[cairo] Performance issue with the PDF backend

[Emmanuel Pacaud]

Hi,

We're facing a performance issue with the cairo PDF backend (cairo 1.5.3).

The next stable version of gnumeric will use GtkPrint instead of
GnomePrint, which mean it will use cairo for the print to PDF file
capability. But, comparing to the PDF files generated by gnome-print,
cairo produces bigger files which are rendered very slowly by either
evince or acroread.

Here's some samples of the generated files:

http://emmanuel.pacaud.free.fr/bugs/cairo/gnumeric-gnome-print.pdf
http://emmanuel.pacaud.free.fr/bugs/cairo/gnumeric-cairo-1.5.3.pdf

Gnumeric, when rendering spreadsheet cells, clip each cell content by the
cell area. Here's a sample of the cairo output if the clipping is
completely discarded:

http://emmanuel.pacaud.free.fr/bugs/cairo/gnumeric-cairo-1.5.3-unclipped.pdf

It looks like we could try to be smart at the gnumeric printing code, and
to clip only when needed.

But I'm wondering if the situation could be improved in cairo itself. Or
if it exists a workaround that would avoid the inefficient files.

	Emmanuel.