I have briefly gone through the sdk material but there are some aspects that remained unclear to me. In more detail, I would like to show the RegionName tag from jpg-file in the LR metadata for searching etc. This tag includes the face recognition data from Picasa. I have already experimented with the exiftool and know how to add the names in RegionName to Subject or Keywords tag in both jpg-file and corresponding .xmp file for the raw-file. However, I would like to find an elegant solution by showing the tag in the LR directly. Before trying the make the LUA code, I would like to understand some basic principles behind the plugin programming namely:
1) How do I read the RegionName tag from the jpg-file and in which part of the plug-in? Is there a way to make LR read it every time the "Read Metadata from File" is used?
2) How do I "publish" it to appear in the Metadata panel on the right side of the LR (this is somewhat handled in the examples even though I do not understand the com.adobe.xxx reference i.e. which structure is it actually referencing to?)
Any comments and help is welcome on this or any advice where to find the information!
LR provides access only to some metadata fields, not all. RegionName is not one of the fields LR knows about, so you won't be able to use the SDK's metadata methods to access or display it. Typically, plugins that want to access such metadata run the free Exiftool on the images and then parse the output of Exiftool.
The ExifMeta plugin exposes all metadata that's accessible by Exiftool as custom metadata fields in LR. I suggest you try out that plugin to see if it meets your needs. If it doesn't, you can examine its source code as an example of how to use Exiftool to access and display metadata. The plugin's author Rob Cole is a frequent contributor to this forum and quite willing to answer questions.
Thanks John, so that explains why I did not find an example as there is no way to do it.
Thanks for the advice on ExifMeta ; I had actually already downloaded it but there was some error installing. I will continue to that direction and ask for help if needed.
Thanks a lot!