gscarc
Purpose
Draws a circular arc between two points.
C Syntax
int gscarc_ (cx, cy, cr, bx, by, ex, ey)
int *cx, *cy, *cr, *bx, *by, *ex, *ey;
FORTRAN Syntax
INTEGER function gscarc (cx, cy, cr, bx, by, ex, ey)
INTEGER cx, cy, cr, bx, by, ex, ey
Pascal Syntax
FUNCTION gscarc_ (
VAR cx, cy, cr, bx, by, ex, ey : INTEGER
): INTEGER [PUBLIC|;
Description
The gscarc subroutine draws a counterclockwise circular
arc of the specified radius from the beginning point to
the ending point. The radius is expressed in number of
pixels.
The relevant attributes are:
o Color map
o Plane mask
o Line color index
o Line style
o Logical operation.
Parameters
cx, cy Define the coordinates of the center of the
circle.
For displays, the center is restricted to -2048
to 2048.
For printers and plotters, the center is
restricted to screen coordinates.
cr Defines the radius of the circle.
bx, by Define the coordinates of the beginning point
on the circle.
ex, ey Define the coordinates of the ending point on
the circle.
If the beginning and ending points are identical, a full
circle is drawn.
Note that the application must control the accuracy of
the end points (bx, by and ex, ey) when drawing circular
arcs. If the start point of the arc and end point of the
arc lie within one pixel of the true circle, the arc will
be drawn successfully. Other values can cause the sub-
routine to fail. If the gscarc subroutine fails because
of an inaccurate starting point, GS_ASTR is returned,
while for an inaccurate ending point, GS_AEND is
returned.
Return Value
GS_SUCC Successful.
GS_CORD Invalid coordinate.
GS_RDUS Invalid radius specification.
GS_INAC Virtual terminal inactive.
GS_AEND Invalid end point.
GS_ASTR Invalid start point.