Player example histogram: Process frames on a separate thread

Change-Id: I6989f9ea9cb6e45c54ed75079a5b5748e15ee0d8
Reviewed-by: Dmytro Poplavskiy <dmytro.poplavskiy@nokia.com>
Reviewed-by: Michael Goddard <michael.goddard@nokia.com>

examples/player/histogramwidget.h

@@ -43,18 +43,31 @@
 
 #include <QWidget>
 #include <qvideoframe.h>
+#include <QThread>
 
 QT_USE_NAMESPACE
 
+class FrameProcessor: public QObject {
+    Q_OBJECT
+
+public slots:
+    void processFrame(QVideoFrame frame, int levels);
+
+signals:
+    void histogramReady(QVector<qreal> histogram);
+};
+
 class HistogramWidget : public QWidget
 {
     Q_OBJECT
 public:
     explicit HistogramWidget(QWidget *parent = 0);
+    ~HistogramWidget();
     void setLevels(int levels) { m_levels = levels; }
 
 public slots:
     void processFrame(QVideoFrame frame);
+    void setHistogram(QVector<qreal> histogram);
 
 protected:
     void paintEvent(QPaintEvent *event);
@@ -62,6 +75,9 @@ protected:
 private:
     QVector<qreal> m_histogram;
     int m_levels;
+    FrameProcessor m_processor;
+    QThread m_processorThread;
+    bool m_isBusy;
 };
 
 #endif // HISTOGRAMWIDGET_H