XmScrolledWindow

The ScrolledWindow widget class

Format

#include <Xm/ScrolledW.h>

DESCRIPTION

The ScrolledWindow widget combines one or two ScrollBar widgets and a viewing area to implement a visible window onto some other (usually larger) data display. The visible part of the window can be scrolled through the larger display by the use of ScrollBars.

To use ScrolledWindow, an application first creates a ScrolledWindow widget, any needed ScrollBar widgets, and a widget capable of displaying any desired data as the work area of ScrolledWindow. ScrolledWindow positions the work area widget and displays the ScrollBars if so requested. When the user performs some action on the ScrollBar, the application is notified through the normal ScrollBar callback interface.

ScrolledWindow can be configured to operate automatically so that it performs all scrolling and display actions with no need for application program involvement. It can also be configured to provide a minimal support framework in which the application is responsible for processing all user input and making all visual changes to the displayed data in response to that input.

When ScrolledWindow is performing automatic scrolling it creates a clipping window and automatically creates the scroll bars. Conceptually, this window becomes the viewport through which the user examines the larger underlying data area. The application simply creates the desired data, then makes that data the work area of the ScrolledWindow. When the user moves the slider to change the displayed data, the workspace is moved under the viewing area so that a new portion of the data becomes visible.

Sometimes it is impractical for an application to create a large data space and simply display it through a small clipping window. For example, in a text editor, creating a single data area that consisted of a large file would involve an undesirable amount of overhead. The application needs to use a ScrolledWindow (a small viewport onto some larger data), but needs to be notified when the user scrolls the viewport so it can bring in more data from storage and update the display area. For these cases, the ScrolledWindow can be configured so that it provides only visual layout support. No clipping window is created, and the application must maintain the data displayed in the work area, as well as respond to user input on the ScrollBars.

The user can specify resources in a resource file for the automatically created widgets that contain the horizontal and vertical scrollbars and the clipping area of the ScrolledWindow widget. The names of these widgets are HorScrollBar , VertScrollBar , and ClipWindow respectively, and remain consistent whether created by XmCreateScrolledList, XmCreateScrolledText or XmCreateScrolledWindow.

ScrolledWindow uses the XmQTnavigator trait, and holds the XmQTscrollFrame trait.

Descendants

ScrolledWindow automatically creates the descendants shown in the following table. An application can use XtNameToWidget to gain access to the named descendant. In addition, a user or an application can use the named descendant when specifying resource values.

Classes

ScrolledWindow inherits behavior, resources, and traits from Core, Composite, Constraint, and XmManager.

The class pointer is xmScrolledWindowWidgetClass.

The class name is XmScrolledWindow.

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).

Inherited Resources

ScrolledWindow inherits behavior and resources from the superclasses described in the following tables. For a complete description of each resource, refer to the reference page for that superclass.

Callback Information

The application must use the ScrollBar callbacks to be notified of user input.

ScrolledWindow defines a callback structure for use with XmNtraverseObscuredCallback callbacks. The XmNtraverseObscuredCallback resource provides a mechanism for traversal to obscured widgets (or gadgets) due to their position in the work area of a ScrolledWindow. The XmNtraverseObscuredCallback routine has responsibility for adjusting the position of the work area such that the specified traversal destination widget is positioned within the viewport of the ScrolledWindow. A NULL XmNtraverseObscuredCallback resource causes obscured widgets within the ScrolledWindow to be nontraversable.

Traversal to an obscured widget or gadget requires these conditions to be met: the widget or gadget can be obscured only due to its position in the work area of a ScrolledWindow relative to the viewport; the viewport of the associated ScrolledWindow is fully visible, or can be made so by virtue of ancestral XmNtraverseObscuredCallback routines; and the XmNtraverseObscuredCallback resource must be non-NULL.

When ScrolledWindow widgets are nested, the XmNtraverseObscuredCallback routine for each ScrolledWindow that obscures the traversal destination is called in ascending order within the given hierarchy.

A pointer to the following structure is passed to callbacks for XmNtraverseObscuredCallback.

typedef struct
{
        int 
reason;
        XEvent *
event:
        Widget 
traversal_destination;
        XmTraversalDirection direction;
} XmTraverseObscuredCallbackStruct;

Translations

XmScrolledWindow includes the translations from XmManager.

Additional Behavior

This widget has the following additional behavior:

Virtual Bindings

The bindings for virtual keys are vendor specific. For information about bindings for virtual buttons and keys, see VirtualBindings (3).

RELATED

Composite (3), Constraint (3), Core (3), XmCreateScrolledWindow (3), XmManager (3), XmProcessTraversal (3), XmScrollBar (3), XmScrollVisible (3), and XmScrolledWindowSetAreas (3).