Engine-Pong/Game/Behaviours/MonoGameCameraBehaviour.cs

using System;

using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;

using Syntriax.Engine.Core;
using Syntriax.Engine.Core.Abstract;

namespace Pong.Behaviours;

public class MonoGameCameraBehaviour : BehaviourOverride, ICamera
{
    public Action<ICamera>? OnPositionChanged { get; set; } = null;
    public Action<ICamera>? OnMatrixTransformChanged { get; set; } = null;
    public Action<ICamera>? OnViewportChanged { get; set; } = null;
    public Action<ICamera>? OnRotationChanged { get; set; } = null;
    public Action<ICamera>? OnZoomChanged { get; set; } = null;

    private Matrix _matrixTransform = Matrix.Identity;

    private Viewport _viewport = default;

    private float _zoom = 1f;

    public Matrix MatrixTransform
    {
        get => _matrixTransform;
        set
        {
            if (_matrixTransform == value)
                return;

            _matrixTransform = value;
            OnMatrixTransformChanged?.Invoke(this);
        }
    }

    public Vector2D Position
    {
        get => Transform.Position;
        set => Transform.Position = value;
    }

    public Viewport Viewport
    {
        get => _viewport;
        set
        {
            if (_viewport.Equals(value))
                return;

            _viewport = value;
            OnViewportChanged?.Invoke(this);
        }
    }

    public float Zoom
    {
        get => _zoom;
        set
        {
            float newValue = value >= .1f ? value : .1f;

            if (_zoom == newValue)
                return;

            _zoom = newValue;
            OnZoomChanged?.Invoke(this);
        }
    }

    public float Rotation
    {
        get => Transform.Rotation;
        set => Transform.Rotation = value;
    }
    public Action<IAssignableTransform>? OnTransformAssigned { get => throw new NotImplementedException(); set => throw new NotImplementedException(); }

    ITransform IAssignableTransform.Transform => throw new NotImplementedException();

    public void Update()
    {
        MatrixTransform =
            Matrix.CreateTranslation(new Vector3(-Position.X, Position.Y, 0f)) *
            Matrix.CreateRotationZ(Rotation) *
            Matrix.CreateScale(Zoom) *
            Matrix.CreateTranslation(new Vector3(_viewport.Width * .5f, _viewport.Height * .5f, 0f));
    }

    protected override void OnInitialize()
    {
        Transform.OnRotationChanged += OnTransformRotationChanged;
        Transform.OnPositionChanged += OnTransformPositionChanged;
    }

    protected override void OnFinalize()
    {
        Transform.OnRotationChanged -= OnTransformRotationChanged;
        Transform.OnPositionChanged -= OnTransformPositionChanged;
    }

    private void OnTransformRotationChanged(ITransform _) => OnRotationChanged?.Invoke(this);
    private void OnTransformPositionChanged(ITransform _) => OnPositionChanged?.Invoke(this);

    public bool Assign(ITransform transform) => GameObject.Assign(transform);
}