On Wed, Aug 18, 2010 at 10:52 AM, Chris Wilson <ch...@chris-wilson.co.uk> wrote: > On Wed, 18 Aug 2010 10:29:52 +0200, Thomas Petazzoni > <thomas.petazz...@enix.org> wrote: >> Is our way of extracting parts of a surface into another surface >> incorrect ? Is there a way of making sure that Cairo includes only once >> in the final PDF the contents of the original surface ? > > The way you are generating the split PDF is valid, just Cairo is very > conservative in what it discards. Currently it doesn't do any culling on > the input geometry, though the mechanism are now in place that we could > easily enable culling of operations that only affect areas outside of the > PDF page boundaries. If you want to look for yourself, all one needs to do > is hook up the PDF draw routines to cairo_composite_rectangles_init*() and > return early if those routines indicate that the operation has zero ink > extents.
Cairo could also reuse the same group on different pages. I think iText does that if a 'watermark' is printed on each page. iText might be the right tool for this job.
