Added support for using XTest to warp the mouse

src/video/x11/SDL_x11dyn.c

@@ -56,6 +56,9 @@ typedef struct
 #ifndef SDL_VIDEO_DRIVER_X11_DYNAMIC_XSS
 #define SDL_VIDEO_DRIVER_X11_DYNAMIC_XSS NULL
 #endif
+#ifndef SDL_VIDEO_DRIVER_X11_DYNAMIC_XTEST
+#define SDL_VIDEO_DRIVER_X11_DYNAMIC_XTEST NULL
+#endif
 
 static x11dynlib x11libs[] = {
     { NULL, SDL_VIDEO_DRIVER_X11_DYNAMIC },
@@ -64,7 +67,8 @@ static x11dynlib x11libs[] = {
     { NULL, SDL_VIDEO_DRIVER_X11_DYNAMIC_XINPUT2 },
     { NULL, SDL_VIDEO_DRIVER_X11_DYNAMIC_XFIXES },
     { NULL, SDL_VIDEO_DRIVER_X11_DYNAMIC_XRANDR },
-    { NULL, SDL_VIDEO_DRIVER_X11_DYNAMIC_XSS }
+    { NULL, SDL_VIDEO_DRIVER_X11_DYNAMIC_XSS },
+    { NULL, SDL_VIDEO_DRIVER_X11_DYNAMIC_XTEST }
 };
 
 static void *X11_GetSym(const char *fnname, int *pHasModule)

src/video/x11/SDL_x11mouse.c

@@ -26,6 +26,7 @@
 #include "SDL_x11video.h"
 #include "SDL_x11mouse.h"
 #include "SDL_x11xinput2.h"
+#include "SDL_x11xtest.h"
 #include "../SDL_video_c.h"
 #include "../../events/SDL_mouse_c.h"
 
@@ -367,6 +368,10 @@ static bool X11_WarpMouse(SDL_Window *window, float x, float y)
 {
     SDL_WindowData *data = window->internal;
 
+    if (X11_WarpMouseXTest(SDL_GetVideoDevice(), window, x, y)) {
+        return true;
+    }
+
 #ifdef SDL_VIDEO_DRIVER_X11_XFIXES
     // If we have no barrier, we need to warp
     if (data->pointer_barrier_active == false) {
@@ -380,6 +385,10 @@ static bool X11_WarpMouse(SDL_Window *window, float x, float y)
 
 static bool X11_WarpMouseGlobal(float x, float y)
 {
+    if (X11_WarpMouseXTest(SDL_GetVideoDevice(), NULL, x, y)) {
+        return true;
+    }
+
     X11_WarpMouseInternal(DefaultRootWindow(GetDisplay()), x, y);
     return true;
 }

src/video/x11/SDL_x11sym.h

@@ -182,6 +182,12 @@ SDL_X11_SYM(Status, XSyncDestroyCounter, (Display* a, XSyncCounter b), (a, b), r
 SDL_X11_SYM(Status, XSyncSetCounter, (Display* a, XSyncCounter b, XSyncValue c), (a, b, c), return)
 #endif
 
+#ifdef SDL_VIDEO_DRIVER_X11_XTEST
+SDL_X11_MODULE(XTEST)
+SDL_X11_SYM(Status, XTestQueryExtension, (Display* a, int* b, int* c), (a, b, c), return)
+SDL_X11_SYM(int, XTestFakeMotionEvent, (Display* a, int b, int c, int d, unsigned long e), (a, b, c, d, e), return)
+#endif
+
 #ifdef SDL_VIDEO_DRIVER_X11_SUPPORTS_GENERIC_EVENTS
 SDL_X11_SYM(Bool,XGetEventData,(Display* a,XGenericEventCookie* b),(a,b),return)
 SDL_X11_SYM(void,XFreeEventData,(Display* a,XGenericEventCookie* b),(a,b),)

src/video/x11/SDL_x11video.c

@@ -39,6 +39,7 @@
 #include "SDL_x11messagebox.h"
 #include "SDL_x11shape.h"
 #include "SDL_x11xsync.h"
+#include "SDL_x11xtest.h"
 
 #ifdef SDL_VIDEO_OPENGL_EGL
 #include "SDL_x11opengles.h"
@@ -443,13 +444,17 @@ static bool X11_VideoInit(SDL_VideoDevice *_this)
 
 #ifdef SDL_VIDEO_DRIVER_X11_XFIXES
     X11_InitXfixes(_this);
-#endif // SDL_VIDEO_DRIVER_X11_XFIXES
+#endif
 
     X11_InitXsettings(_this);
 
 #ifdef SDL_VIDEO_DRIVER_X11_XSYNC
     X11_InitXsync(_this);
-#endif /* SDL_VIDEO_DRIVER_X11_XSYNC */
+#endif
+
+#ifdef SDL_VIDEO_DRIVER_X11_XTEST
+    X11_InitXTest(_this);
+#endif
 
 #ifndef X_HAVE_UTF8_STRING
 #warning X server does not support UTF8_STRING, a feature introduced in 2000! This is likely to become a hard error in a future libSDL3.

src/video/x11/SDL_x11xtest.c

@@ -0,0 +1,83 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2025 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+#include "SDL_internal.h"
+
+#if defined(SDL_VIDEO_DRIVER_X11)
+
+#include "SDL_x11video.h"
+#include "SDL_x11xtest.h"
+
+static bool xtest_initialized = false;
+
+void X11_InitXTest(SDL_VideoDevice *_this)
+{
+#ifdef SDL_VIDEO_DRIVER_X11_XTEST
+    Display *display = _this->internal->display;
+    int event, error;
+    int opcode;
+
+    if (!SDL_X11_HAVE_XTEST ||
+        !X11_XQueryExtension(display, "XTEST", &opcode, &event, &error)) {
+        return;
+    }
+
+    xtest_initialized = true;
+#endif
+}
+
+bool X11_XTestIsInitialized(void)
+{
+    return xtest_initialized;
+}
+
+bool X11_WarpMouseXTest(SDL_VideoDevice *_this, SDL_Window *window, float x, float y)
+{
+#ifdef SDL_VIDEO_DRIVER_X11_XTEST
+    if (!X11_XTestIsInitialized()) {
+        return false;
+    }
+
+    Display *display = _this->internal->display;
+    SDL_DisplayData *displaydata = window ? SDL_GetDisplayDriverDataForWindow(window) : SDL_GetDisplayDriverData(SDL_GetPrimaryDisplay());
+    if (!displaydata) {
+        return false;
+    }
+
+    int motion_x = (int)SDL_roundf(x);
+    int motion_y = (int)SDL_roundf(y);
+    if (window) {
+        motion_x += window->x;
+        motion_y += window->y;
+    }
+
+    if (!X11_XTestFakeMotionEvent(display, displaydata->screen, motion_x, motion_y, CurrentTime)) {
+        return false;
+    }
+    X11_XSync(display, False);
+
+    return true;
+#else
+    return false;
+#endif
+}
+
+#endif // SDL_VIDEO_DRIVER_X11

src/video/x11/SDL_x11xtest.h

@@ -0,0 +1,31 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2025 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+#include "SDL_internal.h"
+
+#ifndef SDL_x11xtest_h_
+#define SDL_x11xtest_h_
+
+extern void X11_InitXTest(SDL_VideoDevice *_this);
+extern bool X11_XTestIsInitialized(void);
+extern bool X11_WarpMouseXTest(SDL_VideoDevice *_this, SDL_Window *window, float x, float y);
+
+#endif // SDL_x11xtest_h_