Enable OpenGL by default.

Use a fake 1x1 window to be able to initialize opengl and get to the version number, also check for glInitFragmentProgramARB.
And if, for whatever reason, we decide not to load the OpenGL code, log why.

git-svn-id: https://xpra.org/svn/Xpra/trunk@929 3bb7dfac-3a0b-4e04-842a-767bc560f471

src/xpra/client.py

@@ -58,14 +58,14 @@ def set_windows_cursor(gtkwindows, new_cursor):
 
 from xpra.client_window import ClientWindow
 ClientWindowClass = ClientWindow
-#the GL backend only works with gtk2 (and is disabled by default)
-USE_OPENGL = False
+#the GL backend only works with gtk2
+USE_OPENGL = True
 if USE_OPENGL and not is_gtk3():
     try:
         from xpra.gl_client_window import GLClientWindow
         ClientWindowClass = GLClientWindow
     except ImportError, e:
-        pass    #GL not available
+        log.info("Disabled OpenGL output: %s" % e)
 
 def nn(x):
     if x is None:

src/xpra/gl_client_window.py

@@ -30,14 +30,33 @@
     glDrawArrays, glMultiTexCoord2i, \
     glVertex2i, glEnd
 from OpenGL.GL.ARB.vertex_program import glGenProgramsARB, glBindProgramARB, glProgramStringARB
+from OpenGL.GL.ARB.fragment_program import glInitFragmentProgramARB
 from xpra.gl_colorspace_conversions import GL_COLORSPACE_CONVERSIONS
 
-#This check would be nice to have,
-#but crashes python on some intel chipsets.. so we can't have it.
-#gl_major = glGetString(GL_VERSION)[0]
-#gl_minor = glGetString(GL_VERSION)[2]
-#if gl_major<=1 and gl_minor<1:
-#    raise ImportError("** OpenGL output requires OpenGL version 1.1 or greater, not %s.%s" % (gl_major, gl_minor))
+#sanity checks: OpenGL version
+try:
+    from gtk import gdk
+    glconfig = gtk.gdkgl.Config(mode=gtk.gdkgl.MODE_RGB|gtk.gdkgl.MODE_SINGLE)
+    glext = gtk.gdkgl.ext(gdk.Pixmap(gdk.get_default_root_window(), 1, 1))
+    gldrawable = glext.set_gl_capability(glconfig)
+    glcontext = gtk.gdkgl.Context(gldrawable, direct=True)
+    if not gldrawable.gl_begin(glcontext):
+        raise ImportError("gl_begin failed on %s" % gldrawable)
+    try:
+        gl_major = int(glGetString(GL_VERSION)[0])
+        gl_minor = int(glGetString(GL_VERSION)[2])
+        if gl_major<=1 and gl_minor<1:
+            raise ImportError("** OpenGL output requires OpenGL version 1.1 or greater, not %s.%s" % (gl_major, gl_minor))
+        log.info("found valid OpenGL: %s.%s", gl_major, gl_minor)
+
+        if not glInitFragmentProgramARB():
+            #see http://www.opengl.org/registry/specs/ARB/fragment_program.txt
+            raise ImportError("** OpenGL output requires the ARB_fragment_program extension")
+    finally:
+        gldrawable.gl_end()
+        del glcontext, gldrawable, glext, glconfig
+except Exception, e:
+    raise ImportError("** OpenGL initialization error: %s" % e)
 
 
 class GLClientWindow(ClientWindow):