Widget.h

#pragma once
 
#include "pch.h"
 
#define WIDGET_CONSTRUCT(type)                                          \
                                                                        \
public:                                                                 \
    type(WidgetSubsystem* parentSubsystem) : Widget(parentSubsystem) {} \
                                                                        \
    type(Widget* parent) : Widget(parent) {}
 
class WidgetSubsystem;
 
// Base widget that can render ImGui UI
class Widget
{
public:
    Widget(WidgetSubsystem* parentSubsystem);
    Widget(Widget* parentWidget);
    virtual ~Widget() {}
 
public:
    virtual void Start();
    virtual void Tick(double deltaTime) {}
    virtual void Render() {}
    virtual void End() {}
 
    template <class T>
    T* AddChildWidget()
    {
        m_childWidgets.push_back(std::make_unique<T>(this));
        Widget* widget = m_childWidgets.back().get();
        if (m_hasStarted)
            widget->Start();
        return dynamic_cast<T*>(widget);
    }
 
    bool HasStarted() { return m_hasStarted; }
 
    void Destroy();
 
public:
    MulticastDelegate<Widget*> m_OnDestroy;
 
protected:
    void RenderChildren();
 
protected:
    class App* GetApp() const;
    Widget* GetParentWidget() const;
    WidgetSubsystem* GetParentSubsystem() const;
 
private:
    WidgetSubsystem* m_parentSubsystem = nullptr;
    Widget* m_parentWidget             = nullptr;
    bool m_hasStarted                  = false;
 
    std::vector<std::unique_ptr<Widget>> m_childWidgets;
 
    friend class WidgetSubsystem;
 
    bool m_wantsDestroy = false;
};