5.2 Contents of Windows

The window pattern in Lidskjalv offers several advanced facilities for specifying the contents of the window. These facilities are e.g. the windowItem, Canvas and Scroller patterns. WindowItem is the basic pattern for describing items to be displayed in a window, canvas (a subpattern of windowItem) is used to group windowItems of a window, and scroller enables scrolling of the window items. Several other subpatterns of windowItem exists, and will be discussed in later sections.

The window pattern defines one attribute, related to handling the window contents: contents. Contents is an operation, returning a canvas as exit parameter. Window displays all windowItems having window.contents as their father (explained later) and handles everything associated with refreshing the window contents in response to windowItems being associated with the window, and related to exposure of previously hidden parts of the window.