When exchanging files, the use of text in these files is a particularly important aspect. This article shows you the possibilities that exist for working with these texts and fonts.

There is always a risk involved to the fonts when transferring graphics containing text. Very few graphics formats allow you to embed fonts. If the font used is not present on the target system, using an alternative font can result in a significant change in the way text is displayed. This would be the case, for example, if Arial or Helvetica were replaced by Courier.

Generally speaking, a call to the author of the technical illustration will usually provide information as to the particular font you should use. But what do you do if it is not known which font and which face have been used in the CGM file? You have two options available.

Text-encoded CGM files
If a CGM file has been exported text-encoded, the "Font List" can be read directly. To do so, open the CGM file with a text editor and search for the entry FONTLIST followed by the font names, as in the following example:

FONTLIST 'Helvetica' 'Helvetica Bold' 'Helvetica Oblique' 'Helvetica BoldOblique';

The font names behind the keyword FONTLIST are the fonts used in the illustration.

Binary-encoded CGM files
If a CGM file has been binary-encoded, it is not quite as easy to determine the fonts used as it is with a text-encoded CGM file. If you open a binary-encoded CGM file with a text editor, you will only see hieroglyphics.

This makes it very difficult to read the FONTLIST if at all, since the font names and faces are relatively difficult to locate in the code. What solution can binary-encoded CGM files offer?

Using MetaCheck™ to determine the FONTLIST
MetaCheck™ is a very powerful program for checking CGM files. In addition to numerous other functions, it can also be used to view the FONTLIST of a binary-encoded CGM file. To do so, MetaCheck™ is used to generate a "Trace Report" which contains the FONTLIST.

This entry may look as follows:

   5:FONT LIST                        Offset:74          Length:65
    P1 : Font List                  Value:
             1 >Helvetica<
             2 >Helvetica Bold<
             3 >Helvetica Oblique<
             4 >Helvetica BoldOblique<

This FONTLIST is very helpful when working with IsoDraw, since the entries in the FONTLIST can be used to adapt font usage or font substitution for IsoDraw. Adaptation is performed in a "Font Mapping Table" in file "OptCGM.prf".

• Further information on MetaCheck™ can be found here: http://www.prba.com/cts.htm