MATLAB: Making STOP – Button

buttonguiMATLAB

Hi everybody! I'm new here and have a question about GUI's.

I have a GUI which contains (among other things) two (push)buttons. The first one is a "Start" button and the second one should be some kind of a "Stop" button. By pressing "Start" an infinite loop begins and the program starts reading a certain amount of data from a port and saves it to a file. When it finished reading it waits a few seconds and starts reading again. This happens x times, where x is a predifined value.

Now I want, that pressing the "Stop"-Button forces the program to stop at n < x runs (n depending on when I press the button).

For that purpose I defined a variable "run", which is 1 and gets 0, when "Stop" is pressed. So an exit is possible.

That's the plan. Unfortunatelly that doesn't work. I assume, that the rest of the GUI is "frozen" while the program is stuck in the loop, so pressing "Stop" doesn't change anything. I supposed pressing the button triggers some kind of interrupt, so being stuck in the loop is no problem, but sadly it seems as I am wrong (or I have to enable the interrupt, without knowing how). I already read a related post, where the questioner was advised to use a checkbox instead, but sadly this is no option for my purpose.

I hope some of you can help me? 🙂

Thank you!

Best Answer

It is hard to guess why it doesn't work without seeing any actual code. Your GUI is not frozen while your loop is running.

Small working exampel:

handles.fig=figure;
handles.pb1=uicontrol('style','pushbutton','position',[100 100 80 40],'callback',@start_cb,'string','Start');
handles.pb2=uicontrol('style','pushbutton','position',[200 100 80 40],'callback',@stop_cb,'string','Stop');
handles.run=1;
guidata(handles.fig,handles)
function start_cb(hObj,~)
while true
    handles=guidata(hObj);
    if handles.run==1
    disp('running')
    pause(1)
    else
        handles.run=1;
        guidata(hObj,handles)
        disp('stopped')
        break
    end
end
end
function stop_cb(hObj,~)
handles.run=0;
guidata(hObj,handles)
end

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MATLAB: Wait/retrieve data from another GUI

Hi,

it is possible to do with small trick.

When passing data between GUIs, the idea is via MAT file.

I have 2 GUIs as shown in picture below :

In the first GUI, button 'Threshold' will execute second GUI.

In second GUI, you should threshold the image by changing the slider position and then click OK.

The thresholded image will appears in axes1 of first GUI.

Just try it. I will not explain more.

You should design the GUIs and here the code :

FIRST GUI

-------------------

function varargout = untitled(varargin)
gui_Singleton = 1;
gui_State = struct('gui_Name',       mfilename, ...
                   'gui_Singleton',  gui_Singleton, ...
                   'gui_OpeningFcn', @untitled_OpeningFcn, ...
                   'gui_OutputFcn',  @untitled_OutputFcn, ...
                   'gui_LayoutFcn',  [] , ...
                   'gui_Callback',   []);
if nargin && ischar(varargin{1}),    gui_State.gui_Callback = str2func(varargin{1});    end
if nargout,    [varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:});
else,    gui_mainfcn(gui_State, varargin{:});    end
function untitled_OpeningFcn(hObject, eventdata, handles, varargin)
handles.output = hObject;
handles.I = imread('cameraman.tif');
imshow(handles.I);
guidata(hObject, handles);
function varargout = untitled_OutputFcn(hObject, eventdata, handles) 
varargout{1} = handles.output;
function pushbutton1_Callback(hObject, eventdata, handles)
handles.output = hObject;
tempImg = handles.I;
save('temp.mat','tempImg','-append');
uiwait(untitled2);
load('temp.mat');
handles.I = tempbw;
imshow(handles.I);
guidata(hObject, handles);

SECOND GUI

-------------------

function varargout = untitled2(varargin)
gui_Singleton = 1;
gui_State = struct('gui_Name',       mfilename, ...
                   'gui_Singleton',  gui_Singleton, ...
                   'gui_OpeningFcn', @untitled2_OpeningFcn, ...
                   'gui_OutputFcn',  @untitled2_OutputFcn, ...
                   'gui_LayoutFcn',  [] , ...
                   'gui_Callback',   []);
if nargin && ischar(varargin{1}),    gui_State.gui_Callback = str2func(varargin{1});    end
if nargout,    [varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:});
else,    gui_mainfcn(gui_State, varargin{:});    end
function untitled2_OpeningFcn(hObject, eventdata, handles, varargin)
handles.output = hObject;
load temp.mat
handles.I = tempImg;
handles.bw = handles.I;
imshow(handles.I);
set(handles.slider1,'min',0,'max',1,'sliderstep',[.1 .1]);
guidata(hObject, handles);
function varargout = untitled2_OutputFcn(hObject, eventdata, handles) 
varargout{1} = handles.output;
function slider1_Callback(hObject, eventdata, handles)
handles.output = hObject;
thresh = get(handles.slider1,'value');
handles.bw = im2bw(handles.I,thresh);
imshow(handles.bw);
guidata(hObject, handles);
function slider1_CreateFcn(hObject, eventdata, handles)
if isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor',[.9 .9 .9]);
end
function pushbutton1_Callback(hObject, eventdata, handles)
handles.output = hObject;
tempbw = handles.bw;
save('temp.mat','tempbw','-append');
close(untitled2);
function pushbutton2_Callback(hObject, eventdata, handles)
close(untitled2);

I hope this clear.

MATLAB: GUI with camera input error

You have a function named startStopCamera_Callback but you are trying to call upon the function named startstopcamera_Callback . Notice the 's' vs 'S' and 'c' vs 'C' .

You will have to change the callback associated with some uicontrol or other whose code you do not show here. Probably it is part of a .fig file.

This sort of problem occurs regularly when people rename their GUIDE GUI. (Just one more of the reasons I don't use GUIDE...)

Best Answer

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