Issue 29 in pulpcore: Allow compression level to be passed into PNGWriter
codesite...@google.com
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Labels: Type-Defect Priority-Medium
New issue 29 by daniel.watling: Allow compression level to be passed into
PNGWriter
http://code.google.com/p/pulpcore/issues/detail?id=29
It would be nice to allow the setting of the compression level when using
PNGWriter instead of defaulting to no compression.
I've attached a patch that will add a second (optional) parameter to the
PNGWriter.write method. The value for this second parameter can be any of
the compression levels found in "Deflater". The default is no compression.
Attachments:
pngwriter.compression.patch 1.6 KB
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codesite...@google.com
Comment #1 on issue 29 by brackeen: Allow compression level to be passed
into PNGWriter
http://code.google.com/p/pulpcore/issues/detail?id=29
This is incorrect because the PNG format specifies "At present, only
compression method 0 (deflate/inflate
compression with a sliding window of at most 32768 bytes) is defined.". So,
1) the default should use
Deflater.DEFAULT_COMPRESSION and 2) the compression method byte should
always be 0. Also, the new write()
method should throw an exception if the compression level is not 1-9 or -1.
Unfortunately, even with compression level 9, the compression won't be as
good as the PNG encoder provided in
tools/assettools/png which does analysis and optimization.
Dan Watling
Is there any specific exception that should be thrown? I've changed
the source I have locally to throw a RuntimeException to maintain
backwards compatibility with existing apps. If there is anything
specific I can make the change and resubmit a patch.
Originally, I was using the PNGWriter to upload a screenshot to my
server when necessary, but as you pointed out, the compression level
turned out to not be that great. I ended up creating a JPEGWriter
class and that works much better (~50k versus ~500k). The source for
it was yanked from an existing source (LGPL) after doing a Google
search but modified a little to support CoreImage. If you'd like I can
post that as well.
-Dan
On Nov 9, 5:07 pm, codesite-nore...@google.com wrote:
> Comment #1 on issue 29 by brackeen: Allow compression level to be passed
