- NAME
ONE_ARROW
- PURPOSE
Draws an arrow labeled with a single character on the current device
- EXPLANATION
ONE_ARROW is called, for example, by ARROWS to create a
"weathervane" showing the N-E orientation of an image.
- CALLING SEQUENCE
one_arrow, xcen, ycen, angle, label, CHARSIZE = , THICK = , COLOR =
ARROWSIZE=, FONT = ]
- INPUT PARAMETERS
xcen, ycen = starting point of arrow, floating point scalars,
In device coordinates unless /DATA or /NORMAL set
angle = angle of arrow in degrees counterclockwise from +X direction
label = single-character label (may be blank)
- OUTPUT PARAMETERS none
- OPTIONAL INPUT PARAMETERS
ARROWSIZE = 3-element vector defining appearance of arrow.
For device coordinates the default is [30.0, 9.0, 35.0],
meaning arrow is 30 pixels long; arrowhead lines 9 pixels
long and inclined 35 degrees from arrow shaft. For
normalized coordinates the default is divided by 512., for
data coordinates the default is multiplied by
(!X.crange[1] - !X.crange[0])/512..
CHARSIZE = usual IDL meaning, default = 2.0
COLOR = name or number give the color to draw the arrow. See
cgCOLOR for a list of color names.
/DATA - If set, then the input position (xcen, ycen) and the ARROWSIZE
lengths are interpreted as being in data coordinates
FONT - IDL vector font number to use (1-20). For example, to write
the 'N' and 'E' characters in complex script, set font=13
/NORMAL - If set, then the input position (xcen, ycen) and the ARROWSIZE
lengths are interpreted as being in normal coordinates
THICK = usual IDL meaning, default = 2.0
- EXAMPLE
Draw an triple size arrow emanating from the point (212,224)
and labeled with the character 'S'
IDL> one_arrow,212,224,270,'S',charsize=3
- PROCEDURE
Calls one_ray to vector-draw arrow.
- MODIFICATION HISTORY
Written by R. S. Hill, Hughes STX Corp., 20-May-1992.
Added font keyword, W.B. Landsman Hughes STX Corp. April 1995
Modified to work correctly for COLOR=0 J.Wm.Parker, HITC 1995 May 25
Add /NORMAL and /DATA keywords W.Landsman November 2006
Work with Coyote graphics W. Landsman February 2011