Hi,
I am just starting out building some Gegl filters and I'm experiencing
some problems with different results, depending on from where I invoke
the filters. I'm using Ubuntu 14.04, Gegl from git (tagged 0.2.0),
current babl from git (and Gimp 2.8 from the Ubuntu repository, just
for testing purposes).
To test the results of my filters, I wrote a very simple program,
which basically looks like this:
GeglNode *root = gegl_node_new();
GeglNode *load = gegl_node_new_child(root,
"operation", "gegl:load",
"path", "test_input.png",
NULL);
GeglNode *test = gegl_node_new_child(root,
"operation", test_operations[i],
NULL);
GeglNode *save = gegl_node_new_child(root,
"operation", "gegl:save",
"path", output_filename,
NULL);
gegl_node_link_many(load, test, save, NULL);
gegl_node_process(save);
My first problem is that if I use this code, my output file resolution
is increasing. When I run my filter and print out some debug
information, I can see that the extra amount of pixels I request in my
prepare function is already applied to the value of the result
argument in my process function. The call to
gegl_operation_get_required_for_output returns me an even larger
rectangle.
This is a brief excerpt from my gegl filter code:
static void prepare(GeglOperation *operation) {
GeglOperationAreaFilter *area =
GEGL_OPERATION_AREA_FILTER(operation);
GeglChantO *o = GEGL_CHANT_PROPERTIES(operation);
// Extra pixels needed in each direction
area->left = area->right = 0;
area->top = area->bottom = o->height; // sloppy, but at least enough
gegl_operation_set_format(operation, "input", babl_format("RGB
float"));
gegl_operation_set_format(operation, "output", babl_format("RGB
float"));
}
process (...
const GeglRectangle *result,
...)
{
const GeglChantO *o = GEGL_CHANT_PROPERTIES(operation);
GeglRectangle source =
gegl_operation_get_required_for_output(operation, "input",
result);
g_print("result - x: %i, y: %i, width: %i, height: %i\n",
result->x, result->y, result->width, result->height);
g_print("source - x: %i, y: %i, width: %i, height: %i\n",
source.x, source.y, source.width, source.height);
...
With the same input file (640 x 480), the same parameters and on the
same machine...
A) Run with the program shown above:
result - x: 0, y: -10, width: 256, height: 500
source - x: 0, y: -20, width: 256, height: 520
result - x: 256, y: -10, width: 384, height: 500
source - x: 256, y: -20, width: 384, height: 520
B) Run within Gimp via UI
result - x: 0, y: 0, width: 256, height: 480
source - x: 0, y: -10, width: 256, height: 500
result - x: 256, y: 0, width: 384, height: 480
source - x: 256, y: -10, width: 384, height: 500
Run with the program above, the output image will have an additional
height of two times o->height (which is in this test cases always 10).
The result are two (black) bars above and below the actual image. This
problem does *not* occur when I run this filter within Gimp!
My second problem - but I don't care very much about this at the
moment - is that the colors of the result are not quite the same as
well, although I'm letting babl do all that work (I think). Because of
the effect of the filter, the difference in brightness is quite easy
to see.
I hope you have any idea that could help avoid the increase of *result
/ the output image in the first place. I appreciate every hint!
Regards,
Florian
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