How to Transfer data from Main gui to another GUI in case , when multiple instances of GUI is used ?

I have a MATLAB GUI (MAIN GUI) which is used to run a simulation and the results are plotted in a separate GUI (Plotting GUI). I have used setappdata/getappdata meathod to transfer data between the GUI. Additionally user can have multiple instances of the plotting GUI (where results are plotted) to plot different signals. Though I have used setappdata to select the GCF (current figure) in the opening function of the Plotting GUI, the results are getting plotted in different GUI (ex. Results intended to be plotted on plotting GUI 2 are plotted in plotting GUI 1).

How can I ensure that the intended instace of the GUI is selected for plotting of results ?

[Geoff Hayes]

Sundeepan - how exactly are you passing data to the plotting GUI so that it "knows" that it is the only one that should be updated and not the other ones? Please provide a small code sample that illustrates this problem.

[Sundeepan Sarkar]

In the MAIN GUI, multiple instance of the plotting GUI are called based on the user input.

%%MAIN GUI
%  User Defines number of figures required & value is saved in num
    for l = 1:num
    setappdata(0,'figureid',l);
    id = strcat('hPlot',num2str(l)); % name assigned to each figure 
    eval(sprintf('%s = PlottingGUI;',id));   % call plotting GUI 
    end

In opening function of the second GUI, the current figure is assigned with the figure ID. Then the Figure ID is used again in the Main GUI for plotting the results.

%%PLOTTING GUI
%  Plotting GUI is selected in the Opening Function 
    function plottingGUI_OpeningFcn(hObject,~,handles, varargin)

      handles.output  = hObject;

    figureid         = getappdata(0,'figureid');
    PlotID           = strcat('Plot',num2str(figureid));
    PlotFig          = strcat('Figure',num2str(figureid));

    eval(sprintf('%s = %s ;',PlotFig,gcf)); 
    eval(sprintf('setappdata(0 ,''%s'', %s);',PlotID,PlotFig)); % stores handle to this gui in root

In Main GUI, the plotting GUI is then called using the following code:

    for figure_number = 1:num 

    GenID = strcat('Plot',num2str(figure_number));

         GenGUI = getappdata(0,GenID);                  % collects handle to the plotting gui
         g_main = findobj(GenGUI , 'type' , 'axes');    % looks for object of type                                                             
         axes(g_main);                                  % axes in the second gui

Answer 1

[Geoff Hayes]

Sundeepan - I strongly suggest that you don't use eval to evaluate your expressions. Your

 id = strcat('hPlot',num2str(l)); % name assigned to each figure 
 eval(sprintf('%s = PlottingGUI;',id));   % call plotting GUI

seems to be dynamically creating local variables to the multiple instances of the PlottingGUI. But what happens to these variables afterwards? How do you reference them? A better solution would be to create an array of handles to the GUIs like

 hPlottingGui = [];
 for l = 1:num
     hPlottingGui(l) = PlottingGUI;
 end

With the above, you will still have all of the handles but they will be stored in an array and so easier to access/manipulate.

With your third piece of code, you state that In Main GUI, the plotting GUI is then called using the following code: which is

 for figure_number = 1:num 
    GenID = strcat('Plot',num2str(figure_number));
    GenGUI = getappdata(0,GenID);                  % collects handle to the plotting gui
    g_main = findobj(GenGUI , 'type' , 'axes');    % looks for object of type                                                             
    axes(g_main);

    % etc.
 end

But the above iterates over ALL of your Plotting GUIs and not just a particular one. This implies that all of them will be updated. So how do you know when the Main GUI should update the Plotting GUI k?

[Sundeepan Sarkar]

Thank you for the suggestion of using arrays instead of using eval.

Regarding the third part, what i intend to do is to select each of the plotting GUI and plot the different signals intended for each Plotting GUI.

    for figure_number = 1:num 

    GenID = strcat('Plot',num2str(figure_number));

         GenGUI = getappdata(0,GenID);                  % collects handle to the plotting gui
         g_main = findobj(GenGUI , 'type' , 'axes');    % looks for object of type                                                             
         axes(g_main);                                  % axes in the second gui 

         % Plot all signals from an array referenced with figure_number
         % in next iteration it plots all the signals from the next array 

    end

The problem I am facing is in the selection of the GUI in the opening function. Ideally the gcf should refer to the current GUI when referenced to in the Opening function. But for me it takes the pervious GUI as the reference, which is incorrect.

Possible Soution:

1. Is there an error in the second part in the way I have used the Setappdata ?
2. Is there a another meathod to select the current GUI and attach a tag to the GUI so that it can be used in Main GUI

[Geoff Hayes]

But your main GUI has the handles to all of the Plotting GUIs, so why isn't that sufficient? Presumably your Main GUI decides what signal should be drawn where.

As for the gcf should refer to the current GUI when referenced to in the Opening function, do you mean that the current GUI is the Plotting GUI that you just launched? If so, the handle for this would be hObject, the first input parameter into the OpeningFcn.

[Sundeepan Sarkar]

One of my team-mate proposed a solution to the problem :

Ideally the gcf should refer to the current GUI when referenced to in the Opening function. But for me it takes the pervious GUI as the reference, which is incorrect.

Apperently MATLAB required some time to refresh the gcf (current figure), so all I needed to do was to add a pause just before the Opening Function of the Plotting GUI.

This helps in correctly selcting the GUI figure as gcf.