Initial UI in src

src/UI/UI_slider.hpp

@@ -0,0 +1,24 @@
+#pragma once
+#include "UI_item.hpp"
+
+#define UI_SLIDER_TYPE std::string("UISlider")
+typedef void(*UI_slider_on_change)(std::string, double value);
+
+class UI_slider : public UI_item
+{
+    public:
+        UI_slider(std::string id, std::string text, Color fg_color, Color bg_color, double min, double max, double value, UI_slider_on_change on_change);
+        UI_slider(const json& j);
+
+        void set_value(double value);
+        double value() const;
+
+        void from_json(const json& j) override;
+        json to_json() const override;
+    private:
+        double p_min;
+        double p_max;
+        double p_value;
+
+        UI_slider_on_change p_on_change;
+};