a property installed on the class of object.

    Returns void

  • Increases the reference count of object.

    Since GLib 2.56, if GLIB_VERSION_MAX_ALLOWED is 2.56 or greater, the type of object will be propagated to the return type (using the GCC typeof() extension), so any casting the caller needs to do on the return type must be explicit.

    Returns GObject.Object

  • Increase the reference count of object, and possibly remove the [floating][floating-ref] reference, if object has a floating reference.

    In other words, if the object is floating, then this call "assumes ownership" of the floating reference, converting it to a normal reference by clearing the floating flag while leaving the reference count unchanged. If the object is not floating, then this call adds a new normal reference increasing the reference count by one.

    Since GLib 2.56, the type of object will be propagated to the return type under the same conditions as for g_object_ref().

    Returns GObject.Object

  • reset(): void
  • run_dispose(): void
  • 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 [signalGtk.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 [signalGtk.DragSource::prepare] signal.

    Parameters

    Returns void

  • set_button(button: number): void
  • Sets the button number gesture listens to.

    If non-0, every button press from a different button number will be ignored. Touch events implicitly match with button 1.

    Parameters

    • button: number

      button number to listen to, or 0 for any button

    Returns void

  • 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 [signalGtk.DragSource::prepare] signal.

    You may consider setting the content provider back to %NULL in a [signalGtk.DragSource::drag-end] signal handler.

    Parameters

    Returns void

  • set_data(key: string, data?: object): void
  • Each object carries around a table of associations from strings to pointers. This function lets you set an association.

    If the object already had an association with that name, the old association will be destroyed.

    Internally, the key is converted to a #GQuark using g_quark_from_string(). This means a copy of key is kept permanently (even after object has been finalized) — so it is recommended to only use a small, bounded set of values for key in your program, to avoid the #GQuark storage growing unbounded.

    Parameters

    • key: string

      name of the key

    • Optional data: object

      data to associate with that key

    Returns void

  • set_exclusive(exclusive: boolean): void
  • Sets whether gesture is exclusive.

    An exclusive gesture will only handle pointer and "pointer emulated" touch events, so at any given time, there is only one sequence able to interact with those.

    Parameters

    • exclusive: boolean

      %TRUE to make gesture exclusive

    Returns void

  • set_icon(paintable: Paintable, hot_x: number, hot_y: number): void
  • 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 [signalGtk.DragSource::prepare] or [signalGtk.DragSource::drag-begin] signal handler.

    Parameters

    • paintable: Paintable

      the GdkPaintable to use as icon

    • hot_x: number

      the hotspot X coordinate on the icon

    • hot_y: number

      the hotspot Y coordinate on the icon

    Returns void

  • set_name(name: string): void
  • set_property(property_name: string, value?: any): void
  • Sets the state of sequence in gesture.

    Sequences start in state %GTK_EVENT_SEQUENCE_NONE, and whenever they change state, they can never go back to that state. Likewise, sequences in state %GTK_EVENT_SEQUENCE_DENIED cannot turn back to a not denied state. With these rules, the lifetime of an event sequence is constrained to the next four:

    • None
    • None → Denied
    • None → Claimed
    • None → Claimed → Denied

    Note: Due to event handling ordering, it may be unsafe to set the state on another gesture within a [signalGtk.Gesture::begin] signal handler, as the callback might be executed before the other gesture knows about the sequence. A safe way to perform this could be:

    static void
    first_gesture_begin_cb (GtkGesture *first_gesture,
    GdkEventSequence *sequence,
    gpointer user_data)
    {
    gtk_gesture_set_sequence_state (first_gesture, sequence, GTK_EVENT_SEQUENCE_CLAIMED);
    gtk_gesture_set_sequence_state (second_gesture, sequence, GTK_EVENT_SEQUENCE_DENIED);
    }

    static void
    second_gesture_begin_cb (GtkGesture *second_gesture,
    GdkEventSequence *sequence,
    gpointer user_data)
    {
    if (gtk_gesture_get_sequence_state (first_gesture, sequence) == GTK_EVENT_SEQUENCE_CLAIMED)
    gtk_gesture_set_sequence_state (second_gesture, sequence, GTK_EVENT_SEQUENCE_DENIED);
    }

    If both gestures are in the same group, just set the state on the gesture emitting the event, the sequence will be already be initialized to the group's global state when the second gesture processes the event.

    Parameters

    Returns boolean

  • set_touch_only(touch_only: boolean): void
  • Sets whether to handle only touch events.

    If touch_only is %TRUE, gesture will only handle events of type %GDK_TOUCH_BEGIN, %GDK_TOUCH_UPDATE or %GDK_TOUCH_END. If %FALSE, mouse events will be handled too.

    Parameters

    • touch_only: boolean

      whether gesture handles only touch events

    Returns void

  • steal_data(key?: string): object
  • steal_qdata(quark: number): object
  • This function gets back user data pointers stored via g_object_set_qdata() and removes the data from object without invoking its destroy() function (if any was set). Usually, calling this function is only required to update user data pointers with a destroy notifier, for example:

    void
    object_add_to_user_list (GObject *object,
    const gchar *new_string)
    {
    // the quark, naming the object data
    GQuark quark_string_list = g_quark_from_static_string ("my-string-list");
    // retrieve the old string list
    GList *list = g_object_steal_qdata (object, quark_string_list);

    // prepend new string
    list = g_list_prepend (list, g_strdup (new_string));
    // this changed 'list', so we need to set it again
    g_object_set_qdata_full (object, quark_string_list, list, free_string_list);
    }
    static void
    free_string_list (gpointer data)
    {
    GList *node, *list = data;

    for (node = list; node; node = node->next)
    g_free (node->data);
    g_list_free (list);
    }

    Using g_object_get_qdata() in the above example, instead of g_object_steal_qdata() would have left the destroy function set, and thus the partial string list would have been freed upon g_object_set_qdata_full().

    Parameters

    • quark: number

      A #GQuark, naming the user data pointer

    Returns object

  • thaw_notify(): void
  • Reverts the effect of a previous call to g_object_freeze_notify(). The freeze count is decreased on object and when it reaches zero, queued "notify" signals are emitted.

    Duplicate notifications for each property are squashed so that at most one #GObject::notify signal is emitted for each property, in the reverse order in which they have been queued.

    It is an error to call this function when the freeze count is zero.

    Returns void

  • ungroup(): void
  • unref(): void
  • Decreases the reference count of object. When its reference count drops to 0, the object is finalized (i.e. its memory is freed).

    If the pointer to the #GObject may be reused in future (for example, if it is an instance variable of another object), it is recommended to clear the pointer to %NULL rather than retain a dangling pointer to a potentially invalid #GObject instance. Use g_clear_object() for this.

    Returns void

  • vfunc_constructed(): void
  • vfunc_dispatch_properties_changed(n_pspecs: number, pspecs: ParamSpec): void
  • vfunc_dispose(): void
  • vfunc_finalize(): void
  • vfunc_get_property(property_id: number, value?: any, pspec?: ParamSpec): void
  • Emits a "notify" signal for the property property_name on object.

    When possible, eg. when signaling a property change from within the class that registered the property, you should use g_object_notify_by_pspec() instead.

    Note that emission of the notify signal may be blocked with g_object_freeze_notify(). In this case, the signal emissions are queued and will be emitted (in reverse order) when g_object_thaw_notify() is called.

    virtual

    Parameters

    Returns void

  • vfunc_set_property(property_id: number, value?: any, pspec?: ParamSpec): void
  • watch_closure(closure: TClosure<any, any>): void
  • This function essentially limits the life time of the closure to the life time of the object. That is, when the object is finalized, the closure is invalidated by calling g_closure_invalidate() on it, in order to prevent invocations of the closure with a finalized (nonexisting) object. Also, g_object_ref() and g_object_unref() are added as marshal guards to the closure, to ensure that an extra reference count is held on object during invocation of the closure. Usually, this function will be called on closures that use this object as closure data.

    Parameters

    • closure: TClosure<any, any>

      #GClosure to watch

    Returns void

  • compat_control(what: number, data: object): number
  • Find the #GParamSpec with the given name for an interface. Generally, the interface vtable passed in as g_iface will be the default vtable from g_type_default_interface_ref(), or, if you know the interface has already been loaded, g_type_default_interface_peek().

    Parameters

    • g_iface: TypeInterface

      any interface vtable for the interface, or the default vtable for the interface

    • property_name: string

      name of a property to look up.

    Returns ParamSpec

  • Add a property to an interface; this is only useful for interfaces that are added to GObject-derived types. Adding a property to an interface forces all objects classes with that interface to have a compatible property. The compatible property could be a newly created #GParamSpec, but normally g_object_class_override_property() will be used so that the object class only needs to provide an implementation and inherits the property description, default value, bounds, and so forth from the interface property.

    This function is meant to be called from the interface's default vtable initialization function (the class_init member of #GTypeInfo.) It must not be called after after class_init has been called for any object types implementing this interface.

    If pspec is a floating reference, it will be consumed.

    Parameters

    • g_iface: TypeInterface

      any interface vtable for the interface, or the default vtable for the interface.

    • pspec: ParamSpec

      the #GParamSpec for the new property

    Returns void

  • Lists the properties of an interface.Generally, the interface vtable passed in as g_iface will be the default vtable from g_type_default_interface_ref(), or, if you know the interface has already been loaded, g_type_default_interface_peek().

    Parameters

    • g_iface: TypeInterface

      any interface vtable for the interface, or the default vtable for the interface

    Returns ParamSpec[]

  • Creates a new instance of a #GObject subtype and sets its properties.

    Construction parameters (see %G_PARAM_CONSTRUCT, %G_PARAM_CONSTRUCT_ONLY) which are not explicitly specified are set to their default values.

    Parameters

    • object_type: GType<unknown>

      the type id of the #GObject subtype to instantiate

    • parameters: GObject.Parameter[]

      an array of #GParameter

    Returns GObject.Object

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