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
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. 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
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
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 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).
+-----------------------------------------------------------------------------------------------------------------+
| | XmDisplay Resource Set | | |
|Name | Class | Type | Default | Access |
+------------------------------+-------------------------------+----------------+------------------------+--------+
|XmNdefaultButtonEmphasis | XmCDefaultButtonEmphasis | XtEnum | XmEXTERNAL_HIGHLIGHT | C |
+------------------------------+-------------------------------+----------------+------------------------+--------+
|XmNdefaultVirtualBindings | XmCDefaultVirtualBindings | String | dynamic | C |
+------------------------------+-------------------------------+----------------+------------------------+--------+
|XmNdragInitiatorProtocolStyle | XmCDragInitiatorProtocolStyle | unsigned char | XmDRAG_PREFER_RECEIVER | CG |
+------------------------------+-------------------------------+----------------+------------------------+--------+
|XmNdragReceiverProtocolStyle | XmCDragReceiverProtocolStyle | unsigned char | XmDRAG_PREFER_DYNAMIC | CG |
+------------------------------+-------------------------------+----------------+------------------------+--------+
|XmNdragStartCallback | XmCCallback | XtCallbackList | NULL | C |
+------------------------------+-------------------------------+----------------+------------------------+--------+
|XmNenableBtn1Transfer | XmCEnableBtn1Transfer | XtEnum | XmOFF | C |
+------------------------------+-------------------------------+----------------+------------------------+--------+
|XmNenableButtonTab | XmCEnableButtonTab | Boolean | False | C |
+------------------------------+-------------------------------+----------------+------------------------+--------+
|XmNenableDragIcon | XmCEnableDragIcon | Boolean | False | C |
+------------------------------+-------------------------------+----------------+------------------------+--------+
|XmNenableEtchedInMenu | XmCEnableEtchedInMenu | Boolean | False | C |
+------------------------------+-------------------------------+----------------+------------------------+--------+
|XmNenableToggleColor | XmCEnableToggleColor | Boolean | False | C |
+------------------------------+-------------------------------+----------------+------------------------+--------+
|XmNenableToggleVisual | XmCEnableToggleVisual | Boolean | False | C |
+------------------------------+-------------------------------+----------------+------------------------+--------+
|XmNenableUnselectableDrag | XmCEnableUnselectableDrag | Boolean | True | C |
+------------------------------+-------------------------------+----------------+------------------------+--------+
|XmNenableWarp | XmCEnableWarp | XtEnum | True | CSG |
+------------------------------+-------------------------------+----------------+------------------------+--------+
|XmNmotifVersion | XmCMotifVersion | int | XmVERSION | CSG |
+------------------------------+-------------------------------+----------------+------------------------+--------+
|XmNnoFontCallback | XmCCallback | XtCallbackList | NULL | C |
+------------------------------+-------------------------------+----------------+------------------------+--------+
|XmNnoRenditionCallback | XmCCallback | XtCallbackList | NULL | C |
+------------------------------+-------------------------------+----------------+------------------------+--------+
|XmNuserData | XmCUserData | XtPointer | NULL | CSG |
+------------------------------+-------------------------------+----------------+------------------------+--------+
+------------------------------+-------------------------------+----------------+------------------------+--------+
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
XmNdefaultButtonEmphasis has the follow possible values,
which affect 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.
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 \n\
...
osfLeft: <Key>left, Ctrl<Key>H
XmNdragInitiatorProtocolStyle
Specifies the drag and drop protocol requirements or
preference when the client is an initiator. The possible
values are
XmDRAG_PREREGISTER
As an initiator, this client does not use the
dynamic protocol and can only arrange visual
effects with receivers who provide preregistered
information.
XmDRAG_DYNAMIC
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.
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
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.
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
provide consistent drag-over feedback.
XmDRAG_PREFER_RECEIVER
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.
XmNdragReceiverProtocolStyle
Specifies the drag and drop protocol requirements or
preference 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
protocol 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
capabilities 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 XmDRAG_PREFER_DYNAMIC, otherwise the default is
XmDRAG_PREFER_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,
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.
XmNdragStartCallback
Specifies the list of callbacks that are invoked when the
XmDragStart function is called. The type of structure whose
address is passed to this callback is
XmDragStartCallbackStruct. 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
modifies 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 modification.
XmNenableDragIcon
Specifies which set of icons are to be used for system
default 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,
ToggleButton, 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
XmNselectPixel) when armed as a default. A PushButton uses
the XmNarmColor if it is defined. A ToggleButton uses the
XmNselectColor if XmNindicatorOn is False and XmNfillOnSelect
is True.
XmNenableToggleColor
Specifies how to determine the default value of the
XmNselectColor 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 appearance of ToggleButton
widgets and gadgets that are in XmONE_OF_MANY or
XmONE_OF_MANY_ROUND mode. In addition, XmNenableToggleColor
only influences the default value of XmNselectColor. 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
resources. 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
ToggleButton 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
implementation is supposed to behave like. By default, this
resource 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
XmLOAD_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
renditions in a given render table. The callback reason is
XmCR_NO_RENDITION. This callback uses the
XmDisplayCallbackStruct 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
structure. 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 further, it should make a copy with the
XmRenderTableCopy function before returning from the
callback.
XmNuserData
Specifies a client data pointer for applications. An
internally 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
XmNdragStartCallback 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
initiated.
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.
The following table describes the reasons for which the individual
callback structure fields are valid.
+------------------+----------------------+
|Reason | Valid Fields |
+------------------+----------------------+
|XmCR_NO_FONT | rendition, font_name |
+------------------+----------------------+
|XmCR_NO_RENDITION | render_table, tag |
+------------------+----------------------+
+------------------+----------------------+
RELATED
ApplicationShell(3), Composite(3), Core(3), TopLevelShell(3),
VendorShell(3), WMShell(3), XmGetXmDisplay(3), and XmScreen(3).
XmDisplay(library call)