progress bar in app design (GUI)

Hi!

I need to create a progress bar like the following bar with the APP DESIGN:

New in r2020a: App button animation & truecolor images - MATLAB® Central (mathworks.com)

% Button pushed function: ProcessDataButton
function ProcessDataButtonPushed(app, event)
    % Change button name to "Processing"
    app.ProcessDataButton.Text = 'Processing...';
    % Put text on top of icon
    app.ProcessDataButton.IconAlignment = 'bottom';
    % Create waitbar with same color as button
    wbar = permute(repmat(app.ProcessDataButton.BackgroundColor,15,1,200),[1,3,2]);
    % Black frame around waitbar
    wbar([1,end],:,:) = 0;
    wbar(:,[1,end],:) = 0;
    % Load the empty waitbar to the button
    app.ProcessDataButton.Icon = wbar;
    % Loop through something and update waitbar
    n = 10;
    for i = 1:n
        % Update image data (royalblue)
        currentProg = min(round((size(wbar,2)-2)*(i/n)),size(wbar,2)-2);
        app.ProcessDataButton.Icon(2:end-1, 2:currentProg+1, 1) = 0.25391;
        app.ProcessDataButton.Icon(2:end-1, 2:currentProg+1, 2) = 0.41016;
        app.ProcessDataButton.Icon(2:end-1, 2:currentProg+1, 3) = 0.87891;
        % Pause to slow down animation
        pause(.3)
    end
    % remove waitbar
    app.ProcessDataButton.Icon = '';
    % Change button name
    app.ProcessDataButton.Text = 'Process Data';
end

I need the progress bar to update AFTER calling my function, so I changed it into something like that:

% Button pushed function: ProcessDataButton
function ProcessDataButtonPushed(app, event)
    % Change button name to "Processing"
    app.ProcessDataButton.Text = 'Processing...';
    % Put text on top of icon
    app.ProcessDataButton.IconAlignment = 'bottom';
    % Create waitbar with same color as button
    wbar = permute(repmat(app.ProcessDataButton.BackgroundColor,15,1,200),[1,3,2]);
    % Black frame around waitbar
    wbar([1,end],:,:) = 0;
    wbar(:,[1,end],:) = 0;
    % Load the empty waitbar to the button
    app.ProcessDataButton.Icon = wbar;
    
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    % Loop through something and update waitbar 
    my_function(do things...)
    <events?>    
   
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    % remove waitbar
    app.ProcessDataButton.Icon = '';
    % Change button name
    app.ProcessDataButton.Text = 'Process Data';
end

My problem: I don't know how to keep trace of my updates. Do I need to create an event? I followed this guide: Define Custom Event Data - MATLAB & Simulink - MathWorks Italia, but I did not manage to solve my problem: I need intermediate output before the end of the function to trace my advancements (hope to explain myself, my technical language is poor in this field). Is my path ok or not?

Do you have suggestions? Thank you

[Adam Danz]

@Veronica Taurino it depends on what's controlling your updates. Are the updates done in a loop? Are the updates done in sections of code?

Also, are the updates done in the app file or outside of the app?

[Veronica Taurino]

The updates are done outside the app, in a loop code within an external function (image) called by the buttoncallback.

[Adam Danz]

See the 3 easy steps below.

[GT]

Would be nice if this shipped with App Designer, it is a common thing for User Interfaces.

[Adam Danz]

@GT see uiprogressbar which is not embedded in a button but otherwise the same thing as this.

Answer 1

[Adam Danz]

Step 0: Set up the app button

Add a button to your app and add a ButtonPushed callback function. Importantly, the height of the button must be extended to have enough space for the progress bar.

Step 1: Send button handle to external function

Call the external function from within the ButtonPushed callback function and pass the button handle to the pseudo-progress-bar as an input to the external function. I call it a pseudo-progress-bar because it's not a typical waitbar or uiprogressdlg.

app.ProcessDataButton is the button handle.

function ProcessDataButtonPushed(app, event)
    myFunction(___, app.ProcessDataButton)
end

Also, define the additional input within the external function.

function myFunction(___, processDataButtonHandle)

Step 2: Set up the progress bar within the external function

Obviously this needs set up prior to the loop that will update the progress bar. Some of this block of code differs from the original example. Thanks to onCleanup in the last line below, the button will return to its original state after the loop or if an error prematurely ends the function.

% Store original button text
originalButtonText = processDataButtonHandle.Text;
% When the function ends, return the original button state
cleanup = onCleanup(@()set(processDataButtonHandle,'Text',originalButtonText,'Icon',''));
% Change button name to "Processing"
processDataButtonHandle.Text = 'Processing...';
% Put text on top of icon
processDataButtonHandle.IconAlignment = 'bottom';
% Create waitbar with same color as button
wbar = permute(repmat(processDataButtonHandle.BackgroundColor,15,1,200),[1,3,2]);
% Black frame around waitbar
wbar([1,end],:,:) = 0;
wbar(:,[1,end],:) = 0;
% Load the empty waitbar to the button
processDataButtonHandle.Icon = wbar;

Step 3: Update the progress bar within a loop

Place the code within the for-loop at the beginning or end of the loop depending on whether you want the progress bar to update before or after your loop processes. This example updates the progress bar at the end of the loop. (note: Code in step 3 was updated on Feb-11-2022 to improve efficiency).

This section uses variables:

• n - the number of iterations
• i - the loop variable

n = 10; 
for i = 1:n
    
    % % % % % % % % % % % % % % % % % % 
    % %  YOUR LOOP STUFF GOES HERE  % %
    % % % % % % % % % % % % % % % % % % 
    
    % Update progress bar 
    currentProg = min(round((size(wbar,2)-2)*(i/n)),size(wbar,2)-2);
    RGB = app.processDataButtonHandle.Icon;
    RGB(2:end-1, 2:currentProg+1, 1) = 0.25391; % (royalblue)
    RGB(2:end-1, 2:currentProg+1, 2) = 0.41016;
    RGB(2:end-1, 2:currentProg+1, 3) = 0.87891;
    
    app.processDataButtonHandle.Icon = RGB;
    % Pause to slow down animation (OPTIONAL)
    % pause(.3)
end

To clear the psueo-progress-bar and return the button to normal you have two options

• Do nothing. The bar will be cleared and the button will return to normal after the external funtion is complete.
• Exectue clear('cleanup') at any point after the loop within the same function to return the button state.

[Veronica Taurino]

Thank you, it works! I thought about it... with your solution I mixed the graphic part with the code, so later I may have trouble with changes in the workflow but for now it works fine! Thank you!! I can move on!

I will post another solution if I change it in the future

[Adam Danz]

These are the basic steps to understand how the pseudo-progressbar is created and controlled. it can be adapted to fit your needs.

> with your solution I mixed the graphic part with the code

With any solution, the section of code that controls the progess will also control the progress bar.

Another approach is to create the progress bar from within the app rather than from within the external function. That just requires moving the existing code around. Then your code could merely call an update function to update the progress bar.

There are several ways to control the pseudo-progress bar once you understand what each section in my answer does.

[Veronica Taurino]

Thank you. Your solution is clear, I get all of it (it is close to my initial idea to solve my issue). I am talking about do not mix the graphic and the code part because an IT engineer I work with told me to use ''events'' to do not mix it, but I have never used events, therefore my previous doubts. I have already written an alternative solution but I get few errors for now. I going to post it if I solve them.

[Adam Danz]

I see. It would help knowing what your loop is going. What would the be the event that triggers the progress update? Is it a variable value change? A graphics update? And does the app have access to that event?

[Mark Golberg]

How to make the progress bar (along with the "processing..." text) to be less jittering....

It looks as it the who thing is being "deleted" and "re-drawen" during each iteration, creating an unnatural look&feel appearance of the progress bar.

In the example the "processing..." is rock solid, and I see only the progress bar advances.

THANK YOU

[Adam Danz]

@Mark Golberg I know what you mean. There are things we can do to reduce the flicker but I can't remove it completely.

I just attached a simple app that demonstrates my ideas to this thread. You'll see that it flickers but less frequently.

Why is it flickering?

The progress bar is actually created with 3D image data and when the image is updated, it appears that the entire icon (or image) is cleared and re-rendered. This happens under the hood. However, the transition doesn't always appear as a flicker so at least sometimes it happens fast enough to not notice it. We have no control over this but I'd love to hear anyone else's ideas.

Two changes that will decrease frequency of flicker

1. Assign the RGB image once instead of separately for each R/G/B channel. I should have done this in the first place. This will reduce the rendering cycles by 1/3. Replace these lines,

currentProg = min(round((size(wbar,2)-2)*(i/n)),size(wbar,2)-2);

processDataButtonHandle.Icon(2:end-1, 2:currentProg+1, 1) = 0.25391; % (royalblue)

processDataButtonHandle.Icon(2:end-1, 2:currentProg+1, 2) = 0.41016;

processDataButtonHandle.Icon(2:end-1, 2:currentProg+1, 3) = 0.87891;

with this more efficient method,

currentProg = min(round((size(wbar,2)-2)*(i/n)),size(wbar,2)-2);

RGB = app.processDataButtonHandle.Icon;

RGB(2:end-1, 2:currentProg+1, 1) = 0.25391; % (royalblue)

RGB(2:end-1, 2:currentProg+1, 2) = 0.41016;

RGB(2:end-1, 2:currentProg+1, 3) = 0.87891;

app.processDataButtonHandle.Icon = RGB;

2. If your loop has many iterations and the cycles are fast, you can update the embedded progress bar evey n cycles instead of every cycle. For example, if your loop has 100 iterations, you could update the graphic every 5 or 10 iterations. To achieve this, move the progress bar update code to a conditional block demonstrated below. Use mod(i,n)==0 to determine if iteration i is a multiple of n .

% Update every 10 cycles

for i = 1:n

% % % % % % % % % % % % % % % % % %

% % YOUR LOOP STUFF GOES HERE % %

% % % % % % % % % % % % % % % % % %

if mod(i,10)==0 % update every 10 cycles; improve efficiency

currentProg = min(round((size(wbar,2)-2)*(i/n)),size(wbar,2)-2);

RGB = app.processDataButtonHandle.Icon;

RGB(2:end-1, 2:currentProg+1, 1) = 0.25391; % (royalblue)

RGB(2:end-1, 2:currentProg+1, 2) = 0.41016;

RGB(2:end-1, 2:currentProg+1, 3) = 0.87891;

app.processDataButtonHandle.Icon = RGB; % (royalblue)

end

[Mark Golberg]

@Adam Danz

unfortunately neither of the tow proposed solutions reduced the jitterging.

It's really a pity. I wanted to use the "old" progress bar, and then saw this cool thread about progress bar that open in a push button. really neat. not sure my clients of the GUI would be too happy if I leave this jittering going on...

[Adam Danz]

Both significantly reduced the jittering when I tested it but neither elimiated it completely.

There are other embedded alternatives if you want to get creative. For example, you could customize a knob or guage that rotates from 0 to 100% or a slider that progresses from 0:100%. You could turn the editable property off so users know that the UI component is not meant for user interaction or you could turn on/off the visibility of the component as needed.

[Oren Lee]

Adding to what Adam did above, I did the same thing but with a few changes.

I created a public function in the app that does all this for me so that a more complex loop elsewhere can run on its own. Additionally I am using an "image" and changing the "imageSource" property to fill the bar.

Note that app.Progress is public property of the app which is continually updated

function progressBarUpdate(app,arg,val)
            % app
            % arg   - 'Setup', 'Reset', 'Increment', 'Set', 'Complete'
            % val   - 0 to 1, based on above selection
            switch lower(arg)
                case {'setup','reset'}
                    pos = app.ProgressBar.OuterPosition;
                    wbar = permute(repmat([1,1,1],pos(4)-2,1,pos(3)-2),[1,3,2]);
                    wbar([1,end],:,:) = 0;
                    wbar(:,[1,end],:) = 0;
                    app.ProgressBar.ImageSource = wbar;
                    app.progress = 0;
                    return
                case 'increment'
                    curProg = app.progress + val;
                case 'set'
                    curProg = val;
                case 'complete'
                    curProg = 1;
            end
            if curProg > 1; curProg = 1; end
            if curProg < 0; curProg = 0; end
            wbar = app.ProgressBar.ImageSource;

            currentProg = min(round((size(wbar,2)-2)*(curProg)),size(wbar,2)-2);
            wbar(2:end-1, 2:currentProg+1, 1) = 0.25391; % (royalblue)
            wbar(2:end-1, 2:currentProg+1, 2) = 0.41016;
            wbar(2:end-1, 2:currentProg+1, 3) = 0.87891;

            app.ProgressBar.ImageSource = wbar;
            % The below line is for a percentage display which I have
            % overlaid on top of the progressbar
            app.ProgressBarText.Text = [num2str(100*curProg,'%0.1f'),'%'];
        end

[Adam Danz]

Thanks for sharing that, @Oren Lee!

[FABRIZIO MONCELLI]

@Oren Lee could you share the full code for the progress bar, please? I tried to follow the steps but the code does not work

[Mohammed Azharuddin]

@Adam Danz I am trying to use this inside startup function. I am on 2022b. I have used the following code as suggested, and there is no colour change or any colour on the progress button, could you please help me troubleshoot what am I overlooking, Thanks!

originalButtonText = app.ProgressButton.Text;

cleanup = onCleanup(@()set(app.ProgressButton,'Text',originalButtonText,'Icon',''));

app.ProgressButton.Text = 'Processing...';

app.ProgressButton.IconAlignment = 'bottom';
wbar = permute(repmat(app.ProgressButton.BackgroundColor,15,1,200),[1,3,2]);

wbar([1,end],:,:) = 0;
wbar(:,[1,end],:) = 0;

app.ProgressButton.Icon = wbar;

n = 10; 
for i = 1:n
    
    %Update progress bar 
    currentProg = min(round((size(wbar,2)-2)*(i/n)),size(wbar,2)-2);
    RGB = app.ProgressButton.Icon;
    RGB(2:end-1, 2:currentProg+1, 1) = 0.25391; % (royalblue)
    RGB(2:end-1, 2:currentProg+1, 2) = 0.41016;
    RGB(2:end-1, 2:currentProg+1, 3) = 0.87891;
    
    app.ProgressButton.Icon = RGB;
    % Pause to slow down animation (OPTIONAL)
    pause(.3)
end

Tried using pause, and drawnow

Nothing changes.

Also, instead of a button can I use axis? and may be use plot function, by extracting the app.progress value?

[Adam Danz]

What the value for app.ProgressButton.BackgroundColor before you make any changes in startup?

[Mohammed Azharuddin]

@Adam Danz Didnt assign any, however, a work around, was I used your idea of patch function and instead of i/n, I just used i in x values to update it, I added for loop in various sections of my startup function, so I know which position it is! Thanks Adam, your comments and replies are really useful.