function hout = imoverviewpanel(varargin)
%IMOVERVIEWPANEL Overview tool panel for image displayed in scroll panel.
%   HPANEL = IMOVERVIEWPANEL(HPARENT, HIMAGE) creates an Overview tool panel
%   associated with the image specified by the handle HIMAGE, called the target
%   image. HIMAGE must be contained in a scroll panel created by
%   IMSCROLLPANEL. HPARENT is a handle to the figure or uipanel object that will
%   contain the Overview tool panel. IMOVERVIEWPANEL returns HPANEL, a handle to
%   the Overview tool uipanel object.
%
%   The Overview tool is a navigation aid for images displayed in a scroll
%   panel. IMOVERVIEWPANEL creates the tool in a uipanel object that can be
%   embedded in a figure or uipanel object. The tool displays the target image
%   in its entirety, scaled to fit.  Over this scaled version of image, the tool
%   draws a rectangle, called the detail rectangle, that shows the portion of
%   the target image that is currently visible in the scroll panel. To view
%   portions of the image that are not currently visible in the scroll panel,
%   move the detail rectangle in the Overview tool.
%
%   Note 
%   ----
%   To create an Overview tool in a separate figure, use IMOVERVIEW.
%   
%   Example
%   -------
%
%       hFig = figure('Toolbar','none',...
%                     'Menubar','none');
%       hIm = imshow('tissue.png'); 
%       hSP = imscrollpanel(hFig,hIm);
%       set(hSP,'Units','normalized',...
%               'Position',[0 .5 1 .5])
%
%       hOvPanel = imoverviewpanel(hFig,hIm);
%       set(hOvPanel,'Units','Normalized',...
%                    'Position',[0 0 1 .5])
%
%   See also IMOVERVIEW, IMPOSITIONRECT, IMSCROLLPANEL.

%   Copyright 1993-2004 The MathWorks, Inc.
%   $Revision: 1.1.8.3 $  $Date: 2004/12/18 07:36:07 $

   iptchecknargin(2, 2, nargin, mfilename);
   parent = varargin{1};
   himage = varargin{2};
   
   iptcheckhandle(parent,{'figure','uipanel','uicontainer'},mfilename,'HPARENT',1)
   iptcheckhandle(himage,{'image'},mfilename,'HIMAGE',2)
  
   hScrollpanel = getimscrollpanel(himage,mfilename,'HIMAGE');
   apiScrollpanel = iptgetapi(hScrollpanel);
   
   hScrollpanelIm = findobj(hScrollpanel,'Type','Image');   
   hScrollpanelAx = findobj(hScrollpanel,'Type','Axes');
   
   hOverviewPanel = uipanel('Parent',parent,...
                            'BorderType','none',...
                            'DeleteFcn',@deleteOverview);

   hOverviewAx = copyobj(hScrollpanelAx, hOverviewPanel);

   hOverviewIm = copyobj(hScrollpanelIm, hOverviewAx);
   set(hOverviewIm,'ButtonDownFcn',[],... % Don't want to copy this
                   'HitTest','off');      % Turn off by default to allow
                                          % rect to be draggable

   hFig = ancestor(himage,'figure');
   hOverviewFig = ancestor(hOverviewIm, 'figure');
   if ndims(get(himage, 'CData')) == 2
       set(hOverviewFig, 'Colormap', get(hFig, 'Colormap'));
   end
   
   hDetailRect = impositionrect(hOverviewAx, ...
                                apiScrollpanel.getVisibleImageRect());
   apiDetailRect = iptgetapi(hDetailRect);
   apiDetailRect.addNewPositionCallback(@detailDragged);
   apiDetailRect.setDragConstraintCallback(@constrainDetail);

   linkAx = linkprop([hScrollpanelAx hOverviewAx],'CLim');

   set(hOverviewAx,...
       'Units','normalized',...
       'Position',[0 0 1 1]);

   hScrollable = handle(get(hScrollpanelAx,'parent'));
   scrollpanelListener = handle.listener(hScrollable, ...
                                        hScrollable.findprop('Position'), ...
                                        'PropertyPostSet', @updateDetail);

   setappdata(hOverviewPanel,'linkAxListener',linkAx)
   setappdata(hOverviewPanel,'scrollpanelListener',scrollpanelListener)
   
   if (nargout==1)
       hout = hOverviewPanel;
   end

   %-------------------------------
   function detailDragged(varargin)

     if exist('apiDetailRect','var') % geck this to nested functions
         posDetail = apiDetailRect.getPosition();
         apiScrollpanel.setVisibleLocation(posDetail(1),posDetail(2));
     end
     
   end

   %------------------------------------------
   function pos = constrainDetail(proposedPos)

     imModel = getimagemodel(hOverviewIm);
     pos = constrainPositionRect(proposedPos, getImageWidth(imModel), ...
                                 getImageHeight(imModel));
   end

   %------------------------------
   function updateDetail(varargin)

     newpos = apiScrollpanel.getVisibleImageRect();
     apiDetailRect.setPosition(newpos);
     
   end

  %---------------------------------
  function deleteOverview(src,event)
  
    clear scrollpanelListener
  
  end
  
end