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Qt: Taking screenshot of EGLFS window - pixel-perfect identical result?

  • We're using EGLFS to run a QML app on an embedded linux device without a X server. So I can't use the usual techniques for getting a screenshot (e.g. using a screenshot utility app). In this question I found the technique of using QQuickView::grabWindow().

    My question: Is the result of this function guaranteed to be pixel-perfect identical to what the user sees on the screen? I'm worried that to grab the window contents, Qt might have to rerender the window using a different code path (e.g. render-to-texture), which may cause results to differ.

    I'd like a reliable reference included in your answers, too.