ArtX Curve mark.

Members:

IG_ARTX_curve_bounds_get	Queries the bounding rectangle.
IG_ARTX_curve_create	Creates curve mark.
IG_ARTX_curve_line_get	Queries the annotation line attribute.
IG_ARTX_curve_line_set	Updates the annotation line attribute.
IG_ARTX_curve_opacity_get	Queries the Opacity attribute.
IG_ARTX_curve_opacity_set	Updates the Opacity attribute.
IG_ARTX_curve_point_count_get	Gets the number of curve points.
IG_ARTX_curve_points_get	Gets the curve points.
IG_ARTX_curve_points_set	Sets the curve points.