Composite every visible overlay onto the capture canvas. No-op
when the overlay manager has nothing to draw.
glCanvas is the renderer's DOM element — its bounding rect maps
CSS pixels to capture pixels (see OverlayCaptureMetrics) and
is the coordinate frame for HTML-overlay positioning.
Composite every visible overlay onto the capture canvas. No-op when the overlay manager has nothing to draw.
glCanvasis the renderer's DOM element — its bounding rect maps CSS pixels to capture pixels (see OverlayCaptureMetrics) and is the coordinate frame for HTML-overlay positioning.