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.. SPDX-License-Identifier: GPL-2.0+:

.. index::
   single: font (command)

font command
============

Synopsis
--------

::

    font list
    font select [<name> [<size>]]
    font size [<size>]
    font info

Description
-----------

The *font* command allows selection of the font to use on the video console.
This is available when the TrueType console is in use.

font list
~~~~~~~~~

This lists the available fonts, using the name of the font file in the build.
Any enabled bitmap fonts are listed as well.

font select
~~~~~~~~~~~

This selects a new font and optionally changes the size. If the name is not
provided, the default font is used.

font size
~~~~~~~~~

This changes the font size only. With no argument it shows the current size.

font info
~~~~~~~~~

This shows glyph rendering statistics, specifically the number of glyphs
rendered since the video console was set up.

This subcommand requires CONFIG_VIDEO_GLYPH_STATS=y.

Examples
--------

::

    => font list
    nimbus_sans_l_regular
    cantoraone_regular
    => font size
    30
    => font size 40
    => font select cantoraone_regular 20
    =>

This shows an example of selecting a bitmap font when Truetype is active::

    => font list
    8x16
    12x22
    nimbus_sans_l_regular
    cantoraone_regular
    => font sel 8x16

This shows glyph rendering statistics::

    => font info
    glyphs rendered: 32705


Configuration
-------------

The command is only available if CONFIG_CONSOLE_TRUETYPE=y.

CONFIG_CONSOLE_TRUETYPE_GLYPH_BUF enables a pre-allocated buffer for glyph
rendering, avoiding malloc/free per character. The buffer starts at 4KB and
grows as needed via realloc().

CONFIG_CONSOLE_TRUETYPE_SCRATCH enables a scratch buffer for internal stbtt
allocations. Without this, the TrueType library performs around 5 allocations
per character (totalling ~26KB), creating malloc/free overhead and heap
fragmentation. With the scratch buffer, memory is allocated once at probe time
and reused for each character. CONFIG_CONSOLE_TRUETYPE_SCRATCH_SIZE sets the
buffer size (default 32KB), which is sufficient for most Latin characters.
Complex glyphs (CJK, emoji) or very large font sizes may need 64KB or more.
Allocations exceeding the buffer size fall back to malloc transparently.

CONFIG_VIDEO_GLYPH_STATS enables tracking of glyph-rendering statistics.