NAME

Core widget class − fundamental object class with a window. 

SYNOPSIS

Public Headers:<X11/StringDefs.h>
<X11/Core.h>

Private Header:<X11/CoreP.h>

Class Name:Core

Class Hierarchy:Object → RectObj → unnamed → Core

Class Pointer:widgetClass or coreWidgetClass

Instantiation:Core is an Intrinsics meta-class, and is not normally instantiated. 

Functions/Macros:XtIsWidget()

DESCRIPTION

Core is the fundamental class for windowed widgets.  All widgets with windows are subclasses of Core.  Core is sometimes instantiated for use as a basic drawing area. 

NEW RESOURCES

Core has the following resources (some of which are actually defined by the Object and RectObj classes):

XtNaccelerators
A translation table bound with its actions for a widget.  A destination widget can be set up to use this accelerator table.  See XtInstallAccelerators(1). 

XtNancestorSensitive
Specifies whether the object has an insensitive ancestor. Default value is (a) True (if the widget is a top-level shell), (b) copied from the XtNancestorSensitive resource of its parent (if the widget is a popup shell), or (c) the bitwise AND of the XtNsensitive and XtNancestorSensitive resources of the parent (for other widgets).  See XtSetSensitive(1). 

XtNbackground
Widget’s background color.

XtNbackgroundPixmap
Pixmap with which to tile the background, beginning at the upper-left corner.

XtNborderColor
Pixel value that defines the color of the border.

XtNborderPixmap
Pixmap with which to tile the border, beginning at the upper-left corner of the border.

XtNborderWidth
Width (in pixels) of the window’s border.

XtNcolormap
Colormap used in converting to pixel values.  Previously created pixel values are unaffected. The default value is the screen’s default colormap (for top-level shells) or is copied from the parent (for other widgets).

XtNdepth
Number of bits allowed for each pixel. The Xt Intrinsics set this resource when the widget is created. As with the XtNcolormap resource, the default value comes from the screen’s default or is copied from the parent. 

XtNdestroyCallback
List of callbacks invoked when the widget is destroyed.

XtNheight
Window height (in pixels), excluding the border.

XtNinitialResourcesPersistent
Specifies whether resources should be reference counted. If True (default), it is assumed that the widget won’t be destroyed while the application is running, and thus the widget’s resources are not reference counted.  Set this resource to False if your application might destroy the widget and will need to deallocate the resources.  See XtConvertAndStore(1). 

XtNmappedWhenManaged
If True (default), the widget becomes visible (is mapped) as soon as it is both realized and managed.  If False, the application performs the mapping and unmapping of the widget.  If changed to False after the widget is realized and managed, the widget is unmapped.  See XtSetMappedWhenManaged(1). 

XtNscreen
Screen of the widget.

XtNsensitive
Specifies whether a widget receives input (is sensitive). XtSetSensitive() can be used to change a widget’s sensitivity and to guarantee that if a parent has its XtNsensitive resource set to False, then its children will have their XtNancestorSensitive resource set to False.  See XtSetSensitive(1). 

XtNtranslations
Points to a translation table; must be compiled with XtParseTranslationTable().  See XtOverrideTranslations(1) and XtAugmentTranslations(1). 

XtNwidth
Window width (in pixels), excluding the border.

XtNx
The x-coordinate of the widget’s upper-left outer corner, relative to the upper-left inner corner of its parent.

XtNy
The y-coordinate of the widget’s upper-left outer corner, relative to the upper-left inner corner of its parent.

CLASS STRUCTURE

The Core class structure is defined as follows: typedef struct _CoreClassPart {  WidgetClass superclass; /∗ pointer to superclass ClassRec ∗/  String class_name; /∗ widget resource class name ∗/  Cardinal widget_size; /∗ size in bytes of widget record ∗/  XtProc class_initialize; /∗ class initialization proc ∗/  XtWidgetClassProc class_part_initialize; /∗ dynamic initialization ∗/  XtEnum class_inited; /∗ has class been initialized? ∗/  XtInitProc initialize; /∗ initialize subclass fields ∗/  XtArgsProc initialize_hook; /∗ notify that initialize called ∗/  XtRealizeProc realize; /∗ XCreateWindow for widget ∗/  XtActionList actions; /∗ widget semantics name to proc map ∗/  Cardinal num_actions; /∗ number of entries in actions ∗/  XtResourceList resources; /∗ resources for subclass fields ∗/  Cardinal num_resources; /∗ number of entries in resources ∗/  XrmClass xrm_class; /∗ resource class quarkified ∗/  Boolean compress_motion; /∗ compress MotionNotify for widget ∗/  XtEnum compress_exposure; /∗ compress Expose events for widget∗/  Boolean compress_enterleave; /∗ compress enter and leave events ∗/  Boolean visible_interest; /∗ select for VisibilityNotify ∗/  XtWidgetProc destroy; /∗ free data for subclass pointers ∗/  XtWidgetProc resize; /∗ geom manager changed widget size ∗/  XtExposeProc expose; /∗ redisplay window ∗/  XtSetValuesFunc set_values; /∗ set subclass resource values ∗/  XtArgsFunc set_values_hook; /∗ notify that set_values called ∗/  XtAlmostProc set_values_almost; /∗ set_values got "Almost" geo reply ∗/  XtArgsProc get_values_hook; /∗ notify that get_values called ∗/  XtAcceptFocusProc accept_focus; /∗ assign input focus to widget ∗/  XtVersionType version; /∗ version of Intrinsics used ∗/  XtPointer callback_private; /∗ list of callback offsets ∗/  String tm_table; /∗ default translation table ∗/  XtGeometryHandler query_geometry; /∗ return preferred geometry ∗/  XtStringProc display_accelerator; /∗ display your accelerator ∗/  XtPointer extension; /∗ pointer to extension record ∗/
 } CoreClassPart;
 
typedef struct {
        CoreClassPart core_class; } WidgetClassRec, ∗WidgetClass, CoreClassRec, ∗CoreWidgetClass; The meanings of each of the fields in the Core class structure are as follows:

superclass
A pointer to the class record of this widget’s superclass. That class record is declared in the superclass’ private header file.

class_name
A constant string that names the class.

widget_size
The size of the instance structure for this widget.  Use sizeof. 

class_initialize()
The class_initialize() method called to perform one-time initialization for this class.  See the reference page in Section 4.  This is a chained method which cannot be inherited.  Set to NULL if no special initialization is needed for the class. 

class_part_initialize()
The class_part_initialize() method called to perform initialization for the class part structure.  See the reference page in Section 4.  This is a chained method which cannot be inherited.  Set to NULL if no special initialization is needed for your class part. 

class_inited
Whether the class structure has been initialized yet. Always initialize to False. 

initialize()
The initialize() method called to initialize the instance structure.  See the reference page in Section 4.  This is a chained method which cannot be inherited.  Set to NULL if no special initialization of the widget instance structure is needed. 

initialize_hook()
The (obsolete) initialize_hook() method.  See the reference page in Section 4.  This is a chained method which cannot be inherited.  Set to NULL if no special initialization is needed. 

realize()
The realize() method called to create a window for the widget.  See the reference page in Section 4.  Use XtInheritRealize to inherit the realize() method of the superclass. 

actions
The action name to action procedure mapping which will be used by this widget when binding translation tables to actions.  These are automatically registered with the Intrinsics when the Core class_part_initialize() method is performed.  The array must be permanently allocated, and the Intrinsics may overwrite it with an internal compiled form of the action table.  The action names must be permanently allocated strings. 

num_actions
The number of elements in the actions array. 

resources
An array of XtResource, each element of which defines a single resource for the widget.  See XtGetApplicationResources(1) for an explanation of how to define resources. 

num_resources
The number of elements in the resources array. 

xrm_class
This field is private to the Resource Manager.  Initialize it to NULLQUARK. 

compress_motion
If True, the Intrinsics will only report the last of a sequence of pointer motion events. 

compress_exposure
Specifies how Expose and GraphicsExpose events should be delivered to the widget.  If False or XtExposeNoCompress, all exposure events will be delivered.  There are a number of other possibilities; see expose(4) for full details. 

compress_enterleave
If True, the Intrinsics will discard pairs of enter and leave events from the input queue that have no intervening events between them. 

visible_interest
If True, the Intrinsics will request VisibilityNotify events for the Widget and update the visible field of the Core instance structure as they arrive.  The visible field is guaranteed to be True by the time an exposure event is processed (i.e., by the time the expose() method is called) if any part of the widget is visible, but is False if the widget is fully obscured.  If visible_interest is False, then the visible instance field is always True. 

destroy()
The destroy() method called when a widget of this class is destroyed.  See the reference page in Section 4.  This is a chained method and cannot be inherited.  Initialize it to NULL if no special processing needs to be done when an instance of this widget class is destroyed. 

resize()
The resize() method called when a widget of this class is resized by its parent.  See the reference page in Section 4.  Use XtInheritResize to inherit the resize() method of the superclass. 

expose()
The expose() method called when exposure events arrive for this widget.  See the reference page in Section 4.  Use XtInheritExpose to inherit the expose() method of the superclass. 

set_values()
The set_values() method called when an application sets resource values in the instance record with XtSetValues().  See the reference page in Section 4.  This is a chained method and cannot be inherited.  Specify NULL if the widget class has no resources. 

set_values_hook()
The (obsolete) set_values_hook() method.  See the reference page in Section 4.  This method is chained and cannot be inherited. 

set_values_almost()
The set_values_almost() method called when a geometry request in an XtSetValues() call cannot be completely satisfied.  See the reference page in Section 4.  Use XtInheritSetValuesAlmost to inherit the set_values_almost() method of the superclass. 

get_values_hook()
The get_values_hook() method called in response to XtGetValues().  See the reference page in Section 4.  This is a chained method and cannot be inherited. 

accept_focus()
The accept_focus() method called by a parent to offer keyboard focus to a child.  See the reference page in Section 4.  Use XtInheritAcceptFocus to inherit the accept_focus() method of the superclass. 

version
The version field indicates the toolkit implementation version number and is used for runtime consistency checking of the toolkit and widgets in an application.  Widget writers must set it to the implementation-defined symbolic value XtVersion in the widget class structure initialization.  Those widget writers who believe that their widget binaries are compatible with other implementations of the Intrinsics can put the special value XtVersionDontCheck in the version field to disable version checking for those widgets.  If a widget needs to compile alternative code for different revisions of the Intrinsics interface definition, it may use the symbol XtSpecificationRelease.  Use of XtVersion allows the Intrinsics implementation to recognize widget binaries that were compiled with older implementations. 

callback_private
This field is private to callback handling; initialize to NULL. 

tm_table
The default translation table for widgets of this class.  It may be overridden by clients that set the XtNtranslations resource of the widget instance.  This field should specify a translation table in string form (see Appendix F for the syntax); the Intrinsics will automatically compile it into an internal form.  Use XtInheritTranslations to inherit the translation table of the superclass. 

query_geometry()
The query_geometry() method, called by a parent widget to discover the preferred geometry of a child.  See the reference page in Section 4.  Use XtInheritQueryGeometry to inherit the query_geometry() method of the superclass. 

display_accelerator()
The display_accelerator() method, called when a widget’s accelerators have been installed on a destination widget.  See the reference page in Section 4.  Use XtInheritDisplayAccelerator to inherit the display_accelerator() method of the superclass. 

extension
A linked list of extension records.  There are currently no extensions defined for the Core widget class, so this field should be initialized to NULL. 

INSTANCE STRUCTURE

The Core instance record contains at least the following fields.  The fields need not be in the order shown, but because the Object and RectObj superclasses were defined after Core was standardized, Core duplicates the instance records of those classes, and the duplicate fields must be in the same position in the Object, RectObj, and Core instance structures.  typedef struct {  Widget self; /∗ pointer to widget itself ∗/  WidgetClass widget_class; /∗ pointer to widget’s ClassRec ∗/  Widget parent; /∗ parent widget ∗/  Boolean being_destroyed; /∗ marked for destroy ∗/  XtCallbackList destroy_callbacks; /∗ called when widget destroyed ∗/  XtPointer constraints; /∗ constraint record ∗/  Position x, y; /∗ window position ∗/  Dimension width, height; /∗ window dimensions ∗/  Dimension border_width; /∗ window border width ∗/  Boolean managed; /∗ is widget geometry managed? ∗/  Boolean sensitive; /∗ is widget sensitive to user events ∗/  Boolean ancestor_sensitive; /∗ are all ancestors sensitive? ∗/  XtTranslations accelerators; /∗ accelerator translations ∗/  Pixel border_pixel; /∗ window border pixel ∗/  Pixmap border_pixmap; /∗ window border pixmap or NULL ∗/  WidgetList popup_list; /∗ list of pop ups ∗/  Cardinal num_popups; /∗ how many pop ups ∗/  String name; /∗ widget resource name ∗/  Screen ∗screen; /∗ window’s screen ∗/  Colormap colormap; /∗ colormap ∗/  Window window; /∗ window ID ∗/  Cardinal depth; /∗ number of planes in window ∗/  Pixel background_pixel; /∗ window background pixel ∗/  Pixmap background_pixmap; /∗ window background pixmap or NULL ∗/  Boolean visible; /∗ is window mapped and not occluded? ∗/  Boolean mapped_when_managed; /∗ map window if it is managed? ∗/ } CorePart;
 
typedef struct { CorePart core; } WidgetRec, ∗Widget, CoreRec, ∗CoreWidget;

SEE ALSO

CoreUNIX SYSTEM V/68 and V/88 Release 4, ObjectUNIX SYSTEM V/68 and V/88 Release 4, RectObjUNIX SYSTEM V/68 and V/88 Release 4,
class_initializeUNIX SYSTEM V/68 and V/88 Release 4, class_part_initializeUNIX SYSTEM V/68 and V/88 Release 4, destroyUNIX SYSTEM V/68 and V/88 Release 4, display_acceleratorUNIX SYSTEM V/68 and V/88 Release 4, exposeUNIX SYSTEM V/68 and V/88 Release 4,
get_values_hookUNIX SYSTEM V/68 and V/88 Release 4, initializeUNIX SYSTEM V/68 and V/88 Release 4, initialize_hookUNIX SYSTEM V/68 and V/88 Release 4, query_geometryUNIX SYSTEM V/68 and V/88 Release 4, realizeUNIX SYSTEM V/68 and V/88 Release 4, resizeUNIX SYSTEM V/68 and V/88 Release 4,
set_valuesUNIX SYSTEM V/68 and V/88 Release 4, set_values_almostUNIX SYSTEM V/68 and V/88 Release 4, set_values_hookUNIX SYSTEM V/68 and V/88 Release 4.