From: Scott Weikert <[EMAIL PROTECTED]>
> I know there are some image-oriented CFX tags and the like out there - but
> I'm curious if anyone knows of an existing tool/tag that could grab a GIF
> file, set a certain RGB color within that GIF file to be transparent, and
> resave the file. Preferably something like a CFX tag that I can trigger once
> the process to generate the GIF in question has finished.
>
http://www.intrafoundation.com/freeware.html
CFX_BinaryR and CFX_BinaryW will do what you want, but you
need to know the .gif file format well. Your .cfm will be low level
byte manipulations that might take you back a few years if you
ever did assembler graphics code.
Gif uses lots of header and extension blocks that may or may not be
present in any given file along with flags that indicate
whether tansparency indexes are present. If you are successful you
will end up learning more about gifs than you may want to know. :)
Here is a source for graphic file format specs.
http://www.dcs.ed.ac.uk/home/mxr/gfx/2d-hi.html
N.B. - Lewis considers BinaryR and BinaryW to be security risks on a
production server - I agree. But you can do some dodges to protect
access and prevent unwanted calls to the tags.
CFX_DynamicGif will overlay transparently but has no facility for
direct bit flipping. To use this tag takes a lot of script lines and
many many query function calls. However it is multi-color and
various primitives are pre-defined. You really can dynamically draw
any gif you want with this one. It's shareware for $30, prints a
copyright on the shareware version images and there is a warning
about Unisys LZW licensing.
CFX_GifGD is good if you want to do charts, but it is single color,
imposes some layout restrictions and, again, has no bit manipulation
facilites.
Other than these I can't reccomend anything ... as long as you understand
gif formats actually writing any code callable by cf_execute or
cf_ConsoleCommand will work. Just read in the file as binary data,
flip some bits and save the file -- done.
Pan
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