Hand written signature control

[Nicola Dell'Amico]

Hi all,

I'll need to implement a control for acquiring an hand written signature or , in a general form, an hand written drawing and get it as bitmap image.
Is it possible with cross platform code or I need to resort to native code (platform should be android and iOS) ?
Any suggestions ?

thanks
Nicola

[Thomas Chatfield]

This should be possible you could create an Image and then draw onto it using the getGraphics() method.

[Nicola Dell'Amico]

Hi Thomas ,

thank you for the answer bu I'm a bit confused.
Which kind of control did you suggest to pick from the GUI designer pallet to have an Image to draw into ?
It seems to me there is no Image control, may be I have to use a Label with an empty white image to use as drawing canvas; did you mean that ?

Nicola

[Thomas Chatfield]

Hi, didn't realise you was using the UIBuilder.

Not sure how this could be done with the builder. The problem would be the actual drawing of the signature.

In code I would possibly override Label and set the icon to some Image.
Then in the labels pointerDragged() method do the drawing there.

You could draw a small circle via drawArc(), and just move that around to draw the signature.

Tom

[Nicola Dell'Amico]

Hi Tom

thank you very much for the tips.
It isn't a problem to add control on the fly with code into a form created with the UIBuilder , so I'll surely try your solution .

Thanks again

Nicola

[Shai Almog]

Thomas's answer is pretty accurate but just to clarify.
I would derive Component and set the component to focusable true. Then override pointer pressed/dragged/released and whenever I get one of these events just draw a line onto the mutable image.
I would also override paint to just invoke drawImage() with that mutable image.
Override calcPreferredSize() to determine a reasonable size for your component.

A few minor tips:
Override paintBackground/Backgrounds with a blank implementation for improved performance.
Create the image only when needed, make sure the component size is larger than 0 before creating the image with the size of the component.
The component size can change in runtime so you might need to replace the image in such a case.

[Nicola Dell'Amico]

Hi Shai,
thank you very much, I'll try to get it working on the next few days.

Nicola

[in...@smsrus.gr]

Hi Nicola,

I'll probably need the same functionality for my App so I'd like to ask if you have managed to implement this.

Regards

[Nicola Dell'Amico]

Hi,

I didn't spent so much time on that because my client has partially lost interest on that, but I wrote a simple Component with very basic functionality, as suggested in previous posts. You can find it as attachment  and you can use it as starting point. Please , don't miss to post any further improvement.

Regards

Nicola

[Ivan]

Hi all,

I tried to use this component but on iOS it caused memory leaks, here is optimized version. May be it will be helpful for somebody :)

bye

Ivan