How use keyboard arrow keys to control the slider GUI in App Designer?

Question

tonybabel 2019-2-14

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评论： Vitek Stepien 2022-8-23

Hi,

I have trouble using keyboard input (like arrow keys) to control a slider GUI in App Designer. For example, when pressing the left arrow key, the slider cursor move to left and pressing the right arrow the slider cursor move to right. I'm trying to use switch/case but totally have no idea what need to be written under each 'case'. Please help! Thank you so much!

Below is the codes I grabbed from "code view" window in App Designer.

% Value changing function: Slider

function SliderValueChanging(app, event)

changingValue = event.Value;

set_param('Output','Value',num2str(changingValue));

end

% Key press function: UIFigure

function UIFigureKeyPress(app, event)

switch event.Key

case 'left arrow key'

??????

case 'right arrow key'

??????

end

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Answer 1

Roche de Guzman 2021-1-8

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https://ww2.mathworks.cn/matlabcentral/answers/445025-how-use-keyboard-arrow-keys-to-control-the-slider-gui-in-app-designer#answer_593953

Under the keypress fx callback:

function UIFigureKeyPress(app, event)

value = app.Slider.Value; % get the slider value

key = event.Key; % get the pressed key value

if strcmp(key,'leftarrow')

value = value-1; % left value

elseif strcmp(key,'rightarrow')

value = value+1; % right value

end

app.Slider.Value = value; % set the slider value

SliderValueChanging(app, event); % execute the slider callback

end

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Vitek Stepien 2022-8-23

This helped me, very simple way. The only caveat is that when I change tabs I have to click somewhere else, or the left-right keys change tabs, and when I use the Zoom tool on an axis I have to deactivate it because the arrows pan the plot. But I know this can be overriden if someone really cares.

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Answer 2

Rik 2019-2-14

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/445025-how-use-keyboard-arrow-keys-to-control-the-slider-gui-in-app-designer#answer_361077

You can use this tester GUI to determine what you should put for the special keys. Don't forget the otherwise option to exit the function if you don't want to respond to other keys.

figure(1),clf(1)
set(gcf,'KeyPressFcn',@keycall)
function keycall(h,e)
disp(e.Key)
end
%rightarrow and leftarrow are the left and right arrow key names

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Rik 2019-2-18

Did this suggestion solve your problem? If so, please consider marking it as accepted answer. It will make it easier for other people with the same question to find an answer. If this didn't solve your question, please comment with what problems you are still having.

Markus Leuthold 2022-7-22

3 years later, this is still a problem. @Rik your solution considers the old java based control, OP talked about the new web based controls

uicontrol('style', 'slider',....) lets you control the slider with the keyboard and has a KeyPressFcn callback
uislider doesn't let you control the slider with the keyboard and has no keyboard related callback

This is a serious shortcoming

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