Font Descriptors

Documentation / Contents - Font Scheme

• Overview of the Font Scheme Panel
  • Fonts and Colours Are Separate
  • What Sets It Apart
• The Nine Roles
  • The House Voice
  • The Small and Tiny Sizes
  • Partial Schemes
• Using the Panel
  • The Scheme List
  • The Role Rows
  • Changing One Role
  • The Buttons
    • Apply
    • Save and Save As
    • Defaults and Revert
    • Close
  • Following the Desktop
• Font Descriptors
  • The Leading Dash Is the Whole Rule
  • When the Resolved Font Differs
  • Reading the Nine Samples
• Point Size, DPI, and Why Layout Holds
  • Where DPI Comes From
  • The Panel Fits Itself Before It Draws
  • Changing the Desktop DPI
  • Bitmap Fonts and the Core Path
  • Looking at What a Canonical Application Will Get
• Where Font Schemes Live
  • The Search Path
  • The File
  • Two Names
  • The Built-in Defaults
• Command Line and Keys
  • Command Line
  • Keys
    • On the Main Panel
    • In the Font Dialog
• Fonts, Colours, and the Rest of the Desktop
  • Colour Schemes
  • Monitor Settings and DPI
  • The Scheme Daemon

Other cards

• Copyright Information

Font Descriptors

A role is bound to one string, called a descriptor. The grammar is the fontconfig pattern form, which is exactly what xterm -fa accepts.

DejaVu Sans-10              family and point size
DejaVu Sans-10:bold         with a style
DejaVu Sans-7.5:oblique     fractional points are legal
-*-helvetica-bold-r-*-14-*  a LEADING '-' means XLFD

The Leading Dash Is the Whole Rule

There is no flag that says which kind of font you mean. A descriptor that starts with a dash pins a server font and takes the core X path. Anything else is a pattern and takes the Xft path where Xft is available.

That single rule is what lets a configuration file, a scheme and a command line all say the same thing and mean it.

The "Source:" radio in the font dialog, "Outline (Xft)" or "Server (XLFD)", picks which catalogue you are browsing. What ends up in the scheme is still just a descriptor, and the dash still decides.

When the Resolved Font Differs

The caption under each sample is the descriptor that actually resolved, not necessarily the one the scheme asked for. A leading tilde marks the difference:

~ DejaVu Sans-10

Three ordinary reasons for it:

• The family is not installed, so fontconfig substituted.
• The scheme named a fallback list on purpose.
• A wildcard XLFD came back concrete.

The caption is shortened to fit the well, and fontconfig's multilingual style list is trimmed off, so it is a summary rather than the literal string. To see the requested and resolved forms side by side, ask from a shell:

cyfont-prefs --resolve 'DejaVu Sans-10:bold'

which prints the requested string, the resolved string, whether Xft or the core path took it, and the ascent, descent and ink band.

There is no hover tip on the sample wells. --resolve is the way to get the full untruncated answer.

Reading the Nine Samples

Two roles that quietly collapsed onto the same font are invisible in a table of strings and obvious in nine differently typeset lines. That is what the panel is for. Look for:

• Two rows that look identical when they should not.
• A row whose caption carries a tilde you did not expect.
• A Small role that is not actually smaller.

Next

• Point Size, DPI, and Why Layout Holds
• Where Font Schemes Live