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Plotting Borders

The astBorder function is provided to draw a (line) border around your graphical output. With most graphics systems, this would simply be a rectangular box around the plotting area. With a Plot, however, this boundary follows the edge of each region containing valid, unclipped physical coordinates ([*]).

This means, for example, that if you were plotting an all-sky projection, this boundary would outline the perimeter of the celestial sphere when projected on to your plotting surface. Of course, if there is no clipping and all physical coordinates are valid, then you will get the traditional rectangular box. astBorder requires only a pointer to the Plot:

int holes;

...

holes = astBorder( plot );

It returns a boolean (integer) value to indicate if any invalid or clipped physical coordinates were found within the plotting area. If they were, it will draw around the valid unclipped regions and return a value of one. Otherwise, it will draw a simple rectangular border and return zero.



next up previous
Next: Plotting Text
Up: Producing Graphical Output (Plots)
Previous: Regions of Valid Physical Coordinates

AST A Library for Handling World Coordinate Systems in Astronomy
Starlink User Note 211
R.F. Warren-Smith & D.S. Berry
30th April 2003
E-mail:ussc@star.rl.ac.uk

Copyright (C) 2003 Central Laboratory of the Research Councils