Crate denise_evdev 

Linux evdev input for Denise.

Reads mice, touchscreens and keyboards straight from /dev/input/event*, with no display server in the way.

Testing

translate and keymap are platform-independent and unit tested everywhere. That is not tidiness: multitouch slot tracking, frame batching and modifier state are the parts that break, and each one is far easier to pin down as a table of raw event codes than by dragging a finger across a panel and guessing. Only device discovery and reading are gated to Linux.

Permissions

Reading /dev/input/event* needs membership in the input group, or root. Being able to read every keystroke on the machine is exactly as sensitive as it sounds, which is why the group exists.

Blocking

[InputBackend::poll] never blocks: it drains whatever is ready and returns. A frame loop that wants to sleep should wait on InputBackend::raw_fds together with the DRM device’s descriptor, so the process idles in the kernel until either input arrives or the display retires a flip — rather than spinning to ask.

Devices that arrive late

The set is not fixed, so that list of descriptors is not either. A wireless mouse asleep when the panel starts has no /dev/input/event* node at all — the receiver enumerates, the mouse does not — and the node appears whenever somebody first moves it, which on a machine left running is measured in minutes rather than seconds. poll opens it then, and a loop holding a list made at startup would neither read it nor wake for it.

So: ask InputBackend::devices_changed each pass, and take InputBackend::raw_fds again when it says yes. examples/bare-linux packages that as Waits and every kiosk example uses it.

Re-exports

pub use keymap::key_code;

pub use translate::AbsAxis;

pub use translate::MAX_SLOTS;

pub use translate::RawEvent;

pub use translate::Translator;

pub use console::Console;

pub use console::ConsoleError;

Modules

codes

The subset of linux/input-event-codes.h this backend needs.

console

Muting the kernel’s virtual terminal.

keymap

evdev key codes to KeyCode positions.

layout

Key positions to characters: layouts, dead keys and composition.

translate

Turning raw evdev events into InputEvents.

Structs

Capabilities

What a device can report.

InputBackend

Every usable input device, read together.

InputDevice

One open input device, with its own translation state.

Enums

EvdevError

Something went wrong reading input devices.