MATLAB: How to load the latest picture automatically

Question

I have a program to vertically integrate the intensity of pictures. There is a push button that allows me to load the latest the picture in the directory. However, if I just run the program, no file is loaded at the beginning. I am wondering if there is a way to automatically load the latest file when I click run the program. Thanks!

   function photobooth

   defaultfileDir = 'C:\Users\physlabuser\Pictures\Camera Roll';  %This path 
directory changes to reflect user
   %defaultfileDir = [pwd, 'C:\Users\physlabuser\Pictures\Camera Roll'];

   default_ub = 300;
   default_lb = 200;

   buttonHeight = 0.03;
   buttonWidth = 0.08;
   spacing = 0.01;
   row1 = 0.94;
   row2 = 0.90;
   row3 = 0.86;
   row4 = 0.82;
   row5 = 0.78;
   panelHeight = (row1 - row5) + 3*spacing + buttonHeight;
   browseWidth = 0.04;
   % specific to ROI section
   col0 = 0.95 - buttonWidth - 2*spacing - browseWidth - 0.38;
   col05 = (col0 + buttonWidth + spacing);
   col1 = 0.95 - buttonWidth - spacing - browseWidth;
   col2 = 0.95 - buttonWidth;
   fieldWidth = 0.12;
   nameWidth = 0.38 - buttonWidth - spacing;
   panelWidth = (col2 - col0) + 2*spacing + buttonWidth;
   % specific to fitting section
   structWidth = 4*buttonWidth + 2*spacing - browseWidth - spacing;
   fcol0 = 0.05;
   fcol1 = 0.05 + buttonWidth + spacing;
   fcol2 = 0.05 + 2*buttonWidth + 2*spacing;
   fbrowsecol = fcol1 + structWidth + spacing;
   fcol3 = fbrowsecol + browseWidth + spacing;
   fpanelWidth = (fcol3 - fcol0) + 2*spacing + buttonWidth;

   mainX = 0.05;
   mainY = 0.3;
   mainW = 0.9;
   mainH = 0.55;

   histX = 0.05;
   histY = 0.05;
   histW = 0.9;
   histH = 0.2;

   hMainFigure = figure(...
            'Visible','off',...
            'NumberTitle','off',...
            'Name','Some random vertically integrating program',...
            'Toolbar','figure',...
            'Position',[128,128,864,864]);

   %Make the GUI visible.
   set(hMainFigure,'Visible','on')

   %  Construct the components
   ah         = axes(...
           'Parent',hMainFigure,...
           'ButtonDownFcn', @get_cursor_pos, ...
           'Position',[mainX mainY mainW mainH]);

   histogram  = axes(...
           'Parent',hMainFigure,...
           'Position',[histX histY histW histH]);

   imagefieldtext = uicontrol(...
            'Parent', hMainFigure, ...
            'Units','normalized',...
            'Style', 'text', ...
            'String','image location',...
            'HorizontalAlignment', 'center', ...
            'Position',[fcol0 row1 buttonWidth buttonHeight]);

   imagefield = uicontrol(...
           'Style','edit',...
           'Parent', hMainFigure, ...
           'String','' ,...
           'Units','normalized',...
           'Max',1,'Min',0,...
           'Callback', @UpdateCallback,...
           'Position',[fcol1 row1 structWidth buttonHeight]);

   imageBrowseButton = uicontrol(...    % button for updating selected plot 
           'Parent', hMainFigure, ...
           'Units','normalized',...
           'HandleVisibility','callback', ...
           'Position',[fbrowsecol row1 browseWidth buttonHeight],...
           'String','...',...
           'Callback', @imageBrowseCallback);

   loadLatestButton = uicontrol(...    % button for updating selected plot 
           'Parent', hMainFigure, ...
           'Units','normalized',...
           'HandleVisibility','on',...
           'Position',[fcol3 row1 buttonWidth buttonHeight],...
           'String','Load Latest',...
           'Callback', @loadLatestImage);

   fileDirtext = uicontrol(...
            'Parent', hMainFigure, ...
            'Units','normalized',...
            'Style', 'text', ...
            'String','Camera Roll dir',...
            'HorizontalAlignment', 'center', ...
            'Position',[fcol0 row2 buttonWidth buttonHeight]);

   fileDirField = uicontrol(...
           'Style','edit',...
           'Parent', hMainFigure, ...
           'String',defaultfileDir,...
           'Units','normalized',...
           'Max',1,'Min',0,...
           'Callback', @fileDirUpdateCallback,...
           'Position',[fcol1 row2 structWidth buttonHeight]);

   fileDirBrowseButton = uicontrol(...    % button for updating selected plot 
           'Parent', hMainFigure, ...
           'Units','normalized',...
           'HandleVisibility','callback', ...
           'Position',[fbrowsecol row2 browseWidth buttonHeight],...
           'String','...',...
           'Callback', @hfileDirBrowseCallback);

   directionstext = uicontrol(...
            'Parent', hMainFigure, ...
            'Units','normalized',...
            'Style', 'text', ...
            'String','use cursor to select point and then hit "Set lb" ("Set ub") to specify lower (upper) integration bounds.',...
            'HorizontalAlignment', 'center', ...
            'Position',[col0 + 2*buttonWidth row2 0.2 2*buttonHeight + spacing]);

   lbButton = uicontrol(...    % button for updating selected plot 
           'Parent', hMainFigure, ...
           'Units','normalized',...
           'HandleVisibility','callback', ...
           'Position',[col2 row1 buttonWidth buttonHeight],...
           'String','Set lb',...
           'Callback', @getlb);

   ubButton = uicontrol(...    % button for updating selected plot 
           'Parent', hMainFigure, ...
           'Units','normalized',...
           'HandleVisibility','callback', ...
           'Position',[col2 row2 buttonWidth buttonHeight],...
           'String','Set ub',...
           'Callback', @getub);

   lbfield = uicontrol(...    % button for updating selected plot 
           'Style','edit',...
           'Parent', hMainFigure, ...
           'Units','normalized',...
           'HandleVisibility','callback', ...
           'Position',[col1 row1 browseWidth buttonHeight],...
           'String',num2str(default_lb),...
           'Callback', @loadImage);

   ubfield = uicontrol(...    % button for updating selected plot 
           'Style','edit',...
           'Parent', hMainFigure, ...
           'Units','normalized',...
           'HandleVisibility','callback', ...
           'Position',[col1 row2 browseWidth buttonHeight],...
           'String',num2str(default_ub),...
           'Callback', @loadImage);

   data = guihandles(hMainFigure); 
   data.fileDir = defaultfileDir;
   data.ub = default_ub;
   data.lb = default_lb;
   guidata(hMainFigure, data) 
   %%%%%%%callbacks %%%%%%%%%

   function hfileDirBrowseCallback(hObject, eventdata)   
   % Callback function run when the update button is pressed


    foldername = uigetdir(pwd, ...
        'Select Photo Booth directory.');
    if foldername == 0
    else
        set(fileDirField, 'String', foldername);
        data = guidata(gcbo);
        data.fileDir = foldername;
        guidata(gcbo, data);
    end
   end

   function UpdateCallback(hObject, eventdata)   
   % Callback function run when the update button is pressed
    loadImage(imagefield, eventdata)
   end

   function fileDirUpdateCallback(hObject, eventdata)   
   % Callback function run when the update button is pressed
    foldername = get(fileDirField, 'String');
    data = guidata(gcbo);
    data.fileDir = foldername;
    guidata(gcbo, data);
   end

   function imageBrowseCallback(hObject, eventdata)   
   % Callback function run when the update button is pressed
    data = guidata(gcbo);
    [filename pathname] = uigetfile(fullfile(data.fileDir, '*.jpg'), ...
        'Select image to display.');
    if filename == 0
    else
        imagename = fullfile(pathname, filename);
        set(imagefield, 'String', imagename);
        loadImage(imagefield, eventdata)
    end
   end

   function loadLatestImage(hObject, eventdata)   
   % Callback function run when the update button is pressed
    data = guidata(gcbo);
    files = dir(fullfile(data.fileDir,'*.jpg'));

    if numel(files) == 0
        warndlg('No JPG files exist in Camera Roll directory.')
    else
        dates = [files(:).datenum];

        [sorted_dates date_order] = sort(dates);
        sorted_files = files(date_order);
        files = sorted_files;

   %        for i = 1:numel(files)
   %        disp('---------new image---------')
   %          files(i).name
   %          files(i).date
   %          files(i).datenum
   %        end
   %
        set(imagefield, 'String', fullfile(data.fileDir, files(end).name));
        loadImage(imagefield, eventdata)
    end
   end

   function get_cursor_pos(hObject, eventdata)
    cursor_pos = get(ah, 'Currentpoint');
   end

   function getub(hObject, eventdata)
    cursor_pos = get(ah, 'Currentpoint');
    set(ubfield, 'String', num2str(round(cursor_pos(1, 2, 1))));
    data = guidata(gcbo);
    data.ub = str2num(get(ubfield, 'String'));
    guidata(gcbo, data);

    loadImage(imagefield, eventdata)
   end

   function getlb(hObject, eventdata)
    cursor_pos = get(ah, 'Currentpoint');
    set(lbfield, 'String', num2str(round(cursor_pos(1, 2, 1))));
    data = guidata(gcbo);
    data.lb = str2num(get(lbfield, 'String'));
    guidata(gcbo, data);

    loadImage(imagefield, eventdata)
   end

   function loadImage(field, eventdata)
    imagename = get(imagefield, 'String');
    [X map] = imread(imagename);
    %imagesc(X, 'Parent', ah, 'HitTest', 'off')
    imagesc(X, 'Parent', ah);
    set(ah, 'ButtonDownFcn', @get_cursor_pos);

    data = guidata(gcbo);
    data.lb = str2num(get(lbfield, 'String'));
    data.ub = str2num(get(ubfield, 'String'));
    guidata(gcbo, data);

    if data.lb > 0 && data.ub > 0
        vert_hist = sum(X(data.lb:data.ub, :, 1), 1);
        vert_hist = vert_hist + sum(X(data.lb:data.ub, :, 2), 1);
     

            

            
            
            

    

        

	
    

        
Best Answer
    

    

								

								
After you call
     guidata(hMainFigure, data)
then call
loadLatestImage(loadLatestButton, [])
and in loadLatestImage change
data = guidata(gcbo);
to
data = guidata(hObject);
(because for that direct call there will not be a callback object.)
						    
						
		
    
        

    

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Hi Sarah,
the way how handles are assigned and used in guidata is not correct. Please refer to the documentation of guidata(). The correct workflow of assigning handles to guidata is to attach the handles to a figure.
Since you have to rewrite several parts of your code, I attached a simple example I used here, to illustrate the work flow:
function GUI_breakOP
    % 1 create figure
    GUI.fh = figure;
    
    % 2 create whatever handle you want to attach to figure GUI.fh
    GUI.h1 = uicontrol('style','Edit',...
                       'string','XX',...
                       'Units','normalized',...
                       'Position',[0.1 0.1 0.8 0.2],...
                       'backgroundcolor','c',...
                       'Tag','EditField2',...
                       'Enable','off');
        
    GUI.h2 = uicontrol('Style','PushButton',...
                       'String','Start',...
                       'Units','normalized',...
                       'Position',[0.1 0.4 0.3 0.2],...
                       'callback',{@func_compute},...
                       'Tag','StartButton',...
                       'backgroundcolor',...
                       'g','FontSize',12);
                       
    GUI.h3 = uicontrol('Style','PushButton',...
                       'String','Stop',...
                       'Units','normalized',...
                       'Position',[0.5 0.4 0.3 0.2],...
                       'callback',{@breakOP},...
                       'Tag','StopButton',...
                       'backgroundcolor',...
                       'r','FontSize',12);
    
    % 3 create own handles & flags/variables to exchange
    myHandle = guihandles(GUI.fh);  % save gui handles to struct
    myHandle.breakOP = false;       % flag for break OP

    
    % 4 attach to figure GUI.fh
    guidata(GUI.fh,myHandle);       % save structure


end
% now guidata can be used within functions called via GUI.fh
function func_compute(~,~)
    % 1 retrieve myHandle

    myHandle = guidata(gcbo);
    % 2 manipulate myHandle values

    myHandle.breakOP = false;   % flag for break OP
    % 3 save changed myHandle via guidata to figure

    guidata(gcbo,myHandle);     % save structure
    
    if ~isempty(str2num(myHandle.EditField2.String))
        a = str2num(myHandle.EditField2.String);
    else
        a = 1;
    end
    
    while 1
        myHandle = guidata(gcbo);                   % get structure

        myHandle.EditField2.String = num2str(a);    % edit field string
        pause(0.01);
        if myHandle.breakOP                         % check for break OP flag
            break;
        end
        a = a +1;
    end
    
end
function breakOP(~,~)
    % 1 retrieve myHandle
    myHandle = guidata(gcbo);   % get structure
    % 2 manipulate myHandle values
    myHandle.breakOP = true;    % change break OP flag
    % 3 save changed myHandle via guidata to figure
    guidata(gcbo,myHandle);     % save structure
end
Kind regards,
Robert
						    
						
        
        

            
            
            
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Answer 1

After you call

     guidata(hMainFigure, data)

then call

loadLatestImage(loadLatestButton, [])

and in loadLatestImage change

data = guidata(gcbo);

to

data = guidata(hObject);

(because for that direct call there will not be a callback object.)