Typesafe, high-level API for setting EXIF fields
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Key: SANSELAN-31
URL: https://issues.apache.org/jira/browse/SANSELAN-31
Project: Commons Sanselan
Issue Type: Improvement
Affects Versions: 0.94-incubator
Environment: all
Reporter: Lulu winlumski
Fix For: 0.94-incubator
The current EXIF API is extremely awkward to use.
I. API is not typesafe and poorly documented.
Currently you have two options:
1) Pass values for EXIF tags as java.lang.Object (TiffOutputField.create)
2) Pass values for EXIF tags as byte arrays (new TiffOutputField())
In the first case, there is no way of knowing what kind of Object is required
except looking at the sanselan source or using reflection.
In the second case, a large part of the implementation of the EXIF
specification remains with the client.
Even if one uses the Object-based API one has to pass around byteorders and
needs to null-terminate strings, which is something that would typically be
handled by the library layer and not by the client.
A usable API should throw a compile time error when a value is passed that has
an incorrect type. This can be achieved either by subclassing TiffOutputField
or by using generics.
II. Code clarity
A TiffOutputField is essentially nothing more than a TagInfo + a value. Than
why don't you have a constructor TiffOutputField(TagInfo tag, bytes) ?
Instead you need to do:
new TiffOutputField(tag, tag.dataTypes[0], tag.length, bytes);
III. Code correctness
Most of e. g. the GPS tags simply do not work:
GPS_TAG_GPS_VERSION_ID: TiffOutputField.create() fails with ImageWriteException
GPS_TAG_GPS_MAP_DATUM: TiffOutputField.create() fails b/o bug Sanselan-12
GPS_TAG_GPS_ALTITUDE_REF: TiffOutputField.create() fails b/o length -1
GPS_TAG_GPS_ALTITUDE: TiffOutputField.create() fails b/o length -1
GPS_TAG_GPS_DATE_STAMP: TiffOutputField.create() fails b/o bug Sanselan-12
This is not 0.94 code quality but 0.01.
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