function trackpz(Editor, event)
%   TRACKPZ  Tracks compensator pole or zero during mouse drag.

%   Author(s): Bora Eryilmaz
%   Revised:
%   Copyright 1986-2004 The MathWorks, Inc.
%   $Revision: 1.31.4.3 $  $Date: 2004/04/10 23:14:14 $

persistent MovedGroup PZID G0
persistent AutoScaleX AutoScaleY InvalidMove
persistent hline % Pole/zero locus curve
persistent TransAction
persistent WarnStatus LastMsg LastID

% Handles
LoopData   = Editor.LoopData;
Axes = Editor.Axes;
PlotAxes = getaxes(Axes);
PhaseUnits = Axes.XUnits;
EventMgr   = Editor.EventManager;
Ts = LoopData.Ts;

% INIT event
if strcmp(event, 'init')
  % Initialization for compensator pole/zero drag
  
  % Turn off warning and store last warning 
  WarnStatus = warning('off');
  [LastMsg, LastID] = lastwarn;
  
  % Identify selected marker and selected root properties
  [MovedGroup, PZID, G0] = LocalGetSelection(gcbo);
  if Ts & MovedGroup.beyondnf(PZID, 0.1)
    % Discrete roots beyond Nyquist freq. cannot be moved
    EventMgr.poststatus(sprintf(['Cannot move roots with natural', ...
		    'frequency beyond the Nyquist frequency.\n', ...
		    'Use the Root Locus Editor to move such poles/zeros.']));
    InvalidMove = 1;
    return
  else
    InvalidMove = 0;
  end
  
  % Initialize parameters used to adjust limits and pointer position
  AutoScaleX = strcmp(Axes.XlimMode, 'auto');
  AutoScaleY = strcmp(Axes.YlimMode, 'auto');
  if (AutoScaleX | AutoScaleY),
    moveptr(PlotAxes,'init');
  end
  
  % Create pole/zero locus curve
  hline = line([1 1], [NaN NaN], ...
	       'parent',    PlotAxes, ...
	       'HitTest',   'off', ...
	       'EraseMode', 'xor', ...
	       'Visible',   get(PlotAxes, 'Visible'), ...
	       'Color',     Editor.LineStyle.Color.Compensator, ...
	       'LineStyle', '--');
  
  % Track root location in status bar 
  EventMgr.poststatus(...
      LocalTrackStatus(MovedGroup, PZID, Ts, Editor.FrequencyUnits));
  
  % Broadcast MOVEPZ:init event
  % REMARK: Sets RefreshMode = 'quick' and installs listeners
  % on Pole/Zero property of selected group
  LoopData.send('MovePZ', ctrluis.dataevent(LoopData, 'MovePZ', ...
      {Editor.EditedObject.Identifier, 'init', MovedGroup}));
   
  % Start transaction
  TransAction = ctrluis.transaction(LoopData, ...
      'Name', sprintf('Move %s', PZID), 'OperationStore', 'on', ...
      'InverseOperationStore', 'on', 'Compression', 'on');
   
  % Start plotting the tracking curve
  Editor.trackpz('acquire');
end

% ACQUIRE and FINISH events
if ~InvalidMove
  switch event
   case 'acquire'
    % Acquire new pole/zero position. 
    CP = get(PlotAxes, 'CurrentPoint');
    
    % Convert mouse coordinates to default units
    X = unitconv(CP(1,1), PhaseUnits, 'rad'); 
    Y = 10^(CP(1,2)/20);
    
    % Clear open loop model (stale)
    LoopData.reset('all');
    
    % Inputs to MOVEPZ must be in (rad/sec, abs, rad)
    [X,Y] = movepz(Editor, MovedGroup, PZID, G0, X, Y, hline);
    
    % Convert back to current units
    X = unitconv(X, 'rad', PhaseUnits);
    Y = mag2dB(Y);
    
    % Broadcast PZDataChanged event (triggers plot updates)
    MovedGroup.send('PZDataChanged');
    
    % Track root location in status bar 
    EventMgr.poststatus(...
	LocalTrackStatus(MovedGroup, PZID, Ts, Editor.FrequencyUnits));
    
    % Adjust axis limits if dragged pole/zero gets out of focus
    if AutoScaleX | AutoScaleY,
      % Adjust limits to track mouse motion
      Editor.reframe(PlotAxes,X,Y)
    end
    
   case 'finish'
    % Delete locus curve
    delete(hline(ishandle(hline)));
    
    % Button up event.  Commit and stack transaction
    EventMgr.record(TransAction);
    TransAction = [];   % release persistent objects
    
    % Broadcast MOVEPZ:finish event (exit RefreshMode=quick,...)  
    LoopData.send('MovePZ', ctrluis.dataevent(LoopData, 'MovePZ', ...
         {Editor.EditedObject.Identifier, 'finish'}));
    
    % Update status and command history
    Str = MovedGroup.movelog(PZID, Ts);
    EventMgr.newstatus(sprintf('%s\nRight-click on plots for more design options.', Str));
    EventMgr.recordtxt('history', Str);
    MovedGroup = [];   % release persistent objects
    
    % Trigger global update
    LoopData.dataevent('all');
    
    % Turn warning back on and reset last warning
    warning(WarnStatus);
    lastwarn(LastMsg, LastID);
  end
end


% ----------------------------------------------------------------------------%
% Local Functions
% ----------------------------------------------------------------------------%

% ----------------------------------------------------------------------------%
% Function: LocalGetSelection
% Purpose:  Identifies selected PZGROUP object (pole/zero group)
% ----------------------------------------------------------------------------%
function [MovedGroup, PZID, G0] = LocalGetSelection(CurrentObj)
% Moved PZVIEW object
MovedPZVIEW = getappdata(CurrentObj, 'PZVIEW');

if any(MovedPZVIEW.Zero == CurrentObj)
  PZID = 'Zero';
else
  PZID = 'Pole';
end

% Moved PZGROUP
MovedGroup = MovedPZVIEW.GroupData; % pointer to pole/zero values (dynamic)
G0 = get(MovedGroup);               % initial pole/zero values (fixed)


% ----------------------------------------------------------------------------%
% Function: LocalTrackStatus
% Display info about moved pole/zero
% ----------------------------------------------------------------------------%
function Status = LocalTrackStatus(PZGroup, PZID, Ts, FreqUnits)
% Definitions
Spacing = blanks(4);

switch PZGroup.Type
 case 'Notch'
  % Custom display for notch filters
  Text = sprintf('Drag this notch to adjust its depth and natural frequency.');
  [Wn, Zeta] = damp([PZGroup.Zero(1) ; PZGroup.Pole(1)], Ts);
  Wn = unitconv(Wn, 'rad/sec', FreqUnits);
  Damping = sprintf('Zero Damping: %0.3g%s Pole Damping: %0.3g', ...
		    Zeta(1), Spacing, Zeta(2));
  Status = sprintf('%s\nNatural Frequency: %0.3g %s%s%s', ...
		   Text, Wn(1), FreqUnits, Spacing, Damping);
  
 case 'Complex'
  % Complex pair
  Text = sprintf('Drag this %s to the desired location.', lower(PZID));
  R = get(PZGroup, PZID);
  R = R(1);
  [Wn, Zeta] = damp(R, Ts);
  Wn = unitconv(Wn, 'rad/sec', FreqUnits);
  Damping = sprintf('Damping: %0.3g%s Natural Frequency: %0.3g %s', ...
		    Zeta, Spacing, Wn, FreqUnits);
  Status = sprintf('%s\nCurrent location: %0.3g %s %0.3gi %s%s',...
		   Text, real(R), char(177), abs(imag(R)), Spacing, Damping);
  
 otherwise
  % Real pole/zero
  Text = sprintf('Drag this %s to the desired location.', lower(PZID));
  R = get(PZGroup, PZID);
  if Ts
    Wn = unitconv(damp(R, Ts), 'rad/sec', FreqUnits);
    NatFreq = sprintf('Natural Frequency: %0.3g %s', Wn, FreqUnits);
    Status = sprintf('%s\nCurrent location: %0.3g %s%s', ...
		     Text, R, Spacing, NatFreq);
  else
    Status = sprintf('%s\nCurrent location: %0.3g', Text, R);
  end
end