erase-contents-ellipse-sector

Function

Package: common-graphics

Arguments: stream center semi-major-axis semi-minor-axis semi-major-axis-angle start-angle length-angle

Erases (i.e. replaces with the background color or texture) the specified filled ellipse-sector from stream. An ellipse-sector is an ellipse-arc with the endpoints of the arc connected to the center of the ellipse, like a piece of an elliptical pie.

The ellipse is defined by the center (a position) and the two half-axes, lengths from the center to the farthest point on the edge and to the nearest point on the edge, called the semi-major-axis and the semi-minor-axis. (Technically, the major axis should be longer than the minor axis but the two arguments need not have that relationship.) The ellipse is rotated so that the semi-major-axis makes angle semi-major-axis-angle with the x-axis passing through the center. Angles are measured clockwise. The portion of the ellipse drawn is the sector starting at start-angle (0 is the x axis when the center is the origin) through the length-angle. Again, angles are measured clockwise. Contrast with fill-ellipse-sector which draws the filled ellipse-sector on stream.

Common Graphics and IDE documentation is described in About Common Graphics and IDE documentation in cgide.htm.

The documentation is described in introduction.htm and the index is in index.htm.

Copyright (c) 1998-2000, Franz Inc. Berkeley, CA., USA. All rights reserved.

Created 2000.10.5.