Provided by: libmotif-dev_2.3.8-3_amd64 
NAME
XmDragContext — The DragContext widget class "XmDragContext" "widget class" "DragContext"
SYNOPSIS
#include <Xm/DragDrop.h>
DESCRIPTION
DragContexts are special widgets used in drag and drop transactions. A DragContext is
implemented as a widget, but a client does not explicitly create a DragContext widget.
Instead, a client initiates a drag and drop transaction by calling XmDragStart, and this
routine initializes and returns a DragContext widget. There is a unique DragContext for
each drag operation. The toolkit frees a DragContext when a transaction is complete;
therefore, an application programmer should not explicitly destroy a DragContext.
Initiator and receiver clients both use DragContexts to track the state of a transaction.
When the initiator and receiver of a transaction are in the same client, they share the
same DragContext instance. If they are in different clients, there are two separate
DragContexts. In this case, the initiator calls XmDragStart and the toolkit provides a
DragContext for the receiver client. The only resources pertinent to the receiver are
XmNexportTargets and XmNnumExportTargets. These can both be passed as arguments to the
XmDropSiteRetrieve function to obtain information about the current drop site.
In general, in order to receive data, a drop site must share at least one target type and
operation in common with a drag source. The DragContext resource, XmNexportTargets,
identifies the selection targets for the drag source. These export targets are compared
with the XmNimportTargets resource list specified by a drop site. The DragContext
resource, XmNdragOperations, identifies the valid operations that can be applied to the
source data by the initiator. The drop site counterpart resource is XmNdropSiteOperations,
which indicates a drop site's supported operations.
A client uses DragIcon widgets to define the drag-over animation effects associated with a
given drag and drop transaction. An initiator specifies a set of drag icons, selects a
blending model, and sets foreground and background cursor colors with DragContext
resources.
The type of drag-over visual used to represent a drag operation depends on the drag
protocol style. In preregister mode, the server is grabbed, and either a cursor or a
pixmap may be used as a drag-over visual. In dynamic mode, drag-over visuals must be
implemented with the X cursor. If the resulting drag protocol style is Drop Only or None
and the XmNdragInitiatorProtocolStyle is XmDRAG_DYNAMIC or XmDRAG_PREFER_DYNAMIC, then a
dynamic visual style (cursor) is used. Otherwise, a preregister visual style is used.
Classes
DragContext inherits behavior and resources from Core.
The class pointer is xmDragContextClass.
The class name is XmDragContext.
New Resources
The following table defines a set of widget resources used by the programmer to specify
data. The programmer can also set the resource values for the inherited classes to set
attributes for this widget. To reference a resource by name or by class in a .Xdefaults
file, remove the XmN or XmC prefix and use the remaining letters. To specify one of the
defined values for a resource in a .Xdefaults file, remove the Xm prefix and use the
remaining letters (in either lowercase or uppercase, but include any underscores between
words). The codes in the access column indicate if the given resource can be set at
creation time (C), set by using XtSetValues (S), retrieved by using XtGetValues (G), or is
not applicable (N/A).
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RELATED INFORMATION
Core(3), XmDisplay(3), XmDragCancel(3), XmDragIcon(3), XmDragStart(3), XmDropSite(3),
XmDropTransfer(3), and XmScreen(3).
XmDragContext(3)