Keep the mouse cursor within desktop

ui/aura/root_window_host_linux.cc

Index: ui/aura/root_window_host_linux.cc
diff --git a/ui/aura/root_window_host_linux.cc b/ui/aura/root_window_host_linux.cc
index aa528b9414a75ea3f03097e382dc27dbe444ab84..50708d3b22fed5a70de3fb00ca70f082b41a3a47 100644
--- a/ui/aura/root_window_host_linux.cc
+++ b/ui/aura/root_window_host_linux.cc
@@ -6,6 +6,7 @@
 
 #include <X11/cursorfont.h>
 #include <X11/extensions/XInput2.h>
+#include <X11/extensions/Xfixes.h>
 #include <X11/extensions/Xrandr.h>
 #include <algorithm>
 
@@ -16,7 +17,6 @@
 #include "ui/aura/env.h"
 #include "ui/aura/event.h"
 #include "ui/aura/monitor.h"
-#include "ui/aura/monitor_change_observer_x11.h"
 #include "ui/aura/monitor_manager.h"
 #include "ui/aura/root_window.h"
 #include "ui/base/keycodes/keyboard_codes.h"
@@ -281,7 +281,8 @@ RootWindowHostLinux::RootWindowHostLinux(const gfx::Rect& bounds)
       current_cursor_(aura::kCursorNull),
       cursor_shown_(true),
       bounds_(bounds),
-      focus_when_shown_(false) {
+      focus_when_shown_(false),
+      pointer_barriers_(NULL) {
   XSetWindowAttributes swa;
   memset(&swa, 0, sizeof(swa));
   swa.background_pixmap = None;
@@ -295,7 +296,7 @@ RootWindowHostLinux::RootWindowHostLinux(const gfx::Rect& bounds)
       CWBackPixmap,
       &swa);
   static_cast<DispatcherLinux*>(Env::GetInstance()->GetDispatcher())->
-      RootWindowHostCreated(xwindow_, x_root_window_, this);
+      WindowDispatcherCreated(xwindow_, this);
 
   long event_mask = ButtonPressMask | ButtonReleaseMask | FocusChangeMask |
                     KeyPressMask | KeyReleaseMask |
@@ -323,7 +324,7 @@ RootWindowHostLinux::RootWindowHostLinux(const gfx::Rect& bounds)
 
 RootWindowHostLinux::~RootWindowHostLinux() {
   static_cast<DispatcherLinux*>(Env::GetInstance()->GetDispatcher())->
-      RootWindowHostDestroying(xwindow_, x_root_window_);
+      WindowDispatcherDestroying(xwindow_);
   XDestroyWindow(xdisplay_, xwindow_);
 
   // Clears XCursorCache.
@@ -367,7 +368,14 @@ base::MessagePumpDispatcher::DispatchStatus RootWindowHostLinux::Dispatch(
     case ConfigureNotify: {
       DCHECK_EQ(xwindow_, xev->xconfigure.window);
       DCHECK_EQ(xwindow_, xev->xconfigure.event);
-
+      // Update barrier and mouse location when the root window has
+      // moved/resized.
+      if (pointer_barriers_.get()) {

[Daniel Erat, 2012/03/23 16:49:16]

It looks like you only update if we already had barriers enabled before.  How
does this get enabled in the first place?  Does ConfineCursorToRootWindow() get
called from somewhere else?

[oshima, 2012/03/23 18:25:09]

This is enabled for root window for primary monitor in 
MonitorManager::CreateRootWindowForPrimaryMonitor

+        UnConfineCursor();
+        gfx::Point p = root_window_->last_mouse_location();
+        XWarpPointer(xdisplay_, None,  xwindow_, 0, 0, 0, 0, p.x(), p.y());
+        ConfineCursorToRootWindow();
+      }
       // It's possible that the X window may be resized by some other means than
       // from within aura (e.g. the X window manager can change the size). Make
       // sure the root window size is maintained properly.
@@ -480,12 +488,6 @@ base::MessagePumpDispatcher::DispatchStatus RootWindowHostLinux::Dispatch(
       handled = root_window_->DispatchMouseEvent(&mouseev);
       break;
     }
-    default: {
-      // TODO(oshima): We probably should change DispatcherLinux so
-      // that it can directly dispatch the event to montor change
-      // observer.
-      Env::GetInstance()->monitor_change_observer()->Dispatch(xev);
-    }
   }
   return handled ? base::MessagePumpDispatcher::EVENT_PROCESSED :
       base::MessagePumpDispatcher::EVENT_IGNORED;
@@ -578,19 +580,34 @@ gfx::Point RootWindowHostLinux::QueryMouseLocation() {
 }
 
 bool RootWindowHostLinux::ConfineCursorToRootWindow() {
-  return XGrabPointer(xdisplay_,
-                      xwindow_,  // grab_window
-                      False,  // owner_events
-                      ButtonPressMask | ButtonReleaseMask | PointerMotionMask,
-                      GrabModeAsync,
-                      GrabModeAsync,
-                      xwindow_,  // confine_to
-                      None,  // cursor
-                      CurrentTime) == GrabSuccess;
+#if XFIXES_MAJOR >= 5
+  if (pointer_barriers_.get())

[Daniel Erat, 2012/03/23 16:49:16]

DCHECK(!pointer_barriers_.get()) instead?

[oshima, 2012/03/23 18:25:09]

I added it. I kept "if" because this isn't critical enough to crash. let me know
if you disagree.

+    return false;
+  // Monitors are vertically laid out, so just create barriers at the top and
+  // the bottom.

[Daniel Erat, 2012/03/23 16:49:16]

Can the monitors be different widths?  If so, it seems like you might need
barriers on the left and right as well.

[oshima, 2012/03/23 18:25:09]

There are already barriers on sides.

+  pointer_barriers_.reset(new XID[2]);
+  pointer_barriers_[0] = XFixesCreatePointerBarrier(
+      xdisplay_, xwindow_,
+      0, 0, bounds_.width(), 0,  // barrier line

[Daniel Erat, 2012/03/23 16:49:16]

Should you be using bounds_.x() and bounds_.y() here?  Or is the monitor that
we're using always guaranteed to be on top?  If it is, why do you need this
barrier?

[oshima, 2012/03/23 18:25:09]

I'm creating barriers relative to xwindow_, so this is correct.

+      BarrierPositiveY,
+      0, NULL);  // default device
+  pointer_barriers_[1] = XFixesCreatePointerBarrier(
+      xdisplay_, xwindow_,
+      0, bounds_.height(), bounds_.width(),  bounds_.height(),  // barrier line
+      BarrierNegativeY,
+      0, NULL);  // default device
+#endif
+  return true;
 }
 
 void RootWindowHostLinux::UnConfineCursor() {

[Daniel Erat, 2012/03/23 16:49:16]

Should probably call this from the d'tor too.

[oshima, 2012/03/23 18:25:09]

Good point. Done.

-  XUngrabPointer(xdisplay_, CurrentTime);
+#if XFIXES_MAJOR >= 5
+  if (pointer_barriers_.get()) {
+    XFixesDestroyPointerBarrier(xdisplay_, pointer_barriers_[0]);
+    XFixesDestroyPointerBarrier(xdisplay_, pointer_barriers_[1]);
+    pointer_barriers_.reset();
+  }
+#endif
 }
 
 void RootWindowHostLinux::MoveCursorTo(const gfx::Point& location) {