SDL: mouse: Clean up virtual touch devices as appropriate.

SDL Commits
1 
From ebb24eedc83d7916b183c1c4223649c847db1e96 Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <[EMAIL REDACTED]>
Date: Wed, 15 Jan 2025 01:55:32 -0500
Subject: [PATCH] mouse: Clean up virtual touch devices as appropriate.

---
 src/events/SDL_mouse.c   | 28 ++++++++++++++++++++++++++--
 src/events/SDL_mouse_c.h |  2 ++
 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/src/events/SDL_mouse.c b/src/events/SDL_mouse.c
index 932cf13610c37..429cc4e97bea8 100644
--- a/src/events/SDL_mouse.c
+++ b/src/events/SDL_mouse.c
@@ -169,7 +169,15 @@ static void SDLCALL SDL_MouseTouchEventsChanged(void *userdata, const char *name
     mouse->mouse_touch_events = SDL_GetStringBoolean(hint, default_value);
 
     if (mouse->mouse_touch_events) {
-        SDL_AddTouch(SDL_MOUSE_TOUCHID, SDL_TOUCH_DEVICE_DIRECT, "mouse_input");
+        if (!mouse->added_mouse_touch_device) {
+            SDL_AddTouch(SDL_MOUSE_TOUCHID, SDL_TOUCH_DEVICE_DIRECT, "mouse_input");
+            mouse->added_mouse_touch_device = true;
+        }
+    } else {
+        if (mouse->added_mouse_touch_device) {
+            SDL_DelTouch(SDL_MOUSE_TOUCHID);
+            mouse->added_mouse_touch_device = false;
+        }
     }
 }
 
@@ -187,7 +195,15 @@ static void SDLCALL SDL_PenTouchEventsChanged(void *userdata, const char *name,
     mouse->pen_touch_events = SDL_GetStringBoolean(hint, true);
 
     if (mouse->pen_touch_events) {
-        SDL_AddTouch(SDL_PEN_TOUCHID, SDL_TOUCH_DEVICE_DIRECT, "pen_input");
+        if (!mouse->added_pen_touch_device) {
+            SDL_AddTouch(SDL_PEN_TOUCHID, SDL_TOUCH_DEVICE_DIRECT, "pen_input");
+            mouse->added_pen_touch_device = true;
+        }
+    } else {
+        if (mouse->added_pen_touch_device) {
+            SDL_DelTouch(SDL_PEN_TOUCHID);
+            mouse->added_pen_touch_device = false;
+        }
     }
 }
 
@@ -1010,6 +1026,14 @@ void SDL_QuitMouse(void)
     SDL_Cursor *cursor, *next;
     SDL_Mouse *mouse = SDL_GetMouse();
 
+    if (mouse->added_mouse_touch_device) {
+        SDL_DelTouch(SDL_MOUSE_TOUCHID);
+    }
+
+    if (mouse->added_pen_touch_device) {
+        SDL_DelTouch(SDL_PEN_TOUCHID);
+    }
+
     if (mouse->CaptureMouse) {
         SDL_CaptureMouse(false);
         SDL_UpdateMouseCapture(true);
diff --git a/src/events/SDL_mouse_c.h b/src/events/SDL_mouse_c.h
index 01974d9a87590..43cc5207da806 100644
--- a/src/events/SDL_mouse_c.h
+++ b/src/events/SDL_mouse_c.h
@@ -121,6 +121,8 @@ typedef struct
     bool pen_mouse_events;
     bool pen_touch_events;
     bool was_touch_mouse_events; // Was a touch-mouse event pending?
+    bool added_mouse_touch_device;  // did we SDL_AddTouch() a virtual touch device for the mouse?
+    bool added_pen_touch_device;  // did we SDL_AddTouch() a virtual touch device for pens?
 #ifdef SDL_PLATFORM_VITA
     Uint8 vita_touch_mouse_device;
 #endif