[Interest] QOpenGLContext::currentContext() returning nullptr (in some cases)

[Andy]

I have some code in my application to get information about the machine's
OpenGL. For most of my customers I'm getting useful, reasonable info from
it.

For example:

        "opengl": {
            "format": {
                "received": {
                    "profile": "1 [core]",
                    "version": "3.3"
                },
                "requested": {
                    "profile": "1 [core]",
                    "version": "3.3"
                }
            },
            "vendor": "Intel",
            "version": "3.3.0 - Build 20.19.15.4531",
            "renderer": "Intel(R) Iris(TM) Pro Graphics 5200",
            "shadingLanguage": "3.30 - Build 20.19.15.4531"


And:

        "opengl": {
            "format": {
                "received": {
                    "profile": "0 [none]",
                    "version": "3.0"
                },
                "requested": {
                    "profile": "1 [core]",
                    "version": "3.3"
                }
            },
            "vendor": "Google Inc.",
            "version": "OpenGL ES 3.0 (ANGLE 2.1.99f075dade7c)",
            "renderer": "ANGLE ( Direct3D11 vs_5_0 ps_5_0)",
            "shadingLanguage": "OpenGL ES GLSL ES 3.00 (ANGLE
2.1.99f075dade7c)"


For some though, it's failing to get a context at all. Here's roughly what
I'm doing:

   QString  openGLInfoString()
   {
      QGLFormat   requestedFormat;

      requestedFormat.setVersion( 3, 3 );
      requestedFormat.setProfile( QGLFormat::CoreProfile );

      QGLWidget   widget( requestedFormat );

      widget.makeCurrent();

      QOpenGLFunctions  *glFuncs = nullptr;

      if ( QOpenGLContext::currentContext() == nullptr )
      {
         return "OpenGL Info Error: Could not get current context";
      }

      glFuncs = QOpenGLContext::currentContext()->functions();

      // ... do some stuff to get some nice OpenGL info about what is
actually available
      return infoString;
   }


I'm using a downloaded Qt 5.6.2 (MinGW) installer.

In what situations should I expect QOpenGLContext::currentContext() to
return a nullptr? I thought with the fallback/ANGLE stuff I could always
expect at least the ANGLE stuff to kick in - as in the second example.

Thanks for any insight!

---
Andy Maloney  //  https://asmaloney.com
twitter ~ @asmaloney <https://twitter.com/asmaloney>
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