Need help in dropdownopening callback.

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Aman kumar
Aman kumar on 5 Sep 2021
Edited: Srijith Kasaragod on 20 Sep 2021
I am designing an app for various signal display. (Attached UI and code).
1: Select a signal from dropdown. (how to write the callback for this)
2: Primary graph of that signal will be plotted on the axes. (how to write the callback for this)
3: Control the value of x axis and y axis from the slider. (how to write the callback for this)
classdef app1 < matlab.apps.AppBase
% Properties that corr
% Callbacks that handle component events
methods (Access = private)
% Value changed function: DropDown
function DropDownValueChanged(app, event)
x = 0:0.01: (360/180)*pi;
y = sin(x);
plot(app.UIAxes,y);
end
% Value changing function: Slider
function SliderValueChanging(app, event)
end
% Drop down opening function: DropDown
function DropDownOpening(app, event)
end
end
% Component initialization
methods (Access = private)
% Create UIFigure and components
function createComponents(app)
% Create UIFigure and hide until all components are created
app.UIFigure = uifigure('Visible', 'off');
app.UIFigure.Position = [100 100 640 480];
app.UIFigure.Name = 'MATLAB App';
% Create Panel
app.Panel = uipanel(app.UIFigure);
app.Panel.Title = 'Panel';
app.Panel.Scrollable = 'on';
app.Panel.Position = [171 43 400 342];
% Create UIAxes
app.UIAxes = uiaxes(app.Panel);
title(app.UIAxes, 'sine signal')
xlabel(app.UIAxes, 'x')
ylabel(app.UIAxes, 'y')
zlabel(app.UIAxes, 'Z')
app.UIAxes.XLim = [0 50];
app.UIAxes.YLim = [0 50];
app.UIAxes.XTick = [0 10 20 30 40 50];
app.UIAxes.XTickLabel = {'0'; '10'; '20'; '30'; '40'; '50'};
app.UIAxes.YTick = [0 25 50];
app.UIAxes.YTickLabel = {'0'; '25'; '50'};
app.UIAxes.XGrid = 'on';
app.UIAxes.YGrid = 'on';
app.UIAxes.Position = [42 14 325 100];
% Create SliderLabel
app.SliderLabel = uilabel(app.Panel);
app.SliderLabel.HorizontalAlignment = 'right';
app.SliderLabel.Position = [104 226 36 22];
app.SliderLabel.Text = 'Slider';
% Create Slider
app.Slider = uislider(app.Panel);
app.Slider.ValueChangingFcn = createCallbackFcn(app, @SliderValueChanging, true);
app.Slider.Position = [161 235 186 7];
% Create Slider2Label
app.Slider2Label = uilabel(app.Panel);
app.Slider2Label.HorizontalAlignment = 'right';
app.Slider2Label.Position = [104 156 42 22];
app.Slider2Label.Text = 'Slider2';
% Create Slider2
app.Slider2 = uislider(app.Panel);
app.Slider2.Position = [167 165 180 7];
% Create xLabel
app.xLabel = uilabel(app.Panel);
app.xLabel.Position = [41 215 52 33];
app.xLabel.Text = 'x';
% Create yLabel
app.yLabel = uilabel(app.Panel);
app.yLabel.Position = [41 148 44 39];
app.yLabel.Text = 'y';
% Create DropDownLabel
app.DropDownLabel = uilabel(app.Panel);
app.DropDownLabel.HorizontalAlignment = 'right';
app.DropDownLabel.Position = [41 281 65 22];
app.DropDownLabel.Text = 'Drop Down';
% Create DropDown
app.DropDown = uidropdown(app.Panel);
app.DropDown.Items = {'Sine signal', ''};
app.DropDown.ItemsData = {'y=sin(x)'};
app.DropDown.DropDownOpeningFcn = createCallbackFcn(app, @DropDownOpening, true);
app.DropDown.ValueChangedFcn = createCallbackFcn(app, @DropDownValueChanged, true);
app.DropDown.Position = [121 269 237 46];
app.DropDown.Value = 'y=sin(x)';

Answers (1)

Srijith Kasaragod
Srijith Kasaragod on 20 Sep 2021
Edited: Srijith Kasaragod on 20 Sep 2021
Assuming the x and y sliders adjust x-axis limit and y-axis limit of the plot respectively, following lines of code shows one of the possible solution to the problem.
The app contains dropdown, x-slider, y-slider, axes and a button. Dropdown enables selection of signals, i.e, either sin or cos. The x-slider and y-slider adjusts the x-axis limit and y-axis limit of the axes. Clicking on the push-button generates signal plot with axes limits as specified.
App variables required to hold user input are:
properties (Access = private)
func; % variable to hold the signal selected from dropdown
xslider; % variable to hold upper limit of xlim
yslider; % variable to hold upper limit of ylim
end
Startup function callback saves default values of dropdown and sliders into app variables.
function startupFcn(app)
app.func= str2func(app.SignalDropDown.Value); %str2func creates function handle from string
app.xslider= app.XSlider.Value;
app.yslider= app.YSlider.Value;
end
Signal dropdown callback function saves the user selected signal into app variable 'func'.
function SignalDropDownValueChanged(app, event)
value = app.SignalDropDown.Value;
app.func= str2func(value);
end
Pushbutton callback function holds the x, y values, generates the plot and sets xlim and ylim as per user input.
function EnterButtonPushed(app, event)
x=0:0.01:(360/180)*pi;
y= app.func(x);
plot(app.UIAxes,x,y);
xlim(app.UIAxes,[0 app.xslider]);
ylim(app.UIAxes,[-2 app.yslider]);
end
Slider callback functions saves user input into app variables 'xslider' and 'yslider'.
function XSliderValueChanged(app, event)
app.xslider = app.XSlider.Value;
end
function YSliderValueChanged(app, event)
app.yslider = app.YSlider.Value;
end
All components can be placed in the app as per user requirement. Refer this link to read more about 'str2func' function.

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R2021a

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