Implemented offscreen rendering path for GLES2CmdDecoder on Linux....

gpu/command_buffer/service/x_utils.cc

Index: gpu/command_buffer/service/x_utils.cc
===================================================================
--- gpu/command_buffer/service/x_utils.cc	(revision 43138)
+++ gpu/command_buffer/service/x_utils.cc	(working copy)
@@ -6,21 +6,33 @@
 
 #include <dlfcn.h>
 
+#include "base/scoped_ptr.h"
 #include "gpu/command_buffer/service/precompile.h"
 #include "gpu/command_buffer/common/logging.h"
 #include "gpu/command_buffer/service/x_utils.h"
 
 namespace gpu {
 
+// scoped_ptr functor for XFree(). Use as follows:
+//   scoped_ptr_malloc<XVisualInfo, ScopedPtrXFree> foo(...);
+// where "XVisualInfo" is any X type that is freed with XFree.
+class ScopedPtrXFree {
+ public:
+  void operator()(void* x) const {
+    ::XFree(x);
+  }
+};
+
 // Some versions of NVIDIA's GL libGL.so include a broken version of
 // dlopen/dlsym, and so linking it into chrome breaks it. So we dynamically
 // load it, and use glew to dynamically resolve symbols.
 // See http://code.google.com/p/chromium/issues/detail?id=16800
 
+static bool g_glxew_initialized = false;
 static bool g_glew_initialized = false;
 
-bool XWindowWrapper::Initialize() {
-  if (!g_glew_initialized) {
+static bool InitializeGLXEW() {
+  if (!g_glxew_initialized) {
     void* handle = dlopen("libGL.so.1", RTLD_LAZY | RTLD_GLOBAL);
     if (!handle) {
       LOG(ERROR) << "Could not find libGL.so.1";
@@ -29,78 +41,210 @@
 
     // Initializes context-independent parts of GLEW
     if (glxewInit() != GLEW_OK) {
-      LOG(ERROR) << "GLXEW failed initialization";
+      LOG(ERROR) << "glxewInit failed";
       return false;
     }
+    // Hack to work around apparently incorrect assumption in
+    // glxewContextInit. Documentation indicates that all of the work
+    // it does is actually context-independent. We require GLX 1.3
+    // entry points to be present for successful initialization of the
+    // off-screen code path in the GLES2Decoder. TODO(kbr): clean this
+    // up.
+    if (glxewContextInit() != GLEW_OK) {
+      LOG(ERROR) << "glxewContextInit failed";
+      return false;
+    }
+    g_glxew_initialized = true;
+  }
+  return true;
+}
+
+// GLEW initialization is extremely expensive because it looks up
+// hundreds of function pointers. Realistically we are not going to
+// switch between GL implementations on the fly, so for the time being
+// we only do the context-dependent GLEW initialization once.
+static bool InitializeGLEW() {
+  if (!g_glew_initialized) {
+    // Initializes context-dependent parts of GLEW
+    if (glewInit() != GLEW_OK) {
+      LOG(ERROR) << "GLEW failed initialization";
+      return false;
+    }
+
+    if (!glewIsSupported("GL_VERSION_2_0")) {
+      LOG(ERROR) << "GL implementation doesn't support GL version 2.0";
+      return false;
+    }
     g_glew_initialized = true;
   }
+  return true;
+}
+
+GLXContextWrapper::~GLXContextWrapper() {
+}
+
+bool GLXContextWrapper::Initialize() {
+  if (!MakeCurrent()) {
+    Destroy();
+    DLOG(ERROR) << "Couldn't make context current for initialization.";
+    return false;
+  }
+
+  if (!InitializeGLEW()) {
+    Destroy();
+    return false;
+  }
+
+  return true;
+}
+
+void GLXContextWrapper::Destroy() {
+  Bool result = glXMakeCurrent(GetDisplay(), 0, 0);
+  // glXMakeCurrent isn't supposed to fail when unsetting the context, unless
+  // we have pending draws on an invalid window - which shouldn't be the case
+  // here.
+  DCHECK(result);
+  if (GetContext()) {
+    glXDestroyContext(GetDisplay(), GetContext());
+    SetContext(NULL);
+  }
+}
+
+bool XWindowWrapper::Initialize() {
+  if (!InitializeGLXEW())
+    return false;
+
   XWindowAttributes attributes;
-  XGetWindowAttributes(display_, window_, &attributes);
+  XGetWindowAttributes(GetDisplay(), window_, &attributes);
   XVisualInfo visual_info_template;
   visual_info_template.visualid = XVisualIDFromVisual(attributes.visual);
   int visual_info_count = 0;
-  XVisualInfo *visual_info_list = XGetVisualInfo(display_, VisualIDMask,
-                                                 &visual_info_template,
-                                                 &visual_info_count);
-  DCHECK(visual_info_list);
+  scoped_ptr_malloc<XVisualInfo, ScopedPtrXFree> visual_info_list(
+      XGetVisualInfo(GetDisplay(), VisualIDMask,
+                     &visual_info_template,
+                     &visual_info_count));
+  DCHECK(visual_info_list.get());
   DCHECK_GT(visual_info_count, 0);
-  context_ = 0;
+  SetContext(NULL);
   for (int i = 0; i < visual_info_count; ++i) {
-    context_ = glXCreateContext(display_, visual_info_list + i, 0,
-                                True);
-    if (context_) break;
+    SetContext(glXCreateContext(GetDisplay(), visual_info_list.get() + i, 0,
+                                True));
+    if (GetContext())
+      break;
   }
-  XFree(visual_info_list);
-  if (!context_) {
+  if (!GetContext()) {
     DLOG(ERROR) << "Couldn't create GL context.";
     return false;
   }
-  if (!MakeCurrent()) {
+  return GLXContextWrapper::Initialize();
+}
+
+bool XWindowWrapper::MakeCurrent() {
+  if (glXGetCurrentDrawable() == window_ &&
+      glXGetCurrentContext() == GetContext()) {
+    return true;
+  }
+  if (glXMakeCurrent(GetDisplay(), window_, GetContext()) != True) {
+    glXDestroyContext(GetDisplay(), GetContext());
+    SetContext(0);
+    DLOG(ERROR) << "Couldn't make context current.";
     return false;
   }
+  return true;
+}
 
-  // Initializes context-dependent parts of GLEW
-  if (glewInit() != GLEW_OK) {
-    LOG(ERROR) << "GLEW failed initialization";
+bool XWindowWrapper::IsOffscreen() {
+  return false;
+}
+
+void XWindowWrapper::SwapBuffers() {
+  glXSwapBuffers(GetDisplay(), window_);
+}
+
+bool GLXPbufferWrapper::Initialize() {
+  if (!InitializeGLXEW())
     return false;
+
+  if (!glXChooseFBConfig ||
+      !glXCreateNewContext ||
+      !glXCreatePbuffer ||
+      !glXDestroyPbuffer) {
+    DLOG(ERROR) << "Pbuffer support not available.";
+    return false;
   }
 
-  if (!glewIsSupported("GL_VERSION_2_0")) {
-    LOG(ERROR) << "GL implementation doesn't support GL version 2.0";
+  static const int config_attributes[] = {
+    GLX_DRAWABLE_TYPE,
+    GLX_PBUFFER_BIT,
+    GLX_RENDER_TYPE,
+    GLX_RGBA_BIT,
+    GLX_DOUBLEBUFFER,
+    0,
+    0
+  };
+
+  int nelements = 0;
+  // TODO(kbr): figure out whether hardcoding screen to 0 is sufficient.
+  scoped_ptr_malloc<GLXFBConfig, ScopedPtrXFree> config(
+      glXChooseFBConfig(GetDisplay(), 0, config_attributes, &nelements));
+  if (!config.get()) {
+    DLOG(ERROR) << "glXChooseFBConfig failed.";
     return false;
   }
+  if (!nelements) {
+    DLOG(ERROR) << "glXChooseFBConfig returned 0 elements.";
+    return false;
+  }
+  SetContext(glXCreateNewContext(GetDisplay(),
+                                 config.get()[0], GLX_RGBA_TYPE, 0, True));
+  if (!GetContext()) {
+    DLOG(ERROR) << "glXCreateNewContext failed.";
+    return false;
+  }
+  static const int pbuffer_attributes[] = {
+    GLX_PBUFFER_WIDTH,
+    1,
+    GLX_PBUFFER_HEIGHT,
+    1,
+    0
+  };
+  pbuffer_ = glXCreatePbuffer(GetDisplay(),
+                              config.get()[0], pbuffer_attributes);
+  if (!pbuffer_) {
+    Destroy();
+    DLOG(ERROR) << "glXCreatePbuffer failed.";
+    return false;
+  }
+  return GLXContextWrapper::Initialize();
+}
 
-  return true;
+void GLXPbufferWrapper::Destroy() {
+  GLXContextWrapper::Destroy();
+  if (pbuffer_) {
+    glXDestroyPbuffer(GetDisplay(), pbuffer_);
+    pbuffer_ = NULL;
+  }
 }
 
-bool XWindowWrapper::MakeCurrent() {
-  if (glXGetCurrentDrawable() == window_ &&
-      glXGetCurrentContext() == context_) {
+bool GLXPbufferWrapper::MakeCurrent() {
+  if (glXGetCurrentDrawable() == pbuffer_ &&
+      glXGetCurrentContext() == GetContext()) {
     return true;
   }
-  if (glXMakeCurrent(display_, window_, context_) != True) {
-    glXDestroyContext(display_, context_);
-    context_ = 0;
+  if (glXMakeCurrent(GetDisplay(), pbuffer_, GetContext()) != True) {
+    glXDestroyContext(GetDisplay(), GetContext());
+    SetContext(0);
     DLOG(ERROR) << "Couldn't make context current.";
     return false;
   }
   return true;
 }
 
-void XWindowWrapper::Destroy() {
-  Bool result = glXMakeCurrent(display_, 0, 0);
-  // glXMakeCurrent isn't supposed to fail when unsetting the context, unless
-  // we have pending draws on an invalid window - which shouldn't be the case
-  // here.
-  DCHECK(result);
-  if (context_) {
-    glXDestroyContext(display_, context_);
-    context_ = 0;
-  }
+bool GLXPbufferWrapper::IsOffscreen() {
+  return true;
 }
 
-void XWindowWrapper::SwapBuffers() {
-  glXSwapBuffers(display_, window_);
+void GLXPbufferWrapper::SwapBuffers() {
 }
 
 }  // namespace gpu