IDL Viewgraph Text

The following topics are discussed in this page:

• Suggested text size for use with large images.
• Problems with XYOUTS and what to do.
• Thicken how to thicken lines and curves.
• Equivalent text size for default screen window.
• Special characters like greek, subscripts, exponents, ...

• Suggested text size

  For a large image, 1500 x 2000 (or the transpose), a text size of about 5 is a good starting point.

• Problems with XYOUTS

  

  The main IDL text dispay routine is XYOUTS. The results of using XYOUTS directly is shown in the top line of text. A character size of 5 was used. IDL constructs vector fonts with a finite number of strokes and for large sizes the number of strokes is too few to fill the inside of the letters. These letters will not copy well on the Kodak.

  The bottom text was written with a routine called XYOUTB for bold text. The calling syntax is very similar to XYOUTS but includes a keyword BOLD=b where b is the factor use to make the text thicker.

  XYOUTS has a keyword called charthick but it has problems as seen in the following example where charthick=3 was used (so use XYOUTB instead):

  

• Thicken

  XYOUTB cannot be used for plot axes and labels. An example section from the corner of a plot shows the data curve, label text, and axes are all made from thin lines.

  

  The curve and axes can be made thicker using the keywords thick, xthick, and ythick. The text can be made thicker using the keyword charthick but the problems discussed above occur. A routine called thicken may be used to thicken a specifed color as shown below. Do thicken,/help for more info.

  

  So create the image, read it back from the window, use thicken to enhance it, and redisplay to verify it is ok.

• Equivalent text size for default screen window

  The suggested large window size is 1500 by 2000. A text size of 4 or 5 works about right for normal text. The default window is 640 by 512, or about 3 times smaller. So the equivalent text size for the default window is about 1.5

• Special characters

  Special characters are possible in IDL. The following statement:

  xyoutb,chars=5,/dev,100,100,'!7h!X!I0!N = 280!E!3O!N!X East'

  gives the following result:
  

  The interpretation is as follows:

     xyoutb:  call the bold text routine.
     chars=5: set the character size to 5.
     /dev:    work in device coordinates (use what you wish).
     100,100: coordinates to use.
     The string to display is inside the quotes.
     !7h:     h is a theta in Complex Greek (font 7).
     !X:      Return to original font.
     !IO:     Display a zero as a subscript.
     !N = 280: Return to original size and display given text.
     !E!3o:   Display small o as an exponent in font 3.
     !N!X:    Return to normal size and font.
      East:   Finish string.