Document ImGui multimonitor not working and other possible pitfalls

CustomResolution2782/Hooks/CursorPosHooks.cs

@@ -10,6 +10,8 @@ public sealed unsafe class CursorPosHooks : IDisposable
 {
     private readonly Hook<GetCursorPosDelegate> _getCursorPosHook;
     private readonly Hook<SetCursorPosDelegate> _setCursorPosHook;
+    private readonly Hook<ScreenToClientDelegate> _screenToClientHook;
+    private readonly Hook<ClientToScreenDelegate> _clientToScreenHook;
 
     public CursorPosHooks()
     {
@@ -18,6 +20,12 @@ public sealed unsafe class CursorPosHooks : IDisposable
 
         _setCursorPosHook = Service.GameInteropProvider.HookFromSymbol<SetCursorPosDelegate>("user32.dll", "SetCursorPos", SetCursorPosDetour);
         _setCursorPosHook.Enable();
+
+        _screenToClientHook = Service.GameInteropProvider.HookFromSymbol<ScreenToClientDelegate>("user32.dll", "ScreenToClient", ScreenToClientDetour);
+        _screenToClientHook.Enable();
+
+        _clientToScreenHook = Service.GameInteropProvider.HookFromSymbol<ClientToScreenDelegate>("user32.dll", "ClientToScreen", ClientToScreenDetour);
+        _clientToScreenHook.Enable();
     }
 
     [UnmanagedFunctionPointer(CallingConvention.StdCall)]
@@ -26,19 +34,46 @@ public sealed unsafe class CursorPosHooks : IDisposable
     [UnmanagedFunctionPointer(CallingConvention.StdCall)]
     private unsafe delegate bool SetCursorPosDelegate(int x, int y);
 
+    [UnmanagedFunctionPointer(CallingConvention.StdCall)]
+    private unsafe delegate bool ScreenToClientDelegate(HWND hWnd, POINT* lpPoint);
+
+    [UnmanagedFunctionPointer(CallingConvention.StdCall)]
+    private unsafe delegate bool ClientToScreenDelegate(HWND hWnd, POINT* lpPoint);
+
     public void Dispose()
     {
         _getCursorPosHook.Dispose();
         _setCursorPosHook.Dispose();
+        _screenToClientHook.Dispose();
+        _clientToScreenHook.Dispose();
+    }
+
+    public bool GetCursorPosOrig(POINT* lpPoint)
+    {
+        return _getCursorPosHook.Original(lpPoint);
+    }
+
+    public bool SetCursorPosOrig(int x, int y)
+    {
+        return _setCursorPosHook.Original(x, y);
+    }
+
+    public bool ScreenToClientOrig(HWND hWnd, POINT* lpPoint)
+    {
+        return _screenToClientHook.Original(hWnd, lpPoint);
+    }
+
+    public bool ClientToScreenOrig(HWND hWnd, POINT* lpPoint)
+    {
+        return _clientToScreenHook.Original(hWnd, lpPoint);
     }
 
     private bool GetCursorPosDetour(POINT* lpPoint)
     {
         var rv = _getCursorPosHook.Original(lpPoint);
-
-        if (!rv)
+        if (!rv || lpPoint == null)
         {
-            return false;
+            return rv;
         }
 
 #if false
@@ -69,4 +104,13 @@ public sealed unsafe class CursorPosHooks : IDisposable
         return _setCursorPosHook.Original(x, y);
     }
 
+    private bool ScreenToClientDetour(HWND hWnd, POINT* lpPoint)
+    {
+        return _screenToClientHook.Original(hWnd, lpPoint);
+    }
+
+    private bool ClientToScreenDetour(HWND hWnd, POINT* lpPoint)
+    {
+        return _clientToScreenHook.Original(hWnd, lpPoint);
+    }
 }

CustomResolution2782/Hooks/WindowRectHooks.cs

@@ -50,7 +50,10 @@ public sealed unsafe class WindowRectHooks : IDisposable
         Service.PluginLog.Debug($"GetClientRectDetour A @ {lpRect->left} {lpRect->top} {lpRect->right} {lpRect->bottom}");
 #endif
 
+        if (hWnd == Service.Plugin.CurrentHWND)
+        {
             Service.Plugin.ConvertCoordsWinToGame(ref lpRect->right, ref lpRect->bottom);
+        }
 
 #if false
         Service.PluginLog.Debug($"GetClientRectDetour B @ {lpRect->left} {lpRect->top} {lpRect->right} {lpRect->bottom}");
@@ -65,7 +68,7 @@ public sealed unsafe class WindowRectHooks : IDisposable
         Service.PluginLog.Debug($"SetWindowPosDetour A @ {X} {Y} {cx} {cy}");
 #endif
 
-        if (Service.DebugConfig.SetSizeMode == SetSizeMode.LegacyHookSetWindowPos)
+        if (Service.DebugConfig.SetSizeMode == SetSizeMode.LegacyHookSetWindowPos && hWnd == Service.Plugin.CurrentHWND)
         {
             Service.Plugin.ConvertCoordsGameToWin(ref cx, ref cy);
         }

CustomResolution2782/Plugin.cs

@@ -65,7 +65,7 @@ public sealed unsafe class Plugin : IDalamudPlugin
 
     public string Name => "CustomResolution";
 
-    public HWND CurrentHWND { get; private set; }
+    public HWND CurrentHWND => _currentHwnd;
 
     public uint CurrentWidth { get; private set; }
     public uint CurrentHeight { get; private set; }
@@ -140,12 +140,12 @@ public sealed unsafe class Plugin : IDalamudPlugin
 
         var p = new POINT(x, y);
 
-        ScreenToClient(_currentHwnd, &p);
+        Service.CursorPosHooks.ScreenToClientOrig(_currentHwnd, &p);
 
         p.x = (int) Math.Round(p.x * scaleX);
         p.y = (int) Math.Round(p.y * scaleY);
 
-        ClientToScreen(_currentHwnd, &p);
+        Service.CursorPosHooks.ClientToScreenOrig(_currentHwnd, &p);
 
         x = p.x;
         y = p.y;
@@ -163,12 +163,12 @@ public sealed unsafe class Plugin : IDalamudPlugin
 
         var p = new POINT(x, y);
 
-        ScreenToClient(_currentHwnd, &p);
+        Service.CursorPosHooks.ScreenToClientOrig(_currentHwnd, &p);
 
         p.x = (int) Math.Round(p.x * scaleX);
         p.y = (int) Math.Round(p.y * scaleY);
 
-        ClientToScreen(_currentHwnd, &p);
+        Service.CursorPosHooks.ClientToScreenOrig(_currentHwnd, &p);
 
         x = p.x;
         y = p.y;

README.md

@@ -4,3 +4,30 @@ Enforces a custom resolution for the game, similar to NVIDIA DSR.
 
 Mirrored at https://gitlab.com/0x0ade/dp-customresolution in case you want to submit a merge request.
 Please do ping me on Discord though (I'm in the Dalamud server) as some notifs might fly under my radar.
+
+# Troubleshooting
+
+<details><summary>My multi-monitor windows aren't working correctly!</summary>
+Similarly to some other plugins (f.e. Umbra), multi-monitor mode in Dalamud might not work correctly.
+In the case of cres, fixing this would be a huge undertaking to make ImGui handle the cursor inside and outside
+the main game window differently, and to also handle window positioning correctly (spoiler: there is not one way
+to handle it correctly - things are already shifting around when just resizing the game normally).
+</details>
+
+<details><summary>The game UI is really really small! I don't want to scale all my HUD manually!</summary>
+Good news: You don't need to! XIV itself has got a "High Resolution UI Settings" scaling option in the system
+configuration window, in the very first category ("Display Settings"), right under the resolution options.
+
+Bad news: We're currently limited to the very options that XIV gives us. Perhaps a deeper dive into how the game
+renders the HUD and decoupling that from the actual game render resolution could help, but it's on the same
+scale of difficulty as fixing multi-monitor windows.
+</details>
+
+<details><summary>I'm scaling by 3x or higher, but I'm still getting jagged edges!</summary>
+The plugin currently only gives FFXIV a fake resolution to work with internally, but it doesn't ensure that the
+extra pixels land on your screen - those will still be used for in-game or ReShade screenshots though.
+
+Windows should perform basic filtering with 2x scaling (it might not work on some graphics cards?), and I haven't
+heard back from anyone using this on Linux yet. But an universal fix for this is possible - it just requires more
+time than I have on my hands right now.
+</details>