Bind building of glx support on whether epoxy has a glx header

So far it was bound to whether we build for GLES. But this is
semantically wrong. It might be possible that even on desktop gl
epoxy is built without GLX support, thus we need to reflect this.

This change ensures that epoxy/glx.h is only included if available,
that relevant code is bound to it and that checks are in place to
enforce EGL if not build with glx support.

In addtion the glxbackend.cpp is now only included in the build set
if available.

CMakeLists.txt

@@ -272,6 +272,7 @@ endif()
 include_directories(${XKB_INCLUDE_DIR})
 
 include_directories(${epoxy_INCLUDE_DIR})
+set(HAVE_EPOXY_GLX ${epoxy_HAS_GLX})
 
 # for things that are also used by kwin libraries
 configure_file(libkwineffects/kwinconfig.h.cmake ${CMAKE_CURRENT_BINARY_DIR}/libkwineffects/kwinconfig.h )
@@ -355,7 +356,6 @@ set(kwin_KDEINIT_SRCS
    scene_xrender.cpp
    scene_opengl.cpp
    scene_qpainter.cpp
-   glxbackend.cpp
    thumbnailitem.cpp
    lanczosfilter.cpp
    deleted.cpp
@@ -392,6 +392,10 @@ set(kwin_KDEINIT_SRCS
     wayland_cursor_theme.cpp
    )
 
+if(HAVE_EPOXY_GLX)
+    set(kwin_KDEINIT_SRCS ${kwin_KDEINIT_SRCS} glxbackend.cpp)
+endif()
+
 if(KWIN_BUILD_TABBOX)
     set(
         kwin_KDEINIT_SRCS ${kwin_KDEINIT_SRCS}

cmake/modules/Findepoxy.cmake

@@ -5,6 +5,7 @@
 #  epoxy_LIBRARY      - The libepoxy library
 #  epoxy_INCLUDE_DIR  - The libepoxy include dir
 #  epoxy_DEFINITIONS  - Compiler switches required for using libepoxy
+#  epoxy_HAS_GLX      - Whether GLX support is available
 
 # Copyright (c) 2014 Fredrik Höglund <fredrik@kde.org>
 #
@@ -40,9 +41,16 @@ if (NOT WIN32)
 
   find_path(epoxy_INCLUDE_DIR NAMES epoxy/gl.h HINTS ${PKG_epoxy_INCLUDEDIR} ${PKG_epoxy_INCLUDE_DIRS})
   find_library(epoxy_LIBRARY  NAMES epoxy      HINTS ${PKG_epoxy_LIBDIR} ${PKG_epoxy_LIBRARY_DIRS})
+  find_file(epoxy_GLX_HEADER NAMES epoxy/glx.h HINTS ${epoxy_INCLUDE_DIR})
+
+  if (epoxy_GLX_HEADER STREQUAL "epoxy_GLX_HEADER-NOTFOUND")
+    set(epoxy_HAS_GLX FALSE CACHE BOOL "whether glx is available")
+  else ()
+    set(epoxy_HAS_GLX TRUE CACHE BOOL "whether glx is available")
+  endif()
 
   include(FindPackageHandleStandardArgs)
   find_package_handle_standard_args(epoxy DEFAULT_MSG epoxy_LIBRARY epoxy_INCLUDE_DIR)
 
-  mark_as_advanced(epoxy_INCLUDE_DIR epoxy_LIBRARY)
+  mark_as_advanced(epoxy_INCLUDE_DIR epoxy_LIBRARY epoxy_HAS_GLX)
 endif()

dbusinterface.cpp

@@ -241,7 +241,10 @@ void CompositorDBusInterface::suspend()
 QStringList CompositorDBusInterface::supportedOpenGLPlatformInterfaces() const
 {
     QStringList interfaces;
-    bool supportsGlx = (kwinApp()->operationMode() == Application::OperationModeX11);
+    bool supportsGlx = false;
+#if HAVE_EPOXY_GLX
+    supportsGlx = (kwinApp()->operationMode() == Application::OperationModeX11);
+#endif
 #ifdef KWIN_HAVE_OPENGLES
     supportsGlx = false;
 #endif

glxbackend.cpp

@@ -22,8 +22,6 @@ You should have received a copy of the GNU General Public License
 along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *********************************************************************/
 
-// TODO: cmake magic
-#ifndef KWIN_HAVE_OPENGLES
 // own
 #include "glxbackend.h"
 // kwin
@@ -870,4 +868,3 @@ OpenGLBackend *GlxTexture::backend()
 }
 
 } // namespace
-#endif

glxbackend.h

@@ -23,6 +23,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "x11eventfilter.h"
 
 #include <xcb/glx.h>
+#include <epoxy/glx.h>
 #include <memory>
 
 namespace KWin

libkwineffects/kwinconfig.h.cmake

@@ -19,5 +19,7 @@
 /* KWIN_HAVE_XRENDER_COMPOSITING - whether XRender-based compositing support is available */
 #cmakedefine KWIN_HAVE_XRENDER_COMPOSITING
 
+#cmakedefine01 HAVE_EPOXY_GLX
+
 
 #endif

libkwineffects/kwinglutils.cpp

@@ -45,6 +45,10 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 #include <math.h>
 
+#if HAVE_EPOXY_GLX
+#include <epoxy/glx.h>
+#endif
+
 #define DEBUG_GLRENDERTARGET 0
 
 #define MAKE_GL_VERSION(major, minor, release)  ( ((major) << 16) | ((minor) << 8) | (release) )
@@ -77,7 +81,7 @@ int glTextureUnitsCount;
 // Functions
 void initGLX()
 {
-#ifndef KWIN_HAVE_OPENGLES
+#if HAVE_EPOXY_GLX
     // Get GLX version
     int major, minor;
     glXQueryVersion(display(), &major, &minor);

libkwineffects/kwinglutils_funcs.cpp

@@ -21,6 +21,9 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "kwinglutils.h"
 
 #include <dlfcn.h>
+#if HAVE_EPOXY_GLX
+#include <epoxy/glx.h>
+#endif
 
 
 // Resolves given function, using getProcAddress
@@ -56,10 +59,12 @@ glGetnUniformfv_func          glGetnUniformfv;
 
 typedef void (*glXFuncPtr)();
 
-#ifndef KWIN_HAVE_OPENGLES
 static glXFuncPtr getProcAddress(const char* name)
 {
-    glXFuncPtr ret = glXGetProcAddress((const GLubyte*) name);
+    glXFuncPtr ret = nullptr;
+#if HAVE_EPOXY_GLX
+    ret = glXGetProcAddress((const GLubyte*) name);
+#endif
     if (ret == nullptr)
         ret = (glXFuncPtr) dlsym(RTLD_DEFAULT, name);
     return ret;
@@ -72,7 +77,6 @@ void glxResolveFunctions()
     else
         glXSwapIntervalMESA = nullptr;
 }
-#endif
 
 void eglResolveFunctions()
 {

libkwineffects/kwinglutils_funcs.h

@@ -27,10 +27,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 #include <epoxy/egl.h>
 
-#ifndef KWIN_HAVE_OPENGLES
-#include <epoxy/glx.h>
-#endif
-
 #include <fixx11h.h>
 
 #include <epoxy/gl.h>
@@ -51,9 +47,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 namespace KWin
 {
 
-#ifndef KWIN_HAVE_OPENGLES
 void KWINGLUTILS_EXPORT glxResolveFunctions();
-#endif
 
 void KWINGLUTILS_EXPORT eglResolveFunctions();
 

options.cpp

@@ -764,6 +764,10 @@ void Options::setGlPlatformInterface(OpenGLPlatformInterface interface)
         qCDebug(KWIN_CORE) << "Forcing EGL native interface for Wayland mode";
         interface = EglPlatformInterface;
     }
+#if !HAVE_EPOXY_GLX
+    qCDebug(KWIN_CORE) << "Forcing EGL native interface as compiled without GLX support";
+    interface = EglPlatformInterface;
+#endif
 #ifdef KWIN_HAVE_OPENGLES
     qCDebug(KWIN_CORE) << "Forcing EGL native interface as compiled against OpenGL ES";
     interface = EglPlatformInterface;

scene_opengl.cpp

@@ -28,9 +28,9 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *********************************************************************/
 #include "scene_opengl.h"
 #include "eglonxbackend.h"
-#ifndef KWIN_HAVE_OPENGLES
+#if HAVE_EPOXY_GLX
 #include "glxbackend.h"
-#endif // KWIN_HAVE_OPENGLES
+#endif
 
 #include "abstract_backend.h"
 #include "wayland_server.h"
@@ -541,7 +541,7 @@ SceneOpenGL *SceneOpenGL::createScene(QObject *parent)
 
     switch (platformInterface) {
     case GlxPlatformInterface:
-#ifndef KWIN_HAVE_OPENGLES
+#if HAVE_EPOXY_GLX
         backend = new GlxBackend();
 #endif
         break;

workspace.cpp

@@ -1383,6 +1383,12 @@ QString Workspace::supportInformation() const
     support.append(yes);
 #else
     support.append(no);
+#endif
+    support.append(QStringLiteral("HAVE_EPOXY_GLX: "));
+#if HAVE_EPOXY_GLX
+    support.append(yes);
+#else
+    support.append(no);
 #endif
     support.append(QStringLiteral("\n"));