layer

Overlays multiple children in the same coordinate space without any layout offset.

from gofish import layer, rect, ellipse

layer([
    rect(w=100, h=80, fill="#9ecae1"),
    ellipse(w=60, h=60, fill="#fcae91"),
]).render(w=200, h=150)

Both shapes occupy the same space. The ellipse is drawn on top of the rectangle because it appears second in the list.

Signature

layer(children, **options) -> Mark

The children are a positional list of marks; layout options are passed as kwargs. Children typically carry .name(...) tags so they can be referenced from a .constrain(...) callback or by a sibling connect / ref.

Parameters

Option	Type	Description
coord	transform	Coordinate transform for this layer
w	float	Override width
h	float	Override height
transform.scale.x	float	Scale factor for x axis
transform.scale.y	float	Scale factor for y axis

Z-ordering

By default, children are drawn in the order they appear in the list — later children appear on top. You can override this with .z_order(n) on any child. Children are sorted by z-order value before rendering; lower values are drawn first (underneath). Children with the same z-order value keep their original list order.

from gofish import layer, rect, ellipse

layer([
    ellipse(w=60, h=60, fill="#fcae91").z_order(1),  # forced on top
    rect(w=100, h=80, fill="#9ecae1").z_order(0),     # forced underneath
])

.z_order() is available on every Mark. The chart-composing form of layer (which overlays whole charts) exposes the same control on a ChartBuilder as .zOrder().

Notes

• This is the low-level combinator-form layer, which wraps an explicit list of marks and renders directly. To overlay whole charts — for example to draw one chart's marks on top of another and relate them with cross-chart constraints — use the chart-composing form layer([chart1, chart2]), which composes ChartBuilder instances and accepts .constrain(...).
• Naming a child (rect(...).name("a")) makes it addressable from a .constrain(...) callback and from a sibling connect drawn over the same layer.