The QElapsedTimer class provides a fast way to calculate elapsed times.| doc.qt.io
The QIODevice class is the base interface class of all I/O devices in Qt.| doc.qt.io
The QDebug class provides an output stream for debugging information.| doc.qt.io
The QFile class provides an interface for reading from and writing to files.| doc.qt.io
The QDir class provides access to directory structures and their contents.| doc.qt.io
An overview of the drag and drop system provided by Qt.| doc.qt.io
The QPicture class is a paint device that records and replays QPainter commands.| doc.qt.io