widget.h

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#ifndef ASW_MODULES_UI_WIDGET_H
#define ASW_MODULES_UI_WIDGET_H
 
#include <memory>
#include <type_traits>
#include <vector>
 
#include "event.h"
 
namespace asw::ui {
 
class Context;
 
using WidgetId = uint32_t;
 
class Widget {
public:
    Widget()
        : id_(generate_id()) { };
 
    virtual ~Widget() = default;
 
    Widget(Widget&&) = default;
 
    Widget& operator=(Widget&&) = default;
 
    Widget(const Widget&) = delete;
    Widget& operator=(const Widget&) = delete;
 
    WidgetId id() const
    {
        return id_;
    }
 
    bool visible = true;
 
    bool enabled = true;
 
    bool focusable = false;
 
    Widget* parent = nullptr;
 
    std::vector<std::unique_ptr<Widget>> children;
 
    virtual void layout(Context& ctx);
 
    virtual bool on_event(Context& ctx, const UIEvent& e);
 
    virtual void on_focus_changed(Context& ctx, bool focused);
 
    virtual void draw(Context& ctx);
 
    template <class T, class... Args> T& add_child(Args&&... args)
    {
        static_assert(std::is_base_of_v<Widget, T>, "add_child<T>: T must derive from Widget");
        auto ptr = std::make_unique<T>(std::forward<Args>(args)...);
        ptr->parent = this;
        auto& ref = *ptr;
        children.emplace_back(std::move(ptr));
        return ref;
    }
 
    asw::Quad<float> transform;
 
private:
    static inline int id_counter_ { 1 };
 
    static int generate_id()
    {
        return id_counter_++;
    }
 
    WidgetId id_;
};
 
} // namespace asw::ui
 
#endif // ASW_MODULES_UI_WIDGET_H