function out = newconstr(Editor,keyword,CurrentConstr)
%NEWCONSTR  Interface with dialog for creating new constraints.
%
%   LIST = NEWCONSTR(Editor) returns the list of all available 
%   constraint types for this editor.
%
%   CONSTR = NEWCONSTR(Editor,TYPE) creates a constraint of the 
%   specified type.

%   Author(s): P. Gahinet
%   Copyright 1986-2004 The MathWorks, Inc. 
%   $Revision: 1.7.4.1 $  $Date: 2004/12/10 19:25:41 $

% RE: Editor.newconstr(type,currentconstr) is reserved for calls by newdlg
ni = nargin;
if ni==1
    % Return list of valid constraints
    out = {'Settling Time';'Percent Overshoot';'Damping Ratio';'Natural Frequency';'Region Constraint'};
else
    switch keyword
        case 'Settling Time'
            Class = 'plotconstr.pzsettling';
        case {'Damping Ratio','Percent Overshoot'}
            Class = 'plotconstr.pzdamping';
        case 'Natural Frequency'
            Class = 'plotconstr.pzfrequency';
       case 'Region Constraint'
          Class = 'plotconstr.pzlocation';
    end
    % Create instance
    if ni>2 & isa(CurrentConstr,Class)
        % Recycle existing instance if of same class
        Constr = CurrentConstr;  
    else
        % Create new instance
        PlotAxes = getaxes(Editor.Axes);
        Constr   = feval(Class,'Parent',PlotAxes,'PatchColor',Editor.ConstraintColor);
        Constr.Ts = Editor.LoopData.Ts;
        if strcmp(keyword,'Natural Frequency')
           if Constr.Ts, Constr.Frequency = 1/Constr.Ts; end
           Constr.FrequencyUnits = Editor.FrequencyUnits;
           % Install temp. listener to track freq. units in newdlg (will be cleared by initialize)
           Constr.Listeners = handle.listener(Editor,Editor.findprop('FrequencyUnits'),...
              'PropertyPostSet',{@LocalUpdate Constr});
        end
        if strcmp(keyword,'Settling Time') & Constr.Ts
           Constr.SettlingTime = 10*Constr.Ts;
        end
    end
    
    % Fine tuning
    switch keyword
       case 'Damping Ratio'
          Constr.Format = 'damping';
       case 'Percent Overshoot'
          Constr.Format = 'overshoot';
    end
   out = Constr;
end



%-------------------- Local functions ---------------------------------

%%%%%%%%%%%%%%%%%
%% LocalUpdate %%
%%%%%%%%%%%%%%%%%
function LocalUpdate(eventSrc,eventData,Constr);
% Syncs constraint props with related Editor props
set(Constr,eventSrc.Name,eventData.NewValue);