AnimatedImage already had these properties, but some typically non-animated
image formats such as PDF, TIFF and ICO can also support multiple pages.
In either case, the currentFrame property can be used to select a specific
frame or page. However an AnimatedImage uses a QMovie to do that, whereas
a plain Image uses QQuickPixmap. So the accessors need to be virtual in
order to have these different implementations.
[ChangeLog][QtQuick][Image] Image and BorderImage now have currentFrame
and frameCount properties which can be used to step through the frames of
multi-page image formats such as TIFF, WEBP and ICO.
Task-number: QTBUG-77506
Change-Id: Id4d95a99a26a862957e44b1bd8ffe06d7eababef
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>
5d995ae122