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How to make a slider GUI with most simple code

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Yode
Yode on 7 Jul 2017
I'm a Mathematica user,so I can make a slider gui with this code
Manipulate[Plot[Sin[a x], {x, 0, 2 Pi}], {a, 1, 2}]
Recently,I'm learning Matlab,the powerful software as my teacher say.But I realize I have to write a ton code for such target
function sliderSin
f=figure('visible','off','position',...
[360 500 400 400]);
slhan=uicontrol('style','slider','position',[100 280 200 20],...
'min',0,'max',4*pi,'callback',@callbackfn);
hsttext=uicontrol('style','text',...
'position',[170 340 40 15],'visible','off');
axes('units','pixels','position',[100 50 200 200]);
movegui(f,'center')
set(f,'visible','on');
function callbackfn(source,eventdata)
num=get(slhan,'value');
set(hsttext,'visible','on','string',num2str(num))
x=linspace(0,4*pi);
y=sin(num*x);
plot(x,y);
ax=gca;
ax.XLim=[0 2*pi]
end
end
Then I will get a slider gui like
The current solution have two problem make me crazy:
  • I have to write so many code?
  • Why it cannot run normally when I drag the slider?
Help please.
  2 Comments
Yode
Yode on 7 Jul 2017
@Adam It is a good lesson for me.Thanks very much. :)

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Accepted Answer

Jan
Jan on 7 Jul 2017
Edited: Jan on 7 Jul 2017
  • Why it cannot run normally when I drag the slider?
This is "normally". The code is using the Callback currently, which is triggered, when the mouse is released. For a continuous callback, use the listener: https://www.mathworks.com/matlabcentral/answers/264979-continuous-slider-callback-how-to-get-value-from-addlistener#answer_207231 .
  • I have to write so many code?
Yes. This is Matlab. Somethings are easier than in Mathematica, some things are harder.
It would save some code lines and makes the animation more fluently, if you create the line object once and update the YData only:
function sliderSin
FigH = figure('position',[360 500 400 400]);
axes('XLim', [0 4*pi], 'units','pixels', ...
'position',[100 50 200 200], 'NextPlot', 'add');
x = linspace(0, 4*pi, 400);
y = sin(x);
LineH = plot(x,y);
TextH = uicontrol('style','text',...
'position',[170 340 40 15]);
SliderH = uicontrol('style','slider','position',[100 280 200 20],...
'min', 0, 'max', 4*pi);
addlistener(SliderH, 'Value', 'PostSet', @callbackfn);
movegui(FigH, 'center')
function callbackfn(source, eventdata)
num = get(eventdata.AffectedObject, 'Value');
LineH.YData = sin(num * x);
TextH.String = num2str(num);
end
end
  1 Comment
Yode
Yode on 7 Jul 2017
Thanks a lot.If there is not better solution,I will accept yours. :)

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More Answers (2)

Geoff Hayes
Geoff Hayes on 7 Jul 2017
Yode - the slider callback (as you've defined) only fires when the slider stops moving and you want the callback to fire whenever there is a change to the slider position. To get this behaviour, you can add a listener (see addlistener to your slider so that whenever there is a change the slider position (or its Value property) then your callback fires. To do this, remove the callback from your slider creation so that you just have
slhan=uicontrol('style','slider','position',[100 280 200 20],'min',0,'max',4*pi);
Then add a listener for this slider that will invoke the callback whenever Value changes
hSliderListener = addlistener(slhan, 'Value', 'PostSet', @callbackfn);
Try the above and see what happens!
  2 Comments
Grigorii Tarasov
Grigorii Tarasov on 30 Jul 2018
Cannot execute this:
Error in sliderSin (line 5) num = get(eventdata.AffectedObject, 'Value');

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