The new flag ItemContainsChildrenInShape is similar to the existing
flag ItemClipsChildrenToShape. Setting the new flag makes QGraphicsScene
assume that children are drawn within the shape of the current item
but this is not enforced by clipping. When an application manually
ensures this clipping boundary, setting the new flag removes the
overhead of enforcing the clip with ItemClipsChildrenToShape, while
still allowing other routines to behave more optimially by assuming
children are within the shape of the current item.
[ChangeLog][QtWidgets][QGraphicsItem] Added the
ItemContainsChildrenInShape flag that enables using optimizations
of ItemClipsChildrenToShape without the overhead of enforcing the clip.
Change-Id: I5496fe1ca331b77fd51e0df8a3ace2b8e939eaf2
Reviewed-by: Andreas Aardal Hanssen <andreas@hanssen.name>
3270b4490b