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astBorder - Draw a border around valid regions of a Plot

Description:
This function draws a (line) border around regions of the plotting area of a Plot which correspond to valid, unclipped physical coordinates. For example, when plotting using an all-sky map projection, this function could be used to draw the boundary of the celestial sphere when it is projected on to the plotting surface.

If the entire plotting area contains valid, unclipped physical coordinates, then the boundary will just be a rectangular box around the edges of the plotting area.

Synopsis:
int astBorder( AstPlot *this )

Parameters:
this
Pointer to the Plot.

Returned Value:
astBorder()
Zero is returned if the plotting area is completely filled by valid, unclipped physical coordinates (so that only a rectangular box was drawn around the edge). Otherwise, one is returned.

Notes:
  • A value of zero will be returned if this function is invoked with the AST error status set, or if it should fail for any reason.
  • An error results if either the current Frame or the base Frame of the Plot is not 2-dimensional.
  • An error also results if the transformation between the base and current Frames of the Plot is not defined (i.e. the Plot's TranForward attribute is zero).



next up previous
Next: astBoundingBox - Return a bounding box for previously drawn graphics
Up: AST Function Descriptions
Previous: astBegin - Begin a new AST context

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