XmDisplay - The Display widget class
#include <Xm/Display.h>
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 application 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 dragunder
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 information 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 [Toc] [Back]
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 [Toc] [Back]
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 [Toc] [Back]
Class: DefaultVirtualBindings
Default: dynamic
Type: String
Access: CG
Class: XmCDragInitiatorProtocolStyle
Default: XmDRAG_PREFER_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\n\
osfInsert : <Key>InsertChar\n\ ...
osfDelete : <Key>DeleteChar Specifies
the drag and drop protocol requirements or preference
when the client is an initiator. 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. Specifies 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 whenever
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 preregister 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 [Toc] [Back]
All of the superclass resources inherited by XmDisplay are
designated N/A (not applicable).
ApplicationShell(3X), Composite(3X), Core(3X),
TopLevelShell(3X), VendorShell(3X), WMShell(3X),
XmGetXmDisplay(3X), XmScreen(3X)
XmDisplay(3X)
[ Back ] |