Struct gtk4::DropTargetAsync[][src]

pub struct DropTargetAsync(_);
Expand description

DropTargetAsync 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 DropTarget doesn’t provide all the features you need.

To use a DropTargetAsync to receive drops on a widget, you create a DropTargetAsync object, configure which data formats and actions you support, connect to its signals, and then attach it to the widget with WidgetExt::add_controller().

During a drag operation, the first signal that a DropTargetAsync emits is signal::DropTargetAsync::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 signal::DropTargetAsync::drag-enter signal, followed by signal::DropTargetAsync::drag-motion signals as the pointer moves, optionally a signal::DropTargetAsync::drop signal when a drop happens, and finally a signal::DropTargetAsync::drag-leave signal when the pointer moves off the widget.

The ::drag-enter and ::drag-motion handler return a gdk::DragAction 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 Drop::finish().

Between the ::drag-enter and ::drag-leave signals the widget is a current drop target, and will receive the StateFlags::DROP_ACTIVE state, which can be used by themes to style the widget as a drop target.

Implements

EventControllerExt, glib::ObjectExt

Implementations

Creates a new DropTargetAsync object.

formats

the supported data formats

actions

the supported actions

Returns

the new DropTargetAsync

Creates a new builder-pattern struct instance to construct DropTargetAsync objects.

This method returns an instance of DropTargetAsyncBuilder which can be used to create DropTargetAsync objects.

Gets the actions that this drop target supports.

Returns

the actions that this drop target supports

Gets the data formats that this drop target accepts.

If the result is None, all formats are expected to be supported.

Returns

the supported data formats

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.

drop

the gdk::Drop of an ongoing drag operation

Sets the actions that this drop target supports.

actions

the supported actions

Sets the data formats that this drop target will accept.

formats

the supported data formats or None for any format.

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. If true is returned, the drop is accepted for now but may be rejected later via a call to reject_drop() or ultimately by returning false from a signal::DropTargetAsync::drop 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 is drop was accepted and if it decides to reject the drop later, it should call reject_drop().

drop

the gdk::Drop

Returns

true if drop is accepted

Emitted on the drop site when the pointer enters the widget.

It can be used to set up custom highlighting.

drop

the gdk::Drop

x

the x coordinate of the current pointer position

y

the y coordinate of the current pointer position

Returns

Preferred action for this drag operation.

Emitted on the drop site when the pointer leaves the widget.

Its main purpose it to undo things done in DropTargetAsync::drag-enter.

drop

the gdk::Drop

Emitted while the pointer is moving over the drop target.

drop

the gdk::Drop

x

the x coordinate of the current pointer position

y

the y coordinate of the current pointer position

Returns

Preferred action for this drag operation.

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 that Drop::finish() is called to let the source know that the drop is done. The call to Drop::finish() must only be done when all data has been received.

To receive the data, use one of the read functions provided by gdk::Drop such as Drop::read_async() or Drop::read_value_async().

drop

the gdk::Drop

x

the x coordinate of the current pointer position

y

the y coordinate of the current pointer position

Returns

whether the drop is accepted at the given pointer position

Trait Implementations

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