XmDropSite(library call) XmDropSite(library call)
NAME
XmDropSite -- The DropSite Registry
SYNOPSIS
#include <Xm/DragDrop.h>
DESCRIPTION
A client registers a widget or gadget as a drop site using the XmDropSiteRegister function. In addition, this routine defines the behavior
and capabilities of a drop site by specifying appropriate resources. For example, the XmNimportTargets and XmNnumImportTargets resources
identify respectively the selection target types and number of types supported by a drop site. The visual animation effects associated with
a drop site are also described with DropSite resources.
Drop site animation effects that occur in response to the pointer entering a valid drop site are called drag-under effects. A receiver can
select from several animation styles supplied by the toolkit or can provide customized animation effects. Drag-under effects supplied by
the toolkit include border highlighting, shadow in/out drawing, and pixmap representation.
When a preregister drag protocol style is used, the toolkit generates drag-under visual effects based on the value of the XmNanimationStyle
resource. In dynamic mode, if the drop site XmNdragProc resource is NULL, the toolkit also provides animation effects based on the XmNani-
mationStyle resource. Otherwise, if the XmNdragProc routine is specified, the receiver can either assume responsibility for animation
effects (through the XmNdragProc routine) or rely on the toolkit to provide animation. An application can either handle all or none of the
animation effects for a particular drop site. That is, an application should never do a partial job of animation on a particular drop
site.
Drop sites may overlap. The initial stacking order corresponds to the order in which the drop sites were registered. When a drop site over-
laps another drop site, the drag-under effects of the drop site underneath are clipped by the obscuring drop site(s).
The XmDropSiteUpdate routine sets resources for a widget that is registered as a drop site. XmDropSiteRetrieve gets drop site resource val-
ues previously specified for a registered widget. These routines are used instead of XtSetValues and XtGetValues.
Classes
XmDropSite does not inherit from any widget class.
New Resources
The following table defines a set of widget resources used by the programmer to specify data. 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 XmDropSiteUpdate (S),
retrieved by using XmDropSiteRetrieve (G), or is not applicable (N/A).
+--------------------------------------------------------------------------------------------------------+
| | XmDropSite|Resource Set | | |
|Name | Class | Type | Default | Access |
+------------------------+-------------------------+----------------+---------------------------+--------+
|XmNanimationMask | XmCAnimationMask | Pixmap | XmUNSPECIFIED_PIXMAP | CSG |
+------------------------+-------------------------+----------------+---------------------------+--------+
|XmNanimationPixmap | XmCAnimationPixmap | Pixmap | XmUNSPECIFIED_PIXMAP | CSG |
+------------------------+-------------------------+----------------+---------------------------+--------+
|XmNanimationPixmapDepth | XmCAnimationPixmapDepth | int | 0 | CSG |
+------------------------+-------------------------+----------------+---------------------------+--------+
|XmNanimationStyle | XmCAnimationStyle | unsigned char | XmDRAG_UNDER_HIGHLIGHT | CSG |
+------------------------+-------------------------+----------------+---------------------------+--------+
|XmNdragProc | XmCDragProc | XtCallbackProc | NULL | CSG |
+------------------------+-------------------------+----------------+---------------------------+--------+
|XmNdropProc | XmCDropProc | XtCallbackProc | NULL | CSG |
+------------------------+-------------------------+----------------+---------------------------+--------+
|XmNdropRectangles | XmCDropRectangles | XRectangle * | dynamic | CSG |
+------------------------+-------------------------+----------------+---------------------------+--------+
|XmNdropSiteActivity | XmCDropSiteActivity | unsigned char | XmDROP_SITE_ACTIVE | CSG |
+------------------------+-------------------------+----------------+---------------------------+--------+
|XmNdropSiteOperations | XmCDropSiteOperations | unsigned char | XmDROP_MOVE | XmDROP_COPY | CSG |
+------------------------+-------------------------+----------------+---------------------------+--------+
|XmNdropSiteType | XmCDropSiteType | unsigned char | XmDROP_SITE_SIMPLE | CG |
+------------------------+-------------------------+----------------+---------------------------+--------+
|XmNimportTargets | XmCImportTargets | Atom * | NULL | CSG |
+------------------------+-------------------------+----------------+---------------------------+--------+
|XmNnumDropRectangles | XmCNumDropRectangles | Cardinal | 1 | CSG |
+------------------------+-------------------------+----------------+---------------------------+--------+
|XmNnumImportTargets | XmCNumImportTargets | Cardinal | 0 | CSG |
+------------------------+-------------------------+----------------+---------------------------+--------+
+------------------------+-------------------------+----------------+---------------------------+--------+
XmNanimationMask
Specifies a mask to use with the pixmap specified by XmNanimationPixmap when the animation style is XmDRAG_UNDER_PIXMAP.
XmNanimationPixmap
Specifies a pixmap for drag-under animation when the animation style is XmDRAG_UNDER_PIXMAP. The pixmap is drawn with its origin
at the upper left corner of the bounding box of the drop site. If the drop site window is larger than the animation pixmap, the
portion of the window not covered by the pixmap will be tiled with the window's background color.
XmNanimationPixmapDepth
Specifies the depth of the pixmap specified by the XmNanimationPixmap resource. When the depth is 1, the colors are taken from
the foreground and background of the drop site widget. For any other value, drop site animation occurs only if the XmNanimation-
PixmapDepth matches the depth of the drop site window. Colors are derived from the current colormap.
XmNanimationStyle
Specifies the drag-under animation style used when a drag enters a valid drop site. The possible values are
XmDRAG_UNDER_HIGHLIGHT
The drop site uses highlighting effects.
XmDRAG_UNDER_SHADOW_OUT
The drop site uses an outset shadow.
XmDRAG_UNDER_SHADOW_IN
The drop site uses an inset shadow.
XmDRAG_UNDER_PIXMAP
The drop site uses the pixmap specified by XmNanimationPixmap to indicate that it can receive the drop.
XmDRAG_UNDER_NONE
The drop site does not use animation effects. A client using a dynamic protocol, may provide drag-under effects in its
XmNdragProc routine.
XmNdragProc
Specifies the procedure that is invoked when the drop site receives a crossing, motion, or operation changed message. This proce-
dure is called only when a dynamic protocol is used. The type of structure whose address is passed to this procedure is XmDrag-
ProcCallbackStruct. The reason sent to the procedure is one of the following:
o XmCR_DROP_SITE_ENTER_MESSAGE
o XmCR_DROP_SITE_LEAVE_MESSAGE
o XmCR_DRAG_MOTION
o XmCR_OPERATION_CHANGED
The drag procedure may change the values of some members of the XmDragProcCallbackStruct passed to it. After the drag procedure
returns, the toolkit uses the final values in initializing some members of the callback structure passed to the appropriate call-
backs of the initiator (the DragContext's XmNdropSiteEnterCallback, XmNdropSiteLeaveCallback, XmNdragMotionCallback, or XmNopera-
tionChangedCallback callbacks).
XmNdropProc
Specifies the procedure that is invoked when a drop (excluding a cancel or interrupt action) occurs on a drop site regardless of
the status of the drop site. The type of the structure whose address is passed to this procedure is XmDropProcCallbackStruct. The
reason sent to the procedure is XmCR_DROP_MESSAGE.
The drop procedure may change the values of some members of the XmDropProcCallbackStruct passed to it. After the drop procedure
returns, the toolkit uses the final values in initializing some members of the XmDropStartCallbackStruct passed to the initia-
tor's drop start callbacks (the DragContext's XmNdropStartCallback callbacks).
XmNdropRectangles
Specifies a list of rectangles that describe the shape of a drop site. The locations of the rectangles are relative to the origin
of the enclosing object. When XmNdropRectangles is NULL, the drop site is assumed to be the sensitive area of the enclosing wid-
get. If XmNdropSiteType is XmDROP_SITE_COMPOSITE, this resource cannot be specified by the application.
Retrieving this resource returns allocated memory that needs to be freed with the XtFree function.
XmNdropSiteActivity
Indicates whether a drop site is active or inactive. The values are XmDROP_SITE_ACTIVE, XmDROP_SITE_INACTIVE, and
XmDROP_SITE_IGNORE. An active drop site can receive a drop, whereas an inactive drop site is dormant. An inactive drop site is
treated as if it was not a registered drop site and any drag-under visuals associated with entering or leaving the drop site do
not occur. However, it is still used for clipping drag-under effects. A value of XmDROP_SITE_IGNORE indicates that a drop site
should be ignored for all purposes.
XmNdropSiteOperations
Specifies the set of valid operations associated with a drop site. 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, and XmDROP_MOVE.
The value XmDROP_NOOP for this resource indicates that no operations are valid.
XmNdropSiteType
Specifies the type of the drop site. The possible values are
XmDROP_SITE_SIMPLE
The widget does not have any additional children that are registered as drop sites.
XmDROP_SITE_COMPOSITE
The widget will have children that are registered as drop sites.
XmNimportTargets
Specifies the list of target atoms that this drop site accepts.
XmNnumDropRectangles
Specifies the number of rectangles in the XmNdropRectangles list. If the drop site type is XmDROP_SITE_COMPOSITE, this resource
can not be specified by the application.
XmNnumImportTargets
Specifies the number of atoms in the target atom list.
Callback Information
A pointer to the following structure is passed to the XmNdragProc routine when the drop site receives crossing, motion, or operation
changed messages:
typedef struct
{
int reason;
XEvent *event;
Time timeStamp;
Widget dragContext;
Position x;
Position y;
unsigned char dropSiteStatus;
unsigned char operation;
unsigned char operations;
Boolean animate;
} XmDragProcCallbackStruct, *XmDragProcCallback;
reason Indicates why the callback was invoked.
event Points to the XEvent that triggered the callback.
timeStamp Specifies the timestamp of the logical event.
dragContext
Specifies the ID of the DragContext widget associated with the transaction.
x Indicates the x-coordinate of the pointer relative to the drop site.
y Indicates the y-coordinate of the pointer relative to the drop site.
dropSiteStatus
An IN/OUT member that indicates whether or not a drop site is valid.
When reason is XmCR_DROP_SITE_ENTER_MESSAGE or XmCR_OPERATION_CHANGED, or reason is XmCR_DRAG_MOTION or XmCR_DROP_SITE_LEAVE_MES-
SAGE and the pointer is not in the same drop site as on the previous invocation of the drag procedure, 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.
When the reason is XmCR_DRAG_MOTION or XmCR_DROP_SITE_LEAVE_MESSAGE and the pointer is within the same drop site as on the previ-
ous invocation of the drag procedure, the toolkit initializes dropSiteStatus to the value of dropSiteStatus at the time the pre-
vious invocation of the drag procedure returns.
The drag procedure may change the value of this member. After the drag procedure returns, the toolkit uses the final value in
initializing the dropSiteStatus member of the callback struct passed to the appropriate callbacks of the initiator.
operation An IN/OUT member that identifies an operation.
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.
The drag procedure may change the value of this member. After the drag procedure returns, the toolkit uses the final value in
initializing the operation member of the callback struct passed to the appropriate callbacks of the initiator.
operations
An IN/OUT member that indicates the set of operations supported for the source data.
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 user does select an operation, the toolkit initializes operations to the bit-
wise 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.
The drag procedure may change the value of this member. After the drag procedure returns, the toolkit uses the final value in
initializing the operations member of the callback struct passed to the appropriate callbacks of the initiator.
animate An OUT member that indicates whether the toolkit or the receiver client provides drag-under effects for a valid drop site. If
animate is set to True, the toolkit provides drop site animation per the XmNanimationStyle resource value; if it is set to False,
the receiver generates drag-under animation effects.
A pointer to the following structure is passed to the XmNdropProc routine when the drop site receives a drop message:
typedef struct
{
int reason;
XEvent *event;
Time timeStamp;
Widget dragContext;
Position x;
Position y;
unsigned char dropSiteStatus;
unsigned char operation;
unsigned char operations;
unsigned char dropAction;
} XmDropProcCallbackStruct, *XmDropProcCallback;
reason Indicates why the callback was invoked.
event Specifies the XEvent that triggered the callback.
timeStamp Specifies the timestamp of the logical event.
dragContext
Specifies the ID of the DragContext widget associated with the transaction.
x Indicates the x-coordinate of the pointer relative to the drop site.
y Indicates the y-coordinate of the pointer relative to the drop site.
dropSiteStatus
An IN/OUT member that indicates whether or not a drop site is valid.
The toolkit initializes dropSiteStatus to XmDROP_SITE_VALID if the DragContext's XmNexportTargets and the DropSite's XmNimport-
Targets are compatible and if the initial value of the operation member is not XmDROP_NOOP. Otherwise, the toolkit initializes
dropSiteStatus to XmDROP_SITE_INVALID.
The drop procedure may change the value of this member. After the drop procedure returns, the toolkit uses the final value in
initializing the dropSiteStatus member of the XmDropStartCallbackStruct passed to the initiator's drop start callbacks (the Drag-
Context's XmNdropStartCallback callbacks).
operation An IN/OUT member that identifies an operation.
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 it finds none of
these operations in the set, it initializes operation to XmDROP_NOOP.
The drop procedure may change the value of this member. After the drop procedure returns, the toolkit uses the final value in
initializing the operation member of the XmDropStartCallbackStruct passed to the initiator's drop start callbacks (the DragCon-
text's XmNdropStartCallback callbacks).
operations
An IN/OUT member that indicates the set of operations supported for the source data.
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 user does select an operation, the toolkit initializes operations to the bit-
wise 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.
The drop procedure may change the value of this member. After the drop procedure returns, the toolkit uses the final value in
initializing the operations member of the XmDropStartCallbackStruct passed to the initiator's drop start callbacks (the DragCon-
text's XmNdropStartCallback callbacks).
dropAction
An IN/OUT member that identifies the action associated with the drop. The possible values are
XmDROP A drop was attempted. If the drop site is valid, drop transfer handling proceeds.
XmDROP_HELP
The user has requested help on the drop site.
The drop procedure may change the value of this member. After the drop procedure returns, the toolkit uses the final value in
initializing the dropAction member of the XmDropStartCallbackStruct passed to the initiator's drop start callbacks (the DragCon-
text's XmNdropStartCallback callbacks).
RELATED INFORMATION
XmDragContext(3), XmDragIcon(3), XmDropSiteConfigureStackingOrder(3), XmDropSiteEndUpdate(3), XmDropSiteQueryStackingOrder(3), XmDrop-
SiteRegister(3), XmDropSiteStartUpdate(3), XmDropSiteUpdate(3), XmDropSiteUnregister(3), XmDropTransfer(3), and XmTargetsAreCompatible(3).
XmDropSite(library call)