Подробное описание

The QStyleOptionProgressBarV2 class is used to describe the parameters necessary for drawing a progress bar in Qt 4.1 or above.

An instance of this class has type SO_ProgressBar and version 2.

The type is used internally by QStyleOption, its subclasses, and qstyleoption_cast() to determine the type of style option. In general you do not need to worry about this unless you want to create your own QStyleOption subclass and your own styles. The version is used by QStyleOption subclasses to implement extensions without breaking compatibility. If you use qstyleoption_cast(), you normally do not need to check it.

If you create your own QStyle subclass, you should handle both QStyleOptionProgressBar and QStyleOptionProgressBarV2. One way to achieve this is to use the QStyleOptionProgressBarV2 copy constructor. Например:

     if (const QStyleOptionProgressBar *progressBarOption =
            qstyleoption_cast<const QStyleOptionProgressBar *>(option)) {
         QStyleOptionProgressBarV2 progressBarV2(*progressBarOption);

         // draw the progress bar using progressBarV2
     }

In the example above: If the progressBarOption's version is 1, the extra members (orientation, invertedAppearance, and bottomToTop) are set to default values for progressBarV2. If the progressBarOption's version is 2, the constructor will simply copy the extra members to progressBarV2.

For an example demonstrating how style options can be used, see the Styles example.