[gimp/metadata-browser] metadata; Extended the readme document.

[Roman Joost <romanofski src gnome org>]

commit c796242a7c9da11c4ebc96bfb985c3d16fad9d4a
Author: Roman Joost <roman bromeco de>
Date:   Mon Mar 4 09:18:30 2013 +1000

    metadata; Extended the readme document.

 plug-ins/metadata/README |   70 ++++++++++++++++++++++++++++-----------------
 1 files changed, 43 insertions(+), 27 deletions(-)
---
diff --git a/plug-ins/metadata/README b/plug-ins/metadata/README
index 36a7e8a..ffc3126 100644
--- a/plug-ins/metadata/README
+++ b/plug-ins/metadata/README
@@ -4,6 +4,21 @@ What is this?
 This is the beginning of an editor for metadata.  It is far from
 complete yet.
 
+History
+-------
+
+Raphaël Quinet is the original author of the editor, but couldn't
+finish it. I - Róman Joost - started over as a C beginner hacking on the
+editor. In the hope to improve the thing I continued following Raphaëls
+initial path.
+
+I want to leave this document as is, since I think Raphaëls thoughts a
+still valid. Since his work a lot has changed in terms of parsing and
+generating XMP.
+
+That's why I'll be integrating the parsing component with a metadata
+library instead of continuing the work of that component.
+
 Current status
 --------------
 - It does not read metadata, except if there is an XMP block in the
@@ -14,11 +29,9 @@ Current status
   basic scalar types (strings, integers, ...).  It is currently not
   possible to add new properties using the editor (but this can be
   done via the PDB call plug_in_metadata_set_simple()).
-- Basically, the current code is only useful for viewing some XMP
-  metadata if the image file contains an XMP block.  The import/export
-  functions are also supposed to work.  Import merges, so it is
-  possible for example to import a license file such as the XMP files
-  from Creative Commons in order to apply a license to an image.
+- The import/export functions are also supposed to work.  Import merges,
+  so it is possible for example to import a license file such as the XMP
+  files from Creative Commons in order to apply a license to an image.
 - The metadata is saved in a persistent parasite that is overwritten
   after each call.  Caution: the editor should not be open while you
   are trying to test some of the PDB calls, otherwise you would
@@ -28,30 +41,24 @@ Current status
 How to find test images?
 ------------------------
 
-The easiest way is to try a Google search for "<?xpacket".  This is
-the marker that is used at the beginning of XMP packets.  Many images
-or PDF files are incorrectly served as text/plain and therefore
-indexed by Google as text files.  By looking for XMP tags such as
-"<?xpacket", it is possible to find a large number of files containing
-XMP metadata.
+The Exiv2 project provides quite a big amount of test images:
+
+    http://www.exiv2.org/
 
 Work in progress:
 -----------------
-- improve XMP code generation (xmp-gen.c) - currently, some structured
+- libgexiv2 integration
+- improve XMP code generation (xmp-encode.c) - currently, some structured
   property types are not written back to the buffer, so the round-trip
   decode/encode can silently discard some properties
 - add tabs for easy editing of metadata, connect them to the tree
-- fix the conversion to/from EXIF (exif-parse.c, exif-gen.c)
+- fix the conversion to/from EXIF (exif-decode.c)
 - register PDB functions correctly (for setting/getting metadata)
-- update the JPEG plug-in
 
 Near future:
-- add custom callbacks for editing in the tree, validate entries, ...
 - smarter display of rational values, closed sets, ...
 - improve the layout of the various tabs
 
-Not-so-near future:
-- move some of this stuff into the core
 
 -------------------------------------------------------------------------------
 Files modified (2004-08-24):
@@ -59,18 +66,27 @@ Files modified (2004-08-24):
   menus/image-menu.xml.in         (added placeholder "<Image>/File/Info")
   plug-ins/Makefile.am            (added "metadata" in SUBDIRS)
   plug-ins/common/jpeg.c          (changed to get/set metadata through PDB)
+
 New files:
   plug-ins/metadata/Makefile.am   (generates Makefile.in to get a Makefile)
-  plug-ins/metadata/metadata.c    (main part: registers the plug-in, etc.)
-  plug-ins/metadata/interface.h
+  plug-ins/metadata/exif-decode.c (converts EXIF into the XMP tree model)
+  plug-ins/metadata/exif-decode.h
   plug-ins/metadata/interface.c   (user interface: widgets and callbacks)
-  plug-ins/metadata/xmp-model.h
+  plug-ins/metadata/interface.h
+  plug-ins/metadata/metadata.c    (main part: registers the plug-in, etc.)
+  plug-ins/metadata/xmp-encode.c  (generates XMP metadata from the tree model)
+  plug-ins/metadata/xmp-encode.h
   plug-ins/metadata/xmp-model.c   (model for the treeview, list of XMP schemas)
-  plug-ins/metadata/xmp-parse.h
+  plug-ins/metadata/xmp-model.h
   plug-ins/metadata/xmp-parse.c   (simple parser for XMP metadata)
-  plug-ins/metadata/xmp-gen.h
-  plug-ins/metadata/xmp-gen.c     (generates XMP metadata from the tree model)
-  plug-ins/metadata/exif-parse.h
-  plug-ins/metadata/exif-parse.c  (converts EXIF into the XMP tree model)
-  plug-ins/metadata/exif-gen.h
-  plug-ins/metadata/exif-gen.c    (generates EXIF metadata from the tree model)
+  plug-ins/metadata/xmp-parse.h
+  plug-ins/metadata/xmp-schemas.c (holds schema definitions for XMP metadata)
+  plug-ins/metadata/xmp-schemas.h
+
+UI:
+  plug-ins/metadata/gimpxmpmodelentry.c     (Entry widget to string values.)
+  plug-ins/metadata/gimpxmpmodelentry.h
+  plug-ins/metadata/gimpxmpmodeltext.c      (Entry widget for text values)
+  plug-ins/metadata/gimpxmpmodeltext.h
+  plug-ins/metadata/gimpxmpmodelwidget.c    (Interface Widget which is subscribed to change events.)
+  plug-ins/metadata/gimpxmpmodelwidget.h