feat: backlight slider

include/modules/backlight_slider.hpp

@@ -0,0 +1,24 @@
+#pragma once
+
+#include <chrono>
+
+#include "ASlider.hpp"
+#include "util/backlight_backend.hpp"
+
+namespace waybar::modules {
+
+class BacklightSlider : public ASlider {
+ public:
+  BacklightSlider(const std::string&, const Json::Value&);
+  virtual ~BacklightSlider() = default;
+
+  void update() override;
+  void onValueChanged() override;
+
+ private:
+  std::chrono::milliseconds interval_;
+  std::string preferred_device_;
+  util::BacklightBackend backend;
+};
+
+}  // namespace waybar::modules