Thanks. If the behavior of ppm-load is considered buggy, then it all makes sense. I'll use the output format if it is set, or otherwise I will fallback to RGBA within prepare.
Regards, Dov On Thu, May 30, 2013 at 10:54 AM, Daniel Sabo <daniels...@gmail.com> wrote: > My first instinct would be to say that ppm-load not setting it's output > format is a bug, and that it should try to sniff the file in prepare() > inorder to set the correct format. If you do format switching in > gaussian-blur's process() then you'll also spoil the format detection of > whatever is connected to gaussian's output. > > As an alternative to that, I would be inclined to process ppm-load to a > buffer then pass that buffer to a second graph. > > Finally (and please don't use this option), the reason you get that error > is because the parent implementation of process() in > gegl/operation/gegl-operation-filter.c calls > gegl_operation_context_get_target for you, it is possible to override this > and still use the rest of the filter class (see operations/common/over.c). > > > On Wed, May 29, 2013 at 8:58 PM, Dov Grobgeld <dov.grobg...@gmail.com>wrote: > >> Hi all, >> >> Yesterday night I started playing around with converting the >> gaussian-blur operation to only work on the channels that are part of the >> input pad. My goal was to make the operation "format transparent", in the >> sense that the output format should be equal to the input format. But after >> several failures, I realized that I was stuck. >> >> The problem is as follows. I want to set my input format based on the >> output format of the previous node. I'm building the following network: >> >> gegl:ppm-load → gegl:gaussian-blur → gegl:npy-save >> >> and I feed the ppm-load with a "Y u8" image. Now, the problem is that if >> I in the gaussian-blur prepare function call: >> >> gegl_operation_get_source_format(operation, "input") >> >> it returns NULL. Why is that? Am I correct to assume that the prepare >> calls are done before any processing has taken place? If so the ppm-load >> still doesn't know what format it will set in its output pad. >> >> So instead I asked about the format in process(). But then I get the >> following warning: >> >> (test-npy.py:2383): GEGL-gegl-operation-context.c-WARNING **: no format >> for gegl:gaussian-blur 0x95bb9b0 presuming RGBA float >> >> I still haven't figured out exactly why this happens, but I would still >> like to know if anyone knows what I'm doing wrong, and whether dynamically >> choosing the input format based on the previous output format is even >> possible? >> >> Thanks! >> Dov >> >> >> _______________________________________________ >> gegl-developer-list mailing list >> gegl-developer-list@gnome.org >> https://mail.gnome.org/mailman/listinfo/gegl-developer-list >> >> >
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