From 46f87cdc5a59aa14142c15fde8745bac2de65f28 Mon Sep 17 00:00:00 2001
From: Cameron Gutman <[EMAIL REDACTED]>
Date: Tue, 28 Apr 2026 21:52:21 -0500
Subject: [PATCH] pen: Only create touch emulation device when a pen is present
(cherry picked from commit 1aa72247af95802d897dabd51b29311e87c41ae0)
---
src/events/SDL_mouse.c | 13 +++----------
src/events/SDL_pen.c | 21 +++++++++++++++++++++
2 files changed, 24 insertions(+), 10 deletions(-)
diff --git a/src/events/SDL_mouse.c b/src/events/SDL_mouse.c
index 80bd6495f261a..e389e47a16197 100644
--- a/src/events/SDL_mouse.c
+++ b/src/events/SDL_mouse.c
@@ -194,16 +194,9 @@ static void SDLCALL SDL_PenTouchEventsChanged(void *userdata, const char *name,
mouse->pen_touch_events = SDL_GetStringBoolean(hint, true);
- if (mouse->pen_touch_events) {
- 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;
- }
+ if (!mouse->pen_touch_events && mouse->added_pen_touch_device) {
+ SDL_DelTouch(SDL_PEN_TOUCHID);
+ mouse->added_pen_touch_device = false;
}
}
diff --git a/src/events/SDL_pen.c b/src/events/SDL_pen.c
index 61d41e1fea49b..83543a695ee9b 100644
--- a/src/events/SDL_pen.c
+++ b/src/events/SDL_pen.c
@@ -228,6 +228,7 @@ SDL_PenID SDL_AddPenDevice(Uint64 timestamp, const char *name, SDL_Window *windo
SDL_LockRWLockForWriting(pen_device_rwlock);
+ bool first_device = false;
SDL_Pen *pen = NULL;
void *ptr = SDL_realloc(pen_devices, (pen_device_count + 1) * sizeof (*pen));
if (ptr) {
@@ -236,6 +237,8 @@ SDL_PenID SDL_AddPenDevice(Uint64 timestamp, const char *name, SDL_Window *windo
pen = &pen_devices[pen_device_count];
pen_device_count++;
+ first_device = (pen_device_count == 1);
+
SDL_zerop(pen);
pen->instance_id = result;
pen->name = namecpy;
@@ -251,6 +254,14 @@ SDL_PenID SDL_AddPenDevice(Uint64 timestamp, const char *name, SDL_Window *windo
SDL_free(namecpy);
}
+ if (first_device) {
+ SDL_Mouse *mouse = SDL_GetMouse();
+ if (mouse->pen_touch_events && !mouse->added_pen_touch_device) {
+ SDL_AddTouch(SDL_PEN_TOUCHID, SDL_TOUCH_DEVICE_DIRECT, "pen_input");
+ mouse->added_pen_touch_device = true;
+ }
+ }
+
if (result && in_proximity) {
SDL_SendPenProximity(timestamp, result, window, true, true);
}
@@ -267,6 +278,7 @@ void SDL_RemovePenDevice(Uint64 timestamp, SDL_Window *window, SDL_PenID instanc
SDL_SendPenProximity(timestamp, instance_id, window, false, true); // bye bye
SDL_LockRWLockForWriting(pen_device_rwlock);
+ bool last_device = false;
SDL_Pen *pen = FindPenByInstanceId(instance_id);
if (pen) {
SDL_free(pen->name);
@@ -288,9 +300,18 @@ void SDL_RemovePenDevice(Uint64 timestamp, SDL_Window *window, SDL_PenID instanc
} else {
SDL_free(pen_devices);
pen_devices = NULL;
+ last_device = true;
}
}
SDL_UnlockRWLock(pen_device_rwlock);
+
+ if (last_device) {
+ SDL_Mouse *mouse = SDL_GetMouse();
+ if (mouse->added_pen_touch_device) {
+ SDL_DelTouch(SDL_PEN_TOUCHID);
+ mouse->added_pen_touch_device = false;
+ }
+ }
}
// This presumably is happening during video quit, so we don't send PROXIMITY_OUT events here.