Layout Managers

ACUCOBOL-GT includes a layout manager facility that can be applied to help manage some of the tricky aspects of a screen's layout. A layout manager is a specialized piece of software that is attached to a window and that manages the placement and size of controls in that window. Individual layout managers have their own rules regarding how controls are sized and placed.

By default, a window does not have a layout manager attached to it. For such windows, controls are sized and placed according to their normal properties (for example, LINE, COLUMN, SIZE, and LINES). When a layout manager is attached to a window, the layout manager determines the size and placement of controls, although it is free to use the normal properties to help make decisions. A control can provide additional information about itself, including special size and placement parameters, to the layout manager through the LAYOUT-DATA property. The precise meaning of LAYOUT-DATA varies from layout manager to layout manager.

Layout managers operate whenever a new control is placed in the window or the window is resized.

Currently, ACUCOBOL-GT supports only a single type of layout manager. This manager is called the resize manager. The resize manager does not attempt to layout controls as they are being placed. Rather, it automatically resizes and repositions controls whenever the associated window is resized. Controls use LAYOUT-DATA to tell the resize manager which automatic actions should be applied to them.

To use a layout manager, the program must:

These steps, and a description of four control properties that can be used to constrain a control's dimensions, are described in the help topics in this section.