From 1b284cd4153d967f17cad9535cf00c153dd62570 Mon Sep 17 00:00:00 2001 From: Christoph Reichenbach Date: Sun, 26 Nov 2023 08:47:32 +0000 Subject: [PATCH] X11 pen detection: fix misclassification due to improper init xinput2_device_is_pen() was testing against default-zero values in the X11 Atom cache on at least the first round of detections, leading to imprecise detection. The patch fixes two aspects of initialisation: 1. Ensure that the selector cache is always initialised in xinput2_device_is_pen(). 2. Ensure that all X11 Atoms used in SDL_x11pen.c are instantiated if missing. This ensures that they are never None and avoids potential failures to detect hot-plugged tablet devices. Acknowledgements: @tilman3 for narrowing down the issue and an initial fix --- src/video/x11/SDL_x11pen.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/src/video/x11/SDL_x11pen.c b/src/video/x11/SDL_x11pen.c index 94b4a5c1b..6d0dbca4e 100644 --- a/src/video/x11/SDL_x11pen.c +++ b/src/video/x11/SDL_x11pen.c @@ -114,9 +114,9 @@ static void pen_atoms_ensure_initialized(SDL_VideoDevice *_this) pen_atoms.device_product_id = X11_XInternAtom(data->display, "Device Product ID", False); pen_atoms.wacom_serial_ids = X11_XInternAtom(data->display, "Wacom Serial IDs", False); pen_atoms.wacom_tool_type = X11_XInternAtom(data->display, "Wacom Tool Type", False); - pen_atoms.abs_pressure = X11_XInternAtom(data->display, "Abs Pressure", True); - pen_atoms.abs_tilt_x = X11_XInternAtom(data->display, "Abs Tilt X", True); - pen_atoms.abs_tilt_y = X11_XInternAtom(data->display, "Abs Tilt Y", True); + pen_atoms.abs_pressure = X11_XInternAtom(data->display, "Abs Pressure", False); + pen_atoms.abs_tilt_x = X11_XInternAtom(data->display, "Abs Tilt X", False); + pen_atoms.abs_tilt_y = X11_XInternAtom(data->display, "Abs Tilt Y", False); pen_atoms.initialized = 1; } @@ -390,9 +390,12 @@ static void xinput2_vendor_peninfo(SDL_VideoDevice *_this, const XIDeviceInfo *d } /* Does this device have a valuator for pressure sensitivity? */ -static SDL_bool xinput2_device_is_pen(const XIDeviceInfo *dev) +static SDL_bool xinput2_device_is_pen(SDL_VideoDevice *_this, const XIDeviceInfo *dev) { int classct; + + pen_atoms_ensure_initialized(_this); + for (classct = 0; classct < dev->num_classes; ++classct) { const XIAnyClassInfo *classinfo = dev->classes[classct]; @@ -445,8 +448,8 @@ void X11_InitPen(SDL_VideoDevice *_this) int old_num_pens_known = pen_map.num_pens_known; int k; - /* Only track physical devices that are enabled */ - if (dev->use != XISlavePointer || dev->enabled == 0 || !xinput2_device_is_pen(dev)) { + /* Only track physical devices that are enabled and look like pens */ + if (dev->use != XISlavePointer || dev->enabled == 0 || !xinput2_device_is_pen(_this, dev)) { continue; }