Paint.Operator (gb.qt4)
Static Property Operator As Integer
Returns or sets the compositing operator to be used for all drawing operations. See each one of the constants below for details on the semantics of each available compositing operator.
This property takes one of the following value:
To keep things simple, the operator descriptions here document the behavior for when both source and destination are either fully transparent or fully opaque. The actual implementation works for translucent layers too. For a more detailed explanation of the effects of each operator, including the mathematical definitions, see
http://cairographics.org/operators/.
The operators marked as unbounded modify their destination even outside of the mask layer (that is, their effect is not bound by the mask layer). However, their effect can still be limited by way of clipping.