component.h

Go to the documentation of this file.

// SPDX-License-Identifier: Apache-2.0
// Copyright 2025-2026 Arnis Lektauers
//
// Created by Arnis Lektauers on 05.09.2025.
//
#pragma once
 
#include <cstddef>
#include <memory>
#include <core/eventHandler.h>
 
namespace visutwin::canvas
{
    class IComponentSystem;
    class Entity;
 
    using ComponentTypeID = std::size_t;
 
    inline ComponentTypeID nextComponentTypeID() {
        static ComponentTypeID lastID = 0;
        return lastID++;
    }
 
    template <typename T>
    ComponentTypeID componentTypeID() {
        static ComponentTypeID id = nextComponentTypeID();
        return id;
    }

    class Component : public EventHandler
    {
    public:
        explicit Component(IComponentSystem* system, Entity* entity);
        virtual ~Component() = default;
 
        Entity* entity() const;
 
        IComponentSystem* system() const { return _system; }
 
        virtual bool enabled() const { return _enabled; }
        virtual void setEnabled(bool value);
 
        virtual void initializeComponentData() = 0;
 
        // Lifecycle methods matching upstream Component.
        // Called when the component becomes active (component enabled AND entity enabled).
        virtual void onEnable() {}
 
        // Called when the component becomes inactive (component disabled OR entity disabled).
        virtual void onDisable() {}
 
        // Called after all hierarchy state changes have been processed.
        virtual void onPostStateChange() {}

        virtual void cloneFrom(const Component* source) {}
 
    protected:
        // Called internally when the enabled setter changes the value.
        // Matching Upstream: only fires onEnable/onDisable if entity is also enabled.
        virtual void onSetEnabled(bool oldValue, bool newValue);
 
        Entity* _entity;
        bool _enabled = true;
 
    private:
        IComponentSystem* _system;
    };
}