Don't call GL debugging methods if there is no context.

Change-Id: Ie6b824953b8ad19fd1b6a146cb6bf52bbb152ef7
Reviewed-on: https://gerrit.libreoffice.org/18277Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Jan Holesovsky <kendy@collabora.com>

include/vcl/opengl/OpenGLContext.hxx

@@ -210,9 +210,11 @@ public:
     OpenGLProgram*      GetProgram( const OUString& rVertexShader, const OUString& rFragmentShader, const OString& preamble = "" );
     OpenGLProgram*      UseProgram( const OUString& rVertexShader, const OUString& rFragmentShader, const OString& preamble = "" );
 
+    /// Is this GL context the current context ?
     bool isCurrent();
     static void clearCurrent();
-
+    /// Is there a current GL context ?
+    static bool hasCurrent();
     /// make this GL context current - so it is implicit in subsequent GL calls
     void makeCurrent();
     /// reset the GL context so this context is not implicit in subsequent GL calls.

vcl/source/opengl/OpenGLContext.cxx

@@ -1402,6 +1402,17 @@ bool OpenGLContext::isCurrent()
 #endif
 }
 
+bool OpenGLContext::hasCurrent()
+{
+#if defined( WNT )
+    return wglGetCurrentContext() != NULL;
+#elif defined( MACOSX ) || defined( IOS ) || defined( ANDROID ) || defined(LIBO_HEADLESS)
+    return false;
+#elif defined( UNX )
+    return glXGetCurrentContext() != None;
+#endif
+}
+
 void OpenGLContext::clearCurrent()
 {
     ImplSVData* pSVData = ImplGetSVData();

vcl/source/opengl/OpenGLHelper.cxx

@@ -32,6 +32,7 @@
 #include "opengl/zone.hxx"
 #include "opengl/watchdog.hxx"
 #include <osl/conditn.h>
+#include <vcl/opengl/OpenGLContext.hxx>
 
 #if defined UNX && !defined MACOSX && !defined IOS && !defined ANDROID
 #include "opengl/x11/X11DeviceInfo.hxx"
@@ -690,15 +691,21 @@ void OpenGLHelper::debugMsgPrint(const char *pArea, const char *pFormat, ...)
     va_list aArgs;
     va_start (aArgs, pFormat);
 
-    char pStr[1024];
+    char pStr[1044];
 #ifdef _WIN32
 #define vsnprintf _vsnprintf
 #endif
     vsnprintf(pStr, sizeof(pStr), pFormat, aArgs);
-    pStr[sizeof(pStr)-1] = '\0';
+    pStr[sizeof(pStr)-20] = '\0';
+
+    bool bHasContext = !OpenGLContext::hasCurrent();
+    if (!bHasContext)
+        strcat(pStr, "- no GL context");
 
     SAL_INFO(pArea, pStr);
 
+    if (bHasContext)
+    {
         OpenGLZone aZone;
 
         if (GLEW_KHR_debug)
@@ -713,6 +720,7 @@ void OpenGLHelper::debugMsgPrint(const char *pArea, const char *pFormat, ...)
                                     GL_DEBUG_SEVERITY_LOW_AMD,
                                     1, // one[sic] id is as good as another ?
                                     strlen(pStr), pStr);
+    }
 
     va_end (aArgs);
 }