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ANNOUNCE: TkPNG 0.5 (initial release)

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Apr 13, 2005, 4:50:58 PM4/13/05
This package implements support for loading and using PNG images with
Tcl/Tk. Although other extensions such as Img also add support for PNG
images, I wanted something that was lightweight, did not depend on libpng,
and which would be suitable* for inclusion in the Tk core, as Tk does not
currently support any image formats natively that take advantage of its
internal support for alpha blending, and alpha antialiasing and drop
shadows really go a long way toward beautifying Tk applications.

(* Not written to the Tcl style guide, but that's because if it doesn't
get included I'd rather it conformed to Muonics' style.)

At this time, the package supports reading images from files or binary
data. Base64 decoding is not supported yet, partly because I'm of the
opinion this should be handled by the Tk core photo code which calls the
image handlers. Exporting images to PNG format is also not supported yet.

The package supports the full range of color types, channels and bit depths
from 1 bit black & white to 16 bit per channel full color with alpha (64
bit RGBA) and interlacing. Ancillary "chunks" such as gamma, color
profile, and text fields are ignored, although they are checked at a
minimum for correct CRC.

Until I decide on a more permanent home for it within a week or two,
the sources can be downloaded from:

If you get a 404, check the wiki page at as I
probably will have given it a more permanent home, or released a new
version at that point.

You'll probably need to edit the so that it will find the
zlib headers and library (its only dependency other than Tcl/Tk its

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