function image_erode(command)
%IMAGE_ERODE - Erode the current binary image
%
%		IMAGE_ERODE(COMMAND)
%
%			COMMAND - valid commands:
%
%				START  - set up the button frame and initialize
%				DOIT   - do the actual erosion
%				UNDO   - undo the erosion
%
%	Claudio  28 Sept. 1995
%

%
% Copyright (c) 1995 by Claudio Rivetti and Mark Young
% claudio@alice.uoregon.edu,    mark@alice.uoregon.edu
%

global I Handlefig Uibgcolor B_frame method_pop Undofun undo_bt exe_bt

if isempty(I)
  return;
end
if ~isbw(I)
  message('||         Image must be binary');
  return;
end

if nargin==0
  command='START';
end

figure(Handlefig);

% Position variables-------------------------------------
pos=get(B_frame, 'Position');
uiwidth=0.12;
uithick=0.035;
middle=pos(1)+(pos(3)-uiwidth)/2;
%--------------------------------------------------------

% Positions of buttons ----------------------------------
undo_pos = [middle pos(2)+0.35 uiwidth, uithick];
exec_pos = [middle pos(2)+0.45 uiwidth, uithick];
mp_pos = [middle pos(2)+.55 uiwidth uithick];
mt_pos = [middle-.005 pos(2)+.59 uiwidth+.005 uithick];
%--------------------------------------------------------

%  Callbacks for the buttons  ---------------------------
exec_cbk = 'image_erode(''DOIT'');'; 
undo_cbk = 'image_erode(''UNDO'');';

%--------------------------------------------------------

if strcmp(command,'START')
	if ~isimage
  		setviewmode('TOPVIEW');
  		showimage;
	end

	initbuttons('Image Erosion', 'Done');

	exe_bt = uicontrol(gcf,'Style','push',...
		'String', 'Execute',...
		'Units', 'normalized', ...
		'Position', exec_pos,...
		'CallBack',exec_cbk);

	undo_bt = uicontrol(gcf,'Style','push',...
		'String','Undo',...
		'Units', 'normalized', ...
		'Enable', 'off',...
		'Position', undo_pos,...
		'CallBack',undo_cbk);

	uicontrol(gcf,'Style','text',...
		'String','Method',...
		'Units','normalized',...
		'Horiz', 'center',...
		'BackgroundColor', Uibgcolor,...
		'Position',mt_pos);


	method_pop=uicontrol(gcf, 'Style', 'popup',...
		'Units', 'normalized',...
		'position', mp_pos,...
		'String', 'Erode|Skeleton|Shrink|Thin',...
		'Value', 1);


end	% START

if strcmp(command,'DOIT')
	f=watchon;
	methods=['Erode   ';'Skeleton';'Shrink  ';'Thin    '];
	statusbar('Eroding binary image...');
    v=get(method_pop, 'value');
	m=methods(v,:);
	m=strrep(m, ' ', '');
    setimage(erode(I,m));
    set(undo_bt, 'Enable', 'on');
	set(exe_bt, 'String', 'Re-Execute');
	clearstatusbar;
	watchoff(f);
end	% DOIT


if strcmp(command,'UNDO')
	undo;
	set(undo_bt, 'Enable', 'off');
end	% UNDO


return