Aura on Linux: Make a DesktopScreenX11 to match the windows one.

ui/aura/desktop/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/aura/desktop/desktop_screen.h"
+
+#include <X11/Xlib.h>
+
+// It clashes with out RootWindow.

[Daniel Erat, 2012/05/01 22:51:48]

nit: s/out/our/

+#undef RootWindow
+
 #include "base/logging.h"
-#include "ui/aura/desktop/desktop_screen.h"
+#include "ui/aura/root_window.h"
+#include "ui/aura/root_window_host.h"
+#include "ui/base/x/x11_util.h"
+#include "ui/gfx/monitor.h"
+#include "ui/gfx/native_widget_types.h"
+#include "ui/gfx/screen_impl.h"
+
+namespace {
+
+// TODO(erg): This method is a temporary hack, until we can reliably extract
+// location data out of Xinerama.

[Daniel Erat, 2012/05/01 22:51:48]

s/Xinerama/XRandR, i think

+gfx::Size GetPrimaryMonitorSize() {
+  ::Display* display = ui::GetXDisplay();
+  ::Screen* screen = DefaultScreenOfDisplay(display);
+  int width = WidthOfScreen(screen);
+  int height = HeightOfScreen(screen);
+
+  return gfx::Size(width, height);
+}
+
+class DesktopScreenX11 : public gfx::ScreenImpl {
+public:

[Ben Goodger (Google), 2012/05/01 22:38:41]

nit: lead with 1 space

+  DesktopScreenX11();
+  virtual ~DesktopScreenX11();
+
+  // Overridden from gfx::ScreenImpl:
+  virtual gfx::Point GetCursorScreenPoint() OVERRIDE;
+  virtual gfx::NativeWindow GetWindowAtCursorScreenPoint() OVERRIDE;
+  virtual int GetNumMonitors() OVERRIDE;
+  virtual gfx::Monitor GetMonitorNearestWindow(
+      gfx::NativeView window) const OVERRIDE;
+  virtual gfx::Monitor GetMonitorNearestPoint(
+      const gfx::Point& point) const OVERRIDE;
+  virtual gfx::Monitor GetPrimaryMonitor() const OVERRIDE;
+
+private:

[Ben Goodger (Google), 2012/05/01 22:38:41]

ditto

+  DISALLOW_COPY_AND_ASSIGN(DesktopScreenX11);
+};
+
+////////////////////////////////////////////////////////////////////////////////
+// DesktopScreenX11, public:
+
+DesktopScreenX11::DesktopScreenX11() {
+}
+
+DesktopScreenX11::~DesktopScreenX11() {
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// DesktopScreenX11, gfx::ScreenImpl implementation:
+
+gfx::Point DesktopScreenX11::GetCursorScreenPoint() {

[Daniel Erat, 2012/05/01 22:51:48]

i'm a bit worried that this method gets called with reckless abandon (in the
aura implementation, the pointer position is cached from motion events).  not
much that can be done about that, i guess. :-/

+  Display* display = ui::GetXDisplay();
+
+  // Unsure if I can leave these as NULL.

[Daniel Erat, 2012/05/01 22:51:48]

pretty sure you can't

+  ::Window root, child;
+  int root_x, root_y, win_x, win_y;
+  unsigned int mask;
+  XQueryPointer(display,
+                DefaultRootWindow(display),
+                &root,
+                &child,
+                &root_x,
+                &root_y,
+                &win_x,
+                &win_y,
+                &mask);
+
+  return gfx::Point(root_x, root_y);
+}
+
+gfx::NativeWindow DesktopScreenX11::GetWindowAtCursorScreenPoint() {
+  gfx::Point cursor = GetCursorScreenPoint();
+  gfx::NativeWindow out_window = NULL;
+
+  // Iterate across the return values of XQuerryTree() here, which are sorted

[Daniel Erat, 2012/05/01 22:51:48]

nit: s/XQuerryTree/XQueryTree/

+  // in z-order.

[Daniel Erat, 2012/05/01 22:51:48]

nit: mention in the comment that they're in bottom-to-top order (at least,
that's not clear to me from "z-order")

+  Display* display = ui::GetXDisplay();
+  ::Window root, parent;
+  unsigned int num_children = 0;
+  ::Window *children = NULL;
+
+  if (XQueryTree(display, DefaultRootWindow(display), &root, &parent,

[Daniel Erat, 2012/05/01 22:51:48]

note that if you intend to use this to find windows that are managed by a
conventional X window manager, most WMs reparent windows that they're managing
into frame windows, so you won't see chrome's windows as direct children of the
root.  _NET_CLIENT_LIST_STACKING is more appropriate in that case (assuming that
you're using a WM that implements it correctly):
http://standards.freedesktop.org/wm-spec/wm-spec-latest.html#id2533840 

+                 &children, &num_children)) {

[Daniel Erat, 2012/05/01 22:51:48]

nit: return early on failure instead of indenting all of this?

+    for (unsigned int i = 0; i < num_children; ++i) {
+      aura::RootWindowHost* host =
+          aura::RootWindowHost::GetForAcceleratedWidget(children[i]);

[Daniel Erat, 2012/05/01 22:51:48]

actually, is this backwards?  you want the topmost window, right?

+      if (host) {
+        out_window = host->GetRootWindow();
+        break;
+      }
+    }
+
+    if (children)
+      XFree(children);
+  }
+
+  return out_window;
+}
+
+int DesktopScreenX11::GetNumMonitors() {
+  // TODO(erg): Figure this out with oshima or piman because I have no clue
+  // about the Xinerama implications here.
+  return 1;
+}
+
+gfx::Monitor DesktopScreenX11::GetMonitorNearestWindow(
+    gfx::NativeView window) const {
+  // TODO(erg): Do the right thing once we know what that is.
+  return gfx::Monitor(0, gfx::Rect(GetPrimaryMonitorSize()));
+}
+
+gfx::Monitor DesktopScreenX11::GetMonitorNearestPoint(
+    const gfx::Point& point) const {
+  // TODO(erg): Do the right thing once we know what that is.
+  return gfx::Monitor(0, gfx::Rect(GetPrimaryMonitorSize()));
+}
+
+gfx::Monitor DesktopScreenX11::GetPrimaryMonitor() const {
+  // TODO(erg): Do the right thing once we know what that is.
+  return gfx::Monitor(0, gfx::Rect(GetPrimaryMonitorSize()));
+}
+
+}  // namespace
+
+////////////////////////////////////////////////////////////////////////////////
 
 namespace aura {
 
-////////////////////////////////////////////////////////////////////////////////
-
 gfx::ScreenImpl* CreateDesktopScreen() {
-  NOTIMPLEMENTED();  // TODO(erg): implement me!
-  return NULL;
+  return new DesktopScreenX11;
 }
 
 }  // namespace aura