Extension point for custom overlays drawn after draw_series.
<insightdock/cartesian_chart.h>
virtual
void
draw_overlay(PlotContext& ctx) const;
Override to add reference lines, bands, annotations, watermarks, or combo-chart geometry without replacing the full render pipeline. The default implementation does nothing.
This hook is the architectural prerequisite for combo/dual-axis charts (Phase 0.6) and annotation layers (Phase 2).
| Name | Description |
|---|---|
| ctx | Context passed to draw_series() and draw_overlay() during rendering. |