qpa: Document a requirement of the backing store implementation

Docuent the requirement that the alpha channels need to be properly
initialized by the implementation.

Change-Id: I03db81b44b43ea75feb1b983fb0725c65a3bd9f4
Reviewed-by: Samuel Rødal <samuel.rodal@nokia.com>
This commit is contained in:
Holger Hans Peter Freyther 2012-02-20 10:30:07 +01:00 committed by Qt by Nokia
parent 4a80a7ced1
commit e6f84312a5

View File

@ -114,6 +114,9 @@ QWindow* QPlatformBackingStore::window() const
This function is called before painting onto the surface begins, This function is called before painting onto the surface begins,
with the \a region in which the painting will occur. with the \a region in which the painting will occur.
\note A platform providing a backing store with an alpha channel
needs to properly initialize the region to be painted.
\sa endPaint(), paintDevice() \sa endPaint(), paintDevice()
*/ */