touchui: support XInput2 MT

base/message_pump_x.cc

Index: base/message_pump_x.cc
diff --git a/base/message_pump_x.cc b/base/message_pump_x.cc
index 8e098af95924e57269b906f21eb7975d926d3c0f..98efb11dbc3a1719988bf83e542713fd9330bd7b 100644
--- a/base/message_pump_x.cc
+++ b/base/message_pump_x.cc
@@ -70,9 +70,14 @@ void InitializeXInput2(void) {
     return;
   }
 
+#if defined(USE_XI2_1)
+  int major = 2, minor = 1;
+#else
   int major = 2, minor = 0;
+#endif
   if (XIQueryVersion(display, &major, &minor) == BadRequest) {
-    VLOG(1) << "XInput2 not supported in the server.";
+    VLOG(1) << "XInput" << major << "." << minor

[Daniel Kurtz, 2011/09/08 23:09:58]

This will actually print the server's supported version, not 2.1:

http://www.x.org/releases/X11R7.5/doc/man/man3/XIQueryVersion.3.html

[ningxin.hu, 2011/09/09 05:08:54]

Thanks. I will revert this change.

+            << "not supported in the server.";
     xiopcode = -1;
     return;
   }

[Daniel Kurtz, 2011/09/08 23:09:58]

Save the server's reported version (returned in major, minor), and, if it is
2.0, use the (#ifndef USE_XI2_1) way to pass multitouch events.

[ningxin.hu, 2011/09/09 05:08:54]

Thanks for the suggestion. Since ubuntu supports multitouch in its XI2.1 and
Xorg will support multitouch in XI2.2, we properly cannot use minor version to
detect MT support simplely. 

So I propose to still use 'use_xi2_mt' gyp switch to turn on the XI2 MT support
when on ubuntu 11.04 or later xorg XI2.2.