beginTransparencyGroup
open override fun beginTransparencyGroup(bbox: KiteRectangle, ctm: KiteMatrix, isolated: Boolean, knockout: Boolean, alpha: Double, blendMode: KiteBlendMode)(source)
A non-isolated group at full alpha in Normal paints straight onto its backdrop, so its blend modes see what lies under it (ISO 32000-1, 11.4.5, #125). Any other group paints into a transparency layer. A transparency layer always starts transparent, which is exact for a non-isolated group only when no paint inside blends. In a knockout group (11.4.6) each paint replaces what lies under it inside its shape.