chart.point Methods

ctx object namespaces for chart points — ctx.line, ctx.label, ctx.box, ctx.polyline when the visual is an object with endpoints or bounds.

ctx Object Namespaces: When the Visual Is an Object#

Choose object namespaces when you need endpoints, bounds, labels, or shapes that are not naturally represented as one value per row. The object still has to come from prepared data; only the object assembly happens inside build_visuals.

Available ctx object namespaces#

Namespace	Use for
`ctx.line.new(...)`	Line segment between two chart points (x1/y1 → x2/y2).
`ctx.label.new(...)`	Text label anchored to a chart point with configurable style.
`ctx.box.new(...)`	Rectangle defined by top-left and bottom-right chart points.
`ctx.polyline.new(...)`	Multi-segment path through an array of chart points.
`ctx.table.new(...)`	Managed table widget with rows, columns, and cell text.

chart.point coordinate convention#

All ctx.* objects accept x as a bar index (integer from the index column) and y as a price float. Always cast coordinates explicitly:

ctx.label.new(
    key="signal_label",
    x=int(last["index"]),
    y=float(last["low"]),
    text="BUY",
    color="#2962ff",
    style="label_down",
)

Rule: prepare coordinates in the frame, assemble objects in build_visuals#

# build_indicator_frame — prepare anchor columns
frame["signal_low"] = np.where(frame["buy_signal"], frame["low"], np.nan)

# build_visuals — assemble object from prepared data only
def build_visuals(frame, params=None, ctx=None):
    last = frame.iloc[-1]
    if not np.isnan(last.get("signal_low", float("nan"))):
        return ctx.label.new(
            key="buy_label",
            x=int(last["index"]),
            y=float(last["signal_low"]),
            text="BUY",
        )
    return None

Open chart.point example

ATK Graphics Bridge

Object Namespaces