XmDropSite(3X) — DG/UX R4.11MU05

XmDropSite(3X) SDK X11 R4.11MU05 XmDropSite(3X)

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
XmNanimationStyle 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.

Drop sites may overlap. The initial stacking order corresponds to
the order in which the drop sites were registered. When a drop site
overlaps 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 values 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).

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 XmNanimationPixmapDepth 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 procedure is called only when a dynamic protocol is
used. The type of structure whose address is passed to
this procedure is XmDragProcCallbackStruct. The reason
sent to the procedure is one of the following:

XmCR_DROP_SITE_ENTER_MESSAGE

XmCR_DROP_SITE_LEAVE_MESSAGE

XmCR_DRAG_MOTION_MESSAGE

XmCR_OPERATION_CHANGED_MESSAGE

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 struct passed to the appropriate callbacks of
the initiator (the DragContext's XmNdropSiteEnterCallback,
XmNdropSiteLeaveCallback, XmNdragMotionCallback, or
XmNoperationChangedCallback 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 initiator'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 widget. If XmNdropSiteType is
XmDROP_SITE_COMPOSITE, this resource cannot be specified by
the application.

XmNdropSiteActivity
Indicates whether a drop site is active or inactive. The
values are XmDROP_SITE_ACTIVE and XmDROP_SITE_INACTIVE. 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.

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 chardropSiteStatus;
unsigned charoperation;
unsigned charoperations;
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 the reason is XmCR_DROP_SITE_ENTER_MESSAGE or
XmCR_OPERATION_CHANGED_MESSAGE, or when the reason is
XmCR_DRAG_MOTION_MESSAGE or XmCR_DROP_SITE_LEAVE_MESSAGE and the
pointer is not in the same drop site as on the previous invocation of
the drag procedure, the toolkit 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.

When the reason is XmCR_DRAG_MOTION_MESSAGE or
XmCR_DROP_SITE_LEAVE_MESSAGE and the pointer is within the same drop
site as on the previous invocation of the drag procedure, the toolkit
initializes dropSiteStatus to the value of dropSiteStatus at the time
the previous 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 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.

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 chardropSiteStatus;
unsigned charoperation;
unsigned charoperations;
unsigned chardropAction;
} 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 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.

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 DragContext'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 DragContext's
XmNdropStartCallback callbacks).

operations An IN/OUT member that indicates the set of operations
supported for the source data.

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 DragContext'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 DragContext's
XmNdropStartCallback callbacks).

RELATED INFORMATION
XmDragContext(3X), XmDragIcon(3X),
XmDropSiteConfigureStackingOrder(3X), XmDropSiteEndUpdate(3X),
XmDropSiteQueryStackingOrder(3), XmDropSiteRegister(3X),
XmDropSiteStartUpdate(3X), XmDropSiteUpdate(3X),
XmDropSiteUnregister(3X), XmDropTransfer(3X), and
XmTargetsAreCompatible(3X).

Museum