Initialize XInput2 on demand

base/message_pump_x.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/message_pump_x.h"
 
 #include <X11/extensions/XInput2.h>
 
 #include "base/basictypes.h"
 #include "base/message_loop.h"
@@ skipping 19 matching lines @@
   return pump->DispatchXEvents();
 }
 
 GSourceFuncs XSourceFuncs = {
   XSourcePrepare,
   XSourceCheck,
   XSourceDispatch,
   NULL
 };
 
-// The opcode used for checking events.
-int xiopcode = -1;
+// The status of XInput2 initialization.
+bool xInput2Initialized = false;

[sadrul, 2012/05/16 21:47:12]

xinput2_initialized
xinput2_supported

camelCase is for webKit!

[Rick Byers, 2012/05/17 14:06:56]

Done.

+bool xInput2Supported = false;
 
 // The message-pump opens a connection to the display and owns it.
 Display* g_xdisplay = NULL;
 
 // The default dispatcher to process native events when no dispatcher
 // is specified.
 base::MessagePumpDispatcher* g_default_dispatcher = NULL;
 
-void InitializeXInput2(void) {
+void InitializeXInput2IfNeeded(void) {
+  if (xInput2Initialized)
+    return;
+  xInput2Initialized = true;
+
   Display* display = base::MessagePumpX::GetDefaultXDisplay();
   if (!display)
     return;
 
   int event, err;
 
+  int xiopcode;
   if (!XQueryExtension(display, "XInputExtension", &xiopcode, &event, &err)) {
     DVLOG(1) << "X Input extension not available.";
-    xiopcode = -1;
     return;
   }
 
 #if defined(USE_XI2_MT)
   // USE_XI2_MT also defines the required XI2 minor minimum version.
   int major = 2, minor = USE_XI2_MT;
 #else
   int major = 2, minor = 0;
 #endif
   if (XIQueryVersion(display, &major, &minor) == BadRequest) {
     DVLOG(1) << "XInput2 not supported in the server.";
-    xiopcode = -1;
     return;
   }
 #if defined(USE_XI2_MT)
   if (major < 2 || (major == 2 && minor < USE_XI2_MT)) {
     DVLOG(1) << "XI version on server is " << major << "." << minor << ". "
             << "But 2." << USE_XI2_MT << " is required.";
-    xiopcode = -1;
     return;
   }
 #endif
+
+  xInput2Supported = true;
 }
 
 }  // namespace
 
 namespace base {
 
 MessagePumpX::MessagePumpX() : MessagePumpGlib(),
     x_source_(NULL) {
-  InitializeXInput2();
+  InitializeXInput2IfNeeded();
   InitXSource();
 }
 
 MessagePumpX::~MessagePumpX() {
   g_source_destroy(x_source_);
   g_source_unref(x_source_);
   XCloseDisplay(g_xdisplay);
   g_xdisplay = NULL;
 }
 
 // static
 Display* MessagePumpX::GetDefaultXDisplay() {
   if (!g_xdisplay)
     g_xdisplay = XOpenDisplay(NULL);
   return g_xdisplay;
 }
 
 // static
 bool MessagePumpX::HasXInput2() {
-  return xiopcode != -1;
+  InitializeXInput2IfNeeded();
+  return xInput2Supported;
 }
 
 // static
 void MessagePumpX::SetDefaultDispatcher(MessagePumpDispatcher* dispatcher) {
   DCHECK(!g_default_dispatcher || !dispatcher);
   g_default_dispatcher = dispatcher;
 }
 
 void MessagePumpX::InitXSource() {
   // CHECKs are to help track down crbug.com/113106.
@@ skipping 64 matching lines @@
       return true;
   }
   return false;
 }
 
 void MessagePumpX::DidProcessXEvent(XEvent* xevent) {
   FOR_EACH_OBSERVER(MessagePumpObserver, observers(), DidProcessEvent(xevent));
 }
 
 }  // namespace base