Unanswered

How do you determine if Pen Input is blank?

(1) Share

Report

Posted on by Shanescows

2,218 Most Valuable Professional

I want to have a pen input to collect a signature and I only want to show the user the submit button after they have signed the form.

How do I check if they have scribbled something in the box or not?

Thanks

Shane

Categories:

Building Power Apps

I have the same question (0)

All responses (30)

Answers (1)

timl 36,383 Super User 2025 Season 2 on at

Like (2)

Report
Hi Shane

Here's a formula you can use:

IsBlank(PenInput1.Strokes)
This will return false when a user scribbles something in the box.

To carry out this task, you can set the DisplayMode property of your submit button to this:

If(IsBlank(PenInput1.Strokes), DisplayMode.Disabled, DisplayMode.Edit )

Was this reply helpful? Yes No
Shanescows 2,218 Most Valuable Professional on at

Like (0)

Report

Hi TimL

I tried that and it doesn't work. Best I can tell there is no value stored in .Strokes

I tried adding the code to the button and it stays disabled.

I also added a Label and set the text to Signature.Strokes and nothing shows. (I named my pen input Signature and it autocompletes without issue.)

Finally tested the app on my phone just to make sure my computer wasn't being dumb. No dice.

Thanks for any thoughts

Shane

Was this reply helpful? Yes No
Verified answer

Shanescows 2,218 Most Valuable Professional on at

Like (4)

Report
I did some messing around and the best workaround I have come up with is to see if the image URL has changed. Hopefully, someone has something better. Here is what I did:

1. Set the Screen OnVisible property to:
UpdateContext({BlankImage: Signature.Image})
2. Set the DisplayMode of my consent button to
If(BlankImage = Signature.Image,DisplayMode.Disabled,DisplayMode.Edit)
3. Set the OnSelect of my consent button to
Office365.SendEmail("shane.young@boldzebras.com","My Consent Form" , "Body Text",{Attachments:Table({Name:"peninput.jpg",ContentBytes:PenInput1.Image , '@odata.type':""})});UpdateContext({BlankImage: Signature.Image})
I reset the variable to disable the button again so I can collect a new sig. Will add code to clear the other fields also.

If you didn't catch it earlier Signature is what I renamed my PenInput field to.

If anyone has a better solution I am all ears. I don't love this but I think it works.

Thanks

Shane

Was this reply helpful? Yes No
Shanescows 2,218 Most Valuable Professional on at

Like (3)

Report

Sorry to keep replying to myself. 🙂

I made this into a video. Conditional Formatting with the Pen Input

I hope it helps.

Shane

Was this reply helpful? Yes No
patrickabel 53 on at

Like (0)

Report

@Shanescows any luck finding a less cumbersome solution?

The absense of a value on .Strokes has got to be a bug. **bleep**'s unfortuante that the simplest of validation isn't doable without image comparisons at this point.

Was this reply helpful? Yes No
timl 36,383 Super User 2025 Season 2 on at

Like (0)

Report

Hi all,

I'm a bit confused. For me, .Strokes returns a value when I scribble into the control. When the pen input control is empty, .Strokes returns blank.

Is there something that I'm misunderstanding here, or is my version of PowerApps behaving differently to everyone else?

Was this reply helpful? Yes No
patrickabel 53 on at

Like (1)

Report
I can do another test to confirm, but this did not work for me after incorporating into a rule which shows/hides a button.
IsBlank(PenInput1.Strokes)
I ended up leveraging an image compare as @Shanescows recommended.

Was this reply helpful? Yes No
timl 36,383 Super User 2025 Season 2 on at

Like (0)

Report

Hi @patrickabel

Thanks for the clarification. It's curious because I can use .Strokes as I'd expect to in a rule. Here for example, I'm able to show the button only when the pen input control contains data.

Was this reply helpful? Yes No
Community Power Pla... on at

Like (0)

Report

Hi Shane,

Thank you for your solution, the YouTube video was very helpful also.
How would you ammend the string so that it looks at two signature fields?
(Assuming Signature1 and Signature2)

Thank you

Kind regards

Was this reply helpful? Yes No
Shanescows 2,218 Most Valuable Professional on at

Like (0)

Report

Hey @timl I missed this the first time. I just tested again and my PenInpu1.Strokes is always Empty. 😞 I have never gotten it to work. 😞

@Anonymous I will be mean and tell you that you want to incorporate the Or function (And could also work) but I will not tell you the syntax. Blame the last guy that I only gave the part solution and he had a great experience figuring it out himself. If you don't get it let me know and I will tell you the solution. 🙂

Was this reply helpful? Yes No