1.58.1 Instance variables

figure <- background: colour|{foreground,background}*

Colour used as background. Commonly used to prevent the figure from being transparent (figure->background: background).

figure <- status: name

The figure<-status of a figure is a name indicating which graphicals of the figure should be visible: if figure<-status equals all_active, all device<-graphicals are visible, otherwise only graphicals with the same name as figure<-status are made visible.

This mechanism may be used to define graphical objects that should be switched between different states. Consider the example where we want to have a diagram which can be displayed opened and as an icon. The code below outlines a possible approach:

create_closable_diagram(F) :-
        new(F, figure),
        send(F, status, opened),
        send(F, display, new(BM, bitmap('my_icon'))),
        send(BM, name, closed),
        send(BM, recogniser,
                 click_gesture(left, '', double,
                               message(F, status, opened),
        send(F, display, new(F2, figure)),
        send(F2, name, opened),
        ...
        <create the real diagram on F2>

figure <- border: num

Extra empty pixels added around the children's bounding box. Used together with graphical<-pen to draw a visible frame at a distance from the contents.

figure <- radius: num

Corner radius for the outline drawn by graphical<-pen/figure<-elevation. 0 yields a square outline.

figure <- elevation: elevation*

elevation object describing a 3-D appearance (raised, sunken, shadow, ...) of the figure's box. @nil disables the effect. The legacy figure<->shadow shortcut creates a shadow elevation.

figure <- transform: transform*

Optional 2-D affine transform applied to the figure's contents. @nil means no transform. The transform is applied to the children while drawing, hit-testing and computing the bounding box, so a rotated/scaled figure is still selectable by the mouse and reports a tight bounding box in its parent's coordinates. The convenience methods figure->translate, figure->scale, figure->rotate and figure->shear compose operations into this transform without the caller having to manage the transform object explicitly.

figure <- local_area: area

Bounding box of the children in the figure's local (pre-transform, pre-offset) coordinate system. Refreshed by figure->compute. Damage handling and child event dispatch use this to keep paint and hit tests correct under rotation/scale.