If the size or DPR of the window we're drawing to with QOpenGLContext changes we need to call [NSOpenGLContext update] to recreate the backing texture. We were doing this in QCocoaGLContext::makeCurrent(), based on the assumption that clients would always call makeCurrent() before drawing, which is a documented requirement of QOpenGLContext: "To be able to support certain platforms, QOpenGLContext requires that you call makeCurrent() again before starting rendering a new frame, after calling swapBuffers()." However RHI doesn't follow this rule, and skips makeCurrent() from QRhiGles2::ensureContext() if the context is already current. This was causing issues when moving a window between screens with different device-pixel-ratios, as we were correctly rendering to the window with the updated DPR, but we had not resized the target texture to match. Changing QRhiGles2::ensureContext() might be an option, but nowadays we have QPlatformOpenGLContext::beginFrame(), which is guaranteed to be called (by RHI, not by generic QOpenGLContext clients). To cater for RHI we now call [NSOpenGLContext update] also from the beginFrame callback. Fixes: QTBUG-114873 Pick-to: 6.8 6.5 Change-Id: I9461135109fb1473ef9965f72f52beeb41b03680 Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>