Use sprintf in callback function to get an output variable

Question

Sam 2020-8-5

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/575515-use-sprintf-in-callback-function-to-get-an-output-variable

评论： Arthur Roué 2020-8-5

Hello,

I've got a very simple callback function 'countclicks', which displays the type of click (normal,alt,extend or open) and its coordinates in the command window when a mouse click is performed on my figure. How can I use sprintf to get the type of click and the associated coordinates in a seperate variable?

Thank you!

function countclicks(gcbo,eventdata,handles)
disp(get(gcf,'SelectionType'))
disp(get(gca,'CurrentPoint'))
end

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Answer 1

Arthur Roué 2020-8-5

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https://ww2.mathworks.cn/matlabcentral/answers/575515-use-sprintf-in-callback-function-to-get-an-output-variable#answer_475432

在 MATLAB Online 中打开

function countclicks(gcbo,eventdata,handles)
    strSelectionType = get(gcf,'SelectionType');
    XY = get(gca,'CurrentPoint');
    sprintf('Type : %s, X = %d / Y = %d', strSelectionType, XY(1), XY(2))
end

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Steven Lord 2020-8-5

Callback functions do not return any output arguments. So where do you want to "get a variable" that captures the click location?

I think you may want to use the ginput function.

Arthur Roué 2020-8-5

在 MATLAB Online 中打开

You can store thoses values in variable shared with the GUI main function and its nested functions.

function myGUI()
    
    % Create a local variable shared with nested function
    XY = []
    % Creat an axe with a callback
    hAxe = axes(.., 'ButtonDownFcn', @countclicks)
    function countclicks(src, evt)
        strSelectionType = get(src.Parent,'SelectionType'); % src.Parent = figure handme
        XY = get(src,'CurrentPoint');
        sprintf('Type : %s, X = %d / Y = %d', strSelectionType, XY(1), XY(2))
    end
end