[Chromoting] Initial plumbing for cursor shape.

remoting/host/capturer_linux.cc

Index: remoting/host/capturer_linux.cc
diff --git a/remoting/host/capturer_linux.cc b/remoting/host/capturer_linux.cc
index e513bb7c8932492f9dcf14c8fb061f885bebc253..3245c338839283eb2e16d696d3603a46023e3780 100644
--- a/remoting/host/capturer_linux.cc
+++ b/remoting/host/capturer_linux.cc
@@ -7,6 +7,7 @@
 #include <X11/Xlib.h>
 #include <X11/Xutil.h>
 #include <X11/extensions/Xdamage.h>
+#include <X11/extensions/Xfixes.h>
 
 #include <set>
 
@@ -77,6 +78,8 @@ class CapturerLinux : public Capturer {
   // Capturer interface.
   virtual void Start() OVERRIDE;
   virtual void Stop() OVERRIDE;
+  virtual void SetCursorShapeChangedCallback(
+      const CursorShapeChangedCallback& callback) OVERRIDE;
   virtual void ScreenConfigurationChanged() OVERRIDE;
   virtual media::VideoFrame::Format pixel_format() const OVERRIDE;
   virtual void ClearInvalidRegion() OVERRIDE;
@@ -106,6 +109,10 @@ class CapturerLinux : public Capturer {
   // previous capture.
   CaptureData* CaptureFrame();
 
+  // Capture the cursor shape pixels and call the CursorShapeChangedCallback,

[Wez, 2012/05/16 00:20:04]

nit: "shape pixels" -> "image" ?

[garykac, 2012/05/22 00:42:03]

Done.

+  // if it has been set (using SetCursorShapeChangedCallback).
+  void CaptureCursor();
+
   // Synchronize the current buffer with |last_buffer_|, by copying pixels from
   // the area of |last_invalid_rects|.
   // Note this only works on the assumption that kNumBuffers == 2, as
@@ -129,6 +136,11 @@ class CapturerLinux : public Capturer {
   GC gc_;
   Window root_window_;
 
+  // XFixes.
+  bool has_xfixes_;
+  int xfixes_event_base_;
+  int xfixes_error_base_;
+
   // XDamage information.
   bool use_damage_;
   Damage damage_handle_;
@@ -143,6 +155,9 @@ class CapturerLinux : public Capturer {
   // recently captured screen.
   CapturerHelper helper_;
 
+  // Callback to call whenever the cursor shape is changed.

[Wez, 2012/05/16 00:20:04]

nit: "Callback notified ..."

[garykac, 2012/05/22 00:42:03]

Done.

+  CursorShapeChangedCallback cursor_shape_changed_callback_;
+
   // Capture state.
   static const int kNumBuffers = 2;
   VideoFrameBuffer buffers_[kNumBuffers];
@@ -168,6 +183,9 @@ CapturerLinux::CapturerLinux()
     : display_(NULL),
       gc_(NULL),
       root_window_(BadValue),
+      has_xfixes_(false),
+      xfixes_event_base_(-1),
+      xfixes_error_base_(-1),
       use_damage_(false),
       damage_handle_(0),
       damage_event_base_(-1),
@@ -208,6 +226,15 @@ bool CapturerLinux::Init() {
     return false;
   }
 
+  // Check for XFixes extension. This is required for our XDamage support and

[Wez, 2012/05/16 00:20:04]

nit: Suggest "This is required for cursor shape notifications, and for our use
of XDamage."

[garykac, 2012/05/22 00:42:03]

Done.

+  // to get the cursor shape notifications.
+  if (XFixesQueryExtension(display_, &xfixes_event_base_,
+                           &xfixes_error_base_)) {
+    has_xfixes_ = true;
+  } else {
+    LOG(INFO) << "X server does not support XFixes.";
+  }
+
   if (ShouldUseXDamage()) {
     InitXDamage();
   }
@@ -215,18 +242,21 @@ bool CapturerLinux::Init() {
   // Register for changes to the dimensions of the root window.
   XSelectInput(display_, root_window_, StructureNotifyMask);
 
+  if (has_xfixes_) {
+    // Register for changes to the cursor shape.
+    XFixesSelectCursorInput(display_, root_window_,
+                            XFixesDisplayCursorNotifyMask);
+  }
+
   return true;
 }
 
 void CapturerLinux::InitXDamage() {
-  // Check for XFixes and XDamage extensions.  If both are found then use
-  // XDamage to get explicit notifications of on-screen changes.
-  int xfixes_event_base;
-  int xfixes_error_base;
-  if (!XFixesQueryExtension(display_, &xfixes_event_base, &xfixes_error_base)) {
-    LOG(INFO) << "X server does not support XFixes.";
+  if (!has_xfixes_)
     return;
-  }
+
+  // Check for XDamage extension. If this and XFixes are both found then use

[Wez, 2012/05/16 00:20:04]

nit: You've already tested for XFixes, so don't mention it in this comment? Or
add a comment to the |has_xfixes| test above.

[garykac, 2012/05/22 00:42:03]

Done.

+  // XDamage to get explicit notifications of on-screen changes.
   if (!XDamageQueryExtension(display_, &damage_event_base_,
                              &damage_error_base_)) {
     LOG(INFO) << "X server does not support XDamage.";
@@ -264,6 +294,11 @@ void CapturerLinux::Start() {
 void CapturerLinux::Stop() {
 }
 
+void CapturerLinux::SetCursorShapeChangedCallback(
+    const CursorShapeChangedCallback& callback) {
+  cursor_shape_changed_callback_ = callback;
+}
+
 void CapturerLinux::ScreenConfigurationChanged() {
   last_buffer_ = NULL;
   for (int i = 0; i < kNumBuffers; ++i) {
@@ -296,8 +331,7 @@ void CapturerLinux::InvalidateFullScreen() {
 
 void CapturerLinux::CaptureInvalidRegion(
     const CaptureCompletedCallback& callback) {
-  // TODO(lambroslambrou): In the non-DAMAGE case, there should be no need
-  // for any X event processing in this class.
+  // Process XEvents for XDamage and cursor shape.

[Wez, 2012/05/16 00:20:04]

nit: "... cursor shape tracking"

[garykac, 2012/05/22 00:42:03]

Done.

   ProcessPendingXEvents();
 
   // Resize the current buffer if there was a recent change of
@@ -326,16 +360,34 @@ void CapturerLinux::ProcessPendingXEvents() {
   for (int i = 0; i < events_to_process; i++) {
     XNextEvent(display_, &e);
     if (use_damage_ && (e.type == damage_event_base_ + XDamageNotify)) {
-      XDamageNotifyEvent *event = reinterpret_cast<XDamageNotifyEvent*>(&e);
+      XDamageNotifyEvent* event = reinterpret_cast<XDamageNotifyEvent*>(&e);
       DCHECK(event->level == XDamageReportNonEmpty);
     } else if (e.type == ConfigureNotify) {
       ScreenConfigurationChanged();
+    } else if (has_xfixes_ &&
+               e.type == xfixes_event_base_ + XFixesCursorNotify) {
+      XFixesCursorNotifyEvent* cne;
+      cne = reinterpret_cast<XFixesCursorNotifyEvent*>(&e);
+      if (cne->subtype == XFixesDisplayCursorNotify) {
+        CaptureCursor();
+      }
     } else {
       LOG(WARNING) << "Got unknown event type: " << e.type;
     }
   }
 }
 
+void CapturerLinux::CaptureCursor() {
+  DCHECK(has_xfixes_);
+  if (cursor_shape_changed_callback_.is_null())
+    return;
+
+  // TODO(garykac) Get cursor shape using XFixesGetCursorImage.
+
+  scoped_refptr<CursorShapeData> cursor_data;
+  cursor_shape_changed_callback_.Run(cursor_data);
+}
+
 CaptureData* CapturerLinux::CaptureFrame() {
   VideoFrameBuffer& buffer = buffers_[current_buffer_];
   DataPlanes planes;