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# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
include <mach.h>
include <gio.h>
include "glabax.h"
# GLB_TICKLEN -- Compute the length of a tick in world coordinates. All tick
# drawing is performed in world coordinates since the ticks show the world
# coordinate system. The position of a tick must be computed in world coords
# when the axis is drawn to reflect log scaling (or any other nonlinear
# scaling. Less obviously, the tick offset should be given in world coords
# so that when the tick is drawn by a GRDRAW the tick will follow a line of
# constant X or Y in world coordinates, and this line will not necessarily be
# a line of constant X or Y in NDC coordinates.
real procedure glb_ticklen (gp, ax, ndc_length)
pointer gp # graphics descriptor
pointer ax # axis descriptor
real ndc_length # length of tick in NDC units
int wcs
real x, y, wx, wy
begin
wcs = GP_WCS(gp)
call gctran (gp, AX_TICK1(ax,1), AX_TICK1(ax,2), x, y, wcs, 0)
if (AX_HORIZONTAL(ax) == YES)
y = y + ndc_length
else
x = x + ndc_length
call gctran (gp, x, y, wx, wy, 0, wcs)
if (AX_HORIZONTAL(ax) == YES) {
call pargr (wy - AX_TICK1(ax,2))
return (wy - AX_TICK1(ax,2))
} else {
call pargr (wx - AX_TICK1(ax,1))
return (wx - AX_TICK1(ax,1))
}
end
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