Termux LibInput

A libinput-compatible library designed for Android/Termux environments. This library provides the same API as the official libinput library and integrates with termux-display-client to provide real Android input events to applications like KWin.

Features

• API Compatible: Provides the same public API as libinput 1.28.0
• Android/Termux Ready: Works without Linux kernel dependencies
• Real Input Integration: Integrates with termux-display-client for actual input events
• Event Handling: Supports keyboard, pointer, touch, and gesture events
• Device Management: Virtual device creation and capability management
• Configuration Stubs: Provides all configuration APIs (returns sensible defaults)
• Meson Build System: Uses Meson like the official libinput

Project Structure

libinput/
├── src/
│   ├── libinput.c              # Core context and event handling
│   ├── libinput.h              # Public API header
│   ├── evdev.c                 # Event processing and creation
│   ├── evdev-mt-touchpad.c     # Device management and mock udev
│   └── [stub files]            # Placeholder implementations
├── meson.build                 # Root Meson configuration (official style)
├── libinput.pc.in              # pkg-config template
└── README.md                   # This file

Building

Meson (Official libinput style)

Note: termux-display-client library must be installed first.

# Build libinput
meson setup builddir
meson compile -C builddir
meson install -C builddir

If termux-display-client is not found, the build will fail with a clear error message.

Prerequisites

• Meson 0.64+
• C compiler with C99 support
• pthread library
• math library (libm)
• termux-display-client library (required - provides Android input integration)

Installation

The library will be installed as:

• Library: /usr/local/lib/libinput.so (or libinput.so.10)
• Headers: /usr/local/include/libinput/libinput.h
• pkg-config: /usr/local/lib/pkgconfig/libinput.pc

Usage

This library can be used as a drop-in replacement for libinput in applications like KWin:

# Check if properly installed
pkg-config --cflags --libs libinput

# Use in your meson.build
dependency('libinput')

Usage Example

#include <libinput.h>
#include <render.h>  // from termux-display-client
#include <sys/epoll.h>

// KWin gets the termux-display-client event fd
int termux_fd = get_conn_fd();

// Initialize libinput with the termux fd
struct libinput *li = libinput_termux_create_context(&interface, userdata, termux_fd);

// Get the same fd for monitoring (libinput_get_fd returns the termux_fd)
int libinput_fd = libinput_get_fd(li);
assert(libinput_fd == termux_fd);

// Add to epoll
struct epoll_event ev = {
    .events = EPOLLIN,
    .data.fd = libinput_fd
};
epoll_ctl(epoll_fd, EPOLL_CTL_ADD, libinput_fd, &ev);

// In event loop
if (events[i].data.fd == libinput_fd) {
    libinput_dispatch(li);  // Read from termux fd and convert events
    while ((event = libinput_get_event(li)) != NULL) {
        // Process converted libinput event
        libinput_event_destroy(event);
    }
}

API Coverage

Implemented Functions

• Context Management: libinput_udev_create_context(), libinput_path_create_context()
• Event Handling: libinput_dispatch(), libinput_get_event(), libinput_next_event_type()
• Event Types: All event creation and getter functions for keyboard, pointer, touch, gesture events
• Device Management: Device creation, capability queries, reference counting
• Configuration: All configuration APIs (return sensible defaults)

Real Input Integration

• termux-display-client Bridge: Connects to termux-display-client for real input events
• Android Keycode Mapping: Uses termux-display-client's Android-to-Linux keycode mapping
• Synchronous Event Processing: Reads events on-demand when KWin calls libinput_dispatch()
• Event Translation: Converts Android touch/mouse/keyboard events to libinput format
• External FD Management: KWin manages termux-display-client connection and passes fd to libinput
• Standard libinput API: Follows official libinput patterns for KWin integration
• Zero-copy FD sharing: libinput_get_fd() returns the same fd KWin got from termux-display-client
• Device Discovery: Creates virtual devices with standard capabilities

Compatibility

This implementation mimics the official libinput structure:

• Uses the same soversion (10) and library name (libinput.so)
• Provides identical API surface
• Compatible with existing build systems expecting libinput
• Uses Meson build system like the official libinput

Integration with KWin

This library allows KWin to compile and run on Android/Termux by providing the required libinput dependency. It integrates directly with termux-display-client to provide real Android input events to KWin.

Build Order

1. First build and install termux-display-client
2. Then build and install this libinput implementation
3. Finally build KWin with this libinput implementation

License

MIT License - Compatible with the original libinput license.