2.5.6 Ellipses and Elliptical Arcs in CLIM

# 2.5.6.1 Constructor Functions for Ellipses and Elliptical Arcs in CLIM

make-ellipse [Function]
Arguments:
center-point radius-1-dx radius-1-dy radius-2-dx radius-2-dy`&key` start-angle end-angle
make-ellipse* [Function]
Arguments:
center-x center-y radius-1-dx radius-1-dy radius-2-dx radius-2-dy`&key` start-angle end-angle
Summary:
Returns an object of class standard-ellipse. The center of the ellipse is at the point center-point (or the position (center-x, center-y)).

Two vectors, (radius-1-dx, radius-1-dy) and (radius-2-dx, radius-2-dy) specify the bounding parallelogram of the ellipse as explained previously. All of the radii are real numbers. If the two vectors are collinear, the ellipse is not well-defined and the ellipse-not-well-defined error will be signaled. The special case of an ellipse with its axes aligned with the coordinate axes can be obtained by setting both radius-1-dy and radius-2-dx to 0.

If start-angle or end-angle are supplied, the ellipse is the "pie slice" area swept out by a line from the center of the ellipse to a point on the boundary as the boundary point moves from the angle start-angle to end-angle. Angles are measured counter-clockwise with respect to the positive x axis. If end-angle is supplied, the default for start-angle is 0; if start-angle is supplied, the default for end-angle is 2p; if neither is supplied, then the region is a full ellipse and the angles are meaningless.

This function captures its mutable inputs; the consequences of modifying those objects are unspecified.

make-elliptical-arc [Function]
Arguments:
center-point radius-1-dx radius-1-dy radius-2-dx radius-2-dy`&key` start-angle end-angle
make-elliptical-arc* [Function]
Arguments:
center-x center-y radius-1-dx radius-1-dy radius-2-dx radius-2-dy`&key` start-angle end-angle
Summary:
Returns an object of class standard-elliptical-arc. The center of the ellipse is at the point center-point (or the position (center-x, center-y)).

Two vectors, (radius-1-dx, radius-1-dy) and (radius-2-dx, radius-2-dy), specify the bounding parallelogram of the ellipse as explained previously. All of the radii are real numbers. If the two vectors are collinear, the ellipse is not well-defined and the ellipse-not-well-defined error will be signaled. The special case of an elliptical arc with its axes aligned with the coordinate axes can be obtained by setting both radius-1-dy and radius-2-dx to 0.

If start-angle and start-angle are supplied, the arc is swept from start-angle to end-angle. Angles are measured counter-clockwise with respect to the positive x axis. If end-angle is supplied, the default for start-angle is 0; if start-angle is supplied, the default for end-angle is 2p; if neither is supplied, then the region is a closed elliptical path and the angles are meaningless.

This function captures its mutable inputs; the consequences of modifying those objects are unspecified.

CLIM 2.0 User's Guide - OCT 1998

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