DP-CustomResolution/CustomResolution/Plugin.cs

using Dalamud.IoC;
using Dalamud.Plugin;
using Dalamud.Plugin.Services;
using FFXIVClientStructs.FFXIV.Client.Graphics.Kernel;
using FFXIVClientStructs.FFXIV.Client.UI;
using System;
using System.Collections.Generic;
using System.Linq;
using TerraFX.Interop.Windows;
using static FFXIVClientStructs.FFXIV.Client.UI.Misc.GroupPoseModule;

namespace CustomResolution;

public sealed unsafe class Plugin : IDalamudPlugin
{
    private readonly List<Cmd> _cmds;
    private bool _unloading = false;
    private int _tickCount = 0;
    private HWND _currentHwnd;
    private RECT _currentClientRect;
    private RECT _currentWindowRect;

    public Plugin([RequiredVersion("1.0")] DalamudPluginInterface pluginInterface)
    {
        pluginInterface.Create<Service>();

        Service.Plugin = this;

        Service.Config = Service.PluginInterface.GetPluginConfig() as Configuration ?? new();
        Service.Config.Initialize(Service.PluginInterface);

        Service.PluginUI = new();

        Service.WndProcHook = new();
        Service.CursorPosHooks = new();

        _cmds = typeof(Plugin).Assembly.GetTypes()
            .Where(t => !t.IsAbstract && typeof(Cmd).IsAssignableFrom(t))
            .Select(t => (Cmd) Activator.CreateInstance(t)!)
            .ToList();

        foreach (Cmd cmd in _cmds)
        {
            cmd.Register(Service.CommandManager);
        }

        Service.Framework.Update += OnFrameworkUpdate;
    }

    public string Name => "CustomResolution";

    public uint CurrentWidth { get; private set; }
    public uint CurrentHeight { get; private set; }
    public uint CurrentWindowWidth { get; private set; }
    public uint CurrentWindowHeight { get; private set; }

    public void Dispose()
    {
        _tickCount = 0;
        _unloading = true;

        Service.Framework.Update -= OnFrameworkUpdate;

        Service.Framework.RunOnFrameworkThread(Update);

        foreach (Cmd cmd in _cmds)
        {
            cmd.Dispose();
        }

        Service.CursorPosHooks.Dispose();
        Service.WndProcHook.Dispose();

        Service.PluginUI.Dispose();

        Service.Plugin = null!;
    }

    public void ConvertCoordsWinToGame(ref int x, ref int y)
    {
        if (CurrentWidth == CurrentWindowWidth &&  CurrentHeight == CurrentWindowHeight)
        {
            return;
        }

        float scaleX = CurrentWidth / (float) CurrentWindowWidth;
        float scaleY = CurrentHeight / (float) CurrentWindowHeight;

        x = (int) Math.Round(x * scaleX);
        y = (int) Math.Round(y * scaleY);
    }

    public void ConvertCoordsGameToWin(ref int x, ref int y)
    {
        if (CurrentWidth == CurrentWindowWidth && CurrentHeight == CurrentWindowHeight)
        {
            return;
        }

        float scaleX = CurrentWindowWidth / (float) CurrentWidth;
        float scaleY = CurrentWindowHeight / (float) CurrentHeight;

        x = (int) Math.Round(x * scaleX);
        y = (int) Math.Round(y * scaleY);
    }

    public void ConvertCoordsGlobalToGame(ref int x, ref int y)
    {
        if (CurrentWidth == CurrentWindowWidth && CurrentHeight == CurrentWindowHeight)
        {
            return;
        }

        float scaleX = CurrentWidth / (float) CurrentWindowWidth;
        float scaleY = CurrentHeight / (float) CurrentWindowHeight;

        var p = new POINT(x, y);

        TerraFX.Interop.Windows.Windows.ScreenToClient(_currentHwnd, &p);

        p.x = (int) Math.Round(p.x * scaleX);
        p.y = (int) Math.Round(p.y * scaleY);

        TerraFX.Interop.Windows.Windows.ClientToScreen(_currentHwnd, &p);

        x = p.x;
        y = p.y;
    }

    public void ConvertCoordsGameToGlobal(ref int x, ref int y)
    {
        if (CurrentWidth == CurrentWindowWidth && CurrentHeight == CurrentWindowHeight)
        {
            return;
        }

        float scaleX = CurrentWindowWidth / (float) CurrentWidth;
        float scaleY = CurrentWindowHeight / (float) CurrentHeight;

        var p = new POINT(x, y);

        TerraFX.Interop.Windows.Windows.ScreenToClient(_currentHwnd, &p);

        p.x = (int) Math.Round(p.x * scaleX);
        p.y = (int) Math.Round(p.y * scaleY);

        TerraFX.Interop.Windows.Windows.ClientToScreen(_currentHwnd, &p);

        x = p.x;
        y = p.y;
    }

    public void Update()
    {
        var dev = Device.Instance();

        int rectWidth = _currentClientRect.right - _currentClientRect.left;
        int rectHeight = _currentClientRect.bottom - _currentClientRect.top;

        if ((rectWidth <= 0 || rectHeight <= 0) && !_unloading)
        {
            return;
        }

        uint width, height;

        if (Service.Config.IsScale || _unloading)
        {
            var scale = _unloading ? 1f : Service.Config.Scale;

            width = (uint) Math.Round(rectWidth * scale);
            height = (uint) Math.Round(rectHeight * scale);
        }
        else
        {
            width = Service.Config.Width;
            height = Service.Config.Height;
        }

        if (Service.Config.IsEnabled)
        {
            if (width != dev->Width || height != dev->Height)
            {
                Service.PluginLog.Info($"Changing resolution to {width} x {height}");

                if (width < 256)
                {
                    width = 256;
                }

                if (height < 256)
                {
                    height = 256;
                }

                dev->NewWidth = width;
                dev->NewHeight = height;
                dev->RequestResolutionChange = 1;
            }
        }
        else
        {
            width = dev->Width;
            height = dev->Height;
        }

        CurrentWidth = width;
        CurrentHeight = height;
        CurrentWindowWidth = (uint) rectWidth;
        CurrentWindowHeight = (uint) rectHeight;
    }

    private void OnFrameworkUpdate(IFramework framework)
    {
        var dev = Device.Instance();

        _currentHwnd = (HWND) (IntPtr) dev->hWnd;

        fixed (RECT* currentClientRectPtr = &_currentClientRect)
        fixed (RECT* currentWindowRectPtr = &_currentWindowRect)
        {
            TerraFX.Interop.Windows.Windows.GetClientRect(_currentHwnd, currentClientRectPtr);
            TerraFX.Interop.Windows.Windows.GetWindowRect(_currentHwnd, currentWindowRectPtr);
        }

        if (_tickCount++ >= 10)
        {
            _tickCount = 0;

            Update();
        }

        _tickCount++;
    }
}