Pager¶

The pager mode tails a configured data source (file, named pipe, or Unix domain socket) and presents its text content on the display surface. It adapts its presentation strategy to the display hardware: fast displays (OLED, TFT) receive smooth pixel-by-pixel upward scrolling at approximately 30 fps, while slow-refresh displays use full-page transitions with fade-out/fade-in animation timed to a configurable reading cadence.

Quick Start¶

cyberhudctl display set 0 pager
cyberhudctl display pager source=/var/log/syslog

How It Works¶

The pager mode manages a background reader goroutine that tails the configured source path, splitting incoming data on newlines into a thread-safe ring buffer. The rendering strategy is selected automatically based on the panel's surface classification:

Fast displays (OLED, TFT): Smooth scroll renders lines flowing upward at scroll_speed pixels per second. When buffered lines exceed visible capacity, scroll velocity adapts automatically to prevent unbounded lag.
Slow displays (e-ink, grayscale slow): Page transitions display one screenful of lines at a time, advancing with a fade-out/fade-in animation. Reading cadence is derived from visible row count and line_time_ms, with max_wait_s as an upper bound before partial pages are shown.

When the source is empty or unset, the mode displays a neutral status message indicating no data source is configured.

Options¶

Key	Type	Description	Default	Allowed Values
`source`	string	Absolute path to file, pipe, or Unix domain socket to tail for incoming text data		any valid string (absolute filesystem path)
`scroll_speed`	int	Pixels per second for smooth scroll on fast displays controlling upward text flow velocity	60	any valid int (1–1000)
`max_lines`	int	Maximum buffered lines in the ring buffer limiting how much scrollback the mode retains	24	any valid int (1–1000)
`scan_ms`	int	Reconnect interval in milliseconds controlling how often the mode retries a missing data source	500	any valid int (100–30000)
`font`	string	Font family identifier for text rendering, or empty string for automatic panel-fitted selection		any valid string (font ID or empty for auto)
`fade_out_ms`	int	Fade-out duration in milliseconds for page transitions on slow-refresh e-ink displays	300	any valid int (0+)
`fade_in_ms`	int	Fade-in duration in milliseconds for page transitions on slow-refresh e-ink displays	300	any valid int (0+)
`line_time_ms`	int	Per-line reading time in milliseconds controlling page cadence pacing on slow displays	1000	any valid int (1+)
`max_wait_s`	int	Maximum wait seconds for a full page before showing a partial page on slow displays	30	any valid int (1+)
`style`	string	Visual style name controlling resolution-specific rendering, empty for automatic fitness selection	mono-slow-122x250	any valid string (style names or empty for auto)

Policy Fields¶

Field	Type	Range	Default	Description
source	string	absolute path or empty	(empty)	Absolute path to file, pipe, or socket to tail
scroll_speed	int	[1, 1000]	60	Pixels per second for smooth scroll
max_lines	int	[1, 1000]	24	Maximum buffered lines in the ring buffer
scan_ms	int	[100, 30000]	500	Reconnect/retry interval in milliseconds
font	string	any	(empty)	Font family identifier; empty for auto-selection
style	string	any	(empty)	Visual style name; empty for default
fade_out_ms	int	>= 0	300	Fade-out duration in ms for page transitions
fade_in_ms	int	>= 0	300	Fade-in duration in ms for page transitions
line_time_ms	int	>= 1	1000	Per-line reading time in ms for page cadence
max_wait_s	int	>= 1	30	Max wait seconds for a full page before partial display

CLI Examples¶

Query the current policy values:

cyberhudctl display pager

Set the data source to tail a log file:

cyberhudctl display pager source=/var/log/syslog

Switch to the pager mode on a specific region:

cyberhudctl display set 0 pager

Configure scroll speed and buffer size:

cyberhudctl display pager scroll_speed=120 max_lines=48

Adjust page transition timing for slow displays:

cyberhudctl display pager fade_out_ms=500 fade_in_ms=500 line_time_ms=1500

Tail a named pipe with a fast reconnect interval:

cyberhudctl display pager source=/tmp/mydata.pipe scan_ms=200

Panel Compatibility¶

The pager mode adapts its rendering strategy based on the panel's capability class, selecting between smooth animated scrolling and static page transitions depending on refresh rate.

Capability	Description	Behavior
MonoFast	Fast-refresh monochrome OLED (128×32, 128×64, 128×128)	Fully supported — smooth pixel-by-pixel upward scroll at configurable speed, automatic font fitting
MonoSlow	Slow-refresh monochrome e-ink (122×250, 176×264, 200×200, 296×128, 400×300)	Fully supported — page-transition mode with fade-out/fade-in animation timed to reading cadence
GrayscaleFast	Fast-refresh grayscale (160×80, 240×135, 240×240, 320×240, 480×320)	Fully supported — smooth scroll with grayscale text rendering
GrayscaleSlow	Slow-refresh grayscale e-ink (122×250, 176×264, 200×200, 400×300)	Fully supported — page-transition mode, static rendering between transitions to avoid artifacts
ColorFast	Fast-refresh color TFT (128×128, 160×80, 240×135, 240×240, 240×320, 320×240, 320×480, 480×320)	Fully supported — smooth scroll with monochrome text on color surface
ColorSlow	Slow-refresh color e-ink (122×250, 176×264, 200×200, 400×300)	Fully supported — page-transition mode with static frames between updates

The pager is non-interactive and does not require buttons or joystick input. All panels are supported regardless of input controls or resolution — the font is automatically fitted to the available display area.