A transparency group in a display list: its attributes, the alpha and blend mode its result composites onto its backdrop with, the area it can paint, and its content, which Replay(IRenderingBackend) hands to a backend. Valid only during the DrawGroup(in DisplayGroup) call that hands it over.
public ref readonly struct DisplayGroup
ISO 32000-2 §11.4: the objects of a group composite with one another into a single colour, shape and alpha per point, against an initial backdrop that is transparent for an isolated group (§11.4.5) and the group's backdrop otherwise; in a knockout group each object composites with that initial backdrop only, replacing what earlier objects of the group painted where it covers (§11.4.6). The result composites onto the backdrop as one object with Opacity and BlendMode, through the clip in force where the group is painted (§8.5.4).
Content: the replay starts with the state the backend holds at the group, and is balanced (SaveState() first, RestoreState() last), so the backend's state after it is what it was before. Inside, the alphas and blend mode the content paints with arrive through SetCompositing(Double, Double, BlendMode) as for any paint; the group's own Opacity and BlendMode are not set on the backend, they are here. A backend may replay the content more than once (for example once per colour plane) or not at all.
kind:method, kind:property, kind:ctor. Press Esc to clear.BlendModeGets the blend mode the group's result composites with: the one where it is painted.BoundingBoxGets the rectangle, in the group's space, outside which the content paints nothing: a group XObject's BBox (§8.10.2), or for a fill and stroke the path's bounds widened by the stroke's reach. Meaningful only when HasBoundingBox.ColorSpaceGets the group colour space, the blending colour space of the group's content, or null when the group blends in its parent's (always so for a non-isolated group). The page group's space without a CS is the backend's.ConversionGets the conversion the graphics state asked for where the group is painted (rendering intent and black point compensation), with Target RGB: the one that converts the group's result to its parent's colour space.DefaultColorSpacesGets the default colour spaces current where the group is painted, which replace a device ColorSpace.HasBoundingBoxGets a value indicating whether BoundingBox bounds what the content can paint; false when only the clip does (the page group, or a form without a usable BBox).IsIsolatedGets a value indicating whether the group is isolated: its objects composite onto a transparent initial backdrop.IsKnockoutGets a value indicating whether the group is a knockout group: each object composites with the initial backdrop only.KindGets where the group comes from: a group XObject, the page group, or the implicit group of a combined fill and stroke.MatrixGets the transform from the group's space, where BoundingBox is given, to the page's default user space: the form matrix concatenated with the CTM at Do, or the CTM of the path. Independent of SetTransform(in Matrix).OpacityGets the constant alpha the group's result composites with: the nonstroking alpha (ca) where it is painted.SoftMaskGets the soft mask the group's result composites through: the one in the graphics state at Do, whose values give the result's shape or opacity per point; IsNone when there is none (always for the page group and the implicit group of a fill and stroke, whose paints carry the mask themselves).Replay(IRenderingBackend)Calls backend once for every operation of the group's content, in order (nested groups included).