X11: Handle change notify for _NET_WORKAREA

ui/views/widget/desktop_aura/desktop_screen_x11.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 "ui/views/widget/desktop_aura/desktop_screen_x11.h"
 
 #include <X11/extensions/Xrandr.h>
 #include <X11/Xlib.h>
 
 // It clashes with out RootWindow.
@@ skipping 15 matching lines @@
 #include "ui/gfx/native_widget_types.h"
 #include "ui/gfx/screen.h"
 #include "ui/gfx/x/x11_types.h"
 #include "ui/views/linux_ui/linux_ui.h"
 #include "ui/views/widget/desktop_aura/desktop_screen.h"
 #include "ui/views/widget/desktop_aura/desktop_window_tree_host_x11.h"
 #include "ui/views/widget/desktop_aura/x11_topmost_window_finder.h"
 
 namespace {
 
+const char* kAtomsToCache[] = {

[Lei Zhang, 2016/04/21 22:45:31]

const char* const, otherwise one can write: kAtomsToCache[0] = nullptr.

[Tom (Use chromium acct), 2016/04/21 22:57:50]

Done.

+  "_NET_WORKAREA",
+  NULL

[Lei Zhang, 2016/04/21 22:45:31]

nullptr

[Tom (Use chromium acct), 2016/04/21 22:57:50]

Done.

+};
+
 // The delay to perform configuration after RRNotify.  See the comment
 // in |Dispatch()|.
 const int64_t kConfigureDelayMs = 500;
 
 double GetDeviceScaleFactor() {
   float device_scale_factor = 1.0f;
   if (views::LinuxUI::instance()) {
     device_scale_factor =
       views::LinuxUI::instance()->GetDeviceScaleFactor();
   } else if (gfx::Display::HasForceDeviceScaleFactor()) {
@@ skipping 33 matching lines @@
 
 namespace views {
 
 ////////////////////////////////////////////////////////////////////////////////
 // DesktopScreenX11, public:
 
 DesktopScreenX11::DesktopScreenX11()
     : xdisplay_(gfx::GetXDisplay()),
       x_root_window_(DefaultRootWindow(xdisplay_)),
       has_xrandr_(false),
-      xrandr_event_base_(0) {
+      xrandr_event_base_(0),
+      atom_cache_(xdisplay_, kAtomsToCache) {
   // We only support 1.3+. There were library changes before this and we should
   // use the new interface instead of the 1.2 one.
   int randr_version_major = 0;
   int randr_version_minor = 0;
   has_xrandr_ = XRRQueryVersion(
         xdisplay_, &randr_version_major, &randr_version_minor) &&
       randr_version_major == 1 &&
       randr_version_minor >= 3;
 
   if (has_xrandr_) {
@@ skipping 122 matching lines @@
 void DesktopScreenX11::AddObserver(gfx::DisplayObserver* observer) {
   change_notifier_.AddObserver(observer);
 }
 
 void DesktopScreenX11::RemoveObserver(gfx::DisplayObserver* observer) {
   change_notifier_.RemoveObserver(observer);
 }
 
 bool DesktopScreenX11::CanDispatchEvent(const ui::PlatformEvent& event) {
   return event->type - xrandr_event_base_ == RRScreenChangeNotify ||
-         event->type - xrandr_event_base_ == RRNotify;
+         event->type - xrandr_event_base_ == RRNotify ||
+         (event->type == PropertyNotify &&
+          event->xproperty.window == x_root_window_ &&
+          event->xproperty.atom == atom_cache_.GetAtom("_NET_WORKAREA"));
 }
 
 uint32_t DesktopScreenX11::DispatchEvent(const ui::PlatformEvent& event) {
   if (event->type - xrandr_event_base_ == RRScreenChangeNotify) {
     // Pass the event through to xlib.
     XRRUpdateConfiguration(event);
-  } else if (event->type - xrandr_event_base_ == RRNotify) {
+  } else if (event->type - xrandr_event_base_ == RRNotify ||
+             event->xproperty.atom == atom_cache_.GetAtom("_NET_WORKAREA")) {

[Elliot Glaysher, 2016/04/21 22:43:05]

XEvent is a giant union, not a struct. Check event->type before you access
memory at event->xproperty.*.

[Tom (Use chromium acct), 2016/04/21 22:57:50]

Done.

     // There's some sort of observer dispatch going on here, but I don't think
     // it's the screen's?
     if (configure_timer_.get() && configure_timer_->IsRunning()) {
       configure_timer_->Reset();
     } else {
       configure_timer_.reset(new base::OneShotTimer());
       configure_timer_->Start(
           FROM_HERE,
           base::TimeDelta::FromMilliseconds(kConfigureDelayMs),
           this,
@@ skipping 15 matching lines @@
 
 ////////////////////////////////////////////////////////////////////////////////
 // DesktopScreenX11, private:
 
 DesktopScreenX11::DesktopScreenX11(
     const std::vector<gfx::Display>& test_displays)
     : xdisplay_(gfx::GetXDisplay()),
       x_root_window_(DefaultRootWindow(xdisplay_)),
       has_xrandr_(false),
       xrandr_event_base_(0),
-      displays_(test_displays) {
+      displays_(test_displays),
+      atom_cache_(xdisplay_, kAtomsToCache) {
 }
 
 std::vector<gfx::Display> DesktopScreenX11::BuildDisplaysFromXRandRInfo() {
   std::vector<gfx::Display> displays;
   gfx::XScopedPtr<
       XRRScreenResources,
       gfx::XObjectDeleter<XRRScreenResources, void, XRRFreeScreenResources>>
       resources(XRRGetScreenResourcesCurrent(xdisplay_, x_root_window_));
   if (!resources) {
     LOG(ERROR) << "XRandR returned no displays. Falling back to Root Window.";
@@ skipping 92 matching lines @@
       GetPrimaryDisplay().device_scale_factor());
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 
 gfx::Screen* CreateDesktopScreen() {
   return new DesktopScreenX11;
 }
 
 }  // namespace views