Create an X window overlay with static ID for GL contexts.

This code creates an X window that overlays where tab contents are drawn. The handle associated with this window never changes (unlike the X window associated with a GTK widget that is created and destroyed whenever the widget is realized and unrealized respectively).  This is helpful when creating a GL context associated with an X window. Also, having a floating overlay allows us to handle detaching GPU accelerated tabs.

This code seems to have uncovered a race condition within the GPU process. When a tab that uses accelerated compositing is detached (e.g. http://webkit.org/blog/386/3d-transforms/), the tab contents often don't get displayed even though the tab is redrawn.  A slight delay of about 100ms in the GPU process on the call to glXSwapBuffers (in gl_context_linux.cc) fixes this. To witness that GL can draw to the overlay after delay, try it with a tab with constant animation (e.g. http://webkit.org/blog-files/3d-transforms/poster-circle.html).

I've written a bare bones test (about 150 lines of C) of the overlay technique, and it requires no such delay b/w reparenting the glXSwapBuffers. I've also confirmed that there is no synchronization issues w.r.t. the X server between my patch and GL draw commands. I propose filing a new bug for the race, if this patch gets accepted.

BUG=53345,56419
TEST=Open two tabs, one with GPU rendered content (http://webkit.org/blog/386/3d-transforms/). Detach the tab with GPU rendered content.  GPU process shouldn't crash.

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=61561

Review URL: http://codereview.chromium.org/3509004
Patch from Jonathan Backer <backer@google.com>.

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@61695 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 117 insertions, 7 deletions

diff --git a/gfx/gtk_native_view_id_manager.cc b/gfx/gtk_native_view_id_manager.cc
index 0cb96df..680ec13 100644
--- a/gfx/gtk_native_view_id_manager.cc
+++ b/gfx/gtk_native_view_id_manager.cc
@@ -4,31 +4,87 @@
 
 #include "gfx/gtk_native_view_id_manager.h"
 
+#include <gtk/gtk.h>
+#include <gdk/gdkx.h>
+#include <gdk/gdk.h>
+#include <X11/Xlib.h>
+
 #include "base/logging.h"
 #include "base/rand_util.h"
 #include "gfx/rect.h"
 
-#include <gtk/gtk.h>
-#include <gdk/gdkx.h>
-
 // -----------------------------------------------------------------------------
 // Bounce functions for GTK to callback into a C++ object...
+namespace {
 
-static void OnRealize(gfx::NativeView widget, void* arg) {
+void OnRealize(gfx::NativeView widget, void* arg) {
   GtkNativeViewManager* manager = reinterpret_cast<GtkNativeViewManager*>(arg);
   manager->OnRealize(widget);
 }
 
-static void OnUnrealize(gfx::NativeView widget, void *arg) {
+void OnUnrealize(gfx::NativeView widget, void *arg) {
   GtkNativeViewManager* manager = reinterpret_cast<GtkNativeViewManager*>(arg);
   manager->OnUnrealize(widget);
 }
 
-static void OnDestroy(GtkObject* obj, void* arg) {
+void OnDestroy(GtkObject* obj, void* arg) {
   GtkNativeViewManager* manager = reinterpret_cast<GtkNativeViewManager*>(arg);
   manager->OnDestroy(reinterpret_cast<GtkWidget*>(obj));
 }
 
+void OnSizeAllocate(gfx::NativeView widget,
+                    GtkAllocation* alloc,
+                    void* arg) {
+  GtkNativeViewManager* manager = reinterpret_cast<GtkNativeViewManager*>(arg);
+  manager->OnSizeAllocate(widget, alloc);
+}
+
+XID CreateOverlay(XID underlying) {
+  XID overlay = 0;
+  Display* dpy = gdk_x11_get_default_xdisplay();
+
+  // Prevent interference with reparenting/mapping of overlay
+  XSetWindowAttributes attr;
+  attr.override_redirect = True;
+
+  if (underlying) {
+    XID root;
+    int x, y;
+    unsigned int width, height;
+    unsigned int border_width;
+    unsigned int depth;
+    XGetGeometry(
+        dpy, underlying, &root, &x, &y,
+        &width, &height, &border_width, &depth);
+    overlay = XCreateWindow(
+        dpy,                      // display
+        underlying,               // parent
+        0, 0, width, height,      // x, y, width, height
+        0,                        // border width
+        CopyFromParent,           // depth
+        InputOutput,              // class
+        CopyFromParent,           // visual
+        CWOverrideRedirect,       // value mask
+        &attr);                   // value attributes
+    XMapWindow(dpy, overlay);
+  } else {
+    overlay = XCreateWindow(
+        dpy,                                 // display
+        gdk_x11_get_default_root_xwindow(),  // parent
+        0, 0, 1, 1,                          // x, y, width, height
+        0,                                   // border width
+        CopyFromParent,                      // depth
+        InputOutput,                         // class
+        CopyFromParent,                      // visual
+        CWOverrideRedirect,                  // value mask
+        &attr);                              // value attributes
+  }
+  XSync(dpy, False);
+  return overlay;
+}
+
+}
+
 // -----------------------------------------------------------------------------
 
 
@@ -65,13 +121,14 @@ gfx::NativeViewId GtkNativeViewManager::GetIdForWidget(gfx::NativeView widget) {
     CHECK(gdk_window);
     info.x_window_id = GDK_WINDOW_XID(gdk_window);
   }
-
   native_view_to_id_[widget] = new_id;
   id_to_info_[new_id] = info;
 
   g_signal_connect(widget, "realize", G_CALLBACK(::OnRealize), this);
   g_signal_connect(widget, "unrealize", G_CALLBACK(::OnUnrealize), this);
   g_signal_connect(widget, "destroy", G_CALLBACK(::OnDestroy), this);
+  g_signal_connect(
+      widget, "size-allocate", G_CALLBACK(::OnSizeAllocate), this);
 
   return new_id;
 }
@@ -89,6 +146,24 @@ bool GtkNativeViewManager::GetXIDForId(XID* output, gfx::NativeViewId id) {
   return true;
 }
 
+bool GtkNativeViewManager::GetPermanentXIDForId(XID* output,
+                                                gfx::NativeViewId id) {
+  AutoLock locked(lock_);
+
+  std::map<gfx::NativeViewId, NativeViewInfo>::iterator i =
+    id_to_info_.find(id);
+
+  if (i == id_to_info_.end())
+    return false;
+
+  if (!i->second.permanent_window_id) {
+    i->second.permanent_window_id = CreateOverlay(i->second.x_window_id);
+  }
+
+  *output = i->second.permanent_window_id;
+  return true;
+}
+
 // -----------------------------------------------------------------------------
 
 
@@ -116,6 +191,14 @@ void GtkNativeViewManager::OnRealize(gfx::NativeView widget) {
   CHECK(widget->window);
 
   i->second.x_window_id = GDK_WINDOW_XID(widget->window);
+
+  if (i->second.permanent_window_id) {
+    Display* dpy = gdk_x11_get_default_xdisplay();
+    XReparentWindow(
+        dpy, i->second.permanent_window_id, i->second.x_window_id, 0, 0);
+    XMapWindow(dpy, i->second.permanent_window_id);
+    XSync(dpy, False);
+  }
 }
 
 void GtkNativeViewManager::OnUnrealize(gfx::NativeView widget) {
@@ -129,6 +212,13 @@ void GtkNativeViewManager::OnUnrealize(gfx::NativeView widget) {
   CHECK(i != id_to_info_.end());
 
   i->second.x_window_id = 0;
+  if (i->second.permanent_window_id) {
+    Display* dpy = gdk_x11_get_default_xdisplay();
+    XUnmapWindow(dpy, i->second.permanent_window_id);
+    XReparentWindow(dpy, i->second.permanent_window_id,
+                    gdk_x11_get_default_root_xwindow(), 0, 0);
+    XSync(dpy, False);
+  }
 }
 
 void GtkNativeViewManager::OnDestroy(gfx::NativeView widget) {
@@ -142,8 +232,28 @@ void GtkNativeViewManager::OnDestroy(gfx::NativeView widget) {
     id_to_info_.find(i->second);
   CHECK(j != id_to_info_.end());
 
+  if (j->second.permanent_window_id) {
+    XDestroyWindow(gdk_x11_get_default_xdisplay(),
+                   j->second.permanent_window_id);
+  }
+
   native_view_to_id_.erase(i);
   id_to_info_.erase(j);
 }
 
+void GtkNativeViewManager::OnSizeAllocate(
+    gfx::NativeView widget, GtkAllocation *alloc) {
+  AutoLock locked(lock_);
+
+  const gfx::NativeViewId id = GetWidgetId(widget);
+  std::map<gfx::NativeViewId, NativeViewInfo>::iterator i =
+    id_to_info_.find(id);
+
+  if (i->second.permanent_window_id) {
+    XResizeWindow(gdk_x11_get_default_xdisplay(),
+                  i->second.permanent_window_id,
+                  alloc->width, alloc->height);
+  }
+}
+
 // -----------------------------------------------------------------------------