function [vertex, control, center] = get_event_display_points(event)

%--
% get event time and frequency limits
%--

start = event.time(1); stop = start + diff(event.time);

low = event.freq(1); high = low + diff(event.freq);

%--
% compute event vertices
%--

% NOTE: these are typically used to draw a single line

vertex.x = [start, stop, stop, start, start]; 

vertex.y = [low, low, high, high, low];

%--
% compute control points if needed
%--

if (nargout < 2)
	return; 
end

% NOTE: these are used to draw multiple marker lines
	
center.x = 0.5 * (start + stop);

center.y = 0.5 * (low + high);

control = [ ...
	stop, center.y; ...
	stop, high; ...
	center.x, high; ...
	start, high; ...
	start, center.y; ...
	start, low; ...
	center.x, low; ...
	stop, low; ...
	center.x, center.y ...
];