ProgressBar.m

classdef ProgressBar < matlab.System
    %PROGRESSBAR A class to provide a convenient and useful progress bar
    % -------------------------------------------------------------------------
    % This class mimics the design and some features of the TQDM
    % (https://github.com/tqdm/tqdm) progress bar in python. All optional
    % functionalities are set via name-value pairs in the constructor after the
    % argument of the total numbers of iterations used in the progress (which
    % can also be empty if unknown or even neglected if no name-value pairs are
    % passed). The central class' method is 'step()' to increment the
    % progress state of the object.
    %
    % Usage:  pbar = ProgressBar()
    %         pbar = ProgressBar(total)
    %         pbar = ProgressBar(total, Name, Value)
    %
    % where 'total' is the total number of iterations.
    %
    %
    % ProgressBar Properties:
    %   Total - the total number of iterations [default: []]
    %   Title - the progress bar's title shown in front [default: 'Processing']
    %   Unit - the unit of the update process. Can either be 'Iterations' or
    %          'Bytes' [default: 'Iterations']
    %   UpdateRate - the progress bar's update rate in Hz. Defines the printing
    %                update interval [default: 5 Hz]
    %
    %
    % ProgressBar Methods:
    %   ProgressBar - class constructor
    %   release - clean up and finish the progress bar's internal state
    %   printMessage - print some infos during the iterations. Messages get
    %                  printed above the bar and the latter shifts one row down
    %   setup - not needed in a common application. Tiny helper function when
    %           setting up nested loops to print a parent bar before the first
    %           update occured. When the inner loop takes long, a nasty white
    %           space is shown in place of the parent bar until the first
    %           update takes place. This function can be used as a remedy.
    %   step - the central update method to increment the internal progress
    %          state
    %
    % Author :  J.-A. Adrian (JA) <jensalrik.adrian AT gmail.com>
    %
    
    
    properties (Constant)
        % Tag every timer with this to find it properly
        TIMER_TAG_NAME = 'ProgressBar';
        VERSION = '3.4.0';
    end
    
    properties (Nontunable)
        % Total number of iterations to compute progress and ETA
        Total;
        
        % Titel of the progress bar if desired. Shown in front of the bar
        Title = 'Processing';
        
        % The visual printing rate in Hz. Default is 5 Hz
        UpdateRate = 5;
        
        % The unit of each update. Can be either 'Iterations' or 'Bytes'.
        % Default is 'Iterations'.
        Unit = 'Iterations';
        
        % Directory in which the worker binary files are being saved when in
        % parallel mode.
        WorkerDirectory = tempdir;
    end
    
    properties (Logical, Nontunable)
        % Boolean whether to activate progress bar at all
        % useful for non-interactive / batch / hpc usage
        IsActive = true;
        
        % Boolean whether to use Unicode symbols or ASCII hash symbols (i.e. #)
        UseUnicode = true;
        
        % Boolean whether the progress bar is to be used in parallel computing setup
        IsParallel = false;
        
        % Boolean whether to override Windows' monospaced font to cure "growing bar" syndrome
        OverrideDefaultFont = false;
    end
    
    properties (Access = private)
        Bar = '';
        IterationCounter = 0;
        
        NumWrittenCharacters = 0;
        FractionMainBlock;
        FractionSubBlock;
        
        HasTotalIterations = false;
        HasBeenUpdated = false;
        HasFiniteUpdateRate = true;
        HasItPerSecBelow1 = false;
        
        BlockCharacters;
        
        IsTimerRunning = false;
        
        TicObject;
        TimerObject;
        
        MaxBarWidth = 90;
        CurrentTitleState = '';
        CurrentFont;
    end
    
    properties (Constant, Hidden)
        % The number of sub blocks in one main block of width of a character.
        % HTML 'left blocks' go in eigths -> 8 sub blocks in one main block
        NUM_SUB_BLOCKS = 8;
        
        % The number of characters the title string should shift each cycle
        NUM_CHARACTERS_SHIFT = 3;
        
        % The maximum length of the title string without banner cycling
        MAX_TITLE_LENGTH = 20;
        
        OVERRIDE_FONT_NAME = 'Courier New';
    end
    
    properties (Access = private, Dependent)
        IsThisBarNested;
    end
    
    
    
    
    methods
        % Class Constructor
        function [obj] = ProgressBar(total, varargin)
            if nargin
                obj.Total = total;
                
                obj.setProperties(nargin-1, varargin{:});
            end
            
            if ~isempty(obj.Total)
                obj.HasTotalIterations = true;
            end
            if isinf(obj.UpdateRate)
                obj.HasFiniteUpdateRate = false;
            end
            
            % check if prog. bar runs in deployed mode and if so, switch to
            % ASCII symbols and a smaller bar width
            if isdeployed
                obj.UseUnicode = false;
                obj.MaxBarWidth = 72;
            end
            
            % setup ASCII symbols if desired
            if obj.UseUnicode
                obj.BlockCharacters = ProgressBar.getUnicodeSubBlocks();
            else
                obj.BlockCharacters = ProgressBar.getAsciiSubBlocks();
            end
        end
        
        function [] = printMessage(obj, message, shouldPrintNextProgBar)
            %PRINTMESSAGE class method to print a message while prog bar running
            %----------------------------------------------------------------------
            % This method lets the user print a message during the processing. A
            % normal fprintf() or disp() would break the bar so this method can be
            % used to print information about iterations or debug infos.
            %
            % Usage: obj.printMessage(obj, message)
            %        obj.printMessage(obj, message, shouldPrintNextProgBar)
            %
            % Input: ---------
            %       message - the message that should be printed to screen
            %       shouldPrintNextProgBar - Boolean to define wether to
            %                                immidiately print another prog. bar
            %                                after print the success message. Can
            %                                be usefule when every iteration takes
            %                                a long time and a white space appears
            %                                where the progress bar used to be.
            %                                [default: shouldPrintNextProgBar = false]
            %
            
            % input parsing and validation
            narginchk(2, 3);
            
            if nargin < 3 || isempty(shouldPrintNextProgBar)
                shouldPrintNextProgBar = false;
            end
            validateattributes(shouldPrintNextProgBar, ...
                {'logical', 'numeric'}, ...
                {'scalar', 'binary', 'nonempty', 'nonnan'} ...
                );
            
            % remove the current prog bar
            fprintf(1, ProgressBar.backspace(obj.NumWrittenCharacters));
            
            % print the message and break the line
            fprintf(1, '\t');
            fprintf(1, message);
            fprintf(1, '\n');
            
            % reset the number of written characters
            obj.NumWrittenCharacters = 0;
            
            % if the next prog bar should be printed immideately do this
            if shouldPrintNextProgBar
                obj.printProgressBar();
            end
        end
        
        function [yesNo] = get.IsThisBarNested(obj)
            % If there are more than one timer object with our tag, the current
            % bar must be nested
            yesNo = length(obj.getTimerList()) > 1;
        end
    end
    
    
    methods (Access = protected)
        function [] = validatePropertiesImpl(obj)
            valFunStrings = @(in) validateattributes(in, {'char'}, {'nonempty'});
            valFunNumeric = @(in) validateattributes(in, ...
                {'numeric'}, ...
                {'scalar', 'positive', 'real', 'nonempty', 'nonnan'} ...
                );
            valFunBoolean = @(in) validateattributes(in, ...
                {'logical', 'numeric'}, ...
                {'scalar', 'binary', 'nonnan', 'nonempty'} ...
                );
            
            assert(ProgressBar.checkInputOfTotal(obj.Total));
            
            assert(any(strcmpi(obj.Unit, {'Iterations', 'Bytes'})));
            
            valFunStrings(obj.Title);
            valFunStrings(obj.WorkerDirectory);
            valFunNumeric(obj.UpdateRate);
            valFunBoolean(obj.UseUnicode);
            valFunBoolean(obj.IsParallel);
        end
        
        function [] = setupImpl(obj)
            if obj.IsActive
                % get a new tic object
                obj.TicObject = tic;
                
                % workaround for issue "Bar Gets Longer With Each Iteration" on windows systems
                s = settings;
                if obj.OverrideDefaultFont && ispc()
                    % store current font to reset the code font back to this value in the release() method
                    obj.CurrentFont = s.matlab.fonts.codefont.Name.ActiveValue;
                    
                    % change to Courier New which is shipped by every Windows distro since Windows 3.1
                    s.matlab.fonts.codefont.Name.TemporaryValue = ob.OVERRIDE_FONT_NAME;
                end
                
                % add a new timer object with the standard tag name and hide it
                obj.TimerObject = timer(...
                    'Tag', obj.TIMER_TAG_NAME, ...
                    'ObjectVisibility', 'off' ...
                    );
                
                % if the bar should not be printed in every iteration setup the
                % timer to the desired update rate
                if obj.HasFiniteUpdateRate
                    obj.setupTimer();
                end
                
                % if 'Total' is known setup the bar correspondingly and compute
                % some constant values
                if obj.HasTotalIterations
                    % initialize the progress bar and pre-compute some measures
                    obj.setupBar();
                    obj.computeBlockFractions();
                end
                
                obj.CurrentTitleState = obj.Title;
                if length(obj.Title) > obj.MAX_TITLE_LENGTH
                    obj.CurrentTitleState = [obj.CurrentTitleState, ' -- '];
                end
                
                % if this is a nested bar hit return
                if obj.IsThisBarNested
                    fprintf(1, '\n');
                end
                
                % if the bar is used in a parallel setup start the timer right now
                if obj.IsParallel
                    obj.startTimer();
                end
                obj.printProgressBar();
            end
        end
        
        function [] = stepImpl(obj, stepSize, wasSuccessful, shouldPrintNextProgBar)
            %STEPIMPL class method to increment the object's progress state
            %----------------------------------------------------------------------
            % This method is the central update function in the loop to indicate
            % the increment of the progress. Pass empty arrays for each input
            % argument if default is desired.
            %
            % Usage: obj.step(stepSize, wasSuccessful, shouldPrintNextProgBar)
            %
            % Input: ---------
            %       stepSize - the size of the progress step when the method is
            %                  called. This can be used to pass the number of
            %                  processed bytes when using 'Bytes' as units.
            %                  [default: stepSize = 1]
            %       wasSuccessful - Boolean to provide information about the
            %                       success of an individual iteration. If you pass
            %                       a 'false' a message will be printed stating the
            %                       current iteration was not successful.
            %                       [default: wasSuccessful = true]
            %       shouldPrintNextProgBar - Boolean to define wether to
            %                                immidiately print another prog. bar
            %                                after print the success message. Can
            %                                be useful when every iteration takes
            %                                a long time and a white space appears
            %                                where the progress bar used to be.
            %                                [default: shouldPrintNextProgBar = false]
            %
            
            % input parsing and validating
            if isempty(shouldPrintNextProgBar)
                shouldPrintNextProgBar = false;
            end
            if isempty(wasSuccessful)
                wasSuccessful = true;
            end
            if isempty(stepSize)
                stepSize = 1;
            end
            
            validateattributes(stepSize, ...
                {'numeric'}, ...
                {'scalar', 'positive', 'real', 'nonnan', 'finite', 'nonempty'} ...
                );
            validateattributes(wasSuccessful, ...
                {'logical', 'numeric'}, ...
                {'scalar', 'binary', 'nonnan', 'nonempty'} ...
                );
            validateattributes(shouldPrintNextProgBar, ...
                {'logical', 'numeric'}, ...
                {'scalar', 'binary', 'nonnan', 'nonempty'} ...
                );
            
            if obj.IsActive
                % increment the iteration counter
                obj.incrementIterationCounter(stepSize);
                
                % if the timer was stopped before, because no update was given,
                % start it now again.
                if ~obj.IsTimerRunning && obj.HasFiniteUpdateRate
                    obj.startTimer();
                end
                
                % if the iteration was not successful print a message saying so.
                if ~wasSuccessful
                    infoMsg = sprintf('Iteration %i was not successful!', ...
                        obj.IterationCounter);
                    obj.printMessage(infoMsg, shouldPrintNextProgBar);
                end
                
                % when the bar should be updated in every iteration, do this with
                % each time calling update()
                if ~obj.HasFiniteUpdateRate
                    obj.printProgressBar();
                end
                
                % stop the timer after the last iteration if an update rate is
                % used. The first condition is needed to prevent the if-statement
                % to fail if obj.Total is empty. This happens when no total number
                % of iterations was passed / is known.
                if         ~isempty(obj.Total) ...
                        && obj.IterationCounter == obj.Total ...
                        && obj.HasFiniteUpdateRate
                    
                    obj.stopTimer();
                end
            end
        end
        
        function [] = releaseImpl(obj)
            % stop the timer
            if obj.IsTimerRunning
                obj.stopTimer();
            end
            
            if obj.IsThisBarNested
                % when this prog bar was nested, remove it from the command
                % line and get back to the end of the parent bar.
                % +1 due to the line break
                fprintf(1, ProgressBar.backspace(obj.NumWrittenCharacters + 1));
            elseif obj.IterationCounter && ~obj.IsThisBarNested
                % when a non-nested progress bar has been plotted, hit return
                fprintf(1, '\n');
            end
            
            % delete the timer object
            delete(obj.TimerObject);
            
            % restore previously used font
            if obj.OverrideDefaultFont && ~isempty(obj.CurrentFont)
                s = settings;
                s.matlab.fonts.codefont.Name.TemporaryValue = obj.CurrentFont;
            end
            
            % if used in parallel processing delete all aux. files and clear
            % the persistent variables inside of updateParallel()
            if obj.IsParallel
                files = ProgressBar.findWorkerFiles(obj.WorkerDirectory);
                
                if ~isempty(files)
                    delete(files{:});
                end
                
                clear updateParallel;
                
                % rest some time to not flood the screen with the parent bar
                pause(0.1);
            end
        end
        
        
        function [] = computeBlockFractions(obj)
            % Compute the progress percentage of a single main and a single sub
            % block
            obj.FractionMainBlock = 1 / length(obj.Bar);
            obj.FractionSubBlock = obj.FractionMainBlock / obj.NUM_SUB_BLOCKS;
        end
        
        
        function [] = setupBar(obj)
            % Set up the growing bar part of the printed line by computing the
            % width of it
            
            [~, preBarFormat, postBarFormat] = obj.returnFormatString();
            
            % insert worst case inputs to get (almost) maximum length of bar
            preBar = sprintf(...
                preBarFormat, ...
                blanks(min(length(obj.CurrentTitleState), obj.MAX_TITLE_LENGTH)), ...
                100 ...
                );
            postBar = sprintf(...
                postBarFormat, ...
                obj.Total, ...
                obj.Total, ...
                10, 60, 60, 10, 60, 60, 1e2 ...
                );
            
            lenBar = obj.MaxBarWidth - length(preBar) - length(postBar);
            
            obj.Bar = blanks(lenBar);
        end
        
        
        function [] = printProgressBar(obj)
            % This method removes the old and prints the current bar to the screen
            % and saves the number of written characters for the next iteration
            
            % remove old previous bar
            fprintf(1, ProgressBar.backspace(obj.NumWrittenCharacters));
            
            formatString = obj.returnFormatString();
            argumentList = obj.returnArgumentList();
            
            % print new bar
            obj.NumWrittenCharacters = fprintf(1, ...
                formatString, ...
                argumentList{:} ...
                );
        end
        
        
        function [format, preString, postString] = returnFormatString(obj)
            % This method returns the format string for the fprintf() function in
            % printProgressBar()
            
            % use the correct units
            if strcmp(obj.Unit, 'Bytes')
                unitString = 'K';
                
                if obj.HasItPerSecBelow1
                    fractionString = {'s', 'KB'};
                else
                    fractionString = {'KB', 's'};
                end
            else
                unitString = 'it';
                
                if obj.HasItPerSecBelow1
                    fractionString = {'s', 'it'};
                else
                    fractionString = {'it', 's'};
                end
            end
            
            % consider a growing bar if the total number of iterations is known
            % and consider a title if one is given.
            if obj.HasTotalIterations
                preString  = '%s:  %03.0f%%  ';
                
                centerString = '|%s|';
                
                postString = ...
                    [
                    ' %i/%i', unitString, ...
                    ' [%02.0f:%02.0f:%02.0f<%02.0f:%02.0f:%02.0f, %.2f ', ...
                    fractionString{1}, '/', fractionString{2}, ']'
                    ];
                
                format = [preString, centerString, postString];
            else
                preString  = '';
                postString = '';
                
                format = [
                    '%s:  %i', unitString, ' [%02.0f:%02.0f:%02.0f, %.2f ', ...
                    fractionString{1}, '/', fractionString{2}, ']'
                    ];
            end
        end
        
        
        function [argList] = returnArgumentList(obj)
            % This method returns the argument list as a cell array for the
            % fprintf() function in printProgressBar()
            
            % elapsed time (ET)
            thisTimeSec = toc(obj.TicObject);
            etHoursMinsSecs = ProgressBar.convertTime(thisTimeSec);
            
            % mean iterations per second counted from the start
            iterationsPerSecond = obj.IterationCounter / thisTimeSec;
            
            if iterationsPerSecond < 1
                iterationsPerSecond = 1 / iterationsPerSecond;
                obj.HasItPerSecBelow1 = true;
            else
                obj.HasItPerSecBelow1 = false;
            end
            
            
            % consider the correct units
            scaledIteration = obj.IterationCounter;
            scaledTotal = obj.Total;
            if strcmp(obj.Unit, 'Bytes')
                % let's show KB
                scaledIteration     = round(scaledIteration / 1000);
                scaledTotal         = round(scaledTotal / 1000);
                iterationsPerSecond = iterationsPerSecond / 1000;
            end
            
            if obj.HasTotalIterations
                % 1 : Title
                % 2 : progress percent
                % 3 : progBar string
                % 4 : iterationCounter
                % 5 : Total
                % 6 : ET.hours
                % 7 : ET.minutes
                % 8 : ET.seconds
                % 9 : ETA.hours
                % 10: ETA.minutes
                % 11: ETA.seconds
                % 12: it/s
                
                % estimated time of arrival (ETA)
                [etaHoursMinsSecs] = obj.estimateETA(thisTimeSec);
                
                if obj.IterationCounter
                    % usual case -> the iteration counter is > 0
                    barString = obj.getCurrentBar;
                else
                    % if startMethod() calls this method return the empty bar
                    barString = obj.Bar;
                end
                
                argList = {
                    obj.CurrentTitleState(...
                    1:min(length(obj.Title), obj.MAX_TITLE_LENGTH) ...
                    ), ...
                    floor(obj.IterationCounter / obj.Total * 100), ...
                    barString, ...
                    scaledIteration, ...
                    scaledTotal, ...
                    etHoursMinsSecs(1), ...
                    etHoursMinsSecs(2), ...
                    etHoursMinsSecs(3), ...
                    etaHoursMinsSecs(1), ...
                    etaHoursMinsSecs(2), ...
                    etaHoursMinsSecs(3), ...
                    iterationsPerSecond ...
                    };
            else
                % 1: Title
                % 2: iterationCounter
                % 3: ET.hours
                % 4: ET.minutes
                % 5: ET.seconds
                % 6: it/s
                
                argList = {
                    obj.CurrentTitleState(...
                    1:min(length(obj.Title), obj.MAX_TITLE_LENGTH) ...
                    ), ..., ...
                    scaledIteration, ...
                    etHoursMinsSecs(1), ...
                    etHoursMinsSecs(2), ...
                    etHoursMinsSecs(3), ...
                    iterationsPerSecond ...
                    };
            end
            
            % cycle the bar's title
            obj.updateCurrentTitle();
        end
        
        
        function [barString] = getCurrentBar(obj)
            % This method constructs the growing bar part of the printed line by
            % indexing the correct part of the blank bar and getting either a
            % Unicode or ASCII symbol.
            
            % set up the bar and the current progress as a ratio
            lenBar = length(obj.Bar);
            currProgress = obj.IterationCounter / obj.Total;
            
            % index of the current main block
            thisMainBlock = min(ceil(currProgress / obj.FractionMainBlock), lenBar);
            
            % index of the current sub block
            continuousBlockIndex = ceil(currProgress / obj.FractionSubBlock);
            thisSubBlock = mod(continuousBlockIndex - 1, obj.NUM_SUB_BLOCKS) + 1;
            
            % fix for non-full last blocks when steps are large: make them full
            obj.Bar(1:max(thisMainBlock-1, 0)) = ...
                repmat(obj.BlockCharacters(end), 1, thisMainBlock - 1);
            
            % return a full bar in the last iteration or update the current
            % main block
            if obj.IterationCounter == obj.Total
                obj.Bar = repmat(obj.BlockCharacters(end), 1, lenBar);
            else
                obj.Bar(thisMainBlock) = obj.BlockCharacters(thisSubBlock);
            end
            
            barString = obj.Bar;
        end
        
        
        function [etaHoursMinsSecs] = estimateETA(obj, elapsedTime)
            % This method estimates linearly the remaining time
            
            % the current progress as ratio
            progress = obj.IterationCounter / obj.Total;
            
            % the remaining seconds
            remainingSeconds = elapsedTime * ((1 / progress) - 1);
            
            % convert seconds to hours:mins:seconds
            etaHoursMinsSecs = ProgressBar.convertTime(remainingSeconds);
        end
        
        
        function [] = setupTimer(obj)
            % This method initializes the timer object if an upate rate is used
            
            obj.TimerObject.BusyMode = 'drop';
            obj.TimerObject.ExecutionMode = 'fixedSpacing';
            
            if ~obj.IsParallel
                obj.TimerObject.TimerFcn = @(~, ~) obj.timerCallback();
                obj.TimerObject.StopFcn  = @(~, ~) obj.timerCallback();
            else
                obj.TimerObject.TimerFcn = @(~, ~) obj.timerCallbackParallel();
                obj.TimerObject.StopFcn  = @(~, ~) obj.timerCallbackParallel();
            end
            updatePeriod = round(1 / obj.UpdateRate * 1000) / 1000;
            obj.TimerObject.Period = updatePeriod;
        end
        
        
        function [] = timerCallback(obj)
            % This method is the timer callback. If an update came in between the
            % last printing and now print a new prog bar, else stop the timer and
            % wait.
            if obj.HasBeenUpdated
                obj.printProgressBar();
            else
                obj.stopTimer();
            end
            
            obj.HasBeenUpdated = false;
        end
        
        
        function [] = timerCallbackParallel(obj)
            % find the aux. worker files
            [files, numFiles] = ProgressBar.findWorkerFiles(obj.WorkerDirectory);
            
            % if none have been written yet just print a progressbar and return
            if ~numFiles
                obj.printProgressBar();
                
                return;
            end
            
            % read the status in every file
            results = zeros(numFiles, 1);
            for iFile = 1:numFiles
                fid = fopen(files{iFile}, 'rb');
                
                if fid > 0
                    results(iFile) = fread(fid, 1, 'uint64');
                    fclose(fid);
                end
            end
            
            % the sum of all files should be the current iteration
            obj.IterationCounter = sum(results);
            
            % print the progress bar
            obj.printProgressBar();
            
            % if total is known and we are at the end stop the timer
            if ~isempty(obj.Total) && obj.IterationCounter == obj.Total
                obj.stopTimer();
            end
        end
        
        
        function [] = startTimer(obj)
            % This method starts the timer object and updates the status bool
            
            start(obj.TimerObject);
            obj.IsTimerRunning = true;
        end
        
        
        function [] = stopTimer(obj)
            % This method stops the timer object and updates the status bool
            
            stop(obj.TimerObject);
            obj.IsTimerRunning = false;
        end
        
        
        function [] = incrementIterationCounter(obj, stepSize)
            % This method increments the iteration counter and updates the status
            % bool
            
            obj.IterationCounter = obj.IterationCounter + stepSize;
            
            obj.HasBeenUpdated = true;
        end
        
        
        function [list] = getTimerList(obj)
            % This function returns the list of all hidden timers which are tagged
            % with our default tag
            
            list = timerfindall('Tag', obj.TIMER_TAG_NAME);
        end
        
        
        function [] = updateCurrentTitle(obj)
            strTitle = obj.CurrentTitleState;
            
            if length(strTitle) > obj.MAX_TITLE_LENGTH
                strTitle = circshift(strTitle, -obj.NUM_CHARACTERS_SHIFT);
                
                obj.CurrentTitleState = strTitle;
            end
        end
    end
    
    methods (Static)
        function deleteAllTimers()
            delete(timerfindall('Tag', ProgressBar.TIMER_TAG_NAME));
        end
        
        
        function [blocks] = getUnicodeSubBlocks()
            % This function returns the HTML 'left blocks' to construct the growing bar. The HTML
            % 'left blocks' range from 1 to 8 excluding the 'space'.
            
            blocks = [
                char(9615), ...
                char(9614), ...
                char(9613), ...
                char(9612), ...
                char(9611), ...
                char(9610), ...
                char(9609), ...
                char(9608) ...
                ];
        end
        
        function [blocks] = getAsciiSubBlocks()
            % This function returns the ASCII number signs (hashes) to construct the growing bar.
            % The HTML 'left blocks' range from 1 to 8 excluding the 'space'.
            
            blocks = repmat('#', 1, 8);
        end
        
        
        function [str] = backspace(numChars)
            % This function returns the desired numbers of backspaces to delete characters from the
            % current line
            
            str = repmat(sprintf('\b'), 1, numChars);
        end
        
        
        function [hoursMinsSecs] = convertTime(secondsIn)
            % This fast implementation to convert seconds to hours:mins:seconds using mod() stems
            % from http://stackoverflow.com/a/21233409
            
            hoursMinsSecs = floor(mod(secondsIn, [0, 3600, 60]) ./ [3600, 60, 1]);
        end
        
        
        function [isOk] = checkInputOfTotal(total)
            % This function is the input checker of the main constructor argument 'total'. It is ok
            % if it's empty but if not it must obey validateattributes.
            
            isTotalEmpty = isempty(total);
            
            if isTotalEmpty
                isOk = true;
                return;
            else
                validateattributes(total, ...
                    {'numeric'}, ...
                    {'scalar', 'integer', 'positive', 'real', 'nonnan', 'finite'} ...
                    );
                isOk = true;
            end
        end
        
        
        function [files, numFiles] = findWorkerFiles(workerDir)
            % This function returns file names and the number of files that were written by the
            % updateParallel() function if the prog. bar is used in a parallel setup.
            %
            % Input: workerDir - directory where the aux. files of the worker are saved
            %
            
            [pattern] = updateParallel();
            
            files = dir(fullfile(workerDir, pattern));
            files = {files.name};
            
            files = cellfun(...
                @(filename) fullfile(workerDir, filename), ...
                files, ...
                'uni', false ...
                );
            numFiles = length(files);
        end
    end
    
end