Drawing app undo & redo button

I am using the example recommended in this thread.

My canvas undo button does not work proper

But I am not sure why the ListPicker1 does not seem to exist or what to do about it.
Any help would be appreciated!

Thank you,

So I implemented these blocks but the ListPicker1 doesn't seem to be defined anywhere.

It would be defined in the Designer, not the Blocks.

Hi there, all! I have a wonderful app that I am trying to finish up. If you all could help me where I am stuck, I think this app would be a nice one for showcasing... and a great template for any other drawing app.

My two main concerns are, First: The Undo/Redo portion which I tried to integrate with Italo's Color Picker, but alas, it is not working at the moment; and so, I ask for your help.
Second: I was attempting to get the Save Button to save the drawings, done on the canvas in the Drawing Section--under the Drawing Tab, to the gallery... say on an android phone and I am quite certain it is not working at present.

Here is what the app looks like:

And here are the blocks with the problem sections highlighted:

If you would like an .aix (or is it .aia?) let me know and how to get it to you.

Thank you for any and all help,

You have to store the file in shared storage and additionally use the GalleryRefresh method from the tools extension

See also Some basics on Android storage system


@Jon_Stier Please stick to one post with same/relative subject in ONE post.

So I got the undo and redo to work... I guess the question is... Is there a way to undo the actual stroke made instead of the strange bar shaped fragments that are "part of" the "line" or "stroke" that has been drawn...? (as in, a single stroke is, whatever has been drawn, from one touch and to wherever it is dragged until ones finger is lifted from the screen)

then you need to store the whole process (all points) from touch-down and touch-up IN ONE LIST.

Oh... any examples?


this is my approach for save a action history:

every history item has 4 items: action name, data, line width, color. you can add other item (like fill color )if you want.

and for data of circle, it's x,y, radius.
for Line, it's list of all points.

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Ok, thank you very much @Kevinkun. Um I might be able to figure out what you mean... I think I pretty well understand the circle part but the line part I am a bit fuzzy on.

Any further details that might be of help??


So, umm, the "LINE" part confuses me. It didn't work. Same as without the lists... if anyone else has any other suggestions, they would be very much appreciated.


Why not try to understand the code instead of dismissing it? Other users spend their free time helping you.


Why not try to understand the code instead of dismissing it? Other users spend their free time helping you.

Yes I know and I appreciate that... all I was saying is that when I did it, it didn't work. Maybe I need to take out the part from the other example.

Thanks for the help everyone.