Re: XInput 2 support

[Po Lu via "Emacs development discussions." <emacs-devel@gnu.org>]

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Alan Third <alan@idiocy.org> writes:

> I think it's definitely worth it.

Thanks!

> it could never directly support multitouch and pixel-scrolling without
> adding XInput2 support and that I wasn't confident enough to do that
> myself.

BTW, the attached version of the change should make it easier for
someone to add pixelwise scrolling support in the future.

Basically, the pixel-wise delta you want is the `delta' in the following
code snippet:

    double delta =
      x_get_scroll_valuator_delta (dpyinfo, xev->deviceid,
				   i, *values, &val);


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From 955b6d59a62def8937c0ac9c1bd83ab7e0e11517 Mon Sep 17 00:00:00 2001
From: Po Lu <luangruo@yahoo.com>
Date: Sat, 16 Oct 2021 13:15:36 +0800
Subject: [PATCH] Add support for event processing via XInput 2

* configure.ac: Add an option to use XInput 2 if available
* src/Makefile.in (XINPUT_LIBS, XINPUT_CFLAGS): New variables
(EMACS_CFLAGS): Add Xinput CFLAGS
(LIBES): Add XInput libs
* src/xmenu.c (popup_activated_flag): Expose flag if XInput 2 is
available
* src/xfns.c (x_window): Set XInput 2 event mask
* src/xterm.c (x_detect_focus_change): Handle XInput 2 GenericEvents
(handle_one_xevent): Handle XInput 2 events
(x_term_init): Ask the server for XInput 2 support and set xkb_desc if
available
(x_delete_terminal): Free XKB kb desc if it exists, and free XI2
devices if they exist
(x_free_xi_devices, x_init_master_valuators): New functions
(x_get_scroll_valuator_delta): New function
(init_xterm): Don't tell GTK to only use Core Input when built with
XInput 2 support
* src/xterm.h (struct x_display_info): Add fields for XKB and XI2
support
* src/gtkutil.c (xg_event_is_for_menubar): Handle XIDeviceEvents
(xg_is_menu_window): New function
(xg_event_is_for_scrollbar): Handle XIDeviceEvents
---
 configure.ac    |   22 +
 src/Makefile.in |    7 +-
 src/gtkutil.c   |   72 +++-
 src/gtkutil.h   |    4 +
 src/xfns.c      |   62 +++
 src/xmenu.c     |    4 +
 src/xterm.c     | 1086 ++++++++++++++++++++++++++++++++++++++++++++++-
 src/xterm.h     |   42 ++
 8 files changed, 1292 insertions(+), 7 deletions(-)

diff --git a/configure.ac b/configure.ac
index 9ab0314428..0af8b65dd7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -485,6 +485,7 @@ AC_DEFUN
 OPTION_DEFAULT_ON([modules],[don't compile with dynamic modules support])
 OPTION_DEFAULT_ON([threads],[don't compile with elisp threading support])
 OPTION_DEFAULT_OFF([native-compilation],[compile with Emacs Lisp native compiler support])
+OPTION_DEFAULT_OFF([xinput2],[use version 2.0 the X Input Extension for input])
 
 AC_ARG_WITH([file-notification],[AS_HELP_STRING([--with-file-notification=LIB],
  [use a file notification library (LIB one of: yes, inotify, kqueue, gfile, w32, no)])],
@@ -4203,6 +4204,26 @@ AC_DEFUN
 AC_SUBST(XFIXES_CFLAGS)
 AC_SUBST(XFIXES_LIBS)
 
+## Use XInput 2.0 if available
+HAVE_XINPUT2=no
+if test "${HAVE_X11}" = "yes" && test "${with_xinput2}" != "no"; then
+   EMACS_CHECK_MODULES([XINPUT], [xi])
+   if test $HAVE_XINPUT = yes; then
+     # Now check for XInput2.h
+     AC_CHECK_HEADER(X11/extensions/XInput2.h,
+       [AC_CHECK_LIB(Xi, XIGrabButton, HAVE_XINPUT2=yes)])
+   fi
+   if test $HAVE_XINPUT2 = yes; then
+     AC_DEFINE(HAVE_XINPUT2, 1, [Define to 1 if the X Input Extension version 2.0 is present.])
+     if test "$USE_GTK_TOOLKIT" = "GTK2"; then
+       AC_MSG_WARN([You are building Emacs with GTK+ 2 and the X Input Extension version 2.
+This might lead to problems if your version of GTK+ is not built with support for XInput 2.])
+     fi
+   fi
+fi
+AC_SUBST(XINPUT_CFLAGS)
+AC_SUBST(XINPUT_LIBS)
+
 ### Use Xdbe (-lXdbe) if available
 HAVE_XDBE=no
 if test "${HAVE_X11}" = "yes"; then
@@ -5959,6 +5980,7 @@ AC_DEFUN
   Does Emacs support legacy unexec dumping?               ${with_unexec}
   Which dumping strategy does Emacs use?                  ${with_dumping}
   Does Emacs have native lisp compiler?                   ${HAVE_NATIVE_COMP}
+  Does Emacs use version 2 of the the X Input Extension?  ${HAVE_XINPUT2}
 "])
 
 if test -n "${EMACSDATA}"; then
diff --git a/src/Makefile.in b/src/Makefile.in
index 6d75e3537a..2b3e1f37e0 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -256,6 +256,9 @@ XINERAMA_CFLAGS =
 XFIXES_LIBS = @XFIXES_LIBS@
 XFIXES_CFLAGS = @XFIXES_CFLAGS@
 
+XINPUT_LIBS = @XINPUT_LIBS@
+XINPUT_CFLAGS = @XINPUT_CFLAGS@
+
 XDBE_LIBS = @XDBE_LIBS@
 XDBE_CFLAGS = @XDBE_CFLAGS@
 
@@ -372,7 +375,7 @@ EMACS_CFLAGS=
   $(GNUSTEP_CFLAGS) $(CFLAGS_SOUND) $(RSVG_CFLAGS) $(IMAGEMAGICK_CFLAGS) \
   $(PNG_CFLAGS) $(LIBXML2_CFLAGS) $(LIBGCCJIT_CFLAGS) $(DBUS_CFLAGS) \
   $(XRANDR_CFLAGS) $(XINERAMA_CFLAGS) $(XFIXES_CFLAGS) $(XDBE_CFLAGS) \
-  $(WEBKIT_CFLAGS) $(LCMS2_CFLAGS) \
+  $(XINPUT_CFLAGS) $(WEBKIT_CFLAGS) $(LCMS2_CFLAGS) \
   $(SETTINGS_CFLAGS) $(FREETYPE_CFLAGS) $(FONTCONFIG_CFLAGS) \
   $(HARFBUZZ_CFLAGS) $(LIBOTF_CFLAGS) $(M17N_FLT_CFLAGS) $(DEPFLAGS) \
   $(LIBSYSTEMD_CFLAGS) $(JSON_CFLAGS) \
@@ -522,7 +525,7 @@ LIBES =
    $(FREETYPE_LIBS) $(FONTCONFIG_LIBS) $(HARFBUZZ_LIBS) $(LIBOTF_LIBS) $(M17N_FLT_LIBS) \
    $(LIBGNUTLS_LIBS) $(LIB_PTHREAD) $(GETADDRINFO_A_LIBS) $(LCMS2_LIBS) \
    $(NOTIFY_LIBS) $(LIB_MATH) $(LIBZ) $(LIBMODULES) $(LIBSYSTEMD_LIBS) \
-   $(JSON_LIBS) $(LIBGMP) $(LIBGCCJIT_LIBS)
+   $(JSON_LIBS) $(LIBGMP) $(LIBGCCJIT_LIBS) $(XINPUT_LIBS)
 
 ## FORCE it so that admin/unidata can decide whether this file is
 ## up-to-date.  Although since charprop depends on bootstrap-emacs,
diff --git a/src/gtkutil.c b/src/gtkutil.c
index e87845caf7..fc4afef510 100644
--- a/src/gtkutil.c
+++ b/src/gtkutil.c
@@ -47,6 +47,10 @@ Copyright (C) 2003-2021 Free Software Foundation, Inc.
 
 #include <gdk/gdkkeysyms.h>
 
+#ifdef HAVE_XINPUT2
+#include <X11/extensions/XInput2.h>
+#endif
+
 #ifdef HAVE_XFT
 #include <X11/Xft/Xft.h>
 #endif
@@ -839,6 +843,23 @@ my_log_handler (const gchar *log_domain, GLogLevelFlags log_level,
 }
 #endif
 
+#if defined HAVE_GTK3 && defined HAVE_XINPUT2
+bool
+xg_is_menu_window (Display *dpy, Window wdesc)
+{
+  GtkWidget *gwdesc = xg_win_to_widget (dpy, wdesc);
+
+  if (GTK_IS_WINDOW (gwdesc))
+    {
+      GtkWidget *fw = gtk_bin_get_child (GTK_BIN (gwdesc));
+      if (GTK_IS_MENU (fw))
+	return true;
+    }
+
+  return false;
+}
+#endif
+
 /* Make a geometry string and pass that to GTK.  It seems this is the
    only way to get geometry position right if the user explicitly
    asked for a position when starting Emacs.
@@ -3575,6 +3596,18 @@ xg_event_is_for_menubar (struct frame *f, const XEvent *event)
 
   if (! x->menubar_widget) return 0;
 
+#ifdef HAVE_XINPUT2
+  XIDeviceEvent *xev = (XIDeviceEvent *) event->xcookie.data;
+  if (event->type == GenericEvent) /* XI_ButtonPress or XI_ButtonRelease */
+    {
+      if (! (xev->event_x >= 0
+	     && xev->event_x < FRAME_PIXEL_WIDTH (f)
+	     && xev->event_y >= 0
+	     && xev->event_y < FRAME_MENUBAR_HEIGHT (f)))
+	return 0;
+    }
+  else
+#endif
   if (! (event->xbutton.x >= 0
          && event->xbutton.x < FRAME_PIXEL_WIDTH (f)
          && event->xbutton.y >= 0
@@ -3583,7 +3616,12 @@ xg_event_is_for_menubar (struct frame *f, const XEvent *event)
     return 0;
 
   gdpy = gdk_x11_lookup_xdisplay (FRAME_X_DISPLAY (f));
-  gw = gdk_x11_window_lookup_for_display (gdpy, event->xbutton.window);
+#ifdef HAVE_XINPUT2
+  if (event->type == GenericEvent)
+    gw = gdk_x11_window_lookup_for_display (gdpy, xev->event);
+  else
+#endif
+    gw = gdk_x11_window_lookup_for_display (gdpy, event->xbutton.window);
   if (! gw) return 0;
   gevent.any.window = gw;
   gevent.any.type = GDK_NOTHING;
@@ -4230,7 +4268,20 @@ xg_event_is_for_scrollbar (struct frame *f, const XEvent *event)
 {
   bool retval = 0;
 
+#ifdef HAVE_XINPUT2
+  XIDeviceEvent *xev = (XIDeviceEvent *) event->xcookie.data;
+  if (f && ((FRAME_DISPLAY_INFO (f)->supports_xi2
+	     && event->type == GenericEvent
+	     && (event->xgeneric.extension
+		 == FRAME_DISPLAY_INFO (f)->xi2_opcode)
+	     && ((event->xgeneric.evtype == XI_ButtonPress
+		  && xev->detail < 4)
+		 || (event->xgeneric.evtype == XI_Motion)))
+	    || (event->type == ButtonPress
+		&& event->xbutton.button < 4)))
+#else
   if (f && event->type == ButtonPress && event->xbutton.button < 4)
+#endif /* HAVE_XINPUT2 */
     {
       /* Check if press occurred outside the edit widget.  */
       GdkDisplay *gdpy = gdk_x11_lookup_xdisplay (FRAME_X_DISPLAY (f));
@@ -4248,10 +4299,29 @@ xg_event_is_for_scrollbar (struct frame *f, const XEvent *event)
       gwin = gdk_display_get_window_at_pointer (gdpy, NULL, NULL);
 #endif
       retval = gwin != gtk_widget_get_window (f->output_data.x->edit_widget);
+#ifdef HAVE_XINPUT2
+      GtkWidget *grab = gtk_grab_get_current ();
+      if (event->type == GenericEvent
+	  && event->xgeneric.evtype == XI_Motion)
+	retval = retval || (grab && GTK_IS_SCROLLBAR (grab));
+#endif
     }
+#ifdef HAVE_XINPUT2
+  else if (f && ((FRAME_DISPLAY_INFO (f)->supports_xi2
+		  && event->type == GenericEvent
+		  && (event->xgeneric.extension
+		      == FRAME_DISPLAY_INFO (f)->xi2_opcode)
+		  && ((event->xgeneric.evtype == XI_ButtonRelease
+		       && xev->detail < 4)
+		      || (event->xgeneric.evtype == XI_Motion)))
+		 || ((event->type == ButtonRelease
+		      && event->xbutton.button < 4)
+		     || event->type == MotionNotify)))
+#else
   else if (f
            && ((event->type == ButtonRelease && event->xbutton.button < 4)
                || event->type == MotionNotify))
+#endif /* HAVE_XINPUT2 */
     {
       /* If we are releasing or moving the scroll bar, it has the grab.  */
       GtkWidget *w = gtk_grab_get_current ();
diff --git a/src/gtkutil.h b/src/gtkutil.h
index 31a12cd5d3..95dd75b7fa 100644
--- a/src/gtkutil.h
+++ b/src/gtkutil.h
@@ -192,6 +192,10 @@ #define XG_ITEM_DATA "emacs_menuitem"
 extern void xg_print_frames_dialog (Lisp_Object);
 #endif
 
+#if defined HAVE_GTK3 && defined HAVE_XINPUT2
+extern bool xg_is_menu_window (Display *dpy, Window);
+#endif
+
 /* Mark all callback data that are Lisp_object:s during GC.  */
 extern void xg_mark_data (void);
 
diff --git a/src/xfns.c b/src/xfns.c
index 785ae3baca..561ee5988f 100644
--- a/src/xfns.c
+++ b/src/xfns.c
@@ -57,6 +57,10 @@ Copyright (C) 1989, 1992-2021 Free Software Foundation, Inc.
 #include <X11/extensions/Xdbe.h>
 #endif
 
+#ifdef HAVE_XINPUT2
+#include <X11/extensions/XInput2.h>
+#endif
+
 #ifdef USE_X_TOOLKIT
 #include <X11/Shell.h>
 
@@ -3074,6 +3078,35 @@ x_window (struct frame *f, long window_prompting)
   class_hints.res_class = SSDATA (Vx_resource_class);
   XSetClassHint (FRAME_X_DISPLAY (f), XtWindow (shell_widget), &class_hints);
 
+#ifdef HAVE_XINPUT2
+  if (FRAME_DISPLAY_INFO (f)->supports_xi2)
+    {
+      XIEventMask mask;
+      ptrdiff_t l = XIMaskLen (XI_LASTEVENT);
+      unsigned char *m;
+      mask.mask = m = alloca (l);
+      memset (m, 0, l);
+      mask.mask_len = l;
+      mask.deviceid = XIAllMasterDevices;
+
+      XISetMask (m, XI_ButtonPress);
+      XISetMask (m, XI_ButtonRelease);
+      XISetMask (m, XI_KeyPress);
+      XISetMask (m, XI_KeyRelease);
+      XISetMask (m, XI_Motion);
+      XISetMask (m, XI_Enter);
+      XISetMask (m, XI_Leave);
+      XISetMask (m, XI_FocusIn);
+      XISetMask (m, XI_FocusOut);
+      XISetMask (m, XI_PropertyEvent);
+      XISetMask (m, XI_HierarchyChanged);
+      XISetMask (m, XI_DeviceChanged);
+      XISelectEvents (FRAME_X_DISPLAY (f),
+		      FRAME_X_WINDOW (f),
+		      &mask, 1);
+    }
+#endif
+
 #ifdef HAVE_X_I18N
   FRAME_XIC (f) = NULL;
   if (use_xim)
@@ -3254,6 +3287,35 @@ x_window (struct frame *f)
     }
 #endif /* HAVE_X_I18N */
 
+#ifdef HAVE_XINPUT2
+  if (FRAME_DISPLAY_INFO (f)->supports_xi2)
+    {
+      XIEventMask mask;
+      ptrdiff_t l = XIMaskLen (XI_LASTEVENT);
+      unsigned char *m;
+      mask.mask = m = alloca (l);
+      memset (m, 0, l);
+      mask.mask_len = l;
+      mask.deviceid = XIAllMasterDevices;
+
+      XISetMask (m, XI_ButtonPress);
+      XISetMask (m, XI_ButtonRelease);
+      XISetMask (m, XI_KeyPress);
+      XISetMask (m, XI_KeyRelease);
+      XISetMask (m, XI_Motion);
+      XISetMask (m, XI_Enter);
+      XISetMask (m, XI_Leave);
+      XISetMask (m, XI_FocusIn);
+      XISetMask (m, XI_FocusOut);
+      XISetMask (m, XI_PropertyEvent);
+      XISetMask (m, XI_HierarchyChanged);
+      XISetMask (m, XI_DeviceChanged);
+      XISelectEvents (FRAME_X_DISPLAY (f),
+		      FRAME_X_WINDOW (f),
+		      &mask, 1);
+    }
+#endif
+
   validate_x_resource_name ();
 
   class_hints.res_name = SSDATA (Vx_resource_name);
diff --git a/src/xmenu.c b/src/xmenu.c
index ea2cbab203..07255911f9 100644
--- a/src/xmenu.c
+++ b/src/xmenu.c
@@ -105,7 +105,11 @@ Copyright (C) 1986, 1988, 1993-1994, 1996, 1999-2021 Free Software
 \f
 /* Flag which when set indicates a dialog or menu has been posted by
    Xt on behalf of one of the widget sets.  */
+#ifndef HAVE_XINPUT2
 static int popup_activated_flag;
+#else
+int popup_activated_flag;
+#endif
 
 \f
 #ifdef USE_X_TOOLKIT
diff --git a/src/xterm.c b/src/xterm.c
index 961c61c245..41b509449e 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -42,6 +42,10 @@ Copyright (C) 1989, 1993-2021 Free Software Foundation, Inc.
 #include <X11/extensions/Xdbe.h>
 #endif
 
+#ifdef HAVE_XINPUT2
+#include <X11/extensions/XInput2.h>
+#endif
+
 /* Load sys/types.h if not already loaded.
    In some systems loading it twice is suicidal.  */
 #ifndef makedev
@@ -223,9 +227,15 @@ #define XtNinitialState "initialState"
 static void x_check_fullscreen (struct frame *);
 static void x_check_expected_move (struct frame *, int, int);
 static void x_sync_with_move (struct frame *, int, int, bool);
+#ifndef HAVE_XINPUT2
 static int handle_one_xevent (struct x_display_info *,
 			      const XEvent *, int *,
 			      struct input_event *);
+#else
+static int handle_one_xevent (struct x_display_info *,
+			      XEvent *, int *,
+			      struct input_event *);
+#endif
 #if ! (defined USE_X_TOOLKIT || defined USE_MOTIF) && defined USE_GTK
 static int x_dispatch_event (XEvent *, Display *);
 #endif
@@ -335,6 +345,156 @@ x_extension_initialize (struct x_display_info *dpyinfo)
   dpyinfo->ext_codes = ext_codes;
 }
 
+
+#ifdef HAVE_XINPUT2
+
+/* Free all XI2 devices on dpyinfo.  */
+static void
+x_free_xi_devices (struct x_display_info *dpyinfo)
+{
+  block_input ();
+
+  if (dpyinfo->num_devices)
+    {
+      for (int i = 0; i < dpyinfo->num_devices; ++i)
+	xfree (dpyinfo->devices[i].valuators);
+
+      xfree (dpyinfo->devices);
+      dpyinfo->devices = NULL;
+      dpyinfo->num_devices = 0;
+    }
+
+  unblock_input ();
+}
+
+/* Setup valuator tracking for XI2 master devices on
+   DPYINFO->display.  */
+
+static void
+x_init_master_valuators (struct x_display_info *dpyinfo)
+{
+  int ndevices;
+  XIDeviceInfo *infos;
+
+  block_input ();
+  x_free_xi_devices (dpyinfo);
+  infos = XIQueryDevice (dpyinfo->display,
+			 XIAllMasterDevices,
+			 &ndevices);
+
+  if (!ndevices)
+    {
+      XIFreeDeviceInfo (infos);
+      unblock_input ();
+      return;
+    }
+
+  int actual_devices = 0;
+  dpyinfo->devices = xmalloc (sizeof *dpyinfo->devices * ndevices);
+
+  for (int i = 0; i < ndevices; ++i)
+    {
+      XIDeviceInfo *device = &infos[i];
+
+      if (device->enabled)
+	{
+	  int actual_valuator_count = 0;
+	  struct xi_device_t *xi_device =
+	    &dpyinfo->devices[actual_devices++];
+	  xi_device->device_id = device->deviceid;
+	  xi_device->valuators =
+	    xmalloc (sizeof *xi_device->valuators * device->num_classes);
+
+	  for (int c = 0; c < device->num_classes; ++c)
+	    {
+	      switch (device->classes[c]->type)
+		{
+#ifdef XIScrollClass /* XInput 2.1 */
+		case XIScrollClass:
+		  {
+		    XIScrollClassInfo *info =
+		      (XIScrollClassInfo *) device->classes[c];
+		    struct xi_scroll_valuator_t *valuator =
+		      &xi_device->valuators[actual_valuator_count++];
+
+		    valuator->horizontal = (info->scroll_type == XIScrollTypeHorizontal);
+		    valuator->invalid_p = true;
+		    valuator->emacs_value = DBL_MIN;
+		    valuator->increment = info->increment;
+		    valuator->number = info->number;
+		    break;
+		  }
+#endif
+		default:
+		  break;
+		}
+	    }
+	  xi_device->scroll_valuator_count = actual_valuator_count;
+	}
+    }
+
+  dpyinfo->num_devices = actual_devices;
+  XIFreeDeviceInfo (infos);
+  unblock_input ();
+}
+
+/* Return the delta of the scroll valuator VALUATOR_NUMBER under
+   DEVICE_ID in the display DPYINFO with VALUE.  The valuator's
+   valuator will be set to VALUE afterwards.  In case no scroll
+   valuator is found, or if device_id is not known to Emacs, DBL_MAX
+   is returned.  Otherwise, the valuator is returned in
+   VALUATOR_RETURN.  */
+static double
+x_get_scroll_valuator_delta (struct x_display_info *dpyinfo, int device_id,
+			     int valuator_number, double value,
+			     struct xi_scroll_valuator_t **valuator_return)
+{
+  block_input ();
+
+  for (int i = 0; i < dpyinfo->num_devices; ++i)
+    {
+      struct xi_device_t *device = &dpyinfo->devices[i];
+
+      if (device->device_id == device_id)
+	{
+	  for (int j = 0; j < device->scroll_valuator_count; ++j)
+	    {
+	      struct xi_scroll_valuator_t *sv = &device->valuators[j];
+
+	      if (sv->number == valuator_number)
+		{
+		  if (sv->invalid_p)
+		    {
+		      sv->current_value = value;
+		      sv->invalid_p = false;
+		      *valuator_return = sv;
+
+		      unblock_input ();
+		      return 0.0;
+		    }
+		  else
+		    {
+		      double delta = sv->current_value - value;
+		      sv->current_value = value;
+		      *valuator_return = sv;
+
+		      unblock_input ();
+		      return delta / sv->increment;
+		    }
+		}
+	    }
+
+	  unblock_input ();
+	  return DBL_MAX;
+	}
+    }
+
+  unblock_input ();
+  return DBL_MAX;
+}
+
+#endif
+
 void
 x_cr_destroy_frame_context (struct frame *f)
 {
@@ -4665,7 +4825,16 @@ x_any_window_to_frame (struct x_display_info *dpyinfo, int wdesc)
 x_menubar_window_to_frame (struct x_display_info *dpyinfo,
 			   const XEvent *event)
 {
-  Window wdesc = event->xany.window;
+  Window wdesc;
+#ifdef HAVE_XINPUT2
+  if (event->type == GenericEvent
+      && dpyinfo->supports_xi2
+      && (event->xcookie.evtype == XI_ButtonPress
+	  || event->xcookie.evtype == XI_ButtonRelease))
+    wdesc = ((XIDeviceEvent *) event->xcookie.data)->event;
+  else
+#endif
+    wdesc = event->xany.window;
   Lisp_Object tail, frame;
   struct frame *f;
   struct x_output *x;
@@ -4768,6 +4937,29 @@ x_detect_focus_change (struct x_display_info *dpyinfo, struct frame *frame,
       }
       break;
 
+#ifdef HAVE_XINPUT2
+    case GenericEvent:
+      {
+	XIEvent *xi_event = (XIEvent *) event;
+
+        struct frame *focus_frame = dpyinfo->x_focus_event_frame;
+        int focus_state
+          = focus_frame ? focus_frame->output_data.x->focus_state : 0;
+
+	if (!((xi_event->evtype == XI_Enter
+	       || xi_event->evtype == XI_Leave)
+	      && (focus_state & FOCUS_EXPLICIT)))
+	  x_focus_changed ((xi_event->evtype == XI_Enter
+			    || xi_event->evtype == XI_FocusIn
+			    ? FocusIn : FocusOut),
+			   (xi_event->evtype == XI_Enter
+			    || xi_event->evtype == XI_Leave
+			    ? FOCUS_IMPLICIT : FOCUS_EXPLICIT),
+			   dpyinfo, frame, bufp);
+	break;
+      }
+#endif
+
     case FocusIn:
     case FocusOut:
       /* Ignore transient focus events from hotkeys, window manager
@@ -7872,7 +8064,11 @@ mouse_or_wdesc_frame (struct x_display_info *dpyinfo, int wdesc)
 
 static int
 handle_one_xevent (struct x_display_info *dpyinfo,
+#ifndef HAVE_XINPUT2
 		   const XEvent *event,
+#else
+		   XEvent *event,
+#endif
 		   int *finish, struct input_event *hold_quit)
 {
   union buffered_input_event inev;
@@ -7898,7 +8094,14 @@ handle_one_xevent (struct x_display_info *dpyinfo,
   inev.ie.kind = NO_EVENT;
   inev.ie.arg = Qnil;
 
-  any = x_any_window_to_frame (dpyinfo, event->xany.window);
+#ifdef HAVE_XINPUT2
+  if (event->type != GenericEvent)
+#endif
+    any = x_any_window_to_frame (dpyinfo, event->xany.window);
+#ifdef HAVE_XINPUT2
+  else
+    any = NULL;
+#endif
 
   if (any && any->wait_event_type == event->type)
     any->wait_event_type = 0; /* Indicates we got it.  */
@@ -8365,6 +8568,10 @@ handle_one_xevent (struct x_display_info *dpyinfo,
       goto OTHER;
 
     case MapNotify:
+#if defined HAVE_XINPUT2 && defined HAVE_GTK3
+      if (xg_is_menu_window (dpyinfo->display, event->xmap.window))
+	popup_activated_flag = 1;
+#endif
       /* We use x_top_window_to_frame because map events can
          come for sub-windows and they don't mean that the
          frame is visible.  */
@@ -9343,6 +9550,832 @@ handle_one_xevent (struct x_display_info *dpyinfo,
     case DestroyNotify:
       xft_settings_event (dpyinfo, event);
       break;
+#ifdef HAVE_XINPUT2
+    case GenericEvent:
+      {
+	if (!dpyinfo->supports_xi2)
+	  goto OTHER;
+	if (event->xgeneric.extension != dpyinfo->xi2_opcode)
+	  /* Not an XI2 event. */
+	  goto OTHER;
+	bool must_free_data = false;
+	XIEvent *xi_event = (XIEvent *) event->xcookie.data;
+	/* Sometimes the event is already claimed by GTK, which
+	   will free its data in due course. */
+	if (!xi_event && XGetEventData (dpyinfo->display, &event->xcookie))
+	  {
+	    must_free_data = true;
+	    xi_event = (XIEvent *) event->xcookie.data;
+	  }
+
+	XIDeviceEvent *xev = (XIDeviceEvent *) xi_event;
+	XILeaveEvent *leave = (XILeaveEvent *) xi_event;
+	XIEnterEvent *enter = (XIEnterEvent *) xi_event;
+	XIFocusInEvent *focusin = (XIFocusInEvent *) xi_event;
+	XIFocusOutEvent *focusout = (XIFocusOutEvent *) xi_event;
+	XIValuatorState *states;
+	double *values;
+	bool found_valuator = false;
+
+	/* A fake XMotionEvent for x_note_mouse_movement. */
+	XMotionEvent ev;
+	/* A fake XButtonEvent for x_construct_mouse_click. */
+	XButtonEvent bv;
+
+	if (!xi_event)
+	  {
+	    eassert (!must_free_data);
+	    goto OTHER;
+	  }
+
+	switch (event->xcookie.evtype)
+	  {
+	  case XI_FocusIn:
+	    any = x_any_window_to_frame (dpyinfo, focusin->event);
+#ifndef USE_GTK
+	    /* Some WMs (e.g. Mutter in Gnome Shell), don't unmap
+	       minimized/iconified windows; thus, for those WMs we won't get
+	       a MapNotify when unminimizing/deconifying.  Check here if we
+	       are deiconizing a window (Bug42655).
+
+	       But don't do that on GTK since it may cause a plain invisible
+	       frame get reported as iconified, compare
+	       https://lists.gnu.org/archive/html/emacs-devel/2017-02/msg00133.html.
+	       That is fixed above but bites us here again.  */
+	    f = any;
+	    if (f && FRAME_ICONIFIED_P (f))
+	      {
+		SET_FRAME_VISIBLE (f, 1);
+		SET_FRAME_ICONIFIED (f, false);
+		f->output_data.x->has_been_visible = true;
+		inev.ie.kind = DEICONIFY_EVENT;
+		XSETFRAME (inev.ie.frame_or_window, f);
+	      }
+#endif /* USE_GTK */
+	    x_detect_focus_change (dpyinfo, any, event, &inev.ie);
+	    goto XI_OTHER;
+	  case XI_FocusOut:
+	    any = x_any_window_to_frame (dpyinfo, focusout->event);
+	    x_detect_focus_change (dpyinfo, any, event, &inev.ie);
+	    goto XI_OTHER;
+	  case XI_Enter:
+	    any = x_any_window_to_frame (dpyinfo, enter->event);
+	    ev.x = lrint (enter->event_x);
+	    ev.y = lrint (enter->event_y);
+	    ev.window = leave->event;
+
+	    x_display_set_last_user_time (dpyinfo, xi_event->time);
+	    x_detect_focus_change (dpyinfo, any, event, &inev.ie);
+	    f = any;
+
+	    if (f && x_mouse_click_focus_ignore_position)
+	      ignore_next_mouse_click_timeout = xi_event->time + 200;
+
+	    /* EnterNotify counts as mouse movement,
+	       so update things that depend on mouse position.  */
+	    if (f && !f->output_data.x->hourglass_p)
+	      x_note_mouse_movement (f, &ev);
+#ifdef USE_GTK
+	    /* We may get an EnterNotify on the buttons in the toolbar.  In that
+	       case we moved out of any highlighted area and need to note this.  */
+	    if (!f && dpyinfo->last_mouse_glyph_frame)
+	      x_note_mouse_movement (dpyinfo->last_mouse_glyph_frame, &ev);
+#endif
+	    goto XI_OTHER;
+	  case XI_Leave:
+	    ev.x = lrint (leave->event_x);
+	    ev.y = lrint (leave->event_y);
+	    ev.window = leave->event;
+	    any = x_any_window_to_frame (dpyinfo, leave->event);
+
+	    x_display_set_last_user_time (dpyinfo, xi_event->time);
+	    x_detect_focus_change (dpyinfo, any, event, &inev.ie);
+
+	    f = x_top_window_to_frame (dpyinfo, leave->event);
+	    if (f)
+	      {
+		if (f == hlinfo->mouse_face_mouse_frame)
+		  {
+		    /* If we move outside the frame, then we're
+		       certainly no longer on any text in the frame.  */
+		    clear_mouse_face (hlinfo);
+		    hlinfo->mouse_face_mouse_frame = 0;
+		  }
+
+		/* Generate a nil HELP_EVENT to cancel a help-echo.
+		   Do it only if there's something to cancel.
+		   Otherwise, the startup message is cleared when
+		   the mouse leaves the frame.  */
+		if (any_help_event_p)
+		  do_help = -1;
+	      }
+#ifdef USE_GTK
+	    /* See comment in EnterNotify above */
+	    else if (dpyinfo->last_mouse_glyph_frame)
+	      x_note_mouse_movement (dpyinfo->last_mouse_glyph_frame, &ev);
+#endif
+	    goto XI_OTHER;
+	  case XI_Motion:
+	    /* First test if there is some kind of scroll event
+	       here! */
+	    states = &xev->valuators;
+	    values = states->values;
+
+	    x_display_set_last_user_time (dpyinfo, xi_event->time);
+
+	    for (int i = 0; i < states->mask_len * 8; i++)
+	      {
+		if (XIMaskIsSet (states->mask, i))
+		  {
+		    block_input ();
+
+		    struct xi_scroll_valuator_t *val;
+		    double delta =
+		      x_get_scroll_valuator_delta (dpyinfo, xev->deviceid,
+						   i, *values, &val);
+
+		    if (delta != DBL_MAX)
+		      {
+			/* TODO: Figure out how pixelwise scrolling should work.
+			   Until that happens, this will have to do.  */
+			delta *= 10;
+
+			f = mouse_or_wdesc_frame (dpyinfo, xev->event);
+			found_valuator = true;
+			if (signbit (delta) != signbit (val->emacs_value))
+			  val->emacs_value = DBL_MIN;
+
+			val->emacs_value += delta;
+
+			if (!f)
+			  {
+			    f = x_any_window_to_frame (dpyinfo, xev->event);
+
+			    if (!f)
+			      {
+				unblock_input ();
+				goto XI_OTHER;
+			      }
+			  }
+
+			if ((val->horizontal
+			     && fabs (val->emacs_value) >= FRAME_COLUMN_WIDTH (f))
+			    || (!val->horizontal
+				&& fabs (val->emacs_value) >= FRAME_LINE_HEIGHT (f)))
+			  {
+			    Lisp_Object tab_bar_arg = Qnil;
+			    bool tab_bar_p = false;
+			    bool tool_bar_p = false;
+			    bool s = signbit (val->emacs_value);
+
+			    bv.button = !val->horizontal ? (s ? 5 : 4) : (s ? 7 : 6);
+			    bv.type = ButtonPress;
+
+			    bv.x = lrint (xev->event_x);
+			    bv.y = lrint (xev->event_y);
+			    bv.window = xev->event;
+			    bv.state = xev->mods.base
+			      | xev->mods.effective
+			      | xev->mods.latched
+			      | xev->mods.locked;
+
+			    /* Is this in the tab-bar?  */
+			    if (WINDOWP (f->tab_bar_window)
+				&& WINDOW_TOTAL_LINES (XWINDOW (f->tab_bar_window)))
+			      {
+				Lisp_Object window;
+				int x = bv.x;
+				int y = bv.y;
+
+				window = window_from_coordinates (f, x, y, 0, true, true);
+				tab_bar_p = EQ (window, f->tab_bar_window);
+
+				if (tab_bar_p)
+				  {
+				    tab_bar_arg = handle_tab_bar_click
+				      (f, x, y, true, x_x_to_emacs_modifiers (dpyinfo, bv.state));
+				    tab_bar_arg = handle_tab_bar_click
+				      (f, x, y, false, x_x_to_emacs_modifiers (dpyinfo, bv.state));
+				  }
+			      }
+
+			    if (!NILP (tab_bar_arg))
+			      inev.ie.arg = tab_bar_arg;
+
+			    if (!tool_bar_p && !(NILP (tab_bar_arg) && tab_bar_p))
+			      {
+				if (ignore_next_mouse_click_timeout)
+				  {
+				    if (xev->time > ignore_next_mouse_click_timeout)
+				      {
+					/* XXX: Wouldn't it be better
+					   to just use wheel events
+					   instead of pretending to be
+					   X here? */
+					x_construct_mouse_click (&inev.ie, &bv, f);
+					if (!NILP (tab_bar_arg))
+					  inev.ie.arg = tab_bar_arg;
+					kbd_buffer_store_event (&inev.ie);
+					inev.ie.modifiers &= ~down_modifier;
+					inev.ie.modifiers |= up_modifier;
+					kbd_buffer_store_event (&inev.ie);
+				      }
+				    ignore_next_mouse_click_timeout = 0;
+				  }
+				else
+				  {
+				    x_construct_mouse_click (&inev.ie, &bv, f);
+				    kbd_buffer_store_event (&inev.ie);
+				    inev.ie.modifiers &= ~down_modifier;
+				    inev.ie.modifiers |= up_modifier;
+				    kbd_buffer_store_event (&inev.ie);
+				  }
+			      }
+
+			    val->emacs_value = DBL_MIN;
+			  }
+		      }
+		    unblock_input ();
+		    values++;
+		  }
+
+		inev.ie.kind = NO_EVENT;
+	      }
+
+	    if (found_valuator)
+	      goto XI_OTHER;
+
+	    ev.x = lrint (xev->event_x);
+	    ev.y = lrint (xev->event_y);
+	    ev.window = xev->event;
+
+	    previous_help_echo_string = help_echo_string;
+	    help_echo_string = Qnil;
+
+	    if (hlinfo->mouse_face_hidden)
+	      {
+		hlinfo->mouse_face_hidden = false;
+		clear_mouse_face (hlinfo);
+	      }
+
+	    f = mouse_or_wdesc_frame (dpyinfo, xev->event);
+
+#ifdef USE_GTK
+	    if (f && xg_event_is_for_scrollbar (f, event))
+	      f = 0;
+#endif
+	    if (f)
+	      {
+		/* Maybe generate a SELECT_WINDOW_EVENT for
+		   `mouse-autoselect-window' but don't let popup menus
+		   interfere with this (Bug#1261).  */
+		if (!NILP (Vmouse_autoselect_window)
+		    && !popup_activated ()
+		    /* Don't switch if we're currently in the minibuffer.
+		       This tries to work around problems where the
+		       minibuffer gets unselected unexpectedly, and where
+		       you then have to move your mouse all the way down to
+		       the minibuffer to select it.  */
+		    && !MINI_WINDOW_P (XWINDOW (selected_window))
+		    /* With `focus-follows-mouse' non-nil create an event
+		       also when the target window is on another frame.  */
+		    && (f == XFRAME (selected_frame)
+			|| !NILP (focus_follows_mouse)))
+		  {
+		    static Lisp_Object last_mouse_window;
+		    Lisp_Object window = window_from_coordinates (f, ev.x, ev.y, 0, false, false);
+
+		    /* A window will be autoselected only when it is not
+		       selected now and the last mouse movement event was
+		       not in it.  The remainder of the code is a bit vague
+		       wrt what a "window" is.  For immediate autoselection,
+		       the window is usually the entire window but for GTK
+		       where the scroll bars don't count.  For delayed
+		       autoselection the window is usually the window's text
+		       area including the margins.  */
+		    if (WINDOWP (window)
+			&& !EQ (window, last_mouse_window)
+			&& !EQ (window, selected_window))
+		      {
+			inev.ie.kind = SELECT_WINDOW_EVENT;
+			inev.ie.frame_or_window = window;
+		      }
+
+		    /* Remember the last window where we saw the mouse.  */
+		    last_mouse_window = window;
+		  }
+
+		if (!x_note_mouse_movement (f, &ev))
+		  help_echo_string = previous_help_echo_string;
+	      }
+	    else
+	      {
+#ifndef USE_TOOLKIT_SCROLL_BARS
+		struct scroll_bar *bar
+		  = x_window_to_scroll_bar (xi_event->display, xev->event, 2);
+
+		if (bar)
+		  x_scroll_bar_note_movement (bar, &ev);
+#endif /* USE_TOOLKIT_SCROLL_BARS */
+
+		/* If we move outside the frame, then we're
+		   certainly no longer on any text in the frame.  */
+		clear_mouse_face (hlinfo);
+	      }
+
+	    /* If the contents of the global variable help_echo_string
+	       has changed, generate a HELP_EVENT.  */
+	    if (!NILP (help_echo_string)
+		|| !NILP (previous_help_echo_string))
+	      do_help = 1;
+	    goto XI_OTHER;
+	  case XI_ButtonRelease:
+	  case XI_ButtonPress:
+	    {
+	      /* If we decide we want to generate an event to be seen
+		 by the rest of Emacs, we put it here.  */
+	      Lisp_Object tab_bar_arg = Qnil;
+	      bool tab_bar_p = false;
+	      bool tool_bar_p = false;
+
+	      /* Ignore emulated scroll events when XI2 native
+		 scroll events are present.  */
+	      if (dpyinfo->xi2_version >= 1 && xev->detail >= 4
+		  && xev->detail <= 8)
+		goto XI_OTHER;
+
+	      bv.button = xev->detail;
+	      bv.type = xev->evtype == XI_ButtonPress ? ButtonPress : ButtonRelease;
+	      bv.x = lrint (xev->event_x);
+	      bv.y = lrint (xev->event_y);
+	      bv.window = xev->event;
+	      bv.state = xev->mods.base
+		| xev->mods.effective
+		| xev->mods.latched
+		| xev->mods.locked;
+
+	      memset (&compose_status, 0, sizeof (compose_status));
+	      dpyinfo->last_mouse_glyph_frame = NULL;
+	      x_display_set_last_user_time (dpyinfo, xev->time);
+
+	      f = mouse_or_wdesc_frame (dpyinfo, xev->event);
+
+	      if (f && xev->evtype == XI_ButtonPress
+		  && !popup_activated ()
+		  && !x_window_to_scroll_bar (xev->display, xev->event, 2)
+		  && !FRAME_NO_ACCEPT_FOCUS (f))
+		{
+		  /* When clicking into a child frame or when clicking
+		     into a parent frame with the child frame selected and
+		     `no-accept-focus' is not set, select the clicked
+		     frame.  */
+		  struct frame *hf = dpyinfo->highlight_frame;
+
+		  if (FRAME_PARENT_FRAME (f) || (hf && frame_ancestor_p (f, hf)))
+		    {
+		      block_input ();
+		      XSetInputFocus (FRAME_X_DISPLAY (f), FRAME_OUTER_WINDOW (f),
+				      RevertToParent, CurrentTime);
+		      if (FRAME_PARENT_FRAME (f))
+			XRaiseWindow (FRAME_X_DISPLAY (f), FRAME_OUTER_WINDOW (f));
+		      unblock_input ();
+		    }
+		}
+
+#ifdef USE_GTK
+	      if (f && xg_event_is_for_scrollbar (f, event))
+		f = 0;
+#endif
+
+	      if (f)
+		{
+		  /* Is this in the tab-bar?  */
+		  if (WINDOWP (f->tab_bar_window)
+		      && WINDOW_TOTAL_LINES (XWINDOW (f->tab_bar_window)))
+		    {
+		      Lisp_Object window;
+		      int x = bv.x;
+		      int y = bv.y;
+
+		      window = window_from_coordinates (f, x, y, 0, true, true);
+		      tab_bar_p = EQ (window, f->tab_bar_window);
+
+		      if (tab_bar_p)
+			tab_bar_arg = handle_tab_bar_click
+			  (f, x, y, xev->evtype == XI_ButtonPress,
+			   x_x_to_emacs_modifiers (dpyinfo, bv.state));
+		    }
+
+#if ! defined (USE_GTK)
+		  /* Is this in the tool-bar?  */
+		  if (WINDOWP (f->tool_bar_window)
+		      && WINDOW_TOTAL_LINES (XWINDOW (f->tool_bar_window)))
+		    {
+		      Lisp_Object window;
+		      int x = bv.x;
+		      int y = bv.y;
+
+		      window = window_from_coordinates (f, x, y, 0, true, true);
+		      tool_bar_p = EQ (window, f->tool_bar_window);
+
+		      if (tool_bar_p && xev->detail < 4)
+			handle_tool_bar_click
+			  (f, x, y, xev->evtype == XI_ButtonPress,
+			   x_x_to_emacs_modifiers (dpyinfo, bv.state));
+		    }
+#endif /* !USE_GTK */
+
+		  if (!(tab_bar_p && NILP (tab_bar_arg)) && !tool_bar_p)
+#if defined (USE_X_TOOLKIT) || defined (USE_GTK)
+		    if (! popup_activated ())
+#endif
+		      {
+			if (ignore_next_mouse_click_timeout)
+			  {
+			    if (xev->evtype == XI_ButtonPress
+				&& xev->time > ignore_next_mouse_click_timeout)
+			      {
+				ignore_next_mouse_click_timeout = 0;
+				x_construct_mouse_click (&inev.ie, &bv, f);
+			      }
+			    if (xev->evtype == XI_ButtonRelease)
+			      ignore_next_mouse_click_timeout = 0;
+			  }
+			else
+			  x_construct_mouse_click (&inev.ie, &bv, f);
+
+			if (!NILP (tab_bar_arg))
+			  inev.ie.arg = tab_bar_arg;
+		      }
+		  if (FRAME_X_EMBEDDED_P (f))
+		    xembed_send_message (f, xev->time,
+					 XEMBED_REQUEST_FOCUS, 0, 0, 0);
+		}
+
+	      if (xev->evtype == XI_ButtonPress)
+		{
+		  dpyinfo->grabbed |= (1 << xev->detail);
+		  dpyinfo->last_mouse_frame = f;
+		  if (f && !tab_bar_p)
+		    f->last_tab_bar_item = -1;
+#if ! defined (USE_GTK)
+		  if (f && !tool_bar_p)
+		    f->last_tool_bar_item = -1;
+#endif /* not USE_GTK */
+
+		}
+	      else
+		dpyinfo->grabbed &= ~(1 << xev->detail);
+
+	      if (f)
+		f->mouse_moved = false;
+
+#if defined (USE_GTK)
+	      /* No Xt toolkit currently available has support for XI2.
+	         So the code here assumes use of GTK.  */
+	      f = x_menubar_window_to_frame (dpyinfo, event);
+	      if (f /* Gtk+ menus only react to the first three buttons. */
+		  && xev->detail < 3)
+		{
+		  /* What is done with Core Input ButtonPressed is not
+		     possible here, because GenericEvents cannot be saved.  */
+		  bool was_waiting_for_input = waiting_for_input;
+		  /* This hack was adopted from the NS port.  Whether
+		     or not it is actually safe is a different story
+		     altogether.  */
+		  if (waiting_for_input)
+		    waiting_for_input = 0;
+		  set_frame_menubar (f, true);
+		  waiting_for_input = was_waiting_for_input;
+		}
+#endif
+	      goto XI_OTHER;
+	    }
+	  case XI_KeyPress:
+	    {
+	      int state = xev->mods.base
+		| xev->mods.effective
+		| xev->mods.latched
+		| xev->mods.locked;
+	      Lisp_Object c;
+#ifdef HAVE_XKB
+	      unsigned int mods_rtrn;
+#endif
+	      int keycode = xev->detail;
+	      KeySym keysym;
+	      char copy_buffer[81];
+	      char *copy_bufptr = copy_buffer;
+	      unsigned char *copy_ubufptr;
+#ifdef HAVE_XKB
+	      int copy_bufsiz = sizeof (copy_buffer);
+#endif
+	      ptrdiff_t i;
+	      int nchars, len;
+
+#ifdef HAVE_XKB
+	      if (dpyinfo->xkb_desc)
+		{
+		  if (!XkbTranslateKeyCode (dpyinfo->xkb_desc, keycode,
+					    state, &mods_rtrn, &keysym))
+		    goto XI_OTHER;
+		}
+	      else
+		{
+#endif
+		  int keysyms_per_keycode_return;
+		  KeySym *ksms = XGetKeyboardMapping (dpyinfo->display, keycode, 1,
+						      &keysyms_per_keycode_return);
+		  if (!(keysym = ksms[0]))
+		    {
+		      XFree (ksms);
+		      goto XI_OTHER;
+		    }
+		  XFree (ksms);
+#ifdef HAVE_XKB
+		}
+#endif
+
+	      if (keysym == NoSymbol)
+		goto XI_OTHER;
+
+	      x_display_set_last_user_time (dpyinfo, xev->time);
+	      ignore_next_mouse_click_timeout = 0;
+
+#if defined (USE_X_TOOLKIT) || defined (USE_GTK)
+	      /* Dispatch XI_KeyPress events when in menu.  */
+	      if (popup_activated ())
+		goto XI_OTHER;
+#endif
+
+	      f = x_any_window_to_frame (dpyinfo, xev->event);
+
+	      /* If mouse-highlight is an integer, input clears out
+		 mouse highlighting.  */
+	      if (!hlinfo->mouse_face_hidden && FIXNUMP (Vmouse_highlight)
+		  && (f == 0
+#if ! defined (USE_GTK)
+		      || !EQ (f->tool_bar_window, hlinfo->mouse_face_window)
+#endif
+		      || !EQ (f->tab_bar_window, hlinfo->mouse_face_window))
+		  )
+		{
+		  clear_mouse_face (hlinfo);
+		  hlinfo->mouse_face_hidden = true;
+		}
+
+	      if (f != 0)
+		{
+#ifdef USE_GTK
+		  /* Don't pass keys to GTK.  A Tab will shift focus to the
+		     tool bar in GTK 2.4.  Keys will still go to menus and
+		     dialogs because in that case popup_activated is nonzero
+		     (see above).  */
+		  *finish = X_EVENT_DROP;
+#endif
+		  /* If not using XIM/XIC, and a compose sequence is in progress,
+		     we break here.  Otherwise, chars_matched is always 0.  */
+		  if (compose_status.chars_matched > 0 && nbytes == 0)
+		    goto XI_OTHER;
+
+		  memset (&compose_status, 0, sizeof (compose_status));
+
+		  XSETFRAME (inev.ie.frame_or_window, f);
+		  inev.ie.modifiers
+		    = x_x_to_emacs_modifiers (FRAME_DISPLAY_INFO (f), state);
+		  inev.ie.timestamp = xev->time;
+
+		  /* First deal with keysyms which have defined
+		     translations to characters.  */
+		  if (keysym >= 32 && keysym < 128)
+		    /* Avoid explicitly decoding each ASCII character.  */
+		    {
+		      inev.ie.kind = ASCII_KEYSTROKE_EVENT;
+		      inev.ie.code = keysym;
+
+		      goto xi_done_keysym;
+		    }
+
+		  /* Keysyms directly mapped to Unicode characters.  */
+		  if (keysym >= 0x01000000 && keysym <= 0x0110FFFF)
+		    {
+		      if (keysym < 0x01000080)
+			inev.ie.kind = ASCII_KEYSTROKE_EVENT;
+		      else
+			inev.ie.kind = MULTIBYTE_CHAR_KEYSTROKE_EVENT;
+		      inev.ie.code = keysym & 0xFFFFFF;
+		      goto xi_done_keysym;
+		    }
+
+		  /* Now non-ASCII.  */
+		  if (HASH_TABLE_P (Vx_keysym_table)
+		      && (c = Fgethash (make_fixnum (keysym),
+					Vx_keysym_table,
+					Qnil),
+			  FIXNATP (c)))
+		    {
+		      inev.ie.kind = (SINGLE_BYTE_CHAR_P (XFIXNAT (c))
+				      ? ASCII_KEYSTROKE_EVENT
+				      : MULTIBYTE_CHAR_KEYSTROKE_EVENT);
+		      inev.ie.code = XFIXNAT (c);
+		      goto xi_done_keysym;
+		    }
+
+		  /* Random non-modifier sorts of keysyms.  */
+		  if (((keysym >= XK_BackSpace && keysym <= XK_Escape)
+		       || keysym == XK_Delete
+#ifdef XK_ISO_Left_Tab
+		       || (keysym >= XK_ISO_Left_Tab
+			   && keysym <= XK_ISO_Enter)
+#endif
+		       || IsCursorKey (keysym) /* 0xff50 <= x < 0xff60 */
+		       || IsMiscFunctionKey (keysym) /* 0xff60 <= x < VARIES */
+#ifdef HPUX
+		       /* This recognizes the "extended function
+			  keys".  It seems there's no cleaner way.
+			  Test IsModifierKey to avoid handling
+			  mode_switch incorrectly.  */
+		       || (XK_Select <= keysym && keysym < XK_KP_Space)
+#endif
+#ifdef XK_dead_circumflex
+		       || keysym == XK_dead_circumflex
+#endif
+#ifdef XK_dead_grave
+		       || keysym == XK_dead_grave
+#endif
+#ifdef XK_dead_tilde
+		       || keysym == XK_dead_tilde
+#endif
+#ifdef XK_dead_diaeresis
+		       || keysym == XK_dead_diaeresis
+#endif
+#ifdef XK_dead_macron
+		       || keysym == XK_dead_macron
+#endif
+#ifdef XK_dead_degree
+		       || keysym == XK_dead_degree
+#endif
+#ifdef XK_dead_acute
+		       || keysym == XK_dead_acute
+#endif
+#ifdef XK_dead_cedilla
+		       || keysym == XK_dead_cedilla
+#endif
+#ifdef XK_dead_breve
+		       || keysym == XK_dead_breve
+#endif
+#ifdef XK_dead_ogonek
+		       || keysym == XK_dead_ogonek
+#endif
+#ifdef XK_dead_caron
+		       || keysym == XK_dead_caron
+#endif
+#ifdef XK_dead_doubleacute
+		       || keysym == XK_dead_doubleacute
+#endif
+#ifdef XK_dead_abovedot
+		       || keysym == XK_dead_abovedot
+#endif
+		       || IsKeypadKey (keysym) /* 0xff80 <= x < 0xffbe */
+		       || IsFunctionKey (keysym) /* 0xffbe <= x < 0xffe1 */
+		       /* Any "vendor-specific" key is ok.  */
+		       || (keysym & (1 << 28))
+		       || (keysym != NoSymbol && nbytes == 0))
+		      && ! (IsModifierKey (keysym)
+			    /* The symbols from XK_ISO_Lock
+			       to XK_ISO_Last_Group_Lock
+			       don't have real modifiers but
+			       should be treated similarly to
+			       Mode_switch by Emacs. */
+#if defined XK_ISO_Lock && defined XK_ISO_Last_Group_Lock
+			    || (XK_ISO_Lock <= keysym
+				&& keysym <= XK_ISO_Last_Group_Lock)
+#endif
+			    ))
+		    {
+		      STORE_KEYSYM_FOR_DEBUG (keysym);
+		      /* make_lispy_event will convert this to a symbolic
+			 key.  */
+		      inev.ie.kind = NON_ASCII_KEYSTROKE_EVENT;
+		      inev.ie.code = keysym;
+		      goto xi_done_keysym;
+		    }
+
+#ifdef HAVE_XKB
+		  int overflow = 0;
+		  KeySym sym = keysym;
+
+		  if (dpyinfo->xkb_desc)
+		    {
+		      if (!(nbytes = XkbTranslateKeySym (dpyinfo->display, &sym,
+							 state & ~mods_rtrn, copy_bufptr,
+							 copy_bufsiz, &overflow)))
+			goto XI_OTHER;
+		    }
+		  else
+#else
+		    {
+		      block_input ();
+		      char *str = XKeysymToString (keysym);
+		      if (!str)
+			{
+			  unblock_input ();
+			  goto XI_OTHER;
+			}
+		      nbytes = strlen (str) + 1;
+		      copy_bufptr = alloca (nbytes);
+		      strcpy (copy_bufptr, str);
+		      unblock_input ();
+		    }
+#endif
+#ifdef HAVE_XKB
+		  if (overflow)
+		    {
+		      overflow = 0;
+		      copy_bufptr = alloca (copy_bufsiz + overflow);
+		      keysym = sym;
+		      if (!(nbytes = XkbTranslateKeySym (dpyinfo->display, &sym,
+							 state & ~mods_rtrn, copy_bufptr,
+							 copy_bufsiz + overflow, &overflow)))
+			goto XI_OTHER;
+
+		      if (overflow)
+			goto XI_OTHER;
+		    }
+#endif
+
+		  for (i = 0, nchars = 0; i < nbytes; i++)
+		    {
+		      if (ASCII_CHAR_P (copy_bufptr[i]))
+			nchars++;
+		      STORE_KEYSYM_FOR_DEBUG (copy_bufptr[i]);
+		    }
+
+		  if (nchars < nbytes)
+		    {
+		      /* Decode the input data.  */
+
+		      setup_coding_system (Vlocale_coding_system, &coding);
+		      coding.src_multibyte = false;
+		      coding.dst_multibyte = true;
+		      /* The input is converted to events, thus we can't
+			 handle composition.  Anyway, there's no XIM that
+			 gives us composition information.  */
+		      coding.common_flags &= ~CODING_ANNOTATION_MASK;
+
+		      SAFE_NALLOCA (coding.destination, MAX_MULTIBYTE_LENGTH,
+				    nbytes);
+		      coding.dst_bytes = MAX_MULTIBYTE_LENGTH * nbytes;
+		      coding.mode |= CODING_MODE_LAST_BLOCK;
+		      decode_coding_c_string (&coding, (unsigned char *) copy_bufptr, nbytes, Qnil);
+		      nbytes = coding.produced;
+		      nchars = coding.produced_char;
+		      copy_bufptr = (char *) coding.destination;
+		    }
+
+		  copy_ubufptr = (unsigned char *) copy_bufptr;
+
+		  /* Convert the input data to a sequence of
+		     character events.  */
+		  for (i = 0; i < nbytes; i += len)
+		    {
+		      int ch;
+		      if (nchars == nbytes)
+			ch = copy_ubufptr[i], len = 1;
+		      else
+			ch = string_char_and_length (copy_ubufptr + i, &len);
+		      inev.ie.kind = (SINGLE_BYTE_CHAR_P (ch)
+				      ? ASCII_KEYSTROKE_EVENT
+				      : MULTIBYTE_CHAR_KEYSTROKE_EVENT);
+		      inev.ie.code = ch;
+		      kbd_buffer_store_buffered_event (&inev, hold_quit);
+		    }
+
+		  inev.ie.kind = NO_EVENT;
+		  goto xi_done_keysym;
+		}
+	      goto XI_OTHER;
+	    }
+	  case XI_KeyRelease:
+	    x_display_set_last_user_time (dpyinfo, xev->time);
+	    goto XI_OTHER;
+	  case XI_PropertyEvent:
+	  case XI_HierarchyChanged:
+	  case XI_DeviceChanged:
+	    x_init_master_valuators (dpyinfo);
+	    goto XI_OTHER;
+	  default:
+	    goto XI_OTHER;
+	  }
+      xi_done_keysym:
+	if (must_free_data)
+	  XFreeEventData (dpyinfo->display, &event->xcookie);
+	goto done_keysym;
+      XI_OTHER:
+	if (must_free_data)
+	  XFreeEventData (dpyinfo->display, &event->xcookie);
+	goto OTHER;
+      }
+#endif
 
     default:
     OTHER:
@@ -13013,6 +14046,40 @@ #define NUM_ARGV 10
     dpyinfo->supports_xdbe = true;
 #endif
 
+#ifdef HAVE_XINPUT2
+  dpyinfo->supports_xi2 = false;
+  int rc;
+  int major = 2;
+#ifdef XI_BarrierHit /* XInput 2.3 */
+  int minor = 3;
+#elif defined XI_TouchBegin /* XInput 2.2 */
+  int minor = 2;
+#elif defined XIScrollClass /* XInput 1.1 */
+  int minor = 1;
+#else /* Some old version of XI2 we're not interested in. */
+  int minor = 0;
+#endif
+  int fer, fee;
+
+  if (XQueryExtension (dpyinfo->display, "XInputExtension",
+		       &dpyinfo->xi2_opcode, &fer, &fee))
+    {
+      rc = XIQueryVersion (dpyinfo->display, &major, &minor);
+      if (rc == Success)
+	{
+	  dpyinfo->supports_xi2 = true;
+	  x_init_master_valuators (dpyinfo);
+	}
+    }
+  dpyinfo->xi2_version = minor;
+#endif
+
+#ifdef HAVE_XKB
+  dpyinfo->xkb_desc = XkbGetMap (dpyinfo->display,
+				 XkbAllComponentsMask,
+				 XkbUseCoreKbd);
+#endif
+
 #if defined USE_CAIRO || defined HAVE_XFT
   {
     /* If we are using Xft, the following precautions should be made:
@@ -13445,6 +14512,14 @@ x_delete_terminal (struct terminal *terminal)
       XrmDestroyDatabase (dpyinfo->rdb);
 #endif
 
+#ifdef HAVE_XKB
+      if (dpyinfo->xkb_desc)
+	XkbFreeKeyboard (dpyinfo->xkb_desc, XkbAllComponentsMask, True);
+#endif
+#ifdef HAVE_XINPUT2
+      if (dpyinfo->supports_xi2)
+	x_free_xi_devices (dpyinfo);
+#endif
 #ifdef USE_GTK
       xg_display_close (dpyinfo->display);
 #else
@@ -13604,9 +14679,12 @@ x_initialize (void)
 void
 init_xterm (void)
 {
-  /* Emacs can handle only core input events, so make sure
-     Gtk doesn't use Xinput or Xinput2 extensions.  */
+#ifndef HAVE_XINPUT2
+  /* Emacs can handle only core input events when built without XI2
+     support, so make sure Gtk doesn't use Xinput or Xinput2
+     extensions.  */
   xputenv ("GDK_CORE_DEVICE_EVENTS=1");
+#endif
 }
 #endif
 
diff --git a/src/xterm.h b/src/xterm.h
index de6ea50385..46238333a9 100644
--- a/src/xterm.h
+++ b/src/xterm.h
@@ -88,6 +88,10 @@ #define XSync(d, b) do { gdk_window_process_all_updates (); \
 #include <X11/Xlib-xcb.h>
 #endif
 
+#ifdef HAVE_XKB
+#include <X11/XKBlib.h>
+#endif
+
 #include "dispextern.h"
 #include "termhooks.h"
 
@@ -163,6 +167,26 @@ #define MAX_CLIP_RECTS 2
   char *name;
 };
 
+#ifdef HAVE_XINPUT2
+struct xi_scroll_valuator_t
+{
+  bool invalid_p;
+  double current_value;
+  double emacs_value;
+  double increment;
+
+  int number;
+  int horizontal;
+};
+
+struct xi_device_t
+{
+  int device_id;
+  int scroll_valuator_count;
+  struct xi_scroll_valuator_t *valuators;
+};
+#endif
+
 Status x_parse_color (struct frame *f, const char *color_name,
 		      XColor *color);
 
@@ -474,6 +498,19 @@ #define MAX_CLIP_RECTS 2
 #ifdef HAVE_XDBE
   bool supports_xdbe;
 #endif
+
+#ifdef HAVE_XINPUT2
+  bool supports_xi2;
+  int xi2_version;
+  int xi2_opcode;
+
+  int num_devices;
+  struct xi_device_t *devices;
+#endif
+
+#ifdef HAVE_XKB
+  XkbDescPtr xkb_desc;
+#endif
 };
 
 #ifdef HAVE_X_I18N
@@ -481,6 +518,11 @@ #define MAX_CLIP_RECTS 2
 extern bool use_xim;
 #endif
 
+#ifdef HAVE_XINPUT2
+/* Defined in xmenu.c. */
+extern int popup_activated_flag;
+#endif
+
 /* This is a chain of structures for all the X displays currently in use.  */
 extern struct x_display_info *x_display_list;
 
-- 
2.31.1


[-- Attachment #3: Type: text/plain, Size: 363 bytes --]


A pain point with this code is how the Lisp-side mwheel code assumes
that the wheel event will always be mouse-4 to 8 under X, so the code
tries to emulate the legacy Core Input behaviour instead of generating
WHEEL_EVENTs.  To properly support XInput 2 scrolling, mwheel.el will
have to be modified to support using both kinds of events under the same
session.