Question

I have created a class-managed GUI in which the following methods are defined

function h = make_figure(this)
    h = figure('CloseRequestFcn',@this.close_figure);
    this.openFigures(end+1) = h;
end

function close_figure(this, src, event)
    this.openFigures(this.openFigures == src) = [];
    delete(src);
end

Throughout the life of the GUI maney figures are created and closed with the aid of the methods above. Now the weird part…

If I double click a figure file eg (myfigure.fig) in MATLAB’s “Current Folder” window and then try to close it (while the GUI is still alive) then the close_figure method of the GUI’s class runs although it wasn’t created with h = figure('CloseRequestFcn',@this.close_figure); of make_figure method!!! This is the first weird part. The second weird part is that, although an unintented part of code is executed, it shouldn’t create problems because the command this.openFigures(this.openFigures == src) = []; actually leaves this.openFigures unchanged and practically all that close_figure does is to delete(src) which is desirable. Despite the above, my program behaves… weird after the above happens.

I have noticed that if I hit figure in the command window and then close it, everything is OK, the close_figure method is not executed. The problem reveals itself only when opening a .fig file created by the GUI’s class.

Any ideas?

Answer 1

I just tried the scenario you described, and I am not seeing any weird behavior; create instance of the class, use it to make a figure, then open a FIG file from the “Current Folder” file browser, and close it..

Here is the class definition I used:

classdef MyFigureClass < handle
    properties
        openFigures = [];
    end

    methods
        function h = make_figure(obj)
            h = figure('CloseRequestFcn',@(src,evt) close_figure(obj,src,evt));
            obj.openFigures(end+1) = h;
        end

        function close_figure(obj, src, evt)
            obj.openFigures(obj.openFigures == src) = [];
            delete(src);
        end

    end
end

(Tested in R2012a on Windows XP 32-bit.)

---

EDIT

Ok I think I know what the problem is. Here are the step to reproduce. First add the following method to the class above:

function save_figure(obj, idx)
    saveas(obj.openFigures(idx), sprintf('fig%02d.fig',idx))
end

Now using our class wrapper, lets create a figure, and save it to FIG file:

f = MyFigureClass();
f.make_figure()
f.save_figure(1)       %# creates fig01.fig

Next clear your workspace clear all, and move the class definition file MyFigureClass.m to some other folder (something not on the path). Now try to load the saved figure hgload fig01.fig, and it will throw the error:

Warning: Cannot load an object of class 'MyFigureClass':
Its class cannot be found. 
> In C:\Program Files\MATLAB\R2012a\toolbox\matlab\graphics\hgload.p>localLoadFile at 167
  In C:\Program Files\MATLAB\R2012a\toolbox\matlab\graphics\hgload.p>hgload at 59
  In openfig at 72
  In open at 159
  In uiopen at 196 

You will have to issue the following command to forcefully close it:

close all force

---

EDIT2

One solution (as mentioned in the comments), is to reset the figure close callback function just before saving it. Here is how I modified the save_figure function above:

function save_figure(obj, idx)
    %# backup callback function
    fcn = get(obj.openFigures(idx),'CloseRequestFcn');

    %# set default callback function
    set(obj.openFigures(idx),'CloseRequestFcn','closereq')

    %# save figure
    saveas(obj.openFigures(idx), sprintf('fig%02d.fig',idx))

    %# restore callback function
    set(obj.openFigures(idx),'CloseRequestFcn',fcn)
end