NAME

Form − form widget

SYNOPSIS

#include <Xol/OpenLook.h>
#include <Xol/Form.h>
 . . .

ANCESTRY

Core-Composite-Constraint-Manager-Form

DESCRIPTION

The Form widget is a constraint-based manager that provides a layout language used to establish spatial relationships between its children.  It then manipulates these relationships when the Form is resized, new children are added to the Form, or its children are moved, resized, unmanaged, remanaged, rearranged, or destroyed. 

Spanning Constraints

A widget can be created with a set of constraints in such a manner that it spans the width or height of a form.  Constraints that cause a widget to span both the width and height of a form can also be specified. 

Sets of widgets can be set up as a row so that resizing a form
may increase or decrease the spacing between the widgets. The form may also make the widgets smaller if desired.

Sets of widgets can be displayed in a single column or in
multiple columns. The form may increase or decrease the spacing between widgets or resize the widgets.

Automatic Resizing

The form calculates new sizes or positions for its children whenever they change size or position.  The new form size thus generated is passed as a geometry request to the parent of the form.  Once resized, the form, using its children’s constraints, tries to rearrange its children as intelligently as possible. 

Child Management

When a widget within a form is unmanaged or destroyed, it is removed from the constraint processing and the constraints are reprocessed to resize the form and reposition and/or resize the form’s contents.  Any widgets that referenced it are rereferenced to the widget that it had been referencing.  For the unmanaged case, if the widget is remanaged, the widgets that were previously referencing it are rereferenced to it, thereby reestablishing the original layout. 

Limitations

The Form composite widget works with all the widgets defined in this document, except those that are sub-classed from the Shell widget class. 

Coloration

of the Form widget. 

  Figure 1 Form Coloration

RESOURCES

  Table 1 Form Resource Set

Name                      Type           Default             Access
XtNancestorSensitive-   Boolean          TRUE                  GO
XtNbackground-          Pixel            XtDefaultBackground   SGI
XtNbackgroundPixmap-    Pixmap           (none)                SGI
XtNborderColor-         Pixel            XtDefaultForeground   SGI
XtNborderPixmap-        Pixmap           (none)                SGI
XtNborderWidth-         Dimension        0                     SGI
XtNconsumeEvent-        XtCallbackList   NULL                  SG
XtNdepth-               int              (parent’s)            GI
XtNdestroyCallback-     XtCallbackList   NULL                  SI
XtNheight-              Dimension        (calculated)          SGI
XtNmappedWhenManaged-   Boolean          TRUE                  SGI
XtNsensitive-           Boolean          TRUE                  GIO
XtNtraversalManager     Boolean          FALSE                 SGI
XtNuserData-            XtPointer        NULL                  SGI
XtNwidth-               Dimension        (calculated)          SGI
XtNx-                   Position         0                     SGI
XtNy-                   Position         0                     SGI

Access:   S = XtSetValues   G = XtGetValues
            I = init time   O = other access
† see resources(3W)

XtNtraversalManager

class:XtCTraversalManager type:Boolean default:FALSEaccess:SGI

Action: controls whether this widget manages traversal for its descendants. 
 

CONSTRAINT RESOURCES

Each child widget attached to the Form composite widget is constrained by the resources detailed in the following table.  In essence, these resources become resources for each child widget and can be set and read just like any other resources defined for the child. 

  Table 2 Form Child Constraining Resources

Name              Type       Default  Access
XtNxAddWidth       Boolean   FALSE     SGI
XtNxAttachOffset   int       0         SGI
XtNxAttachRight    Boolean   FALSE     SGI
XtNxOffset         int       0         SGI
XtNxRefName        String    NULL      SGI
XtNxRefWidget      Widget    (form)    SGI
XtNxResizable      Boolean   FALSE     SGI
XtNxVaryOffset     Boolean   FALSE     SGI
XtNyAddHeight      Boolean   FALSE     SGI
XtNyAttachBottom   Boolean   FALSE     SGI
XtNyAttachOffset   int       0         SGI
XtNyOffset         int       0         SGI
XtNyRefName        String    NULL      SGI
XtNyRefWidget      Widget    (form)    SGI
XtNyResizable      Boolean   FALSE     SGI
XtNyVaryOffset     Boolean   FALSE     SGI

Access:   S = XtSetValues   G = XtGetValues
            I = init time   O = other access

XtNxAddWidth

class:XtCXAddWidth type:Boolean default:FALSEaccess:SGI class:XtCYAddHeight type:Boolean default:FALSEaccess:SGI

Action: indicate whether to add the width or height of the corresponding reference widget to a widget’s location when determining the widget’s position. 

Values: TRUE, FALSE

XtNxAttachOffset

class:XtCXAttachOffset type:int default:0access:SGI class:XtCYAttachOffset type:int default:0access:SGI

Action: determine separation between Form widget and children. 

Values: 0 ≤ XtNxAttachOffset
0 ≤ XtNyAttachOffset

When a widget is attached to the right or bottom edge of the form, the separation between the widget and the form defaults to zero pixels.  These resources allow that separation to be set to some other value.  Also, for widgets that are not attached to the right or bottom edge of the form, these resources specify the minimum spacing between the widget and the form. 

XtNxAttachRight

class:XtCXAttachRight type:Boolean default:FALSEaccess:SGI class:XtCYAttachBottom type:Boolean default:FALSEaccess:SGI

Action: set the reference direction on the form

Values: TRUE, FALSE

Widgets are normally referenced from form left to form right or from form top to form bottom. These resources allow this reference to occur on the opposite edges of the form.

When used with XtNxVaryOffset and XtNyVaryOffset, these resources allow a widget to float along the right or bottom edge of the form. 

In the x–direction, this is done by setting both the XtNxAttachRight and XtNxVaryOffset resources to TRUE A widget can also span the width of the form by setting the XtNxAttachRight resource to TRUE and the XtNxVaryOffset resource to FALSE. 

In the y–direction, this is done by setting both the XtNyAttachBottom and XtNyVaryOffset resources to TRUE A widget can also span the height of the form by setting the XtNyAttachBottom resource to TRUE and the XtNyVaryOffset resource to FALSE. 

XtNxOffset

class:XtCXOffset type:int default:0access:SGI class:XtCYOffset type:int default:0access:SGI

Action: define the offset from reference widget. 

Values: 0 ≤ XtNxOffset
0 ≤ XtNyOffset

The location of a widget is determined by the widget it references.  As the default, a widget’s position on the form exactly matches its reference widget’s location.  There are two additional data used to determine the location.  These resources define integer values representing the number of pixels to add to the reference widget’s location when calculating the widget’s location. 

XtNxRefName

class:XtCXRefName type:String default:NULLaccess:SGI class:XtCYRefName type:String default:NULLaccess:SGI

Action: specify reference widget by name. 

Values: name of a widget already created as a child of the form. 

When a widget is added as a child of the form, its position is determined by the widget it references.  These resources allow the name of the reference widget to be given.  The form converts this name to a widget to use for the referencing.  Any widget that is a direct child of the form or the form widget itself can be used as a reference widget.  If one of these resources is set and the corresponding resource, XtNxRefWidget or XtNyRefWidget is also set, they must agree: the name given in XtNxRefName or XtNyRefName must match the name of the identified widget. 

XtNxRefWidget

class:XtCXRefWidget type:Widget default:(form)access:SGI class:XtCYRefWidget type:Widget default:(form)access:SGI

Action: specify reference widget by id. 

Values: ID of a widget already created as a child.  The default value is the Form widget itself. 

Instead of naming the reference widget, an application can give the reference widget’s ID using these resources.  If both a widget ID and a widget name is given for a reference in the same dimension (x or y), they must refer to the same widget.  If not, a warning is made and the widget referred to by name is used. 

XtNxResizable

class:XtCXResizable type:Boolean default:FALSEaccess:SGI class:XtCYResizable type:Boolean default:FALSEaccess:SGI

Action: specify whether the Form resizes children. 

Values: TRUE, FALSE

When a form’s size becomes smaller, the form will resize its children only after resizing all the inter-widget spacing of widgets with their XtNxVaryOffset, or XtNyVaryOffset resource set to TRUE. 

The form keeps track of a widget’s initial size or its size generated through calls to XtSetValues() so that when the form then becomes larger, the widget will grow to its original size and no larger. 

XtNxVaryOffset

class:XtCXVaryOffset type:Boolean default:FALSEaccess:SGI class:XtCYVaryOffset type:Boolean default:FALSEaccess:SGI

Action: specify variable spacing between widget and reference widget. 

Values: TRUE, FALSE

When a form is resized, it processes the constraints contained within its children.  These resources allow the spacing between a widget and the widget it references to vary (either increase or decrease) when a form’s size changes.  For widgets that directly reference the form widget, these resources are ignored if the XtNxAttachRight (XtNyAttachBottom) resource is not set to TRUE.  The spacing between a widget and its reference widget can decrease to zero pixels if the XtNxAddWidth (XtNyAddHeight) resource is FALSE or to one pixel if XtNxAddWidth (XtNyAddHeight) is TRUE. 
 

Version 3.0.1  —  Last change: June 92