[Development] X11/XCB QPA: QPlatformIntegration::ThreadedOpenGL returning false

[James Turner]

Hello,

I'm trying to understand some behaviour on an embedded target, where the XCB plugin is failing to select the threaded QSG render loop. This turns out to be because QPlatformIntegration::ThreadedOpenGL is returning false on the target.

(The target is linux-ARM, running X11)

This becomes:

bool QXcbIntegration::hasCapability(QPlatformIntegration::Capability cap) const
{
    switch (cap) {
<snip>
    case ThreadedOpenGL: return m_connections.at(0)->supportsThreadedRendering();

Which in turn becomes:

	(in qxcbconnection.h)

    bool supportsThreadedRendering() const { return m_reader->isRunning(); }

I need someone to explain the rational for this test, since I'm no X11 or XCB expert, and hopefully this will illuminate why it's failing on the particular target. (Which as far as I know has a standard X11 build on it)

Kind regards,
James