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XmDragContext(3X)
OSF/Motif
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
XmNblendModel
Class: XmCBlendModel
Default: XmBLEND_ALL
Type: unsigned char
Access: CG
XmNclientData
Class: XmCClientData
Default: NULL
Type: XtPointer
Access: CSG
XmNconvertProc
Class: XmCConvertProc
Default: NULL
Type: XtConvertSelectionIncrProc
Access: CSG
XmNcursorBackground
Class: XmCCursorBackground
Default: dynamic
Type: Pixel
Access: CSG
XmNdragDropFinishCallback
Class: XmCCallback
Default: NULL
Type: XtCallbackList
Access: CSG
XmNdragMotionCallback
Class: XmCCallback
Default: NULL
Type: XtCallbackList
Access: C
XmNdragOperations
Class: XmCDragOperations
Default: XmDROP_COPY XmDROP_MOVE
Type: unsigned char
Access: C
XmNdropFinishCallback
Class: XmCCallback
Default: NULL
Type: XtCallbackList
Access: C
XmNdropSiteEnterCallback
Class: XmCCallback
Default: NULL
Type: XtCallbackList
Access: C
XmNdropSiteLeaveCallback
Class: XmCCallback
Default: NULL
Type: XtCallbackList
Access: C
XmNdropStartCallback
Class: XmCCallback
Default: NULL
Type: XtCallbackList
Access: C
XmNexportTargets
Class: XmCExportTargets
Default: NULL
Type: Atom *
Access: CSG
XmNincremental
Class: XmCIncremental
Default: False
Type: Boolean
Access: CSG
XmNinvalidCursorForeground
Class: XmCCursorForeground
Default: dynamic
Type: Pixel
Access: CSG
XmNnoneCursorForeground
Class: XmCCursorForeground
Default: dynamic
Type: Pixel
Access: CSG
XmNnumExportTargets
Class: XmCNumExportTargets
Default: 0
Type: Cardinal
Access: CSG
XmNoperationChangedCallback
Class: XmCCallback
Default: NULL
Type: XtCallbackList
Access: C
XmNoperationCursorIcon
Class: XmCOperationCursorIcon
Default: dynamic
Type: Widget
Access: CSG
XmNsourceCursorIcon
Class: XmCSourceCursorIcon
Default: dynamic
Type: Widget
Access: CSG
XmNsourcePixmapIcon
Class: XmCSourcePixmapIcon
Default: dynamic
Type: Widget
Access: CSG
XmNstateCursorIcon
Class: XmCStateCursorIcon
Default: dynamic
Type: Widget
Access: CSG
XmNtopLevelEnterCallback
Class: XmCCallback
Default: NULL
Type: XtCallbackList
Access: C
XmNtopLevelLeaveCallback
Class: XmCCallback
Default: NULL
Type: XtCallbackList
Access: C
XmNvalidCursorForeground
Class: XmCCursorForeground
Default: dynamic
Type: Pixel
Access: 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.
XmNclientData
Specifies the client data to be passed to the XmNconvertProc when it is
invoked.
XmNconvertProc
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.
XmNcursorBackground
Specifies the background pixel value of the cursor.
XmNcursorForeground
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.
XmNdragDropFinishCallback
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.
XmNdragMotionCallback
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.
XmNdragOperations
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.
XmNdropFinishCallback
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.
XmNdropSiteEnterCallback
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.
XmNdropSiteLeaveCallback
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.
XmNdropStartCallback
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.
XmNexportTargets
Specifies the list of target atoms associated with this source. This
resource identifies the selection targets this source can be converted
to.
XmNincremental
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.
XmNinvalidCursorForeground
Specifies the foreground pixel value of the cursor when the state is
invalid. This resource defaults to the value of the
XmNcursorForeground resource.
XmNnoneCursorForeground
Specifies the foreground pixel value of the cursor when the state is
none. This resource defaults to the value of the XmNcursorForeground
resource.
XmNnumExportTargets
Specifies the number of entries in the list of export targets.
XmNoperationChangedCallback
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.
XmNoperationCursorIcon
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.
XmNsourceCursorIcon
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.
XmNsourcePixmapIcon
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.
XmNstateCursorIcon
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.
XmNtopLevelEnterCallback
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.
XmNtopLevelLeaveCallback
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.
XmNvalidCursorForeground
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(3X) man
page.
Core Resource Set
XmNaccelerators
Class: XmCAccelerators
Default: dynamic
Type: XtAccelerators
Access: CSG
XmNancestorSensitive
Class: XmCSensitive
Default: dynamic
Type: Boolean
Access: G
XmNbackground
Class: XmCBackground
Default: dynamic
Type: Pixel
Access: CSG
XmNbackgroundPixmap
Class: XmCPixmap
Default: XmUNSPECIFIED_PIXMAP
Type: Pixmap
Access: CSG
XmNborderColor
Class: XmCBorderColor
Default: XtDefaultForeground
Type: Pixel
Access: CSG
XmNborderPixmap
Class: XmCPixmap
Default: XmUNSPECIFIED_PIXMAP
Type: Pixmap
Access: CSG
XmNborderWidth
Class: XmCBorderWidth
Default: 0
Type: Dimension
Access: CSG
XmNcolormap
Class: XmCColormap
Default: dynamic
Type: Colormap
Access: CG
XmNdepth
Class: XmCDepth
Default: dynamic
Type: int
Access: CG
XmNdestroyCallback
Class: XmCCallback
Default: NULL
Type: XtCallbackList
Access: C
XmNheight
Class: XmCHeight
Default: dynamic
Type: Dimension
Access: CSG
XmNinitialResourcesPersistent
Class: XmCInitialResourcesPersistent
Default: True
Type: Boolean
Access: C
XmNmappedWhenManaged
Class: XmCMappedWhenManaged
Default: True
Type: Boolean
Access: CSG
XmNscreen
Class: XmCScreen
Default: dynamic
Type: Screen *
Access: CG
XmNsensitive
Class: XmCSensitive
Default: True
Type: Boolean
Access: CSG
XmNtranslations
Class: XmCTranslations
Default: dynamic
Type: XtTranslations
Access: CSG
XmNwidth
Class: XmCWidth
Default: dynamic
Type: Dimension
Access: CSG
XmNx
Class: XmCPosition
Default: 0
Type: Position
Access: CSG
XmNy
Class: XmCPosition
Default: 0
Type: Position
Access: 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
{
int reason;
XEvent *event;
Time timeStamp;
}XmDragDropFinishCallbackStruct, *XmDragDropFinishCallback;
reason
Indicates why the callback was invoked.
event
Points to the XEvent that triggered the callback.
timestamp
Specifies 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
{
int reason;
XEvent *event;
Time timeStamp;
unsigned char operation;
unsigned char operations;
unsigned char dropSiteStatus;
Position x;
Position y;
}XmDragMotionCallbackStruct, *XmDragMotionCallback;
reason
Indicates why the callback was invoked.
event
Points to the XEvent that triggered the callback.
timeStamp
Specifies the timestamp of the logical event.
operation
Identifies 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.
operations
Indicates 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.
dropSiteStatus
Indicates 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
{
int reason;
XEvent *event;
Time timeStamp;
unsigned char operation;
unsigned char operations;
unsigned char dropSiteStatus;
unsigned char dropAction;
unsigned char completionStatus;
}XmDropFinishCallbackStruct, *XmDropFinishCallback;
reason
Indicates why the callback was invoked.
event
Points to the XEvent that triggered the callback.
timeStamp
Specifies the time at which the drop was completed.
operation
Identifies 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.
operations
Indicates 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.
dropSiteStatus
Indicates 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.
dropAction
Identifies 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.
completionStatus
An 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_SUCCESS
The drop was successful.
XmDROP_FAILURE
The drop was unsuccessful.
A pointer to the following structure is passed to callbacks for
XmNdropSiteEnterCallback:
typedef struct
{
int reason;
XEvent *event;
Time timeStamp;
unsigned char operation;
unsigned char operations;
unsigned char dropSiteStatus;
Position x;
Position y;
}XmDropSiteEnterCallbackStruct, *XmDropSiteEnterCallback;
reason
Indicates why the callback was invoked.
event
Points to the XEvent that triggered the callback.
timestamp
Specifies the time the crossing event occurred.
operation
Identifies 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.
operations
Indicates 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.
dropSiteStatus
Indicates 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.
x Indicates the x-coordinate of the pointer in root window coordinates.
y Indicates the y-coordinate of the pointer in root window coordinates.
A pointer to the following structure is passed to callbacks for
XmNdropSiteLeaveCallback.
typedef struct
{
int reason;
XEvent *event;
Time timeStamp;
}XmDropSiteLeaveCallbackStruct, *XmDropSiteLeaveCallback;
reason
Indicates why the callback was invoked.
event
Points to the XEvent that triggered the callback.
timeStamp
Specifies the timestamp of the logical event.
A pointer to the following structure is passed for the XmNdropStartCallback
callback:
typedef struct
{
int reason;
XEvent *event;
Time timeStamp;
unsigned char operation;
unsigned char operations;
unsigned char dropSiteStatus;
unsigned char dropAction;
Position x;
Position y;
}XmDropStartCallbackStruct, *XmDropStartCallback;
reason
Indicates why the callback was invoked.
event
Points to the XEvent that triggered the callback.
timeStamp
Specifies the time at which the drag was completed.
operation
Identifies 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.
operations
Indicates 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.
dropSiteStatus
Indicates 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.
dropAction
An 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.
x Indicates the x-coordinate of the pointer in root window coordinates.
y Indicates the y-coordinate of the pointer in root window coordinates.
A pointer to the following structure is passed to the
XmNoperationChangedCallback callback:
typedef struct
{
int reason;
XEvent *event;
Time timeStamp;
unsigned char operation;
unsigned char operations;
unsigned char dropSiteStatus;
}XmOperationChangedCallbackStruct, *XmOperationChangedCallback;
reason
Indicates why the callback was invoked.
event
Points to the XEvent that triggered the callback.
timestamp
Specifies the time at which the crossing event occurred.
operation
Identifies 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.
operations
Indicates 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.
dropSiteStatus
Indicates 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
{
int reason;
XEvent *event;
Time timestamp;
Screen screen;
Window window;
Position x;
Position y;
unsigned char dragProtocolStyle;
}XmTopLevelEnterCallbackStruct, *XmTopLevelEnterCallback;
reason
Indicates why the callback was invoked.
event
Points to the XEvent that triggered the callback.
timeStamp
Specifies the timestamp of the logical event.
screen
Specifies the screen associated with the top-level window or root
window being entered.
window
Specifies the ID of the top-level window or root window being entered.
x Indicates the x-coordinate of the pointer in root window coordinates.
y Indicates the y-coordinate of the pointer in root window coordinates.
dragProtocolStyle
Specifies 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
{
int reason;
XEvent *event;
Time timestamp;
Screen screen;
Window window;
}XmTopLevelLeaveCallbackStruct, *XmTopLevelLeaveCallback;
reason
Indicates why the callback was invoked.
event
Points to the XEvent that triggered the callback.
timeStamp
Specifies the timestamp of the logical event.
screen
Specifies a screen associated with the top-level window or root window
being left.
window
Specifies 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).
SEE ALSO
Core(3X), XmDisplay(3X), XmDragCancel(3X), XmDragIcon(3X), XmDragStart(3X),
XmDropSite(3X), XmDropTransfer(3X), XmScreen(3X)
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