ScreenEntry.h

#pragma once
 
#include "IManagedScreen.h"
 
 
using ScreenId = uint8_t;
 
class ScreenEntry {
    friend class ScreenManager;
 
    public: 
    
    virtual ~ScreenEntry() = default;
    
    protected:
 
    ScreenEntry* nextScreenEntry = nullptr; 
    ScreenEntry* prevScreenEntry = nullptr; 
 
    IManagedScreen* instance = nullptr; 
    ScreenId id = 0;    
 
 
    bool isManaged = true;  
    bool isOverlay = false; 
 
    virtual IManagedScreen* load() = 0;
 
    virtual void unload() = 0;
};
 
class ScreenEntryExternal final : public ScreenEntry {
    friend class ScreenManager;
    
    public:
 
    explicit ScreenEntryExternal(IManagedScreen* screen, ScreenId id) {
        this->instance = screen;
        this->id = id;
        this->isManaged = false;
    }
 
    protected:
    IManagedScreen* load() override {
        return this->instance;
    }
 
    void unload() override {
    }
};
 
template<typename T>
class ScreenEntryManaged final : public ScreenEntry {
    friend class ScreenManager;
    
    public:
 
    explicit ScreenEntryManaged(ScreenId id) { 
        this->id = id;
        this->isManaged = true;
    }
 
    ~ScreenEntryManaged() override {
            this->unload();
    }
 
    protected:
    IManagedScreen* load() override {
        if (!this->instance) {
            this->instance = new T;
            this->instance->begin();
        }
        return this->instance;
    }
 
    void unload() override {
        delete this->instance;
        this->instance = nullptr;
    }
};