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POHow can I optimize the performance of a QGraphicsView-based app?
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  1. POHow can I optimize the performance of a QGraphicsView-based app?
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    copied!<p>I have an app which is based on the Qt Graphics View framework.<br> It's a jigsaw puzzle game which basically cuts a pixmap into smaller pixmaps (puzzle pieces) and displays them as <code>QGraphicsItem</code>s in a <code>QGraphicsView</code>. I want this app to run on smartphones and tablets. <em>(It already runs on the Nokia N900 and some Symbian phones. Not optimized for Symbian^3 yet.)</em><br> The source is <a href="https://gitorious.org/colorful-apps/puzzle-master" rel="nofollow">on Gitorious</a>.</p> <p>The items inherit <code>QGraphicsItem</code> and <code>QObject</code>, and have <code>Q_PROPERTY</code> macros for the <code>pos()</code> and <code>rotation()</code> of the <code>QGraphicsItem</code> to enable animating them with the Qt Animation framework.<br> I perform transformations on the items, such as scaling and rotating (the latter only in the in-development multitouch branch), and I also use <code>QGraphicsDropShadowEffect</code> on them.</p> <p>I use a <code>QGLWidget</code> as viewport of the <code>QGraphicsView</code> in order to enable OpenGL acceleration for the app.</p> <p>The problem is that despite being OpenGL-accelerated, the app is not smooth at all. (Especially the animations and especially since I added the rotation transform to the multitouch branch.) There are not many graphics items displayed, and there are no 3D operations or anything serious, just 2D drawing.<br> I'm not a graphics expert at all, so I have no idea why this app runs slowly. I've seen other games with lot more complicated effects run a lot smoother than this.</p> <p>What's the secret? How could I optimize this app?</p>
 

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