OpenGLContext: Provide all data for SystemChildWindow creation.

Change-Id: I7a0ceee6c784af8240fb908f19622d4ede1f5a6a

include/vcl/opengl/OpenGLContext.hxx

@@ -157,6 +157,8 @@ public:
         return mbInitialized;
     }
 
+    static SystemWindowData generateWinData(Window* pParent);
+
 private:
     SAL_DLLPRIVATE bool initWindow();
 

vcl/source/opengl/OpenGLContext.cxx

@@ -684,4 +684,93 @@ bool OpenGLContext::initWindow()
 
 #endif
 
+#if defined( WNT ) || defined( MACOSX ) || defined( IOS) || defined( ANDROID )
+
+SystemWindowData OpenGLContext::generateWinData(Window* /*pParent*/)
+{
+    SystemWindowData aWinData;
+    aWinData.nSize = sizeof(aWinData);
+    return aWinData;
+}
+
+#elif defined( UNX )
+
+SystemWindowData OpenGLContext::generateWinData(Window* pParent)
+{
+    SystemWindowData aWinData;
+    aWinData.nSize = sizeof(aWinData);
+
+    const SystemEnvData* sysData(pParent->GetSystemData());
+
+    Display *dpy = reinterpret_cast<Display*>(sysData->pDisplay);
+
+    if( !glXQueryExtension( dpy, NULL, NULL ) )
+        return aWinData;
+
+    XLIB_Window win = sysData->aWindow;
+
+    SAL_INFO("vcl.opengl", "parent window: " << win);
+
+    XWindowAttributes xattr;
+    XGetWindowAttributes( dpy, win, &xattr );
+
+    int screen = XScreenNumberOfScreen( xattr.screen );
+
+    static int visual_attribs[] =
+    {
+        GLX_RED_SIZE,           8,
+        GLX_GREEN_SIZE,         8,
+        GLX_BLUE_SIZE,          8,
+        GLX_ALPHA_SIZE,         8,
+        GLX_DEPTH_SIZE,         24,
+        GLX_X_VISUAL_TYPE,      GLX_TRUE_COLOR,
+        None
+    };
+
+    initOpenGLFunctionPointers();
+
+    int fbCount = 0;
+    GLXFBConfig* pFBC = glXChooseFBConfig( dpy,
+            screen,
+            visual_attribs, &fbCount );
+
+    if(!pFBC)
+    {
+        SAL_WARN("vcl.opengl", "no suitable fb format found");
+        return aWinData;
+    }
+
+    int best_fbc = -1, best_num_samp = -1;
+    for(int i = 0; i < fbCount; ++i)
+    {
+        XVisualInfo* pVi = glXGetVisualFromFBConfig( dpy, pFBC[i] );
+        if(pVi)
+        {
+            // pick the one with the most samples per pixel
+            int nSampleBuf = 0;
+            int nSamples = 0;
+            glXGetFBConfigAttrib( dpy, pFBC[i], GLX_SAMPLE_BUFFERS, &nSampleBuf );
+            glXGetFBConfigAttrib( dpy, pFBC[i], GLX_SAMPLES       , &nSamples  );
+
+            if ( best_fbc < 0 || (nSampleBuf && ( nSamples > best_num_samp )) )
+            {
+                best_fbc = i;
+                best_num_samp = nSamples;
+            }
+        }
+        XFree( pVi );
+    }
+
+    XVisualInfo* vi = glXGetVisualFromFBConfig( dpy, pFBC[best_fbc] );
+    if( vi )
+    {
+        SAL_INFO("vcl.opengl", "using VisualID " << vi->visualid);
+        aWinData.pVisual = (void*)(vi->visual);
+    }
+
+    return aWinData;
+}
+
+#endif
+
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