cogl/glx: Move onscreen code to a separate file

Mostly in order to untangle it from the rest, preparing turning it into
a GObject.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1514>

cogl/cogl/meson.build

@@ -380,6 +380,8 @@ if have_glx
   cogl_sources += [
     'winsys/cogl-glx-display-private.h',
     'winsys/cogl-glx-renderer-private.h',
+    'winsys/cogl-onscreen-glx.c',
+    'winsys/cogl-onscreen-glx.h',
     'winsys/cogl-winsys-glx-feature-functions.h',
     'winsys/cogl-winsys-glx-private.h',
     'winsys/cogl-winsys-glx.c',

cogl/cogl/winsys/cogl-onscreen-glx.h

@@ -0,0 +1,87 @@
+/*
+ * Copyright (C) 2007,2008,2009,2010,2011,2013 Intel Corporation.
+ * Copyright (C) 2020 Red Hat
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy,
+ * modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef COGL_ONSCREEN_GLX_H
+#define COGL_ONSCREEN_GLX_H
+
+#include <GL/glx.h>
+#include <X11/Xlib.h>
+
+#include "cogl-onscreen.h"
+
+gboolean
+_cogl_winsys_onscreen_glx_init (CoglOnscreen  *onscreen,
+                                GError       **error);
+
+void
+_cogl_winsys_onscreen_glx_deinit (CoglOnscreen *onscreen);
+
+void
+_cogl_winsys_onscreen_glx_bind (CoglOnscreen *onscreen);
+
+int
+_cogl_winsys_onscreen_glx_get_buffer_age (CoglOnscreen *onscreen);
+
+void
+_cogl_winsys_onscreen_glx_swap_region (CoglOnscreen  *onscreen,
+                                       const int     *user_rectangles,
+                                       int            n_rectangles,
+                                       CoglFrameInfo *info,
+                                       gpointer       user_data);
+
+void
+_cogl_winsys_onscreen_glx_swap_buffers_with_damage (CoglOnscreen  *onscreen,
+                                                    const int     *rectangles,
+                                                    int            n_rectangles,
+                                                    CoglFrameInfo *info,
+                                                    gpointer       user_data);
+
+uint32_t
+_cogl_winsys_onscreen_glx_get_window_xid (CoglOnscreen *onscreen);
+
+void
+_cogl_winsys_onscreen_glx_set_visibility (CoglOnscreen *onscreen,
+                                          gboolean      visibility);
+
+void
+_cogl_winsys_onscreen_glx_set_resizable (CoglOnscreen *onscreen,
+                                         gboolean      resizable);
+
+void
+cogl_onscreen_glx_resize (CoglOnscreen    *onscreen,
+                          XConfigureEvent *configure_event);
+
+void
+cogl_onscreen_glx_update_output (CoglOnscreen *onscreen);
+
+void
+cogl_onscreen_glx_notify_swap_buffers (CoglOnscreen          *onscreen,
+                                       GLXBufferSwapComplete *swap_event);
+
+gboolean
+cogl_onscreen_glx_is_for_window (CoglOnscreen *onscreen,
+                                 Window        window);
+
+#endif /* COGL_ONSCREEN_GLX_H */

cogl/cogl/winsys/cogl-winsys-glx-private.h

@@ -34,4 +34,17 @@
 COGL_EXPORT const CoglWinsysVtable *
 _cogl_winsys_glx_get_vtable (void);
 
+gboolean
+cogl_display_glx_find_fbconfig (CoglDisplay                  *display,
+                                const CoglFramebufferConfig  *config,
+                                GLXFBConfig                  *config_ret,
+                                GError                      **error);
+
+void
+cogl_context_glx_set_current_drawable (CoglContext *context,
+                                       GLXDrawable  drawable);
+
+GLXDrawable
+cogl_context_glx_get_current_drawable (CoglContext *context);
+
 #endif /* __COGL_WINSYS_GLX_PRIVATE_H */

src/backends/x11/meta-renderer-x11.c

@@ -34,12 +34,17 @@
 #include "clutter/x11/clutter-x11.h"
 #include "cogl/cogl-xlib.h"
 #include "cogl/cogl.h"
-#include "cogl/winsys/cogl-winsys-egl-x11-private.h"
-#include "cogl/winsys/cogl-winsys-glx-private.h"
 #include "core/boxes-private.h"
 #include "meta/meta-backend.h"
 #include "meta/util.h"
 
+#ifdef COGL_HAS_EGL_SUPPORT
+#include "cogl/winsys/cogl-winsys-egl-x11-private.h"
+#endif
+#ifdef COGL_HAS_GLX_SUPPORT
+#include "cogl/winsys/cogl-winsys-glx-private.h"
+#endif
+
 G_DEFINE_TYPE (MetaRendererX11, meta_renderer_x11, META_TYPE_RENDERER)
 
 static const CoglWinsysVtable *