ANY CONTAINER LAYOUT NONE
deferred class interface WIDGET
   -- WIDGET is the most abstract class for all graphics objects.
   -- width and height are current object size
   -- min_width and min_height are the absolute minimal size
   -- std_width and std_height are the needed dimensions to see the
   -- entire object
   --
   -- If the object may not be shrink, size >= std
   -- If the object may be shrink, size >= min
   -- If the object may not be expanded, size <= std
   -- If the object may be expanded, size may increase
   --

feature(s) from STATE
   state: INTEGER
      -- use values from STATE_CONSTANTS

   is_state_normal: BOOLEAN

   is_state_active: BOOLEAN

   is_state_prelight: BOOLEAN

   is_state_selected: BOOLEAN

   is_state_insensitive: BOOLEAN

feature(s) from WIDGET
   parent: CONTAINER

   pos_x: INTEGER

   pos_y: INTEGER

   x_shrink_allowed: BOOLEAN

   x_expand_allowed: BOOLEAN

   y_shrink_allowed: BOOLEAN

   y_expand_allowed: BOOLEAN

   min_width: INTEGER

   min_height: INTEGER

   std_width: INTEGER

   std_height: INTEGER

   width: INTEGER

   height: INTEGER

   valid_width (w: INTEGER): BOOLEAN

   valid_height (h: INTEGER): BOOLEAN

   area: RECT

   root_area: RECT

   computing_size: BOOLEAN

   set_x_shrink (b: BOOLEAN)

   set_x_expand (b: BOOLEAN)

   set_y_shrink (b: BOOLEAN)

   set_y_expand (b: BOOLEAN)

   set_shrink (b: BOOLEAN)
      -- change both x and y shrink state

   set_expand (b: BOOLEAN)
      -- change both x and y expand state


invariant

    width >= min_width or computing_size;

    height >= min_height or computing_size;

    std_width > 0;

    std_height > 0;

    (not x_shrink_allowed implies width >= std_width) or computing_size;

    (not x_expand_allowed implies width <= std_width) or computing_size;

    (not y_shrink_allowed implies height >= std_height) or computing_size;

    (not y_expand_allowed implies height <= std_height) or computing_size;

end of deferred WIDGET