如何在Android中读取/编写自定义PNG元数据？

Question

I have to associate a couple of text parameters (a UUID and a couple of strings representing integers) to a PNG image in a way they can follow the image when the PNG file is passed from an Android device to another through the Net. This is the typical situation in which I would use a couple of custom auxiliary chuncks (similar to EXIF fields ) to store my data inside the PNG image itself.

Maybe it is just me but the only info I was able to find about reading and writing PNG custom metadata from Java code on Android was this SO post:

Writing image metadata in Java, preferably PNG

that even offers some code (quite verbose, as usual with Java).

Those same SO post refers also to PNGJ: http://code.google.com/p/pngj/

To be honest, I would be happy to not use yet another library in this project.

Does anybody know of others ways to write and read text metadata in a PNG file in Android? Maybe a less verbose way... Maybe a way that does not require a separated library....

Any other source of information? Any tutorial? Any example?

I'm open to use a different (but equivalent) image file format, if needed (JPEG, whatever).

A solution working also on iOS and Windows 8 Phone would be a plus but it is not actually required.

Answer 1

I had to do something similar lately, so I had to study the subject. Android offers you no option of manipulating png metadata. You will have to use an external library (PNGJ seems like a good option). In my case, since I am making changes to the Android frameworks, I didn't use an external lib, but made changes to skia (the Android graphics library instead).

If you need more info on that I can give you, but I think it's irrelevant in your case.