(Bir sürüm bilgisi bulunamadı; sadece SVN'de olabilir.)
This is used to set the compositing operator for all cairo drawing operations.
The default operator is CairoOperator::OVER
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.
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/.
CairoOperator::CLEAR
Clear destination layer (bounded)
CairoOperator::SOURCE
Replace destination layer (bounded)
CairoOperator::OVER
Draw source layer on top of destination layer (bounded)
CairoOperator::IN
Draw source where there was destination content (unbounded)
CairoOperator::OUT
Draw source where there was no destination content (unbounded)
CairoOperator::ATOP
Draw source on top of destination content and only there
CairoOperator::DEST
Ignore the source
CairoOperator::DEST_OVER
Draw destination on top of source
CairoOperator::DEST_IN
Leave destination only where there was source content (unbounded)
CairoOperator::DEST_OUT
Leave destination only where there was no source content
CairoOperator::DEST_ATOP
Leave destination on top of source content and only there (unbounded)
CairoOperator::XOR
Source and destination are shown where there is only one of them
CairoOperator::ADD
Source and destination layers are accumulated
CairoOperator::SATURATE
Like CairoOperator::OVER
, but assuming source and dest are disjoint geometries