NAME

XmDragContext − The DragContext widget class

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). 

XmDragContext Resource Set
Name	Class	Type	Default	Access
XmNblendModel	XmCBlendModel	unsigned char	XmBLEND_ALL	CG
XmNclientData	XmCClientData	XtPointer	NULL	CSG
XmNconvertProc	XmCConvertProc	XtConvertSelectionIncrProc	NULL	CSG
XmNcursorBackground	XmCCursorBackground	Pixel	dynamic	CSG
XmNcursorForeground	XmCCursorForeground	Pixel	dynamic	CSG
XmNdragDropFinishCallback	XmCCallback	XtCallbackList	NULL	CSG
XmNdragMotionCallback	XmCCallback	XtCallbackList	NULL	C
XmNdragOperations	XmCDragOperations	unsigned char	XmDROP_COPY | XmDROP_MOVE	C
XmNdropFinishCallback	XmCCallback	XtCallbackList	NULL	C
XmNdropSiteEnterCallback	XmCCallback	XtCallbackList	NULL	C
XmNdropSiteLeaveCallback	XmCCallback	XtCallbackList	NULL	C
XmNdropStartCallback	XmCCallback	XtCallbackList	NULL	C
XmNexportTargets	XmCExportTargets	Atom ∗	NULL	CSG
XmNincremental	XmCIncremental	Boolean	False	CSG
XmNinvalidCursorForeground	XmCCursorForeground	Pixel	dynamic	CSG
XmNnoneCursorForeground	XmCCursorForeground	Pixel	dynamic	CSG
XmNnumExportTargets	XmCNumExportTargets	Cardinal	0	CSG
XmNoperationChangedCallback	XmCCallback	XtCallbackList	NULL	C
XmNoperationCursorIcon	XmCOperationCursorIcon	Widget	dynamic	CSG
XmNsourceCursorIcon	XmCSourceCursorIcon	Widget	dynamic	CSG
XmNsourcePixmapIcon	XmCSourcePixmapIcon	Widget	dynamic	CSG
XmNstateCursorIcon	XmCStateCursorIcon	Widget	dynamic	CSG
XmNtopLevelEnterCallback	XmCCallback	XtCallbackList	NULL	C
XmNtopLevelLeaveCallback	XmCCallback	XtCallbackList	NULL	C
XmNvalidCursorForeground	XmCCursorForeground	Pixel	dynamic	CSG

XmNblendModel
Specifies which combination of DragIcons are blended to produce a drag-over visual.

XmBLEND_ALL
Blends all three DragIcons - the source, state and operation icon. The icons are layered from top to bottom with the operation icon on top and the source icon on the bottom. The hotspot is derived from the state icon.

XmBLEND_STATE_SOURCE
Blends the state and source icons only.  The hotspot is derived from the state icon.

XmBLEND_JUST_SOURCE
Specifies that only the source icon is used, which the initiator updates as required.

XmBLEND_NONE
Specifies that no drag-over visual is generated.  The client tracks the drop site status through callback routines and updates the drag-over visuals as necessary. Specifies the client data to be passed to the XmNconvertProc when it is invoked.  Specifies a procedure of type XtConvertSelectionIncrProc that converts the source data to the format(s) requested by the receiver client.  The widget argument passed to this procedure is the DragContext widget.  The selection atom passed is _MOTIF_DROP.  If XmNincremental is False, the procedure should ignore the max_length, client_data, and request_id arguments and should handle the conversion atomically.  Data returned by XmNconvertProc must be allocated using XtMalloc and will be freed automatically by the toolkit after the transfer.  For additional information on selection conversion procedures, see X Toolkit Intrinsics − C Language Interface.  Specifies the background pixel value of the cursor.  Specifies the foreground pixel value of the cursor when the state icon is not blended.  This resource defaults to the foreground color of the widget passed to the XmDragStart function.  Specifies the list of callbacks that are called when the transaction is completed.  The type of the structure whose address is passed to this callback is XmDragDropFinishCallbackStruct.  The reason sent by the callback is XmCR_DRAG_DROP_FINISH.  Specifies the list of callbacks that are invoked when the pointer moves.  The type of structure whose address is passed to this callback is XmDragMotionCallbackStruct.   The reason sent by the callback is XmCR_DRAG_MOTION.  Specifies the set of valid operations associated with an initiator client for a drag transaction.  This resource is a bit mask that is formed by combining one or more of the following values using a bitwise operation such as inclusive OR (|): XmDROP_COPY, XmDROP_LINK, XmDROP_MOVE.  The value XmDROP_NOOP for this resource indicates that no operations are valid.  For Text and TextField widgets, this resource is set to XmDROP_COPY | XmDROP_MOVE; for List widgets, it is set to XmDROP_COPY.  Specifies the list of callbacks that are invoked when the drop is completed.   The type of the structure whose address is passed to this callback is XmDropFinishCallbackStruct.   The reason sent by the callback is XmCR_DROP_FINISH.  Specifies the list of callbacks that are invoked when the pointer enters a drop site.  The type of the structure whose address is passed to this callback is XmDropSiteEnterCallbackStruct.  The reason sent by the callback is XmCR_DROP_SITE_ENTER.  Specifies the list of callbacks that are invoked when the pointer leaves a drop site.  The type of the structure whose address is passed to this callback is XmDropSiteLeaveCallbackStruct.  The reason sent by the callback is XmCR_DROP_SITE_LEAVE.  Specifies the list of callbacks that are invoked when a drop is initiated.  The type of the structure whose address is passed to this callback is XmDropStartCallbackStruct.  The reason sent by the callback is XmCR_DROP_START.  Specifies the list of target atoms associated with this source.  This resource identifies the selection targets this source can be converted to.  Specifies a Boolean value that indicates whether the transfer on the initiator side uses the Xt incremental selection transfer mechanism described in X Toolkit Intrinsics − C Language Interface.  If the value is True, the initiator uses incremental transfer; if the value is False, the initiator uses atomic transfer.  Specifies the foreground pixel value of the cursor when the state is invalid.  This resource defaults to the value of the XmNcursorForeground resource.  Specifies the foreground pixel value of the cursor when the state is none.  This resource defaults to the value of the XmNcursorForeground resource.  Specifies the number of entries in the list of export targets.  Specifies the list of callbacks that are invoked when the drag is started and when the user requests that a different operation be applied to the drop.  The type of the structure whose address is passed to this callback is XmOperationChangedCallbackStruct.  The reason sent by the callback is XmCR_OPERATION_CHANGED.  Specifies the cursor icon used to designate the type of operation performed by the drag transaction.  If  NULL, XmScreen resources provide default icons for copy, link, and move operations.  Specifies the cursor icon used to represent the source when a dynamic visual style is used.  If NULL, the XmNdefaultSourceCursorIcon resource of XmScreen provides a default cursor icon.  Specifies the pixmap icon used to represent the source when a preregister visual style is used.  The icon is used in conjunction with the colormap of the widget passed to XmDragStart.  If NULL, XmNsourceCursorIcon is used.  Specifies the cursor icon used to designate the state of a drop site.  If NULL, XmScreen resources provide default icons for a valid, invalid, and no drop site condition.  Specifies the list of callbacks that are called when the pointer enters a top-level window or root window (due to changing screens).  The type of the structure whose address is passed to this callback is XmTopLevelEnterCallbackStruct.  The reason sent by the callback is XmCR_TOP_LEVEL_ENTER.  Specifies the list of callbacks that are called when the pointer leaves a top level window or the root window (due to changing screens).  The type of the structure whose address is passed to this callback is XmTopLevelLeaveCallbackStruct.  The reason sent by the callback is XmCR_TOP_LEVEL_LEAVE.  Specifies the foreground pixel value of the cursor designated as a valid cursor icon. 

Inherited Resources

DragContext inherits behavior and resources from the following superclass.  For a complete description of each resource, refer to the Core man page. 

Core Resource Set
Name	Class	Type	Default	Access
XmNaccelerators	XmCAccelerators	XtAccelerators	dynamic	CSG
XmNancestorSensitive	XmCSensitive	Boolean	dynamic	G
XmNbackground	XmCBackground	Pixel	dynamic	CSG
XmNbackgroundPixmap	XmCPixmap	Pixmap	XmUNSPECIFIED_PIXMAP	CSG
XmNborderColor	XmCBorderColor	Pixel	XtDefaultForeground	CSG
XmNborderPixmap	XmCPixmap	Pixmap	XmUNSPECIFIED_PIXMAP	CSG
XmNborderWidth	XmCBorderWidth	Dimension	0	CSG
XmNcolormap	XmCColormap	Colormap	dynamic	CG
XmNdepth	XmCDepth	int	dynamic	CG
XmNdestroyCallback	XmCCallback	XtCallbackList	NULL	C
XmNheight	XmCHeight	Dimension	dynamic	CSG
XmNinitialResourcesPersistent	XmCInitialResourcesPersistent	Boolean	True	C
XmNmappedWhenManaged	XmCMappedWhenManaged	Boolean	True	CSG
XmNscreen	XmCScreen	Screen ∗	dynamic	CG
XmNsensitive	XmCSensitive	Boolean	True	CSG
XmNtranslations	XmCTranslations	XtTranslations	dynamic	CSG
XmNwidth	XmCWidth	Dimension	dynamic	CSG
XmNx	XmCPosition	Position	0	CSG
XmNy	XmCPosition	Position	0	CSG

Callback Information

Each of the DragContext callbacks has an associated callback structure. 

A pointer to the following structure is passed to the XmNdragDropFinishCallback callback. 

typedef struct
{
intreason;
XEvent∗event;
TimetimeStamp;
}XmDragDropFinishCallbackStruct, ∗XmDragDropFinishCallback;

reasonIndicates why the callback was invoked.

eventPoints to the XEvent that triggered the callback.

timestampSpecifies the time at which either the drag or the drop was completed.

A pointer to the following structure is passed to callbacks for
XmNdragMotionCallback.

typedef struct
{
intreason;
XEvent∗event;
TimetimeStamp;
unsigned charoperation;
unsigned charoperations;
unsigned chardropSiteStatus;
Positionx;
Positiony;
}XmDragMotionCallbackStruct, ∗XmDragMotionCallback;

reasonIndicates why the callback was invoked.

eventPoints to the XEvent that triggered the callback.

timeStampSpecifies the timestamp of the logical event.

operationIdentifies an operation.

If the toolkit has just called a DropSite’s XmNdragProc, the
toolkit initializes operation to the value of the operation
member of the XmDragProcCallbackStruct at the time the DropSite’s
XmNdragProc returns.

If the toolkit has not called an XmNdragProc and the pointer is
within an active drop site, the toolkit initializes operation by
selecting an operation from the bitwise AND of the initial value of the
operations member and the value of the DropSite’s
XmNdropSiteOperations resource.
The toolkit searches this set first for XmDROP_MOVE, then for
XmDROP_COPY, then for XmDROP_LINK, and initializes
operation to the first operation it finds in the set.
If the toolkit finds none of these operations in the set, it initializes
operation to XmDROP_NOOP.

If the toolkit has not called an XmNdragProc and the pointer is
not within an active drop site, the toolkit initializes operation
by selecting an operation from the initial value of the operations
member.
The toolkit searches this set first for XmDROP_MOVE, then for
XmDROP_COPY, then for XmDROP_LINK, and initializes
operation to the first operation it finds in the set.
If the toolkit finds none of these operations in the set, it initializes
operation to XmDROP_NOOP.

operationsIndicates the set of operations supported for the source data.

If the toolkit has just called a DropSite’s XmNdragProc, the
toolkit initializes operations to the bitwise AND of the
DropSite’s XmNdropOperations and the value of the operations
member of the XmDragProcCallbackStruct at the time the DropSite’s
XmNdragProc returns.
If the resulting set of operations is empty, the toolkit initializes
operations to XmDROP_NOOP.

If the toolkit has not called an XmNdragProc and the user does not
select an operation (by pressing a modifier key), the toolkit
initializes operations to the value of the DragContext’s
XmNdragOperations resource.

If the toolkit has not called an XmNdragProc and the user does
select an operation, the toolkit initializes operations to the
bitwise AND of the corresponding operation and the value of the
DragContext’s XmNdragOperations resource.
If the resulting set of operations is empty, the toolkit initializes
operations to XmDROP_NOOP.

dropSiteStatusIndicates whether or not a drop site is valid.

If the toolkit has just called a DropSite’s XmNdragProc, the
toolkit initializes dropSiteStatus to the value of the
dropSiteStatus member of the XmDragProcCallbackStruct at the
time the DropSite’s XmNdragProc returns.

If the toolkit has not called an XmNdragProc, it initializes
dropSiteStatus as follows:
the toolkit initializes dropSiteStatus to XmNO_DROP_SITE if
the pointer is over an inactive drop site or is not over a drop site.
The toolkit initializes dropSiteStatus to XmDROP_SITE_VALID
if all the following conditions are met:

•
The pointer is over an active drop site.

•
The DragContext’s XmNexportTargets and the DropSite’s
XmNimportTargets are compatible.

•
The initial value of the operation member is not
XmDROP_NOOP.
Otherwise, the toolkit initializes dropSiteStatus to
XmDROP_SITE_INVALID.

A pointer to the following structure is passed for the
XmNdropFinishCallback callback:

typedef struct
{
intreason;
XEvent∗event;
TimetimeStamp;
unsigned charoperation;
unsigned charoperations;
unsigned chardropSiteStatus;
unsigned chardropAction;
unsigned charcompletionStatus;
}XmDropFinishCallbackStruct, ∗XmDropFinishCallback;

reasonIndicates why the callback was invoked.

eventPoints to the XEvent that triggered the callback.

timeStampSpecifies the time at which the drop was completed.

operationIdentifies an operation.

If the pointer is over an active drop site when the drop begins, the
toolkit initializes operation to the value of the operation
member of the XmDropProcCallbackStruct at the time the DropSite’s
XmNdropProc returns.

If the pointer is not over an active drop site when the drop begins, the
toolkit initializes operation by selecting an operation from the
initial value of the operations member.
The toolkit searches this set first for XmDROP_MOVE, then for
XmDROP_COPY, then for XmDROP_LINK, and initializes
operation to the first operation it finds in the set.
If it finds none of these operations in the set, it initializes
operation to XmDROP_NOOP.

operationsIndicates the set of operations supported for the source data.

If the pointer is over an active drop site when the drop begins, the
toolkit initializes operations to the bitwise AND of the
DropSite’s XmNdropOperations and the value of the operations
member of the XmDropProcCallbackStruct at the time the DropSite’s
XmNdropProc returns.
If the resulting set of operations is empty, the toolkit initializes
operations to XmDROP_NOOP.

If the pointer is not over an active drop site when the drop begins and
if the user does not select an operation (by pressing a modifier key),
the toolkit initializes operations to the value of the
DragContext’s XmNdragOperations resource.

If the pointer is not over an active drop site when the drop begins and
if the user does select an operation, the toolkit initializes
operations to the bitwise AND of the corresponding operation and
the value of the DragContext’s XmNdragOperations resource.
If the resulting set of operations is empty, the toolkit initializes
operations to XmDROP_NOOP.

dropSiteStatusIndicates whether or not a drop site is valid.

If the pointer is over an active drop site when the drop begins, the
toolkit initializes dropSiteStatus to the value of the
dropSiteStatus member of the XmDropProcCallbackStruct at the
time the DropSite’s XmNdropProc returns.

If the pointer is not over an active drop site when the drop begins, the
toolkit initializes dropSiteStatus to XmNO_DROP_SITE.

dropActionIdentifies the drop action.  The values are: XmDROP,
XmDROP_CANCEL, XmDROP_HELP, and XmDROP_INTERRUPT.
The value XmDROP_INTERRUPT is currently unsupported; if
specified, it will be interpreted as an XmDROP_CANCEL.

completionStatusAn IN/OUT member that indicates the status of the drop action.
After the last callback procedure has returned, the final value of this
member determines what visual transition effects will be applied.
There are two values:

XmDROP_SUCCESSThe drop was successful.

XmDROP_FAILUREThe drop was unsuccessful.

A pointer to the following structure is passed to callbacks for
XmNdropSiteEnterCallback:

typedef struct
{
intreason;
XEvent∗event;
TimetimeStamp;
unsigned charoperation;
unsigned charoperations;
unsigned chardropSiteStatus;
Positionx;
Positiony;
}XmDropSiteEnterCallbackStruct, ∗XmDropSiteEnterCallback;

reasonIndicates why the callback was invoked.

eventPoints to the XEvent that triggered the callback.

timestampSpecifies the time the crossing event occurred.

operationIdentifies an operation.

If the toolkit has just called a DropSite’s XmNdragProc, the
toolkit initializes operation to the value of the operation
member of the XmDragProcCallbackStruct at the time the DropSite’s
XmNdragProc returns.

If the toolkit has not called an XmNdragProc, it initializes
operation by selecting an operation from the bitwise AND of the
initial value of the operations member and the value of the
DropSite’s XmNdropSiteOperations resource.
The toolkit searches this set first for XmDROP_MOVE, then for
XmDROP_COPY, then for XmDROP_LINK, and initializes
operation to the first operation it finds in the set.
If the toolkit finds none of these operations in the set, it initializes
operation to XmDROP_NOOP.

operationsIndicates the set of operations supported for the source data.

If the toolkit has just called a DropSite’s XmNdragProc, the
toolkit initializes operations to the bitwise AND of the
DropSite’s XmNdropOperations and the value of the operations
member of the XmDragProcCallbackStruct at the time the DropSite’s
XmNdragProc returns.
If the resulting set of operations is empty, the toolkit initializes
operations to XmDROP_NOOP.

If the toolkit has not called an XmNdragProc and the user does not
select an operation (by pressing a modifier key), the toolkit
initializes operations to the value of the DragContext’s
XmNdragOperations resource.

If the toolkit has not called an XmNdragProc and the user does
select an operation, the toolkit initializes operations to the
bitwise AND of the corresponding operation and the value of the
DragContext’s XmNdragOperations resource.
If the resulting set of operations is empty, the toolkit initializes
operations to XmDROP_NOOP.

dropSiteStatusIndicates whether or not a drop site is valid.

If the toolkit has just called a DropSite’s XmNdragProc, the
toolkit initializes dropSiteStatus to the value of the
dropSiteStatus member of the XmDragProcCallbackStruct at the
time the DropSite’s XmNdragProc returns.

If the toolkit has not called an XmNdragProc, it initializes
dropSiteStatus as follows:
the toolkit initializes dropSiteStatus to XmDROP_SITE_VALID
if the DragContext’s XmNexportTargets and the DropSite’s
XmNimportTargets are compatible and if the initial value of the
operation member is not XmDROP_NOOP.
Otherwise, the toolkit initializes dropSiteStatus to
XmDROP_SITE_INVALID.

xIndicates the x-coordinate of the pointer in root window coordinates.

yIndicates the y-coordinate of the pointer in root window coordinates.

A pointer to the following structure is passed to callbacks for
XmNdropSiteLeaveCallback.

typedef struct
{
intreason;
XEvent∗event;
TimetimeStamp;
}XmDropSiteLeaveCallbackStruct, ∗XmDropSiteLeaveCallback;

reasonIndicates why the callback was invoked.

eventPoints to the XEvent that triggered the callback.

timeStampSpecifies the timestamp of the logical event.

A pointer to the following structure is passed for the
XmNdropStartCallback callback:

typedef struct
{
intreason;
XEvent∗event;
TimetimeStamp;
unsigned charoperation;
unsigned charoperations;
unsigned chardropSiteStatus;
unsigned chardropAction;
Positionx;
Positiony;
}XmDropStartCallbackStruct, ∗XmDropStartCallback;

reasonIndicates why the callback was invoked.

eventPoints to the XEvent that triggered the callback.

timeStampSpecifies the time at which the drag was completed.

operationIdentifies an operation.

If the pointer is over an active drop site when the drop begins, the
toolkit initializes operation to the value of the operation
member of the XmDropProcCallbackStruct at the time the DropSite’s
XmNdropProc returns.

If the pointer is not over an active drop site when the drop begins, the
toolkit initializes operation by selecting an operation from the
initial value of the operations member.
The toolkit searches this set first for XmDROP_MOVE, then for
XmDROP_COPY, then for XmDROP_LINK, and initializes
operation to the first operation it finds in the set.
If it finds none of these operations in the set, it initializes
operation to XmDROP_NOOP.

operationsIndicates the set of operations supported for the source data.

If the pointer is over an active drop site when the drop begins, the
toolkit initializes operations to the bitwise AND of the
DropSite’s XmNdropOperations and the value of the operations
member of the XmDropProcCallbackStruct at the time the DropSite’s
XmNdropProc returns.
If the resulting set of operations is empty, the toolkit initializes
operations to XmDROP_NOOP.

If the pointer is not over an active drop site when the drop begins and
if the user does not select an operation (by pressing a modifier key),
the toolkit initializes operations to the value of the
DragContext’s XmNdragOperations resource.

If the pointer is not over an active drop site when the drop begins and
if the user does select an operation, the toolkit initializes
operations to the bitwise AND of the corresponding operation and
the value of the DragContext’s XmNdragOperations resource.
If the resulting set of operations is empty, the toolkit initializes
operations to XmDROP_NOOP.

dropSiteStatusIndicates whether or not a drop site is valid.

If the pointer is over an active drop site when the drop begins, the
toolkit initializes dropSiteStatus to the value of the
dropSiteStatus member of the XmDropProcCallbackStruct at the
time the DropSite’s XmNdropProc returns.

If the pointer is not over an active drop site when the drop begins, the
toolkit initializes dropSiteStatus to XmNO_DROP_SITE.

dropActionAn IN/OUT member that identifies the drop action.
The values are XmDROP, XmDROP_CANCEL, XmDROP_HELP,
and XmDROP_INTERRUPT.  The value of dropAction can be
modified to change the action actually initiated.
The value XmDROP_INTERRUPT is currently unsupported; if
specified, it will be interpreted as a XmDROP_CANCEL.

xIndicates the x-coordinate of the pointer in root window coordinates.

yIndicates the y-coordinate of the pointer in root window coordinates.

A pointer to the following structure is passed to the
XmNoperationChangedCallback callback:

typedef struct
{
intreason;
XEvent∗event;
TimetimeStamp;
unsigned charoperation;
unsigned charoperations;
unsigned chardropSiteStatus;
}XmOperationChangedCallbackStruct, ∗XmOperationChangedCallback;

reasonIndicates why the callback was invoked.

eventPoints to the XEvent that triggered the callback.

timestampSpecifies the time at which the crossing event occurred.

operationIdentifies an operation.

If the toolkit has just called a DropSite’s XmNdragProc, the
toolkit initializes operation to the value of the operation
member of the XmDragProcCallbackStruct at the time the DropSite’s
XmNdragProc returns.

If the toolkit has not called an XmNdragProc and the pointer is
within an active drop site, the toolkit initializes operation by
selecting an operation from the bitwise AND of the initial value of the
operations member and the value of the DropSite’s
XmNdropSiteOperations resource.
The toolkit searches this set first for XmDROP_MOVE, then for
XmDROP_COPY, then for XmDROP_LINK, and initializes
operation to the first operation it finds in the set.
If the toolkit finds none of these operations in the set, it initializes
operation to XmDROP_NOOP.

If the toolkit has not called an XmNdragProc and the pointer is
not within an active drop site, the toolkit initializes operation
by selecting an operation from the initial value of the operations
member.
The toolkit searches this set first for XmDROP_MOVE, then for
XmDROP_COPY, then for XmDROP_LINK, and initializes
operation to the first operation it finds in the set.
If the toolkit finds none of these operations in the set, it initializes
operation to XmDROP_NOOP.

operationsIndicates the set of operations supported for the source data.

If the toolkit has just called a DropSite’s XmNdragProc, the
toolkit initializes operations to the bitwise AND of the
DropSite’s XmNdropOperations and the value of the operations
member of the XmDragProcCallbackStruct at the time the DropSite’s
XmNdragProc returns.
If the resulting set of operations is empty, the toolkit initializes
operations to XmDROP_NOOP.

If the toolkit has not called an XmNdragProc and the user does not
select an operation (by pressing a modifier key), the toolkit
initializes operations to the value of the DragContext’s
XmNdragOperations resource.

If the toolkit has not called an XmNdragProc and the user does
select an operation, the toolkit initializes operations to the
bitwise AND of the corresponding operation and the value of the
DragContext’s XmNdragOperations resource.
If the resulting set of operations is empty, the toolkit initializes
operations to XmDROP_NOOP.

dropSiteStatusIndicates whether or not a drop site is valid.

If the toolkit has just called a DropSite’s XmNdragProc, the
toolkit initializes dropSiteStatus to the value of the
dropSiteStatus member of the XmDragProcCallbackStruct at the
time the DropSite’s XmNdragProc returns.

If the toolkit has not called an XmNdragProc, it initializes
dropSiteStatus as follows:
the toolkit initializes dropSiteStatus to XmNO_DROP_SITE if
the pointer is over an inactive drop site or is not over a drop site.
The toolkit initializes dropSiteStatus to XmDROP_SITE_VALID
if all the following conditions are met:

•
The pointer is over an active drop site

•
The DragContext’s XmNexportTargets and the DropSite’s
XmNimportTargets are compatible

•
The initial value of the operation member is not
XmDROP_NOOP
Otherwise, the toolkit initializes dropSiteStatus to
XmDROP_SITE_INVALID.

A pointer to the following structure is passed to callbacks for
XmNtopLevelEnterCallback:

typedef struct
{
intreason;
XEvent∗event;
Timetimestamp;
Screenscreen;
Windowwindow;
Positionx;
Positiony;
unsigned chardragProtocolStyle;
}XmTopLevelEnterCallbackStruct, ∗XmTopLevelEnterCallback;

reasonIndicates why the callback was invoked.

eventPoints to the XEvent that triggered the callback.

timeStampSpecifies the timestamp of the logical event.

screenSpecifies the screen associated with the top-level window or root
window being entered.

windowSpecifies the ID of the top-level window or root window being entered.

xIndicates the x-coordinate of the pointer in root window coordinates.

yIndicates the y-coordinate of the pointer in root window coordinates.

dragProtocolStyleSpecifies the protocol style adopted by the initiator.  The values
are XmDRAG_DROP_ONLY, XmDRAG_DYNAMIC, XmDRAG_NONE,
and XmDRAG_PREREGISTER.

A pointer to the following structure is passed to callbacks for
XmNtopLevelLeaveCallback:

typedef struct
{
intreason;
XEvent∗event;
Timetimestamp;
Screenscreen;
Windowwindow;
}XmTopLevelLeaveCallbackStruct, ∗XmTopLevelLeaveCallback;

reasonIndicates why the callback was invoked.

eventPoints to the XEvent that triggered the callback.

timeStampSpecifies the timestamp of the logical event.

screenSpecifies a screen associated with the top-level window or root
window being left.

windowSpecifies the ID of the top-level window or root window being left.

Translations

The XmDragContext translations are listed below.  These translations may not directly correspond to a translation table. 

BDrag Motion:DragMotion()
BDrag Release:FinishDrag()
KCancel:CancelDrag()
KHelp:HelpDrag()

Action Routines

The XmDragContext action routines are described below:

CancelDrag():
Cancels the drag operation and frees the associated DragContext.

DragMotion():
Drags the selected data as the pointer is moved.

FinishDrag():
Finishes the drag operation and starts the drop operation.

HelpDrag():
Initiates a conditional drop that enables the receiver to provide help information to the user.  The user can cancel or continue the drop operation in response to this information.

Virtual Bindings

The bindings for virtual keys are vendor specific.  For information about bindings for virtual buttons and keys, see VirtualBindings(3X). 

RELATED INFORMATION

Core(3X), XmDisplay(3X), XmDragCancel(3X), XmDragIcon(3X), XmDragStart(3X), XmDropSite(3X), XmDropTransfer(3X), and XmScreen(3X). 

Motif Release 1.2: May 1992  —  Last change: