DropTargetAsync
Superclasses: EventController
, Object
GtkDropTargetAsync
is an event controller to receive Drag-and-Drop
operations, asynchronously.
It is the more complete but also more complex method of handling drop
operations compared to DropTarget
, and you should only use
it if GtkDropTarget
doesn’t provide all the features you need.
To use a GtkDropTargetAsync
to receive drops on a widget, you create
a GtkDropTargetAsync
object, configure which data formats and actions
you support, connect to its signals, and then attach it to the widget
with add_controller
.
During a drag operation, the first signal that a GtkDropTargetAsync
emits is accept
, which is meant to determine
whether the target is a possible drop site for the ongoing drop. The
default handler for the ::accept signal accepts the drop if it finds
a compatible data format and an action that is supported on both sides.
If it is, and the widget becomes a target, you will receive a
drag_enter
signal, followed by
drag_motion
signals as the pointer moves,
optionally a drop
signal when a drop happens,
and finally a drag_leave
signal when the
pointer moves off the widget.
The ::drag-enter and ::drag-motion handler return a GdkDragAction
to update the status of the ongoing operation. The ::drop handler
should decide if it ultimately accepts the drop and if it does, it
should initiate the data transfer and finish the operation by calling
finish
.
Between the ::drag-enter and ::drag-leave signals the widget is a
current drop target, and will receive the DROP_ACTIVE
state, which can be used by themes to style the widget as a drop target.
Constructors
- class DropTargetAsync
- classmethod new(formats: ContentFormats | None, actions: DragAction) DropTargetAsync
Creates a new
GtkDropTargetAsync
object.- Parameters:
formats – the supported data formats
actions – the supported actions
Methods
- class DropTargetAsync
- get_actions() DragAction
Gets the actions that this drop target supports.
- get_formats() ContentFormats | None
Gets the data formats that this drop target accepts.
If the result is
None
, all formats are expected to be supported.
- reject_drop(drop: Drop) None
Sets the
drop
as not accepted on this drag site.This function should be used when delaying the decision on whether to accept a drag or not until after reading the data.
- Parameters:
drop – the
GdkDrop
of an ongoing drag operation
- set_actions(actions: DragAction) None
Sets the actions that this drop target supports.
- Parameters:
actions – the supported actions
- set_formats(formats: ContentFormats | None = None) None
Sets the data formats that this drop target will accept.
- Parameters:
formats – the supported data formats or
None
for any format
Properties
- class DropTargetAsync
- props.actions: DragAction
The
GdkDragActions
that this drop target supports.
- props.formats: ContentFormats
The
GdkContentFormats
that determines the supported data formats.
Signals
- class DropTargetAsync.signals
- accept(drop: Drop) bool
Emitted on the drop site when a drop operation is about to begin.
If the drop is not accepted,
False
will be returned and the drop target will ignore the drop. IfTrue
is returned, the drop is accepted for now but may be rejected later via a call toreject_drop
or ultimately by returningFalse
from adrop
handler.The default handler for this signal decides whether to accept the drop based on the formats provided by the
drop
.If the decision whether the drop will be accepted or rejected needs further processing, such as inspecting the data, this function should return
True
and proceed as isdrop
was accepted and if it decides to reject the drop later, it should callreject_drop
.- Parameters:
drop – the
GdkDrop
- drag_enter(drop: Drop, x: float, y: float) DragAction
Emitted on the drop site when the pointer enters the widget.
It can be used to set up custom highlighting.
- Parameters:
drop – the
GdkDrop
x – the x coordinate of the current pointer position
y – the y coordinate of the current pointer position
- drag_leave(drop: Drop) None
Emitted on the drop site when the pointer leaves the widget.
Its main purpose it to undo things done in
GtkDropTargetAsync
::drag-enter.- Parameters:
drop – the
GdkDrop
- drag_motion(drop: Drop, x: float, y: float) DragAction
Emitted while the pointer is moving over the drop target.
- Parameters:
drop – the
GdkDrop
x – the x coordinate of the current pointer position
y – the y coordinate of the current pointer position
- drop(drop: Drop, x: float, y: float) bool
Emitted on the drop site when the user drops the data onto the widget.
The signal handler must determine whether the pointer position is in a drop zone or not. If it is not in a drop zone, it returns
False
and no further processing is necessary.Otherwise, the handler returns
True
. In this case, this handler will accept the drop. The handler must ensure thatfinish
is called to let the source know that the drop is done. The call tofinish
must only be done when all data has been received.To receive the data, use one of the read functions provided by
Drop
such asread_async
orread_value_async
.- Parameters:
drop – the
GdkDrop
x – the x coordinate of the current pointer position
y – the y coordinate of the current pointer position