Composite (3) - Linux Manuals
Composite: The Composite widget class
NAMEComposite --- The Composite widget class
Composite widgets are intended to be containers for other widgets and can have an arbitrary number of children. Their responsibilities (implemented either directly by the widget class or indirectly by Intrinsics functions) include:
- Overall management of children from creation to destruction.
- Destruction of descendants when the composite widget is destroyed.
- Physical arrangement (geometry management) of a displayable subset of managed children.
- Mapping and unmapping of a subset of the managed children. Instances of composite widgets need to specify the order in which their children are kept. For example, an application may want a set of command buttons in some logical order grouped by function, and it may want buttons that represent filenames to be kept in alphabetical order.
Composite inherits behavior and resources from Core.
The class pointer is compositeWidgetClass.
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).
- A read-only list of the children of the widget.
- Points to the XtOrderProc function described below.
- A read-only resource specifying the length of the list of children in XmNchildren.
The following procedure pointer in a composite widget instance is of type XtOrderProc:
Cardinal (* XtOrderProc) (Widget w);
- Specifies the widget.
Composite widgets that allow clients to order their children (usually homogeneous boxes) can call their widget instance's XmNinsertPosition procedure from the class's insert_child procedure to determine where a new child should go in its children array. Thus, a client of a composite class can apply different sorting criteria to widget instances of the class, passing in a different XmNinsertPosition procedure when it creates each composite widget instance.
The return value of the XmNinsertPosition procedure indicates how many children should go before the widget. A value of 0 (zero) indicates that the widget should go before all other children; returning the value of XmNumChildren indicates that it should go after all other children. By default, unless a subclass or an application provides an XmNinsertPosition procedure, each child is inserted at the end of the XmNchildren list. The XmNinsertPosition procedure can be overridden by a specific composite widget's resource list or by the argument list provided when the composite widget is created.
Composite inherits behavior and resources from the superclass described in the following table. For a complete description of each resource, refer to the reference page for that superclass.