The PDF reference manual version 1.7 reads on page 511 : "For clipping, the clipping region consists of the set of pixels that would be included by a fill operation.". Our implementation doesn't follow it. When a path is filled, we paint those pixels, which's centers fall inside the path expanded with fill adjustement. The fill adjustment depends on resolution. With small resolutions it is 0.25, with high resolutions it is 0.5 . When clipping with a single rectangle gx_clip_list_from_rectangle rounds the lower boundary down to integral pixels and does the upper boundary up, what is equivalent to fill_adjust=0.5 . When clipping with a complex path, gx_cpath_intersect_path_slow applies fill_adjust=0.5 . Thus with small resolution our clipping differs from Adobe. This problem was discovered while analyzing Bug 689264 "Regression: differences in Testform.v1.0.2.pdf".
Reassigning path and fill problems to Robin Watts.
Reassigning to new email address.
Bug still reproducible in Ghostscript 9.03
This is the underlying problem with bug 693509, which is a customer bug with a file attached, so I am marking this one a duplicate of that one. *** This bug has been marked as a duplicate of bug 693509 ***