[gtk+] configure.ac: Improve the checks for XInput 2.2

[Matthias Clasen <matthiasc src gnome org>]

commit 4b05f4178a60bc6a8e1d3706c5128cad34bf106f
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue Mar 6 07:45:04 2012 -0500

    configure.ac: Improve the checks for XInput 2.2
    
    Check for the XIScrollClassInfo struct in addition to the existing
    check for XIAllowTouchEvents() because Ubuntu Oneiric seems to
    have an incomplete backport which has one but not the other.
    
    Based on a patch by Murray Cumming,
    https://bugzilla.gnome.org/show_bug.cgi?id=671453

 configure.ac |   17 +++++++++++++++--
 1 files changed, 15 insertions(+), 2 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 17c560a..616ee78 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1114,13 +1114,26 @@ if test "x$enable_x11_backend" = xyes; then
 
     AC_CHECK_HEADER(X11/extensions/XInput2.h,
                     have_xinput2=yes
-                    X_EXTENSIONS="$X_EXTENSIONS XI2"
                     AC_DEFINE(XINPUT_2, 1, [Define to 1 if XInput 2.0 is available]))
 
     gtk_save_LIBS="$LIBS"
     LIBS="$LIBS -lXi"
-    AC_CHECK_FUNC(XIAllowTouchEvents, AC_DEFINE(XINPUT_2_2, 1, [Define to 1 if XInput 2.2 is available]))
+
+    # Note that we also check that the XIScrollClassInfo struct is defined,
+    # because at least Ubuntu Oneiric seems to have XIAllowTouchEvents(), but not the XIScrollClassInfo struct.
+    AC_CHECK_FUNC([XIAllowTouchEvents],
+      [AC_CHECK_MEMBER([XIScrollClassInfo.number],
+                       have_xinput2_2=yes
+                       AC_DEFINE(XINPUT_2_2, 1, [Define to 1 if XInput 2.2 is available]),
+                       have_xinput2_2=no,
+                       [[#include <X11/extensions/XInput2.h>]])])
     LIBS="$gtk_save_LIBS"
+
+    if test "x$have_xinput2_2" = "xyes"; then
+      X_EXTENSIONS="$X_EXTENSIONS XI2.2"
+    else
+      X_EXTENSIONS="$X_EXTENSIONS XI2"
+    fi
   fi
 
   AM_CONDITIONAL(XINPUT_2,     test "x$have_xinput2" = "xyes")