From c5029cb2bb510bfdfd10b33c6e1489f57376cc02 Mon Sep 17 00:00:00 2001
From: CasualPokePlayer <50538166+CasualPokePlayer@users.noreply.github.com>
Date: Sun, 23 Feb 2025 02:53:36 -0800
Subject: [PATCH] Add function to lock the mouse

Unused currently. Cursor.Clip code copied from feos. Hopefully works on Linux too
---
 src/BizHawk.Client.EmuHawk/MainForm.cs | 54 +++++++++++++++++++++++++
 src/BizHawk.Common/LSB/XlibImports.cs  | 56 ++++++++++++++++++++++++++
 2 files changed, 110 insertions(+)

diff --git a/src/BizHawk.Client.EmuHawk/MainForm.cs b/src/BizHawk.Client.EmuHawk/MainForm.cs
index 19d99143d7..d43a3671d7 100644
--- a/src/BizHawk.Client.EmuHawk/MainForm.cs
+++ b/src/BizHawk.Client.EmuHawk/MainForm.cs
@@ -962,6 +962,15 @@ namespace BizHawk.Client.EmuHawk
 				SingleInstanceDispose();
 			}
 
+			if (OSTailoredCode.IsUnixHost)
+			{
+				if (_x11Display != IntPtr.Zero)
+				{
+					XlibImports.XCloseDisplay(_x11Display);
+					_x11Display = IntPtr.Zero;
+				}
+			}
+
 			base.Dispose(disposing);
 		}
 
@@ -4807,5 +4816,50 @@ namespace BizHawk.Client.EmuHawk
 
 			RA?.Restart();
 		}
+
+		private IntPtr _x11Display;
+
+		public void LockMouse(bool wantLock)
+		{
+			if (wantLock)
+			{
+				var fbLocation = Point.Subtract(Bounds.Location, new(PointToClient(Location)));
+				fbLocation.Offset(_presentationPanel.Control.Location);
+				Cursor.Clip = new(fbLocation, _presentationPanel.Control.Size);
+			}
+			else
+			{
+				Cursor.Clip = Rectangle.Empty;
+			}
+
+			// Cursor.Clip is a no-op on Linux, so we need this too
+			if (OSTailoredCode.IsUnixHost)
+			{
+				if (_x11Display == IntPtr.Zero)
+				{
+					_x11Display = XlibImports.XOpenDisplay(null);
+				}
+
+				if (wantLock)
+				{
+					const XlibImports.EventMask eventMask = XlibImports.EventMask.ButtonPressMask | XlibImports.EventMask.ButtonMotionMask
+						| XlibImports.EventMask.ButtonReleaseMask | XlibImports.EventMask.PointerMotionMask
+						| XlibImports.EventMask.PointerMotionHintMask | XlibImports.EventMask.LeaveWindowMask;
+					var grabResult = XlibImports.XGrabPointer(_x11Display, Handle, false, eventMask,
+						XlibImports.GrabMode.Async, XlibImports.GrabMode.Async, Handle, IntPtr.Zero, XlibImports.CurrentTime);
+					if (grabResult == XlibImports.GrabResult.AlreadyGrabbed)
+					{
+						// try to grab again after releasing whatever current active grab
+						_ = XlibImports.XUngrabPointer(_x11Display, XlibImports.CurrentTime);
+						_ = XlibImports.XGrabPointer(_x11Display, Handle, false, eventMask,
+							XlibImports.GrabMode.Async, XlibImports.GrabMode.Async, Handle, IntPtr.Zero, XlibImports.CurrentTime);
+					}
+				}
+				else
+				{
+					_ = XlibImports.XUngrabPointer(_x11Display, XlibImports.CurrentTime);
+				}
+			}
+		}
 	}
 }
diff --git a/src/BizHawk.Common/LSB/XlibImports.cs b/src/BizHawk.Common/LSB/XlibImports.cs
index f760c3196e..ba96ea2fd5 100644
--- a/src/BizHawk.Common/LSB/XlibImports.cs
+++ b/src/BizHawk.Common/LSB/XlibImports.cs
@@ -138,6 +138,62 @@ namespace BizHawk.Common
 		[DllImport(XLIB)]
 		public static extern int XFreeEventData(IntPtr display, ref XGenericEventCookie cookie);
 
+		[Flags]
+		public enum EventMask : uint
+		{
+			NoEventMask = 0,
+			KeyPressMask = 1 << 0,
+			KeyReleaseMask = 1 << 1,
+			ButtonPressMask = 1 << 2,
+			ButtonReleaseMask = 1 << 3,
+			EnterWindowMask = 1 << 4,
+			LeaveWindowMask = 1 << 5,
+			PointerMotionMask = 1 << 6,
+			PointerMotionHintMask = 1 << 7,
+			Button1MotionMask = 1 << 8,
+			Button2MotionMask = 1 << 9,
+			Button3MotionMask = 1 << 10,
+			Button4MotionMask = 1 << 11,
+			Button5MotionMask = 1 << 12,
+			ButtonMotionMask = 1 << 13,
+			KeymapStateMask = 1 << 14,
+			ExposureMask = 1 << 15,
+			VisibilityChangeMask = 1 << 16,
+			StructureNotifyMask = 1 << 17,
+			ResizeRedirectMask = 1 << 18,
+			SubstructureNotifyMask = 1 << 19,
+			SubstructureRedirectMask= 1 << 20,
+			FocusChangeMask = 1 << 21,
+			PropertyChangeMask = 1 << 22,
+			ColormapChangeMask = 1 << 23,
+			OwnerGrabButtonMask = 1 << 24
+		}
+
+		public enum GrabMode : int
+		{
+			Sync = 0,
+			Async = 1,
+		}
+
+		// special Time
+		public const uint CurrentTime = 0;
+
+		public enum GrabResult : int
+		{
+			GrabSuccess = 0,
+			AlreadyGrabbed = 1,
+			GrabInvalidTime = 2,
+			GrabNotViewable = 3,
+			GrabFrozen = 4,
+		}
+
+		[DllImport(XLIB)]
+		public static extern GrabResult XGrabPointer(IntPtr display, IntPtr grab_window, [MarshalAs(UnmanagedType.Bool)] bool owner_events,
+			EventMask event_mask, GrabMode pointer_mode, GrabMode keyboard_mode, IntPtr confine_to, IntPtr cursor, nuint time);
+
+		[DllImport(XLIB)]
+		public static extern int XUngrabPointer(IntPtr display, nuint time);
+
 		[DllImport(XLIB)]
 		public static extern unsafe int XQueryKeymap(IntPtr display, byte* keys_return);