Add metadata information to a png file

[dcelso]

Helllo to all,
How can I add extra information to a png file?

I have tried use TPortableNetworkGraphic but I can not find any property to add custom information.

Thanks.

[wp]

The png file format does not support metadata (https://stackoverflow.com/questions/8113314/does-png-support-metadata-fields-like-author-camera-model-etc). You must use jpg or tiff for this.

[dcelso]

Are you sure?

https://en.wikipedia.org/wiki/Portable_Network_Graphics  <---  "Ancillary chunks" section

Have a nice day, bro.

[Thaddy]

http://dev.exiv2.org/projects/exiv2/wiki/The_Metadata_in_PNG_files
https://en.wikipedia.org/wiki/Portable_Network_Graphics#Ancillary_chunks
https://www.w3.org/TR/PNG/#11textinfo

So png does support metadata. It just is not supported by the LCL component atm.
I suggest you ask the maintainer to support it. Can be on the bug tracker.

@wp SO is not always a good source of information. Look for the specifications.....

[apeoperaio]

I would like to know if metadata is now supported using TPortableNetworkGraphic.

[wp]

Certainly no.

I wrote an exif library (fpexif, https://sourceforge.net/p/lazarus-ccr/svn/HEAD/tree/components/fpexif/), but it inspects only the jpeg and tiff file formats, and I don't have time atm to extend it to png.

[apeoperaio]

Thank you, I will look at it