If I understood Philippe correctly, he got that value from an OpenOffice file. He said he'd try to change it. Anyway, despite this being a poor use case, this is still something we should keep in sight. Even I have seen strange effects of border painting inside Acrobat Reader because of effects from anti-aliasing, for example, two border with the same width but not displaying at the same width.
You're right. It's not a FOP bug, it's a glitch in Acrobat Reader but always the easily reachable party is blamed. I have myself filed a bug against Adobe Acrobat once before and never heard a word back. That's life. :-) On 15.05.2006 13:22:29 Chris Bowditch wrote: > Jeremias Maerki wrote: > > > Philippe Drix made me look into why his borders don't show up properly > > in Acrobat Reader and his printer. > > > > He specified border widths as 0.002cm: 0.002cm = 0.0567pt = 0.02mm > > :o I don't think this is a valid use case. Why would anyone want a > border so thin??? Just tell Philippe to widen his border to say 0.5pt. > Or provide a real world example of why such a thin border is required. > > > > > At 600dpi one dot/pixel is 1/600in = 0.00166666in = 0.12pt = 0.0423mm > > > > So the border is less than half a pixel wide at 600dpi which is the > > nominal resolution for most laser printers today. Even at 1200dpi you > > don't have a full pixel, yet. > > Yes I know. Precisely why I don't think anything less than 0.5pt is a > valid use case. > > > > > Digging into the source code, I found out: In FOP 0.20.5 horizontal and > > vertical lines are painted as rectangles (0.056pt wide). In FOP 0.92beta > > we're painting these lines as lines (0.056pt wide). So it appears that > > Acrobat Reader handles the two differently. Apparently, it cannot be > > said that FOP does something wrong per se. But the question pops up if > > we should change the way we paint horizontal and vertical lines as part > > of our border painting code. > > Actually I played a part in changing the border drawing code from > rectangles to lines. Using a rectangle to draw a line didn't seem > correct to me, when PDF provides a perfectly good line drawing command. > > > > > There's another thing. PDF allows to specify "0" as line width which > > should result in 1 pixel on the target device. From the PDF Reference: > > "However, some devices cannot reproduce 1-pixel lines, and on > > high-resolution devices, they are nearly invisible. Since the results of > > rendering such zero-width lines are device-dependent, their use is not > > recommended." It would also be questionable how exactly we would > > determine when to use "0" as line width. Probably not the best of ideas. > > > > WDYT? > > I don't think FOP does anything wrong, so I'd leave it. > > Chris Jeremias Maerki
