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2.2.7 Arcs

Arc objects are specified by center position, radius, and start and end angles. They are purely graphical with no electrical meaning. They can be drawn in different colors, and with various stroke settings.

— Function: arc? object

Returns ‘#t’ if and only if object is an arc object.

— Function: make-arc center radius start-angle end-angle [color]

Creates and returns a new arc object. center is the position of the center of the new arc in the form (x . y), and radius is the integer radius of the arc. start-angle and end-angle are the angles at which to start and end the arc, in degrees. If color is specified, it should be the integer color map index of the color with which to draw the arc. If color is not specified, the default arc color is used.

— Function: set-arc! arc center radius start-angle end-angle [color]

Sets the parameters of arc. The arguments are the same as to make-arc. Returns arc.

— Function: arc-info arc

Returns the parameters of arc as a list of the form:

          ((center-x . center-y) radius start-angle end-angle color)
— Function: arc-center arc

Returns the position of the center of arc in the form (x . y).

— Function: arc-radius arc

Returns the radius of arc as an integer.

— Function: arc-start-angle arc

Returns the start angle of arc as an integer number of degrees.

— Function: arc-end-angle arc

Returns the end angle of arc as an integer number of degrees.