From d5a44eb40c05a8047dd26a2d3a10aa86f879d30b Mon Sep 17 00:00:00 2001
From: narzoul <narzoul@users.noreply.github.com>
Date: Sat, 20 Apr 2024 17:00:30 +0200
Subject: [PATCH] Fixed inaccurate cursor clipping in DPI unaware mode

---
 DDrawCompat/DDraw/RealPrimarySurface.cpp | 18 ++----------
 DDrawCompat/Gdi/Cursor.cpp               | 36 ++++++++++++++++++++++--
 DDrawCompat/Gdi/Cursor.h                 |  2 ++
 DDrawCompat/Gdi/WinProc.cpp              | 10 ++++++-
 4 files changed, 47 insertions(+), 19 deletions(-)

diff --git a/DDrawCompat/DDraw/RealPrimarySurface.cpp b/DDrawCompat/DDraw/RealPrimarySurface.cpp
index 32cfe35..386b7a5 100644
--- a/DDrawCompat/DDraw/RealPrimarySurface.cpp
+++ b/DDrawCompat/DDraw/RealPrimarySurface.cpp
@@ -340,22 +340,8 @@ namespace
 
 	void setFullscreenPresentationMode(const Win32::DisplayMode::MonitorInfo& mi)
 	{
-		if (IsRectEmpty(&mi.rcDpiAware))
-		{
-			Gdi::Cursor::setEmulated(false);
-			Gdi::Cursor::setMonitorClipRect({});
-		}
-		else
-		{
-			auto clipRect = mi.rcEmulated;
-			if (!EqualRect(&mi.rcMonitor, &mi.rcReal))
-			{
-				InflateRect(&clipRect, -1, -1);
-			}
-
-			Gdi::Cursor::setMonitorClipRect(clipRect);
-			Gdi::Cursor::setEmulated(!Overlay::Steam::isOverlayOpen());
-		}
+		Gdi::Cursor::setEmulated(!IsRectEmpty(&mi.rcEmulated) && !Overlay::Steam::isOverlayOpen());
+		Gdi::Cursor::setMonitorClipRect(mi.rcEmulated);
 	}
 
 	void updateNow(CompatWeakPtr<IDirectDrawSurface7> src, bool isOverlayOnly)
diff --git a/DDrawCompat/Gdi/Cursor.cpp b/DDrawCompat/Gdi/Cursor.cpp
index 01849e5..a277f79 100644
--- a/DDrawCompat/Gdi/Cursor.cpp
+++ b/DDrawCompat/Gdi/Cursor.cpp
@@ -62,9 +62,13 @@ namespace
 		LOG_FUNC("GetCursorInfo", pci);
 		Compat::ScopedCriticalSection lock(g_cs);
 		BOOL result = CALL_ORIG_FUNC(GetCursorInfo)(pci);
-		if (result && pci->hCursor == g_nullCursor)
+		if (result)
 		{
-			pci->hCursor = g_cursor;
+			if (pci->hCursor == g_nullCursor)
+			{
+				pci->hCursor = g_cursor;
+			}
+			Gdi::Cursor::clip(pci->ptScreenPos);
 		}
 		return LOG_RESULT(result);
 	}
@@ -121,6 +125,33 @@ namespace Gdi
 {
 	namespace Cursor
 	{
+		void clip()
+		{
+			Compat::ScopedCriticalSection lock(g_cs);
+			if (!IsRectEmpty(&g_monitorClipRect))
+			{
+				POINT cp = {};
+				CALL_ORIG_FUNC(GetCursorPos)(&cp);
+				if (!PtInRect(&g_monitorClipRect, cp))
+				{
+					clip(cp);
+					CALL_ORIG_FUNC(SetCursorPos)(cp.x, cp.y);
+				}
+			}
+		}
+
+		void clip(POINT& pt)
+		{
+			Compat::ScopedCriticalSection lock(g_cs);
+			if (!IsRectEmpty(&g_monitorClipRect))
+			{
+				pt.x = std::max(pt.x, g_monitorClipRect.left);
+				pt.x = std::min(pt.x, g_monitorClipRect.right);
+				pt.y = std::max(pt.y, g_monitorClipRect.top);
+				pt.y = std::min(pt.y, g_monitorClipRect.bottom);
+			}
+		}
+
 		CURSORINFO getEmulatedCursorInfo()
 		{
 			CURSORINFO ci = {};
@@ -139,6 +170,7 @@ namespace Gdi
 					ci.hCursor = nullptr;
 					ci.flags = 0;
 				}
+				clip(ci.ptScreenPos);
 			}
 
 			return ci;
diff --git a/DDrawCompat/Gdi/Cursor.h b/DDrawCompat/Gdi/Cursor.h
index 620bf0a..d98a205 100644
--- a/DDrawCompat/Gdi/Cursor.h
+++ b/DDrawCompat/Gdi/Cursor.h
@@ -6,6 +6,8 @@ namespace Gdi
 {
 	namespace Cursor
 	{
+		void clip();
+		void clip(POINT& pt);
 		CURSORINFO getEmulatedCursorInfo();
 		void installHooks();
 		bool isEmulated();
diff --git a/DDrawCompat/Gdi/WinProc.cpp b/DDrawCompat/Gdi/WinProc.cpp
index 3e985e1..a0820ee 100644
--- a/DDrawCompat/Gdi/WinProc.cpp
+++ b/DDrawCompat/Gdi/WinProc.cpp
@@ -337,13 +337,20 @@ namespace
 			*lpPoint = *g_cursorPos;
 			return TRUE;
 		}
-		return CALL_ORIG_FUNC(GetCursorPos)(lpPoint);
+
+		BOOL result = CALL_ORIG_FUNC(GetCursorPos)(lpPoint);
+		if (result)
+		{
+			Gdi::Cursor::clip(*lpPoint);
+		}
+		return result;
 	}
 
 	BOOL WINAPI getMessage(LPMSG lpMsg, HWND hWnd, UINT wMsgFilterMin, UINT wMsgFilterMax,
 		decltype(&GetMessageA) origGetMessage)
 	{
 		DDraw::RealPrimarySurface::setUpdateReady();
+		Gdi::Cursor::clip();
 		return origGetMessage(lpMsg, hWnd, wMsgFilterMin, wMsgFilterMax);
 	}
 
@@ -564,6 +571,7 @@ namespace
 		decltype(&PeekMessageA) origPeekMessage)
 	{
 		DDraw::RealPrimarySurface::setUpdateReady();
+		Gdi::Cursor::clip();
 		BOOL result = origPeekMessage(lpMsg, hWnd, wMsgFilterMin, wMsgFilterMax, wRemoveMsg);
 		if (!g_isFrameStarted || Config::Settings::FpsLimiter::MSGLOOP != Config::fpsLimiter.get())
 		{