The first step is to create a logical font (you may start with the predefined names though - see the font_Init routine) with Font def. From now on you can use the logical font name wherever you would normally use an X font name (eg in all -font options. Changing one or more attributes of a font is done with either Font set for permanent changes or Font get for temporary changes to a font.

Font copy copies one font to another name so that you can change the appearance of the new font without affecting the old defintion.

Font names returns all logical names that are currently defined and Font info fontname returns the attributes of a given font.

Font exists checks if a logical font name is defined. Note that this does not currently check if the name refers to a legal or existing X font.

-foundry

options may be adobe, misc etc.

-family

options are helvetica, fixed etc

-weight

controls boldness of font. Options are light, normal and bold

-slant

can have the following values: italic or normal

-width

defines the character width, one of condensed, normal or wide

-style

describes the character style. Not used in most font descriptions

-pixel

gives the size in pixel

-size

this is the size in points - note that these are real points, not decipoints as in X - 12 will be converted to 120 automatically

-xres, -yres

see the X manual

-spacing

describes fixed or proportional fonts.

-avgwidth

see the X manual

-charset

a character set descriptions, eg iso8859

-encoding

a character set encoding, eg 1 for iso8859

         Font def LabelFont \
	    {-foundry adobe -family helvetica -charset iso8859 \
	     -encoding 1 -spacing proportional -pixel 0 } \
	    {-slant normal -width normal -weight normal  -size 14}

To use the newly created label font say

         button .b -text "huhu?" -font [Font get LabelFont]

To give the button a bold appearance you can define a new logical font or (if this is just a onetime change) do this

         button .b config -font [Font get LabelFont -weight bold]

Of course you can do more complicated things:

         button .b -font [Font get LabelFont -weight bold \
                  -slant italic -size 24]