Adding text comments to graphics device output files?

On Jul 31, 2013, at 12:12 AM, Henrik Bengtsson wrote:

Hi Duncan,

this is perfect timing.  Your
https://github.com/duncantl/png/blob/master/testMeta.R example
illustrates what I'm looking for.

Yes, it would be great if this would be incorporated into the 'png' package.

Ok, I have added support for both text chunks and arbitrary R metadata to the PNG package.
http://rforge.net/png
The it is based on Duncan's idea, but the implementation and API is different -- Duncan's approach was implemented before png has support for the PNG info, so it is now simply extending that concept. You can store native text key/values pairs. In addition, R-native matadata can be attached -- it is stored as a special key "R.metadata" holding the serialization of the R object. See the last example in
http://rforge.net/doc/packages/png/writePNG.html
Feedback is welcome.

Cheers,
Simon

Thanks,

Henrik

On Tue, Jul 30, 2013 at 8:04 PM, Duncan Temple Lang
<dtemplelang at ucdavis.edu> wrote:

Hi Henrik

I have some extensions of Simon U's png package
to read and write metadata elements for PNG.
They are at
  https://github.com/duncantl/png.git

When I have time to completely test them, maybe Simon
may incorporate them.

 D.

On 7/30/13 7:59 PM, Henrik Bengtsson wrote:

Hi,

several image file format supports textual/meta data comments in one
way or the other.  For me an obvious usage would be to add
sessionInfo() information to PNG and PDF image files, ideally from
within R although external tools would work as well(*).  Has anyone
looked into this or have any suggestions or comments?

/Henrik

(*) One could even imagine including self-contained R
scripts/vignettes within such comments.