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regions, we have images, each with an \c onClick() handler that calls \c addImage(). \snippet examples/webkit/imageanalyzer/resources/index.html sample images Clicking an image adds it to an images list. \snippet examples/webkit/imageanalyzer/resources/index.html addImage The \bold {Analyze} button at the bottom of the image list is clicked when we want to start the analysis: \snippet examples/webkit/imageanalyzer/resources/index.html images list When the user clicks the \bold {Analyze} button, \c analyzeImages() is called, another regular JavaScript method, shown below. Notice it assumes the \c imageAnalyzer object is already defined and initialized in JavaScript space, but we guaranteed that by connecting our setup slot to the appropriate signal, \l{QWebFrame::}{javaScriptWindowObjectCleared()}. \snippet examples/webkit/imageanalyzer/resources/index.html analyzeImages The only methods on \c ImageAnalyzer that we can or do call from JavaScript are those which are exposed through \{The Meta-Object System}{Qt's MetaObject} system: \l{The Property System}{property} getter/setter methods, \c public \l {Signals & Slots}{signals and slots}, and other \l{Q_INVOKABLE}{Q_INVOKABLE} functions. \snippet examples/webkit/imageanalyzer/imageanalyzer.h ImageAnalyzer - public interface \dots \snippet examples/webkit/imageanalyzer/imageanalyzer.h ImageAnalyzer - private members Most of the members are set up in the constructor: \snippet examples/webkit/imageanalyzer/imageanalyzer.cpp ImageAnalyzer - Constructor Back on the JavaScript side, we want to connect signals from this object to JavaScript functions on our web page, after the web page is loaded, but before the images are analyzed. From \c connectSlots(), we can see how to connect signals from the imageAnalyzer object to regular JavaScript functions, which can also behave like slots. We use this to monitor and display progress from the C++ side. \snippet examples/webkit/imageanalyzer/resources/index.html connect slots The only public slot is \c startAnalysis(), called to place a list of URLs into the image analyzer's QtConcurrent processing queue from JavaScript space. \snippet examples/webkit/imageanalyzer/imageanalyzer.cpp ImageAnalyzer - startAnalysis The images need to be loaded again now, which is why fetchURLs first checks the cache to see if we can save an extra network get. \snippet examples/webkit/imageanalyzer/imageanalyzer.cpp ImageAnalyzer - fetchURLs For the images that were not in the cache, \c handleReply() will load them into a QImage when the data is ready. \snippet examples/webkit/imageanalyzer/imageanalyzer.cpp ImageAnalyzer - handleReply After the images are loaded, they are queued up in preparation to be sent in a batch for analysis to a \l QFutureWatcher, which will distribute the processing across multiple threads and cores, depending on how many are available. \snippet examples/webkit/imageanalyzer/imageanalyzer.cpp ImageAnalyzer - queueImage The function that gets performed on each image is \c averageRGB(), as specified in argument 2 to the \l{QtConcurrent::mapped()} function. Notice it repeats the same calculations 100 times on each pixel to keep the CPU very busy. This is done only for the purposes of the demo so that the analysis takes a noticeable time to complete. \snippet examples/webkit/imageanalyzer/imageanalyzer.cpp ImageAnalyzer - averageRGB */