% function h=hline(y, linetype, label)
% 
% Draws a horizontal line on the current axes at the location specified by 'y'.  Optional arguments are
% 'linetype' (default is 'r:') and 'label', which applies a text label to the graph near the line.  The
% label appears in the same color as the line.
%
% The line is held on the current axes, and after plotting the line, the function returns the axes to
% its prior hold state.
%
% The HandleVisibility property of the line object is set to "off", so not only does it not appear on
% legends, but it is not findable by using findobj.  Specifying an output argument causes the function to
% return a handle to the line, so it can be manipulated or deleted.  Also, the HandleVisibility can be 
% overridden by setting the root's ShowHiddenHandles property to on.
%
% h = hline(42,'g','The Answer')
%
% returns a handle to a green horizontal line on the current axes at y=42, and creates a text object on
% the current axes, close to the line, which reads "The Answer".
%
% hline also supports vector inputs to draw multiple lines at once.  For example,
%
% hline([4 8 12],{'g','r','b'},{'l1','lab2','LABELC'})
%
% draws three lines with the appropriate labels and colors.
% 
% By Brandon Kuczenski for Kensington Labs.
% brandon_kuczenski@kensingtonlabs.com
% 8 November 2001


% Copyright (c) 2001, Brandon Kuczenski
% All rights reserved.
% 
% Redistribution and use in source and binary forms, with or without
% modification, are permitted provided that the following conditions are
% met:
% 
% * Redistributions of source code must retain the above copyright
% notice, this list of conditions and the following disclaimer.
% * Redistributions in binary form must reproduce the above copyright
% notice, this list of conditions and the following disclaimer in
% the documentation and/or other materials provided with the distribution
% 
% THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
% AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
% IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
% ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
% LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
% CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
% SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
% INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
% CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
% ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
% POSSIBILITY OF SUCH DAMAGE.

function hhh=hline(y,in1,in2)

if length(y)>1  % vector input
    for I=1:length(y)
        switch nargin
        case 1
            linetype='r:';
            label='';
        case 2
            if ~iscell(in1)
                in1={in1};
            end
            if I>length(in1)
                linetype=in1{end};
            else
                linetype=in1{I};
            end
            label='';
        case 3
            if ~iscell(in1)
                in1={in1};
            end
            if ~iscell(in2)
                in2={in2};
            end
            if I>length(in1)
                linetype=in1{end};
            else
                linetype=in1{I};
            end
            if I>length(in2)
                label=in2{end};
            else
                label=in2{I};
            end
        end
        h(I)=hline(y(I),linetype,label);
    end
else
    switch nargin
    case 1
        linetype='r:';
        label='';
    case 2
        linetype=in1;
        label='';
    case 3
        linetype=in1;
        label=in2;
    end

    
    
    
    g=ishold(gca);
    hold on

    x=get(gca,'xlim');
    h=plot(x,[y y],linetype);
    if ~isempty(label)
        yy=get(gca,'ylim');
        yrange=yy(2)-yy(1);
        yunit=(y-yy(1))/yrange;
        if yunit<0.2
            text(x(1)+0.02*(x(2)-x(1)),y+0.02*yrange,label,'color',get(h,'color'))
        else
            text(x(1)+0.02*(x(2)-x(1)),y-0.02*yrange,label,'color',get(h,'color'))
        end
    end

    if g==0
    hold off
    end
    set(h,'tag','hline','handlevisibility','off') % this last part is so that it doesn't show up on legends
end % else

if nargout
    hhh=h;
end
