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Direction(axis)
-
Display axis in conventional direction?
- Description:
This attribute is a boolean value which suggests how the axes of
a Frame should be displayed (e.g.) in graphical output. By
default, it has the value one, indicating that they should be
shown in the conventional sense (increasing left to right for an
abscissa, and bottom to top for an ordinate). If set to zero,
this attribute indicates that the direction should be reversed,
as would often be done for an astronomical magnitude or a right
ascension axis.
- Type:
- Integer (boolean).
- Class Applicability:
-
Frame
-
The default Direction value supplied by the Frame class is 1,
indicating that all axes should be displayed in the
conventional direction.
-
SkyFrame
-
The SkyFrame class re-defines the default Direction value to
suggest that certain axes (e.g. right ascension) should be
plotted in reverse when appropriate.
-
FrameSet
-
The Direction attribute of a FrameSet axis is the same as
that of its current Frame (as specified by the Current
attribute).
- Notes:
-
When specifying this attribute by name, it should be
subscripted with the number of the Frame axis to which it
applies.
-
The Direction attribute does not directly affect the behaviour
of the AST library. Instead, it serves as a hint to applications
programs about the orientation in which they may wish to display
any data associated with the Frame. Applications are free to
ignore this hint if they wish.
Next: Disco - PcdMap pincushion/barrel distortion coefficient
Up: AST Attribute Descriptions
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AST A Library for Handling World Coordinate Systems in Astronomy
Starlink User Note 210
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