Better management of transparency in SWIG Java bindings

[danieleromagnoli]

This is a proposal to improve the transparency management when generating JAVA Bindings: Actually, the bindings allow to return an IndexColorModel from a GDALColorTable. ​http://java.sun.com/j2se/1.4.2/docs/api/java/awt/image/IndexColorModel.html

However, there isn't special management for cases where there is only a single fully transparent alpha element or cases where all pixels are opaque.

The proposed patch allows to setup an IndexColorModel with the following set of rules:

• If the ColorTable contains N elements and all the elements are opaques, then setup a simple IndexColorModel with R,G,B entries.
• Else, if the ColorTable contains N elements where N-1 elements are fully opaque and only a single one has alpha == 0 (fully transparent), then setup an IndexColorModel where you specify the index in the table of the unique transparent pixel.
• Else (there are several alpha pixels with different opacity) setup an IndexColorModel with R,G,B,Alpha entries.

Can you please review that patch and apply it if ok?

[Even Rouault]

Applied in trunk (r19007). Thanks

[danieleromagnoli]

Could be possible to include that patch on the 1.7.X branch (to be included in the next 1.7 releases)?

[Even Rouault]

We usually don't backport enhancements into stable branches, but it doesn't seem too risky and you provided the patch ;-), I commited it in r19012 in branches/1.7

It was just a performance enhancement right ?