JDK-4304999 : EOU: it's poorly (if at all) documented how to access the PNG user data segment.
  • Type: Bug
  • Component: client-libs
  • Sub-Component: 2d
  • Affected Version: 1.3.0
  • Priority: P4
  • Status: Closed
  • Resolution: Duplicate
  • OS: generic
  • CPU: generic
  • Submitted: 2000-01-15
  • Updated: 2000-01-17
  • Resolved: 2000-01-17
Related Reports
Duplicate :  
Description

Name: rlT66838			Date: 01/14/2000


java version "1.3beta"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.3beta-O)
Java(TM) HotSpot Client VM (build 1.3beta-O, mixed mode)


The documentation regarding the new PNG support in the JDK 1.3 is sketchy at
best in the 1.3 beta's docs. I am fairly certain that it includes the feature
that you can use a PNG in a constructor to an ImageIcon. However, the PNG
format, like its predecessor GIF, allows a user defined data block to be
included in an image. The popular Fractal program Fractint for instance uses it
to record into a fractal GIF image some data to allow the GIF to be loaded and
then zoomed into immediately. A future version is planned that will migrate to
PNG because of the damnable Unisys patent.

However, in all the API docs I've looked at for both Swing and Java 2D, I don't
see anything about accessing the user defined data block in PNG files -- or,
for that matter, in GIF files.

Please correct these documentation oversights by making it relatively easy for
a user with the question of how to access the user data segment to quickly
locate the answer. Right now it isn't even clear what *package* the API for
this is in -- java.awt, java.awt.image, javax.swing? The documentation doesn't
even seem to mention the user data segment or how to get it -- I only assume it
can be done because if it can't be, then there's been a major feature
overlooked in the so-called PNG support for the SDK 1.3.

While you're internally reviewing the EOU, I'd like to be told (or pointed to)
how to get at the user data block (preferably treating the block as the source
for an InputStream) and how to write the block (preferably treating the block
as the destination for an OutputStream).
(Review ID: 99980) 
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Comments
WORK AROUND Name: rlT66838 Date: 01/14/2000 I don't know of one, short of being psychic or else asking lots of questions. ======================================================================
11-06-2004

PUBLIC COMMENTS Support for access to ancillary data will be addressed by the Image I/O package
10-06-2004

EVALUATION This is not a EOU (ease of use) since what the user is requesting is not, nor was ever claimed to be, part of the support for PNG in the core Java platform. The lack of API documentation is because there is no API. PNG & GIF support is limited to the ability to return a java.awt.Image from a data source which represents an image encoded in one of those formats. Capabilities of the kind requested here are subsumed by the Image I/O package which is being designed. That is expected to include mechanisms which allow access to such ancillary non-image data for a range of formats. Closing out this EOU/RFE as a duplicate of that (4101949) phil.race@eng 2000-01-17
17-01-2000