HiDPI: The region of when call QWidgetPrivate::setSystemClip does not match the region that was imported when call QPlatformBackingStore::beginPaint

Example:
    The window device ratio is: 1.5
    We have a to be paint region:
       

QRegion(size=3, bounds=(0,50 101x101) - [(0,50 100x1), (0,51 101x99), (1,150 100x1)]) QRect(0,50 101x101)

    The value of "systemClip" for paint engine after calling QWidgetPrivate::setSystemClip:
         

QRegion(size=3, bounds=(0,75 152x152) - [(0,75 150x2), (0,77 152x148), (2,225 150x2)])

     The value of "region" in QPlatformBackingStore::beginPaint:
          

QRegion(size=3, bounds=(0,75 152x152) - [(0,75 150x2), (0,77 152x149), (2,226 150x1)])

QWidgetPrivate::setSystemClip uses the QTransform::map function to calculate "systemClip", but uses the QHighDpi::toNativeLocalRegion function in QBackingStore::beginPaint to calculate the new region. The results of these two functions tend to be inconsistent