About patterns in cells and graphs

[Jean Bréfort <jean brefort ac-dijon fr>]

Hi,

I am currently working on using patterns as background in graphs. I 
would like to know if somebody has an opinion about the usefulness to 
allow transparency either for the back or the fore color. It is quite 
possible to do that, just writing a helper function is necessary.
About printing the patterns, it is more difficult, because there is no 
appropriate function in gnome-print although patterns exist both in 
Postscript and PDF; probably someone (I?) should write the corresponding 
code and submit the patch to libgnomeprint (not before 2.5 now). At the 
moment, what is possibe to do is filling a pixbuf with the pattern and 
print the pixbuf. This is not without problem. The most obvious is a 
resolution one. Gnome-print use 72 dpi, while Gnumeric uses a resolution 
in its configuration, default being 96 dpi. If we want a wisiwig 
printout, we must adapt the size of the pattern, but unfortunately, the 
GogRenderer does not know anything about resolution. One size is passed 
when rendering on the screen and another when printing. Any idea?
Also, before writing the code, I looked at the corresponding code for 
cells background. I found one problem: if the pattern is not solid or 
grey, the cell is printed as a black rectangle since 
gnome_print_setrgbcolor is not called. I suggest to use the back color 
in such cases.
Best regards,

Jean