I am writing code to create a GUI, so How do I set slider values to change RGB axes values?

I am writing code to create a GUI.

The guidelines are as listed:

So first, open up App Designer in Matlab.

Then create a new GUI and in the “Design View” tab, place all the components for the GUI

• 3 Sliders
• 1 Axis
• 1 Button
• 1 Label
• Add a CallBack function for the Button

Next, go to the “Code View” tab, and add the code for the Button callback function so that the background color of the Axes changes based on the value of the sliders AND the values of the sliders are printed. This callback function will be executed when the Update Color Button is pushed.

• The values from the sliders can be saved as variables by storing the “.Value” property
• The color of the axes can be changed by setting the “.Color” property to the RGB values from the sliders
• Use the sprintf function to print the values for R, G and B to the Label component by setting the .Text property. The sprintf function works very similar to fprintf -- but instead of printing to the Command Window, sprintf prints to a char Array variable.

I followed these guidelines and have the Design View of:

and a Code View of:

It is not working and I am unsure how to set the values of the sliders to ensure that they change the axes background color. Help would be greatly appreciated. Thank you for yor time!

[Jan]

Screenshots are not useful in the forum, because they cannot be used to create a modified version of your code. Prefer posting code as formatted code.

What does "it is not working" mean? Please share this important information with the readers.

Use the callbacks of the sliders.

[Me]

I did use the callback of the button. By it's not working I mean that when I run the GUI and move the sliders, the sliders do not change the background color of the axes. It remains white regardless of what I do. The slider values sometimes appear on the label and other times it does not.

The code:

classdef colorBox < matlab.apps.AppBase

% Properties that correspond to app components

properties (Access = public)

UIFigure matlab.ui.Figure

Label matlab.ui.control.Label

UpdateColorButton matlab.ui.control.Button

BSlider matlab.ui.control.Slider

BSliderLabel matlab.ui.control.Label

GSlider matlab.ui.control.Slider

GSliderLabel matlab.ui.control.Label

RSlider matlab.ui.control.Slider

RSliderLabel matlab.ui.control.Label

UIAxes matlab.ui.control.UIAxes

end

% Callbacks that handle component events

methods (Access = private)

% Button down function: UIFigure

function UIFigureButtonDown(app, event)

% background color of the axes changes based on value of

% sliders

% values of sliders are printed

RVal = app.RSlider.Value;

GVal = app.RSlider.Value;

BVal = app.BSlider.Value;

app.UIAxes.BackgroundColor = [RVal,GVal,BVal];

app.Label.Text = sprintf('[%.2f %.2f %.2f]', RVal, GVal, BVal);

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';

app.UIFigure.ButtonDownFcn = createCallbackFcn(app, @UIFigureButtonDown, true);

% Create UIAxes

app.UIAxes = uiaxes(app.UIFigure);

title(app.UIAxes, 'Custom Color')

app.UIAxes.XTick = [];

app.UIAxes.XTickLabel = '';

app.UIAxes.YTick = [];

app.UIAxes.YTickLabel = '';

app.UIAxes.Position = [283 153 300 255];

% Create RSliderLabel

app.RSliderLabel = uilabel(app.UIFigure);

app.RSliderLabel.HorizontalAlignment = 'right';

app.RSliderLabel.Position = [42 337 25 22];

app.RSliderLabel.Text = 'R';

% Create RSlider

app.RSlider = uislider(app.UIFigure);

app.RSlider.Limits = [0 1];

app.RSlider.MajorTicks = [0 0.5 1];

app.RSlider.Position = [88 346 150 3];

% Create GSliderLabel

app.GSliderLabel = uilabel(app.UIFigure);

app.GSliderLabel.HorizontalAlignment = 'right';

app.GSliderLabel.Position = [42 271 25 22];

app.GSliderLabel.Text = 'G';

% Create GSlider

app.GSlider = uislider(app.UIFigure);

app.GSlider.Limits = [0 1];

app.GSlider.MajorTicks = [0 0.5 1];

app.GSlider.Position = [88 280 150 3];

% Create BSliderLabel

app.BSliderLabel = uilabel(app.UIFigure);

app.BSliderLabel.HorizontalAlignment = 'right';

app.BSliderLabel.Position = [42 198 25 22];

app.BSliderLabel.Text = 'B';

% Create BSlider

app.BSlider = uislider(app.UIFigure);

app.BSlider.Limits = [0 1];

app.BSlider.MajorTicks = [0 0.5 1];

app.BSlider.Position = [88 207 150 3];

% Create UpdateColorButton

app.UpdateColorButton = uibutton(app.UIFigure, 'push');

app.UpdateColorButton.Position = [383 110 100 23];

app.UpdateColorButton.Text = 'Update Color';

% Create Label

app.Label = uilabel(app.UIFigure);

app.Label.BackgroundColor = [1 1 1];

app.Label.HorizontalAlignment = 'center';

app.Label.Position = [111 110 104 22];

app.Label.Text = '';

% Show the figure after all components are created

app.UIFigure.Visible = 'on';

end

end

% App creation and deletion

methods (Access = public)

% Construct app

function app = colorBox

% Create UIFigure and components

createComponents(app)

% Register the app with App Designer

registerApp(app, app.UIFigure)

if nargout == 0

clear app

end

end

% Code that executes before app deletion

function delete(app)

% Delete UIFigure when app is deleted

delete(app.UIFigure)

end

end

end

[Me]

Sorry, I noticed you said use callback of the sliders. If I were to do that, what information would need to be present in those sliders? Would each slider need to be set to app.UIAxes.BackgroundColor = [RVal, GVal, BVal]? The guidelines instruct me to use the button callback to change the background color and print to the label. Would I instead set each value of the slider within each slider's callback?

[Jan]

Sorry, I've struggled to much with the tiny screenshots. No, do not use thecallbacks of the sliders, but the callbacl of the button. Currently you have com code in the UIFigureButtonUp callback, but this is not useful.