Brilliant! How did I miss that constructor?! Josh
Hi,Why not construct the image object from the shared memory buffer to begin with? Then lock the sm while drawing. Look for example this constructor: http://doc.qt.io/qt-5/qimage.html#QImage-3 On Mon, Dec 12, 2016 at 11:45 PM, Joshua Grauman <jnf...@grauman.com> wrote: Hello all, I have been able to generate a screen capture of my program by rendering a window into a QImage at 30fps (called from QTimer), and then copying the QImage to shared memory (QSharedMemory) where another program grabs the frames and outputs them to ffmpeg. It all works great. However, my cpu is barely keeping up if I do much on my app. One of the ways I thought of to speed it up is to avoid the memcpy from the QImage (img) to QSharedMemory (sharedMemory) by deriving from QImage to a new class (QSharedMemoryImage) which allocates its image data in shared memory to begin with so that the window->render() function renders the window right into shared memory so the copy isn't necessary. QImage was a bit too complex for me to figure out how to do this. For you experts, is this possible? How hard would it be? Here's the relevant code in the QTimer: window->render(&img, QPoint(), QRegion(), QWidget::DrawChildren); sharedMemory.lock(); char *to = (char*)sharedMemory.data(); const unsigned char *from = img.constBits(); memcpy(to, from, sharedMemory.size()); sharedMemory.unlock(); Josh _______________________________________________ Interest mailing list Interest@qt-project.org http://lists.qt-project.org/mailman/listinfo/interest
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