Point Size, DPI, and Why Layout Holds

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

Point Size, DPI, and Why Layout Holds

A descriptor names a size in POINTS, not pixels. How many pixels a point turns into depends on what the display says its resolution is. Change the resolution and every face in the desktop changes size.

Where DPI Comes From

The font dialog reads the display's resolution in this order:

• Xft.dpi from the X resource database, if it is set and sensible.
• Otherwise the screen height in pixels divided by the screen height in millimetres, as the X server reports them.
• Otherwise 96.

The Panel Fits Itself Before It Draws

This panel measures its own layout in the faces it is actually going to use, before a single control is created, and sizes itself from those measurements. It measures the widest of the nine role names, the width of the "Change..." label, the widest scheme name in the list, and the height a row needs for a sample and a caption stacked with their real ascents and descents.

It never shrinks below the 96 dpi figures, so a normal display looks exactly as it always did. On a high-resolution display it grows instead of clipping.

This is not cosmetic. The failures it fixes were real: role names cut down to "SmallPlainLabelFo", samples sliced off at the top, and the two column headings colliding into each other.

One thing is still fixed rather than fitted: the row height accommodates the panel's own faces, not an unusually large face you pick FOR a role. Bind a role to something very large and that row's sample can clip. The binding is still correct; only the preview is cramped.

Changing the Desktop DPI

This panel does not set the display resolution. That belongs to monitor settings, and it is where a DPI change is made once for the whole desktop.

The monitor panel is specified and not yet built. When it ships it is called cymonitor-prefs, its window is titled "Monitor Settings", and its DPI page is the reason it exists. Until then, set Xft.dpi in your X resources, then restart the applications you want to follow it.

Bitmap Fonts and the Core Path

An XLFD names a size in pixels at a particular resolution and does not scale. A bitmap face that looks right at 96 dpi will be too small at 144 dpi and there is no way to stretch it. If you run at a high resolution, prefer outline faces for the eight text roles and keep XLFDs for the cases where the exact 1993 pixel grid is what you want.

The shipped classic-bitmap scheme is the all-XLFD scheme, for exactly that purpose.

Looking at What a Canonical Application Will Get

Canonical applications never touch Xft, because their layouts are measured against real bitmaps. To see the nine roles resolve the way a canonical application will see them, start the panel with the core-only gate on:

cyfont-prefs --core-only

That is a RESOLUTION gate, not a second face. The panel itself is still the ordinary extended panel; only the way descriptors resolve changes. This panel has no canonical face of its own, and will not get one: IRIX never shipped a font panel, so there is no original to reproduce.

See Also

• Font Descriptors
• Fonts, Colours, and the Rest of the Desktop