Extracting the value of a slider

I created a slider using the GUIDE. I want to use the slider's numeric output as the input to another m-file, but I do not know how to get it so that I can use the sliders output for another file.

I have been looking around a lot and it seems that I have to do something with a callback function but I am not sure if I should put this in my slider code or my other m-file's code.

Answer 1

[Doug Hull]

The value of a slider is available when you use the get command on the handle of the slider. For instance:

>> h = uicontrol('style','slider')

h =

      0.0123

>> get(h,'value')

ans =

       0

%Mess with slider a bit

>> get(h,'value')

ans =

      0.1000

The trick for you is getting the handle of the slider. For that, we need to know how you made the slider. It is easiest to do this when you already know the handle to the slider. Otherwise findobj might be helpful, or look into the handles structure if using the GUIDE.

Answer 2

[Gar]

Here is the code that the GUIDE generated when I made the slider. I noticed that several times in the code the program gets that value of the slider, but I am not sure what I have to call in a seperate .m file to get this value. It seems like I should use the callback function but I am not sure what to enter for the input parameters. I tried to put 'return' after one of the spots where the program finds the value. I also tried to write a small function in this code that just found the slider value but I could not get it to work. Like I said, I am very new to matlab so any help would be greatly appriciated. Thanks!

% --- Outputs from this function are returned to the command line. 
function varargout = WaveLength_OutputFcn(hObject, eventdata, handles) 
% varargout cell array for returning output args (see VARARGOUT); 
% hObject handle to figure 
% eventdata reserved - to be defined in a future version of MATLAB 
% handles structure with handles and user data (see GUIDATA)

% Get default command line output from handles structure 
varargout{1} = handles.output;

% --- Executes on slider movement. 
function slider1_Callback(hObject, eventdata, handles) 
% hObject handle to slider1 (see GCBO) 
% eventdata reserved - to be defined in a future version of MATLAB 
% handles structure with handles and user data (see GUIDATA)

%obtains the slider value from the slider component

sliderValue = get(handles.slider1,'Value');

%puts the slider value into the edit text component 
set(handles.sliderValue_editText,'String', num2str(sliderValue)); 

% Update handles structure 
guidata(hObject, handles);

% Hints: get(hObject,'Value') returns position of slider 
% get(hObject,'Min') and get(hObject,'Max') to determine range of slider

% --- Executes during object creation, after setting all properties. 
function slider1_CreateFcn(hObject, eventdata, handles) 
% hObject handle to slider1 (see GCBO) 
% eventdata reserved - to be defined in a future version of MATLAB 
% handles empty - handles not created until after all CreateFcns called

% Hint: slider controls usually have a light gray background. 
if isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor')) 
set(hObject,'BackgroundColor',[.9 .9 .9]); 
end

function sliderValue_editText_Callback(hObject, eventdata, handles) 
% hObject handle to sliderValue_editText (see GCBO) 
% eventdata reserved - to be defined in a future version of MATLAB 
% handles structure with handles and user data (see GUIDATA) 
%get the string for the editText component 
sliderValue = get(handles.sliderValue_editText,'String'); 

%convert from string to number if possible, otherwise returns empty 
sliderValue = str2num(sliderValue); 

%if user inputs something is not a number, or if the input is less than 0 
%or greater than 100, then the slider value defaults to 0 
if (isempty(sliderValue) || sliderValue < 920 || sliderValue > 1000) 
set(handles.slider1,'Value',940); 
set(handles.sliderValue_editText,'String','940'); 
else 
set(handles.slider1,'Value',sliderValue); 
end

% Hints: get(hObject,'String') returns contents of sliderValue_editText as text 
% str2double(get(hObject,'String')) returns contents of sliderValue_editText as a double

% --- Executes during object creation, after setting all properties. 
function sliderValue_editText_CreateFcn(hObject, eventdata, handles) 
% hObject handle to sliderValue_editText (see GCBO) 
% eventdata reserved - to be defined in a future version of MATLAB 
% handles empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows. 
% See ISPC and COMPUTER. 
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor')) 
set(hObject,'BackgroundColor','white'); 
end

[Chanchal Dass]

Majority people do not have this answer..

Answer 3

[Matt Tearle]

Your slider has a callback property that defines the function that will be called when the slider is moved. It's inside that function that you need to query the value property of the slider handle, as Doug says.

Example:

Callback function:

function slidercb(h,event)
val = get(h,'value')
% do something with the slider value

Somewhere else:

figure
uicontrol('units','normalized','position',[0.2,0.2,0.5,0.1],...
  'style','slider','callback',@slidercb)

Answer 4

[Gar]

I figured it out. I kept my code for my WaveLength.m file the same. In the .m file that I wanted to obtain the value in I simply had to put

   handles = guihandles(WaveLength)
   %gets handles for figure and sets them to 'handles'

   waveLen=get(handles.slider1,'Value')  
   % gets the number occupying the 'Value' of the figure 'slider1' 
   % in the 
   % handles structure

Answer 5

[Oscar Machuca]

Im having the exact problem as you . But i didn't understand where did you write this code?

 handles = guihandles(WaveLength)
   %gets handles for figure and sets them to 'handles'
   waveLen=get(handles.slider1,'Value')  
   % gets the number occupying the 'Value' of the figure 'slider1' 
   % in the 
   % handles structure

Do you write it on the same .m file or is it a new file . please post your code