Shape layers (scripting)

New shape layers

comp.layers.addShape() makes a shape layer. layer.property("Contents").addProperty(matchName) builds AE's contents:

matchName	Properties
`ADBE Vector Group`	Its `property("Contents")`, and `property("Transform")`: Position, Anchor Point
`ADBE Vector Shape - Rect`	Size, Position, Roundness
`ADBE Vector Shape - Ellipse`	Size, Position
`ADBE Vector Shape - Star`	Type (1 star / 2 polygon), Points, Position, Rotation, Inner Radius, Outer Radius
`ADBE Vector Graphic - Fill`	Color, Opacity
`ADBE Vector Graphic - Stroke`	Color, Opacity, Stroke Width

A group's Fill and Stroke paint every path in it and in its subgroups. Set values with setValue. Contents of a new layer can't be keyframed in the same run, except Repeaters and Trim Paths.

var comp = app.project.activeItem;
var sl = comp.layers.addShape();
var g = sl.property("Contents").addProperty("ADBE Vector Group");
var r = g.property("Contents").addProperty("ADBE Vector Shape - Rect");
r.property("Size").setValue([200, 120]);
g.property("Contents").addProperty("ADBE Vector Graphic - Fill").property("Color").setValue([1, 0.5, 0]);

Existing shape layers

layer.property("Contents") lists the layer's groups (ADBE Vector Group, by name or 1-based index).
Each group's property("Contents") holds its paths (Rectangle / Ellipse / Polystar Path, named as in AE or by the name you gave them), then Fill 1 and Stroke 1 when the group shows them.
Read and setValue or setValueAtTime: Rect Size, Position, Roundness; Ellipse Size, Position; Polystar Points, Position, Rotation, Outer/Inner Radius; Fill Color, Opacity; Stroke Color, Opacity, Stroke Width.
addProperty adds a group to the layer, and rectangles, ellipses, polystars, a Fill or a Stroke to a group. Brio's groups don't nest.
remove() removes a group, a path or a Fill/Stroke. Groups and paths can be renamed. A group's enabled hides it. Moving a group's Transform Position moves its shapes.
Keyframes already on contents aren't read (numKeys is 0).

Repeaters and Trim Paths

ADBE Vector Filter - Repeater and ADBE Vector Filter - Trim become Brio's group Shape Ops, on new and existing layers. All their values can be keyframed with setValueAtTime, on a new layer too.

Repeater	Notes
Copies
Transform ▸ Anchor Point, Position, Rotation
Transform ▸ Scale	Even x and y.
Transform ▸ End Opacity	A fade per copy.
Offset, Composite, Start Opacity	Only at their defaults (0, Below, 100%).

Trim Paths	Notes
Start, End, Offset	Measured along AE's outline (an ellipse from the top, a rectangle from the top of its right edge), so the same values trim the same part.
Trim Multiple Shapes	Accepted, but Brio always trims each path on its own (AE's Individually). A group uses its first Trim Paths.

One added to a group works on that group; one added to the layer's Contents works on every group under it. Brio's own Grid and Transform Shape Ops list as BRIO Shape Op - Grid / - Transform (on/off and remove() only).

Drawn paths

ADBE Vector Shape - Group ("Path 1"): property("Path").value is an AE Shape — vertices, inTangents, outTangents (offsets from their vertex) and closed, Y-down and relative to the group, at the playhead.

setValue(shape) replaces the points (any number). A path with keyframes needs setValueAtTime.
setValueAtTime(t, shape) keys the pose with the same number of points as the path has; a still path can take a different count.
new Shape() makes one. addProperty("ADBE Vector Shape - Group") adds a drawn path to a group.
A path made of several subpaths shows its first one; the others are kept.

Not available

Shape group scale/rotation; keying a different number of points on an animated path.