how to get uicontrol value inside a callback function?

Question

lou 2015-9-23

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https://ww2.mathworks.cn/matlabcentral/answers/244735-how-to-get-uicontrol-value-inside-a-callback-function

评论： Walter Roberson 2015-9-24

Hi, I have a have written a function which has several callback functions. My function acts on a figure. I have added a uicontrol button to my figure and this is where my problem starts.

I would like to get the value of the GUIbutton state while I am still inside another callback function.

    %==another callback function===
    button1 = uicontrol('Style','pushbutton', 'Value', f,'pos',...
    [20 10 10 10],'string','text_here'); 
    state=get(handles.button1, 'Value');
    if state==1;%button is clicked
            %do something
        else
           %do something else
    end
    %===another callback function====

this doesnt work, because the class handles is undefined, but unfortunately I am unable to understand how to fix it.

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Answer 1

Walter Roberson 2015-9-23

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Functions cannot have callbacks. Objects (especially graphic objects) can have callbacks.

http://matlab.wikia.com/wiki/FAQ#How_can_I_share_data_between_callback_functions_in_my_GUI.3F

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lou 2015-9-24

Yes, you're right. My created figure has several callback functions, not the function. I have added a togglebutton to my figure and I would like to extract the state of the togglebutton, but I do not know how to do this correctly when the state of the togglebutton needs to be extracted inside another callback function.

Walter Roberson 2015-9-24

编辑：Walter Roberson 2015-9-24

在 MATLAB Online 中打开

If you are using GUIDE, then you get() the Value property of the handles structure entry named the same thing as the Tag of the toggle button. For example,

get(handles.togglebutton1, 'Value')

If you are not using GUIDE or you are creating the toggle button dynamically then you need to use one of the techniques for sharing data from the link I posted.

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Answer 2

Stephen23 2015-9-24

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编辑：Stephen23 2015-9-24

在 MATLAB Online 中打开

The easiest way would be to use nested functions, then the variable handles is visible inside the callback workspaces as well, without needing to pass it explicitly:

function main
handles.cancelBut = ...
...
    function callback_cancel_button
    get(handles.cancelBut,'Value')
    end
end

Otherwise you should read the documentation, which describes all of the ways to pass variables (e.g. your handles structure) between callbacks:

http://www.mathworks.com/help/matlab/creating_guis/share-data-among-callbacks.html

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Walter Roberson 2015-9-24

If you are using GUIDE, then this is not the easiest way, as GUIDE historically does not terminate each function with a matching "end" statement as is required for all functions in the same file if you want to use nested functions.

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