MATLAB: GUIDATA updating “handles” in GUIDE with nested functions

guiguidehandlesvertical line

This is an extension to a current question answered by Geoff Hayes and Walter Roberson:

Attached you can find a simple GUIDE with 2 push buttons:

Button #1 plots a sine graph.

Button #2 adds a "movable" vertical line to the graph.

Everything works fine and I can drag vertical line as desired (Thanks to Geoff and Walter)

What I'm trying to do now is to record x-position of vertical line (x_history) as I move it, and save this x_history to handles (via guidata) such that if I stop moving the line (mouse-up) and then resume moving the line (mouse-down and mouse-move) I can restore previous x_history from handles (via guidata).

The problem I'm facing is that every time I stop moving the line and go mouse-up, handles resets(!) the x_history field (removes the field), so I loose the previous record of x_history when I resume mouse-down and move the line.

What am I missing here?

Alborz

Best Answer

This is a confusing mixture of storing the handles struct in two figures by guidata, using handles from the inputs of the callbacks (where it is a static copy of the contents from this struct at the time of the creation of the callback), and the common using of local variables in nested functions. This is more complexity than you require.

Decide for one mechanism to share the handles struct, e.g. in the figure's ApplicationData by using guidata and prefer the figure, which contains the activated object. Then insert this in each callback:

function XYZ_Callback(hObject, EventData, handlesFromInput)
handles = guidata(hObject);
...
guidata(hObject, handles);
end

Convert the nested functions to "non-nested normal" (how is it called?) function and use the input hObject.

In addition the guidata concern the figure, which contain the figure with the two buttons, not the figure, which contains the diagram and the moved line. Better keep your data locally in the figure, which is processed.

By the way: I could not reproduce your observation:

 The problem I'm facing is that every time I stop moving the line and go
 mouse-up, handles resets

How and where do you observe this?

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MATLAB: GUIDATA does not trasfer data in GUIDE with subfunctions.

Alborz - your code has interesting approach by assigning the ButtonDownFcn to the line object so that when the user presses down on the line (and only the line), this event will fire. Though instead of calling guidata with hObject which is the handle to the line object, you probably want to call it with the handle to the button, h, since it is a child of the GUI and the handles structure is "associated" with that. So the pushbutton_vertline_Callback code would change to

 function pushbutton_vertline_Callback_Callback(hButton, eventdata,handles)
    axis_h = handles.axis_h;
    vertline_h = line('parent',axis_h,'xdata',[1 1],'ydata',[-1 1], 'ButtonDownFcn', @mouseDown );
    handles.vertline_h = vertline_h;
    guidata(h,handles)
    % MouseMove subfunction in callback 2

    function mouseDown(hObject,event)
        mousedown = true;
        handles.mousedown = mousedown;
        guidata(hButton,handles)
    end
 end

Like Walter has indicated, your mousedown variable is local to the MouseUp function and so setting it to true won't affect the field within the handles structure. So this function should change to

 function MouseUp(h,event) %#ok<*INUSD>

    handles = guidata(hObject);
    handles.mousedown = false;
    guidata(hObject,handles);
 end

Note how in the above code, we use hObject (the handle to the pushbutton_plot) to get the latest updated version of handles rather than the older copy from the pushbutton_plot_Callback callback. So we get the latest version, change the mousedown field, and then save the updated handles structure.

And the MouseMove is almost correct with the only problem being that the handles of copy being used rather than the latest version. Again, we just need to call guidata as

 function MouseMove(h,event)
     handles = guidata(hObject);
     if isfield(handles,'mousedown')
         mousedown = handles.mousedown;
     else
         mousedown = false;
     end
     if mousedown
         cp = get ( axis_h, 'CurrentPoint' );
         vertline_h = handles.vertline_h;
         set ( vertline_h, 'XData', [cp(1,1) cp(1,1)] );
     end
 end

See below for the full code which should work.

 % Callbacl 1: Graph SIN function 
 function pushbutton_plot_Callback(hObject, eventdata, handles)   
    clc;
    open_figs_h = get(0,'children');
    close(open_figs_h(2:end));
    x = -pi:0.01:pi;
    y = sin(x);
    fig_h = figure('units','normalized','outerposition',[0.2 0.2 .5 .5],...
                   'WindowButtonMotionFcn', @MouseMove, 'WindowButtonUpFcn', @MouseUp );
    axis_h = axes('parent',fig_h,'position',[0.1 0.1 .8 .8]);
    line('parent',axis_h,'xdata',x,'ydata',y);
    handles.axis_h = axis_h;
    guidata(hObject,handles);
    % MouseUp and MouseMove subfunctions in callback 1
    function MouseUp(h,event) %#ok<*INUSD>
        handles = guidata(hObject);
        handles.mousedown = false;
        guidata(hObject,handles);
    end
    function MouseMove(h,event)
        handles = guidata(hObject);
        if isfield(handles,'mousedown')
            mousedown = handles.mousedown;
        else
            mousedown = false;
        end
        if mousedown
            cp = get ( axis_h, 'CurrentPoint' );
            vertline_h = handles.vertline_h;
            set ( vertline_h, 'XData', [cp(1,1) cp(1,1)] );
        end
    end
 end 
 % Callbacl 2: Graph movables vertical line      
 function pushbutton_vertline_Callback(hButton, eventdata,handles)
    axis_h = handles.axis_h;
    vertline_h = line('parent',axis_h,'xdata',[1 1],'ydata',[-1 1], 'ButtonDownFcn', @mouseDown );
    handles.vertline_h = vertline_h;
    guidata(h,handles)
    % MouseMove subfunction in callback 2
    function mouseDown(hObject,event)
        mousedown = true;
        handles.mousedown = mousedown;
        guidata(hButton,handles)
    end
  end

MATLAB: How to extract data from a selected file by pressing a push button in GUI

fscanf(), textscan(), dlmread() -- all can be used to extract data from a text file and convert the data to numeric form.

plot() can be used to plot line graphs.

To transfer data between routines see http://matlab.wikia.com/wiki/FAQ#How_can_I_share_data_between_callback_functions_in_my_GUI.3F

Best Answer

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MATLAB: GUIDATA does not trasfer data in GUIDE with subfunctions.

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