XmDisplay(3X) XmDisplay(3X)
NAME
XmDisplay - The Display widget class
SYNOPSIS
#include <Xm/Display.h>
DESCRIPTION
The XmDisplay object is used by the Motif widgets to store information that is specific to a display. It also allows the toolkit to access
certain information on widget hierarchies that would otherwise be unavailable. Each client has one XmDisplay object for each display it
accesses.
An XmDisplay object is automatically created when the application creates the first shell on a display (usually accomplished by a call to
XtAppInitialize or XtAppCreateShell). It is not necessary to create an XmDisplay object by any other means. An application can use the
function XmGetXmDisplay to obtain the widget ID of the XmDisplay object for a given display.
An application cannot supply initial values for XmDisplay resources as arguments to a call to any function that creates widgets. The appli-
cation or user can supply initial values in a resource file. After creating the first shell on the display, the application can use
XmGetXmDisplay to obtain the widget ID of the XmDisplay object and then call XtSetValues to set the XmDisplay resources.
XmDisplay resources specify the drag protocol style for a client participating in drag and drop transactions. There are two basic protocol
types, preregister and dynamic. When a preregister protocol is used, the toolkit handles any communication between the initiator and
receiver clients, and displays the appropriate drag-over and drag-under visual effects. A client registers its drop sites in advance and
this information is stored in a property for each top-level window. When the drag pointer enters a top level window, the drop site infor-
mation is read by the initiator. A dynamic protocol allows the source and destination clients to dynamically communicate drag and drop
state information between each other, and to update their respective visuals accordingly. The toolkit provides drop site information as
the pointer passes over any given drop site. In this mode, a receiver can supply a procedure to generate its own drag-under effects.
Classes
Display inherits behavior and resources from Core, Composite, Shell, WMShell, VendorShell, TopLevelShell, and ApplicationShell classes.
The class pointer is xmDisplayClass.
The class name is XmDisplay.
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 an .Xdefaults file,
remove the XmN or XmC prefix and use the remaining letters. To specify one of the defined values for a resource in an .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).
XmDisplay Resource Set
Class: DefaultVirtualBindings Default: dynamic Type: String Access: CG Class: XmCDragInitiatorProtocolStyle Default: XmDRAG_PRE-
FER_RECEIVER Type: unsigned char Access: CG Class: XmCDragReceiverProtocolStyle Default: XmDRAG_PREFER_PREREGISTER Type: unsigned char
Access: CG
Specifies the default virtual bindings for the display. Following is an example of a specification for the defaultVirtualBindings
resource in a resource file:
*defaultVirtualBindings:
osfBackSpace : <Key>BackSpace
osfInsert : <Key>InsertChar
...
osfDelete : <Key>DeleteChar Specifies the drag and drop protocol requirements or preference when the client is an ini-
tiator. The possible values are: As an initiator, this client does not use the dynamic protocol and can only arrange visual effects
with receivers who provide preregistered information. As an initiator, this client does not make use of any preregistered drop site
information made available by other clients, and can only arrange visual effects with receivers who use the dynamic protocol. Spec-
ifies that drag and drop is disabled for this client. As an initiator, this client does not use either the preregistered drop site
information or the dynamic protocol. It supports dragging, and any time the cursor is over a client that supports drag and drop,
valid feedback is provided. There are no other visual effects. As an initiator, this client can support both the preregister and
dynamic protocols, but prefers to use dynamic protocols whenever possible in order to provide high-quality drag-under feedback. As
an initiator, this client can support both the preregister and dynamic protocols, but prefers to use the preregister protocol when-
ever possible in order to accommodate performance needs or to provide consistent drag-over feedback. Indicates that this client can
support both preregister and dynamic protocols, but will defer to the preference of the receiver client. This value is valid only
for the XmNdragInitiatorProtocolStyle resource, and is its default value. Specifies the drag and drop protocol requirements or
preference when this client is a receiver. The values are: As a receiver, this client preregisters drop site information and does
not use the dynamic protocol. It can only arrange visual effects with initiators who make use of the preregistered information. As
a receiver, this client uses the dynamic protocol and does not preregister drop site information. It can only arrange visual
effects with initiators who use the dynamic protocol. Specifies that drag and drop is disabled for this client. As a receiver,
this client neither uses the dynamic protocol nor preregisters drop site information. It supports dropping, and when dragging over
this client, valid feedback is always provided, but there are no other visual effects. As a receiver, this client can support both
the preregister and dynamic protocols, but prefers to use dynamic protocol whenever possible in order to provide high-quality drag-
under feedback. As a receiver, this client can support both the preregister and dynamic protocols, but prefers to use the preregis-
ter protocol whenever possible in order to accommodate performance needs.
The actual protocol used between an initiator and a receiver is based on the protocol style of the receiver and initiator. The decision
matrix is as follows:
_______________________________________________________
| Drag Initiator | Drag Receiver Protocol Style Protocol Style |
---------------|---------------------------------------
|
| Pre Prefer Pre Prefer Dyn Dyn ---------------|---------------------------------------
Pre | Pre Pre Pre D-O
|
Prefer Pre | Pre Pre Pre Dyn
|
Prefer Rec | Pre Pre Dyn Dyn
|
Prefer Dyn | Pre Dyn Dyn Dyn
|
Dyn | D-O Dyn Dyn Dyn _______________|_______________________________________
Pre = Preregister
Dyn = Dynamic
D-P = Drop Only
The value XmDRAG_NONE does not appear in the above matrix. When specified for either the initiator or receiver side, XmDRAG_NONE implies
that drag and drop transactions are not supported. A value of XmDRAG_DROP_ONLY (Drop Only) results when an initiator and receiver cannot
compromise protocol styles, that is, one client requires dynamic mode while the other can only support preregister mode, or if either
explicitly has specified XmDRAG_DROP_ONLY.
Inherited Resources
All of the superclass resources inherited by XmDisplay are designated N/A (not applicable).
SEE ALSO
ApplicationShell(3X), Composite(3X), Core(3X), TopLevelShell(3X), VendorShell(3X), WMShell(3X), XmGetXmDisplay(3X), XmScreen(3X)
XmDisplay(3X)