ListBox MultiSelect simulate always with Ctrl modifier?

Question

Jonas 2023-2-13

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1911490-listbox-multiselect-simulate-always-with-ctrl-modifier

编辑： Jonas 2023-2-16

dear community,

can someone check the ListBox MultiSelect Example from the documentation for me? It does not work for me, I can only select one item, not multiple at once

function multiselect
fig = uifigure('Position',[100 100 350 275]);
% Create Text Area
txt = uitextarea(fig,...
    'Position',[125 80 100 50]);
% Create List Box
lbox = uilistbox(fig,...
    'Position',[125 150 100 78],...
    'Multiselect','on',...
    'ValueChangedFcn',@selectionChanged);
% ValueChangedFcn callback
function selectionChanged(src,event)
    txt.Value = src.Value;
end
end

best regards

EDIT:

I noticed that I Have to press Ctrl for MultiSelect. How unconvenient.

Is there a way to modify inputs such that they are interpreted always as ctrl+left click?

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Answer 1

Jonas 2023-2-13

0
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https://ww2.mathworks.cn/matlabcentral/answers/1911490-listbox-multiselect-simulate-always-with-ctrl-modifier#answer_1170170

编辑：Jonas 2023-2-16

在 MATLAB Online 中打开

I tried to circumvent the ctrl modofier in such a way, that I look into the event's previous value and delete/save as necessary. Now, there is also always one option selected

I modified the callback as follows:

function selectionChanged(src,evt)
    prevVal=evt.PreviousValue;
    currVal=src.Value;
    
    if strcmp(fig.SelectionType,'normal') % to preserve ctrl behavior
    
        isThere=ismember(prevVal,currVal);
    
        if any(isThere)
            prevVal=prevVal(~isThere);
        else
            prevVal=[prevVal currVal];
        end
    
        src.Value=prevVal;
    end
end