Fix racing condition in comic.cpp pdf render code (issue 25)

common/scroll_management.h

@@ -0,0 +1,25 @@
+#ifndef SCROLLMANAGAMENT_H
+#define SCROLLMANAGAMENT_H
+
+#include <QTime>
+#include <QWheelEvent>
+
+class ScrollManagement
+{
+public:
+    enum Movement{
+        None,
+        Forward,
+        Backward
+    };
+
+    ScrollManagement();
+    ScrollManagement::Movement getMovement(QWheelEvent * event);
+    ~ScrollManagement();
+
+private:
+    QTime * wheelTimer;
+    int wheelAccumulator;
+};
+
+#endif // SCROLLMANAGAMENT_H