Establecer DrawingMode JavaScript
drawingManager.setDrawingMode(google.maps.drawing.OverlayType.CIRCLE);
Glamorous Gazelle
drawingManager.setDrawingMode(google.maps.drawing.OverlayType.CIRCLE);
google.maps.drawing.OverlayType.MARKER
google.maps.drawing.OverlayType.POLYGON
google.maps.drawing.OverlayType.POLYLINE
google.maps.drawing.OverlayType.RECTANGLE
google.maps.drawing.OverlayType.CIRCLE