Basic keyboard state module

README.md

@@ -68,6 +68,7 @@ libappindicator-gtk3 [Tray module]
 libdbusmenu-gtk3 [Tray module]
 libmpdclient [MPD module]
 libsndio [sndio module]
+libevdev [KeyboardState module]
 ```
 
 **Build dependencies**
@@ -86,6 +87,7 @@ sudo apt install \
   clang-tidy \
   gobject-introspection \
   libdbusmenu-gtk3-dev \
+  libevdev-dev \
   libfmt-dev \
   libgirepository1.0-dev \
   libgtk-3-dev \

include/factory.hpp

@@ -38,6 +38,9 @@
 #ifdef HAVE_LIBUDEV
 #include "modules/backlight.hpp"
 #endif
+#ifdef HAVE_LIBEVDEV
+#include "modules/keyboard_state.hpp"
+#endif
 #ifdef HAVE_LIBPULSE
 #include "modules/pulseaudio.hpp"
 #endif

include/modules/keyboard_state.hpp

@@ -0,0 +1,31 @@
+#pragma once
+
+#include <fmt/format.h>
+#if FMT_VERSION < 60000
+#include <fmt/time.h>
+#else
+#include <fmt/chrono.h>
+#endif
+#include "ALabel.hpp"
+#include "util/sleeper_thread.hpp"
+
+extern "C" {
+#include <libevdev/libevdev.h>
+}
+
+namespace waybar::modules {
+
+class KeyboardState : public ALabel {
+ public:
+  KeyboardState(const std::string&, const Json::Value&);
+  ~KeyboardState();
+  auto update() -> void;
+
+ private:
+  std::string dev_path_;
+  int         fd_;
+  libevdev*   dev_;
+  util::SleeperThread thread_;
+};
+
+}  // namespace waybar::modules

meson.build

@@ -94,6 +94,7 @@ libnl = dependency('libnl-3.0', required: get_option('libnl'))
 libnlgen = dependency('libnl-genl-3.0', required: get_option('libnl'))
 libpulse = dependency('libpulse', required: get_option('pulseaudio'))
 libudev = dependency('libudev', required: get_option('libudev'))
+libevdev = dependency('libevdev', required: get_option('libevdev'))
 libmpdclient = dependency('libmpdclient', required: get_option('mpd'))
 
 libsndio = compiler.find_library('sndio', required: get_option('sndio'))
@@ -215,6 +216,11 @@ if libudev.found() and (is_linux or libepoll.found())
     src_files += 'src/modules/backlight.cpp'
 endif
 
+if libevdev.found() and (is_linux or libepoll.found())
+    add_project_arguments('-DHAVE_LIBEVDEV', language: 'cpp')
+    src_files += 'src/modules/keyboard_state.cpp'
+endif
+
 if libmpdclient.found()
     add_project_arguments('-DHAVE_LIBMPDCLIENT', language: 'cpp')
     src_files += 'src/modules/mpd/mpd.cpp'
@@ -270,6 +276,7 @@ executable(
         libudev,
         libepoll,
         libmpdclient,
+        libevdev,
         gtk_layer_shell,
         libsndio,
         tz_dep

meson_options.txt

@@ -1,6 +1,7 @@
 option('libcxx', type : 'boolean', value : false, description : 'Build with Clang\'s libc++ instead of libstdc++ on Linux.')
 option('libnl', type: 'feature', value: 'auto', description: 'Enable libnl support for network related features')
 option('libudev', type: 'feature', value: 'auto', description: 'Enable libudev support for udev related features')
+option('libevdev', type: 'feature', value: 'auto', description: 'Enable libevdev support for evdev related features')
 option('pulseaudio', type: 'feature', value: 'auto', description: 'Enable support for pulseaudio')
 option('systemd', type: 'feature', value: 'auto', description: 'Install systemd user service unit')
 option('dbusmenu-gtk', type: 'feature', value: 'auto', description: 'Enable support for tray')

src/factory.cpp

@@ -70,6 +70,11 @@ waybar::AModule* waybar::Factory::makeModule(const std::string& name) const {
       return new waybar::modules::Backlight(id, config_[name]);
     }
 #endif
+#ifdef HAVE_LIBEVDEV
+    if (ref == "keyboard_state") {
+      return new waybar::modules::KeyboardState(id, config_[name]);
+    }
+#endif
 #ifdef HAVE_LIBPULSE
     if (ref == "pulseaudio") {
       return new waybar::modules::Pulseaudio(id, config_[name]);

src/modules/keyboard_state.cpp

@@ -0,0 +1,73 @@
+#include "modules/keyboard_state.hpp"
+#include <filesystem>
+
+extern "C" {
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+}
+
+waybar::modules::KeyboardState::KeyboardState(const std::string& id, const Json::Value& config)
+    : ALabel(config, "keyboard_state", id, "{temperatureC}", 1) {
+  if (config_["device-path"].isString()) {
+    dev_path_ = config_["device-path"].asString();
+  } else {
+    dev_path_ = "";
+  }
+
+  fd_ = open(dev_path_.c_str(), O_NONBLOCK | O_CLOEXEC | O_RDONLY);
+  if (fd_ < 0) {
+    throw std::runtime_error("Can't open " + dev_path_);
+  }
+  int err = libevdev_new_from_fd(fd_, &dev_);
+  if (err < 0) {
+    throw std::runtime_error("Can't create libevdev device");
+  }
+  if (!libevdev_has_event_type(dev_, EV_LED)) {
+    throw std::runtime_error("Device doesn't support LED events");
+  }
+  if (!libevdev_has_event_code(dev_, EV_LED, LED_NUML) || !libevdev_has_event_code(dev_, EV_LED, LED_CAPSL)) {
+    throw std::runtime_error("Device doesn't support num lock or caps lock events");
+  }
+
+  thread_ = [this] {
+    dp.emit();
+    thread_.sleep_for(interval_);
+  };
+}
+
+waybar::modules::KeyboardState::~KeyboardState() {
+  libevdev_free(dev_);
+  int err = close(fd_);
+  if (err < 0) {
+    // Not much we can do, so ignore it.
+  }
+}
+
+auto waybar::modules::KeyboardState::update() -> void {
+  int err = LIBEVDEV_READ_STATUS_SUCCESS;
+  while (err == LIBEVDEV_READ_STATUS_SUCCESS) {
+    input_event ev;
+    err = libevdev_next_event(dev_, LIBEVDEV_READ_FLAG_NORMAL, &ev);
+    while (err == LIBEVDEV_READ_STATUS_SYNC) {
+      err = libevdev_next_event(dev_, LIBEVDEV_READ_FLAG_SYNC, &ev);
+    }
+  }
+  if (err != -EAGAIN) {
+    throw std::runtime_error("Failed to sync evdev device");
+  }
+
+  int numl = libevdev_get_event_value(dev_, EV_LED, LED_NUML);
+  //int capsl = libevdev_get_event_value(dev_, EV_LED, LED_CAPSL);
+
+  std::string text;
+  if (numl) {
+    text = fmt::format(format_, "num lock enabled");
+    label_.set_markup(text);
+  } else {
+    text = fmt::format(format_, "num lock disabled");
+    label_.set_markup(text);
+  }
+
+  ALabel::update();
+}