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XmDisplay(3) Library Functions Manual XmDisplay(3)

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 un-
available. Each client has one XmDisplay object for each display it ac-
cesses.

An XmDisplay object is automatically created when the application cre-
ates 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 func-
tion 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 applica-
tion or user can supply initial values in a resource file. After cre-
ating 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 par-
ticipating in drag and drop transactions. The two basic protocol types
are 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 informa-
tion 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 be-
tween 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 pro-
grammer to specify data. The programmer can also set the resource val-
ues 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).

XmNdefaultButtonEmphasis
Specifies whether to change the look of the PushButton widget
and gadget that have the XmNshowAsDefault resource set. When
the PushButton is the default, it has an etched out button
which is enclosed with another etched in border. The XmNde-
faultButtonEmphasis has the follow possible values, which af-
fect the location cursor:

XmINTERNAL_HIGHLIGHT
Causes the location cursor to appear in between the
two etched borders to minimize the space required.

XmEXTERNAL_HIGHLIGHT
Causes the PushButton to draw the location cursor
outside the second border.

XmNdefaultVirtualBindings
Specifies the default virtual bindings for the display. Fol-
lowing is an example of a specification for the defaultVirtu-
alBindings resource in a resource file:

*defaultVirtualBindings: \
osfBackSpace: <Key>BackSpace \n\
osfInsert: <Key>InsertChar \n\
osfDelete: <Key>DeleteChar \n\
...
osfLeft: <Key>left, Ctrl<Key>H

XmNdragInitiatorProtocolStyle
Specifies the drag and drop protocol requirements or prefer-
ence when the client is an initiator. The possible values are

XmDRAG_PREREGISTER
As an initiator, this client does not use the dy-
namic protocol and can only arrange visual effects
with receivers who provide preregistered informa-
tion.

XmDRAG_DYNAMIC
As an initiator, this client does not make use of
any preregistered drop site information made avail-
able by other clients, and can only arrange visual
effects with receivers who use the dynamic proto-
col.

XmDRAG_NONE
Specifies that drag and drop is disabled for this
client.

XmDRAG_DROP_ONLY
As an initiator, this client does not use either
the preregistered drop site information or the dy-
namic 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.

XmDRAG_PREFER_DYNAMIC
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.

XmDRAG_PREFER_PREREGISTER
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 pro-
vide consistent drag-over feedback.

XmDRAG_PREFER_RECEIVER
Indicates that this client can support both prereg-
ister 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.

XmNdragReceiverProtocolStyle
Specifies the drag and drop protocol requirements or prefer-
ence when this client is a receiver. The values are

XmDRAG_PREREGISTER
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.

XmDRAG_DYNAMIC
As a receiver, this client uses the dynamic proto-
col and does not preregister drop site information.
It can only arrange visual effects with initiators
who use the dynamic protocol.

XmDRAG_NONE
Specifies that drag and drop is disabled for this
client.

XmDRAG_DROP_ONLY
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.

XmDRAG_PREFER_DYNAMIC
As a receiver, this client can support both the
preregister and dynamic protocols, but prefers to
use the dynamic protocol whenever possible in order
to provide high-quality drag-under feedback.

XmDRAG_PREFER_PREREGISTER
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 default value of this resource is dependent on the capa-
bilities of the display. If the display supports the shape
extension, allowing the dynamic protocol to use arbitrarily
sized drag cursors, the default of this resource is Xm-
DRAG_PREFER_DYNAMIC, otherwise the default is XmDRAG_PRE-
FER_PREREGISTER.

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 described in the following table.
+----------------+----------------------------------------------+
| Drag Initiator | | | | |
| | Drag Receiver Protocol Style | | | |
+----------------+------------------------------+---+---+-------+
+----------------+------------------------------+---+---+-------+
+----------------+------------------------------+---+---+-------+
+----------------+------------------------------+---+---+-------+
+----------------+------------------------------+---+---+-------+
+----------------+------------------------------+---+---+-------+
+----------------+------------------------------+---+---+-------+

The value XmDRAG_NONE does not appear in the matrix. When
specified for either the initiator or receiver side, Xm-
DRAG_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 explic-
itly has specified XmDRAG_DROP_ONLY.

XmNdragStartCallback
Specifies the list of callbacks that are invoked when the Xm-
DragStart function is called. The type of structure whose ad-
dress is passed to this callback is XmDragStartCallback-
Struct. The callback reason is XmCR_DRAG_START.

XmNenableBtn1Transfer
Specifies if selection and transfer actions are integrated on
Btn1 and extend actions are activated on Btn2. This resource
can take the following values:

XmOFF Disables integration and selection activation on
Btn1.

XmBUTTON2_TRANSFER
Enables integration and selection activation on
Btn1 and transfer on Btn2.

XmBUTTON2_ADJUST
Enables integration and selection activation on
Btn1 and adjust on Btn2.

This resource affects the actions of Text, TextField, List,
and Container.

XmNenableButtonTab
Specifies if the action for the <Tab> key (KNextField and
KPrevField actions) is to be modified. A value of True modi-
fies the key to move as an arrow key until the boundary of a
tab group is reached. Then, at the boundary of the tab group,
KNextField and KPrevField will move to the next or previous
tab group, respectively. A value of False does not cause mod-
ification.

XmNenableDragIcon
Specifies which set of icons are to be used for system de-
fault cursors during drag and drop operations. A value of
False specifies that earlier versions of Motif release icons
are used, a value of True specifies that alternate icons are
used. This resource affects both the 16x16 and the 32x32
icons that the system defaults for each of the Screen objects
associated with this display.

XmNenableEtchedInMenu
Specifies the shadowing of the button widgets and gadgets in
menus when the control is activated. A value of True causes
the selected menu to be drawn with the shadow etched in; this
shadow style is consistent with the selected appearance of
other button widgets outside of menus. A value of False
causes the selected menu to be draw with the shadow etched
out. This resource affects the actions of PushButton, Toggle-
Button, and CascadeButton widgets and gadgets when they are
children of Menu.

When this resource is set, the background of a button in a
menu uses the XmNselectColor (derived from the XmNselect-
Pixel) when armed as a default. A PushButton uses the XmNarm-
Color if it is defined. A ToggleButton uses the XmNselect-
Color if XmNindicatorOn is False and XmNfillOnSelect is True.

XmNenableToggleColor
Specifies how to determine the default value of the XmNse-
lectColor resource of ToggleButton and ToggleButtonGadget. A
value of True causes the default value of XmNselectColor to
be set to the value of XmNhighlightColor. A value of False
causes the default value of XmNselectColor to be set to the
value of XmNbackground. This resource only affects the ap-
pearance of ToggleButton widgets and gadgets that are in
XmONE_OF_MANY or XmONE_OF_MANY_ROUND mode. In addition, Xm-
NenableToggleColor only influences the default value of XmNs-
electColor. That is, if the user or application sets a value
for XmNselectColor, then XmNenableToggleColor is ignored.

XmNenableToggleVisual
Specifies the visual appearance of the ToggleButton widget
and/or gadget. This resource affects the default value of the
ToggleButton[Gadget] XmNindicatorType and XmNindicatorOn re-
sources. When the ToggleButton is in a RadioBox, a value of
True causes the XmONE_OF_MANY_ROUND (a shadowed circle) to be
the default. Otherwise, when this resource is True, the Tog-
gleButton XmNindicatorOn resource causes a default of
XmN_OF_MANY, which will be a shadowed square with a check
mark (check box).

A value of False causes the following:

XmONE_OF_MANY
Is a shadowed diamond.

XmN_OF_MANY
Is a shadowed square.

XmNenableUnselectableDrag
Specifies whether or not it is possible to drag from Label
and Scale. A value of True enables the drag; a value of
False disables it.

XmNenableWarp
Specifies if an application is allowed to warp the pointer
from the user. A value of True enables warping, a value of
False does not.

XmNmotifVersion
Specifies the current version of Motif that the current im-
plementation is supposed to behave like. By default, this re-
source gets its value from release values in Xm.h.

XmNnoFontCallback
This callback is called whenever a rendition attempts to load
a font or fontset and fails. This can happen on creation if
the font is specified as XmLOAD_IMMEDIATE or when an attempt
is made to render an XmString using a font specified as Xm-
LOAD_DEFERRED. An application can have this callback attempt
to remedy this problem by calling XmRenditionUpdate on the
input rendition to provide a font for the widget to use. This
may be done by either providing an an alternative font name
to be loaded using the XmNfontName and XmNfontType resources
or with an already loaded font using the XmNfont resource.
The callback reason is XmCR_NO_FONT. This callback uses the
XmDisplayCallbackStruct structure.

XmNnoRenditionCallback
This callback is called whenever an attempt is made to render
a segment with a RENDITION tag which does not match any ren-
ditions in a given render table. The callback reason is
XmCR_NO_RENDITION. This callback uses the XmDisplayCallback-
Struct structure.

An application can have this callback attempt to remedy this
problem by creating a new rendition with the given tag and
adding it to render_table.

The XmNnoRenditionCallback should deallocate the render table
passed in in the render_table field of the callback struc-
ture. Note that the table will automatically be deallocated
if the XmRenderTableAddRenditions function is called on it.
The callback should NOT deallocate the modified render table
that is passed back to Motif in the render_table field. If
the application wishes to manipulate this render table fur-
ther, it should make a copy with the XmRenderTableCopy func-
tion before returning from the callback.

XmNuserData
Specifies a client data pointer for applications. An inter-
nally unused resource.

Inherited Resources
All of the superclass resources inherited by XmDisplay are designated
N/A (not applicable).

Callback Information
A pointer to the following structure is passed to the XmNdragStartCall-
back callback:

typedef struct
{
int reason;
XEvent *event;
Widget timeStamp;
Boolean doit;
}XmDragStartCallbackStruct;

reason Indicates why the callback was invoked

event Points to the XEvent that triggered the callback

widget Indicates the ID of the widget from which the drag was initi-
ated.

doit Is an IN/OUT member that allows the callback to determine
whether to continue with the drag or cancel. Setting doit to
False will cancel the drag. The default value is NULL.

A pointer to the following structure is passed to the XmNnoFontCallback
and XmNnoRenditionCallback callbacks:

typedef struct
{
int reason;
XEvent *event;
XmRendition rendition;
char *font_name;
XmRenderTable render_table;
XmStringTag tag;
}XmDisplayCallbackStruct;

reason Indicates why the callback was invoked.

event Points to the XEvent that triggered the callback. It can be
NULL.

rendition Specifies the rendition with the missing font.

font_name Specifies the name of the font or font set which could not be
loaded.

render_table
Specifies the render table with the missing rendition.

tag Specifies the tag of the missing rendition.

RELATED
ApplicationShell(3), Composite(3), Core(3), TopLevelShell(3), Vendor-
Shell(3), WMShell(3), XmGetXmDisplay(3), and XmScreen(3).

XmDisplay(3)

NAME | SYNOPSIS | DESCRIPTION | RELATED

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