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+.TH RTGRPBLIB_DRAW_CIRCULAR_ARC 3 LIBRIFUNKTIONSTECKENSNITTSGLYFRASTERISERINGSPROGRAMBIBLIOTEKET
+.SH NAME
+rtgrpblib_draw_circular_arc - Draw a circular arc
+
+.SH DESCRIPTION
+.LP
+.nf
+#include <librifunktionsteckensnittsglyfrasteriseringsprogrambiblioteket.h>
+
+void rtgrpblib_draw_circular_arc(RTGRPBLIB_RASTER *\fIraster\fP,
+                                 double \fIx0\fP, double \fIy0\fP,
+                                 double \fIsemiwidth\fP, double \fIsemiheight\fP,
+                                 double \fIstart\fP, double \fIend\fP);
+.fi
+.PP
+Link with
+.IR "-lrifunktionsteckensnittsglyfrasteriseringsprogrambiblioteket -lm" .
+
+.SH DESCRIPTION
+The
+.BR rtgrpblib_draw_circular_arc ()
+function draws onto
+.I raster
+a circular arch, as part of a contour. The arc's circle
+is defined as the circle with the midpoint
+.RI ( x0 ,
+.IR y0 )
+and the radius that is
+.I semiwidth
+cells horizontally and
+.I semiheight
+cells vertically. The arc itself is drawn from the angle
+.I start
+to the
+.IR end ,
+both are specified in radians.
+
+.SH RETURN VALUES
+None.
+
+.SH ERRORS
+None.
+
+.SH NOTES
+The
+.BR rtgrpblib_draw_circular_arc ()
+function is intended to draw the arc of a circle, not the
+arc of an ellipse, which is why it doesn't have a way to
+rotate the ellipse despite the function providing a way
+to specify the semimajor and the semiminor, not just a
+radius. The function provides this two parameters, rather
+than a single radius parameter because the image may, and
+indeed probably will, have a different horizontal cell
+density than vertical cell density, this is because the
+pixels on a monitor are not perfect squares (and might
+not even approximate square), and because the image may
+be created (for example) for a horizontal cell density
+three times greater than the monitor's horizontal pixel
+density, but the same vertical density, in order to
+render an image that will use subpixel antialiasing.
+
+.SH SEE ALSO
+.BR librifunktionsteckensnittsglyfrasteriseringsprogrambiblioteket (7),
+.BR rtgrpblib_create_raster (3),
+.BR rtgrpblib_fill_shapes (3),
+.BR rtgrpblib_draw_linear_bezier (3),
+.BR rtgrpblib_draw_quadratic_bezier (3),
+.BR rtgrpblib_draw_cubic_bezier (3)