swooshprop(varargin)

function swooshprop(varargin)
% SWOOSHPROP(OBJ, PROP, VALUE, ...)
%
% Make the setting of the object OBJ property PROP be lazy, or
% slow.  The VALUE is the destination value.
%
% This works with a timer, so that users can continue interacting
% with a plot, and possibly redirect an in progress animation.
    
    if mod(nargin,3) ~= 0
        error('Wrong number of arguments for swooshprop.'); %#ok
    end
    
    idx = 1;
    for i=1:3:length(varargin)
        opv(idx).obj = varargin{i}; %#ok
        if ~ishandle(opv(idx).obj)
            error('Argument %d must be an HG handle.', i); %#ok
        end
        
        opv(idx).prop = varargin{i+1}; %#ok
        if ~ischar(opv(idx).prop)
            error('Argument %d must be a string/Property name for %s',...
                  i+1, get(opv(idx).obj,'type')); %#ok
        end
        
        opv(idx).val = varargin{i+2}; %#ok
        if ~isnumeric(opv(idx).val)
            error('Argument %d must be numeric',...
                  i+2); %#ok
        end
        
        opv(idx).steps = 10; %#ok
        idx = idx+1;
    end

    origopv = getappdata(0,'SwooshPropVector');
    
    newopv = struct('obj',[],'prop',[],'val',[],'steps',[]);

    idx = 1;
    for i=1:length(origopv)
        if origopv.steps > 0
            newopv(idx) = origopv(i);
            idx = idx+1;
        end
    end
    
    for i=1:length(opv)
        matchingobj = find([newopv.obj] == opv(i).obj);
        matchingprop = find(strcmp({newopv(matchingobj).prop}, opv(i).prop));
        if ~isempty(matchingprop)
            newopv(matchingprop) = opv(i);
        else
            newopv(idx) = opv(i);
            idx = idx+1;
        end
    end
    
    setappdata(0,'SwooshPropVector', newopv);
    
    llt = getappdata(0,'SwooshPropTimer');
    
    if isempty(llt)
        llt = timer('Period',.1,...
                    'StopFcn',@stopfcn,...
                    'TimerFcn',@timeoutfcn,...
                    'ErrorFcn',@errfcn,...
                    'BusyMode','Queue',...
                    'ExecutionMode','fixedDelay');
        setappdata(0,'SwooshPropTimer', llt);
    end

    % llt
    
    set(llt,'TasksToExecute',max([newopv.steps]));

    if strcmp(get(llt,'Running'),'off')
        start(llt);
    end
    
function errfcn(obj, event) %#ok

    disp('An error occured in the timeout fcn.');
    
function timeoutfcn(obj, event)

    obj; %#ok
    event; %#ok
    
    opv = getappdata(0,'SwooshPropVector');
    
    for i=1:length(opv)
        try
            %opv(i)
            nextvalue(opv(i));
            opv(i).steps = opv(i).steps - 1;
        catch
            opv(i).step = 0;
        end
    end
    setappdata(0,'SwooshPropVector',opv);
    drawnow;
    
function stopfcn(obj, event)
    
    obj; %#ok
    event; %#ok
    
    opv = getappdata(0,'SwooshPropVector');
    
    for i=1:length(opv)
        try %#ok
            nextvalue(opv(i), opv(i).val);
        end
        opv(i).steps = 0;
    end
    rmappdata(0,'SwooshPropVector');
    drawnow;
    
function value = nextvalue(opv, value)
    
    prop = opv.prop;
    
    startval = get(opv.obj,prop);

    if nargin == 1
        dest = opv.val;

        value = (dest - startval) / 2 + startval;
    end

    set(opv.obj,prop,value);