1.133 class region

A region object defines a sub-area of an area, expressed using function objects to denote the X, Y, W and H of the sub-area in terms of the dimensions of the main area.

Regions are used by handler objects to denote the handler should only respond when an event object occurred in some sub-area of a graphical. As handler objects have become old-fashioned since the introduction of class gesture this class too is seldomly used.

For example, the region

region(x, y, w/10, h/10)

Denotes a region with the same origin as the area it is related to, extending to 10% in both directions.

See also

- class expression
- class area
- class handler

1.133.1 Instance variables

region <-> height: expression

Expresses the named dimension of the region in terms of the dimensions of the area (see region->inside). The expression is passed the variables x, y, w and h denoting the dimensions of the area. See also class binary_expression.

region <-> width: expression

Inherits description from: region-height

region <-> x: expression

Inherits description from: region-height

region <-> y: expression

Inherits description from: region-height

1.133.2 Get methods

region <-area_width: area -> int

region <-area_x: area -> int

region <-area_y: area -> int

region <-area_height: area -> int

Dimension of the described region for the specified area. Example:

?- get(region(x+w/2, y+h/2, w/2, h/2), area_height,
           area(100, 100, 200, 200), H),

H = 100