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Super User

How do you determine if Pen Input is blank?

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?





Shane - Microsoft MVP, YouTube, and PowerApps Consulting for when you are in a bind to get this fixed quickly. And finally we now have PowerApps Training

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. 🙂

Shane - Microsoft MVP, YouTube, and PowerApps Consulting for when you are in a bind to get this fixed quickly. And finally we now have PowerApps Training

Hi @Shanescows


I've just tested this again and I think I understand what's going on!  .Strokes only works in the Windows version of Studio.


In the browser, I can recreate the behavior that you see where .Strokes is always empty. But in the Windows version, it returns data. I think this must be a bug.


Here's a screenshot of the test that I just carried out. Something you might find interesting is that compared to the screenshot that I made earlier in the post (on the 21st Feb), the format of the data that .Stokes returns is now different. It used to begin "blob:" whereas now, it begins "appres://blobmanager/".








Not applicable


No worries, thank you! I will have a play around and let you know how I go 🙂


Actually Shane, seems as soon as you mouse over in preview mode at least it goes to not the same... even if you dont have a mouse click.


mouse over it.. signed....


Hm. I have not had this experience.

  1. Set a variable OnVisible of screen: Set(varPenInput, PenInput.Image)
  2. Insert a Label Control and set its Text Property to varPenInput
  3. When the screen becomes visible, you should see a URL "of sorts" (appres://xyz123)
  4. Move to Preview Mode (click the Play icon in top right corner of IDE)
  5. When you hover over the Pen Input, this value does NOT change
  6. When you scribble something in the Pen Input box, the value DOES change

I'd like to know when your value changes.


I tried the workaround and I am running into the same problem. I think they changed the way they store the blob image.  Now it stores something like this:




This will be the value when the form opens, but as the screen is being rendered, that value changes, to something like



And the before & after values will never equal each other, therefore the Save / Consent button will always be in Edit mode, not Disabled.


How do I get it to work now?


@grahampasmurf  did you ever get a solution to this? I am trying to inspect the my PenInput.Image to see if it has changed so that I can skip a call to my flow with the use of an If statement. I'm using a canvas app. Everytime the screen with the pen input renders the PenInput.Image value changes as you have stated.


Did you try the step-by-step instructions above?
Attached is an example app for your reference.

Import and enjoy.


@seadude thank you, works great, very cleverSmiley LOL


If its marked as a solution, others will find it 🙂

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