On Sep 25, 2012, at 5:45 PM, Mojca Miklavec <mojca.miklavec.li...@gmail.com> wrote:
> On Tue, Sep 25, 2012 at 7:28 AM, Xiao-Yong Jin wrote: >> >> Dear all, >> >> I just upgrade to Mountain Lion and found out that "dashed dashpattern (on >> 1)" no longer shows any line in Preview. The attached file is a snapshot of >> the Preview window showing the pdf file generated by the following code. >> >> \starttext >> \startMPpage >> >> draw unitsquare scaled 4cm dashed dashpattern (on 1cm off 1cm) ; >> draw unitsquare scaled 4cm shifted (5cm,0) dashed dashpattern (on 1cm) ; >> draw unitsquare scaled 4cm shifted (10cm,0) dashed dashpattern (off 1cm) ; >> >> setbounds currentpicture to boundingbox currentpicture enlarged 0.1cm ; >> \stopMPpage >> \stoptext >> >> You can see, from the attached file, that the unitsquare which was >> supposed to appear in the middle does not show up in the Preview window. >> However the same file is displayed correctly in Acrobat Reader. > > Awesome ;) > > Just curious: what do you get if you try to draw the same plots with > PostScript terminal in gnuplot? The PostScript terminal in gnuplot works fine. However, if I wrap the metapost code in my previous message with begin/endfig and run it with "mpost" to generate postscript, Preview does not show lines with "dashpattern (on 1)" either. >> I am not sure whether it is a context problem, or it is just a bug in >> Mountain Lion. I found out this issue when I saw that all the pdf files I >> previously generated with gnuplot context term are showing up incorrectly >> under the Preview after upgrading to Mountain Lion. I had to change the >> dash pattern in file "metapost/context/third/gnuplot/mp-gnuplot.mp", so the >> pdf generated by gnuplot context term can be viewed correctly with Preview >> under Mountain Lion. > > What modifications did you do exactly? I simply changed "on" to "off" for line type -2 and 0. > > It seems that "(on 1cm)" generates > [28.34645 0 ] 0 setdash > and "(off 1cm)" generates > [] 0 setdash > in PostScript file. > > What I had in mind when I was writing the code was for "(on 1cm)" to generate > [] 0 setdash > meaning a solid line. The other pattern "(off 1cm)" for linetype -3 is > described in gnuplot's README as follows: > An lt of -3 is solid and drawn with xor (for temporary interactive > annotations). > and I actually had no idea what to draw since PostScript cannot draw > XORed lines - I was most probably hoping to get an invisible line ;) > > Thinking again about it, different transparency models in PDF are > actually able to do some weird transformations (color subtraction > etc.), but I'm not sure if I could get what I want. > > Now, according to specification, the pattern > [28.34645 0 ] 0 setdash > should actually draw almost "a solid line", or, to be mathematically > precise, a line composed of 1cm long segments with zero-width gaps. > The difference might be evident when drawing semi-transparent lines > and linecaps might overlap. If you ask me, it's definitely a bug in > Mountain Lion's renderer if it doesn't draw the line. On the other > hand, it probably makes sense to patch MetaPost to generate "[] 0 > setdash" instead of "[<x> 0 ] 0 setdash" in case when it gets "(on > <x>)" as an argument. But then again, the original code should > probably call dashpattern() without any argument to get solid lines. Simply call dashpattern() works as expected. > > The argument "(off 1cm)" is weird anyway (my "bug") and honestly I'm > not sure what would be the most appropriate behaviour in the eyes of > metapost. Maybe not drawing anything at all? Throwing an error? > Inserting "(on 0pt)" would be wrong as that actually draws dots. When > using "(off 1cm on 0cm)" it works as it should - it draws dots (when > using round linecaps). > > I believe the best course of actions would be: > - Filing a bug to Apple with a minimal EPS example. (I can try to > prepare one.) But that won't help anyway. I've filed several bug > reports and the only time when they replied was with asking if it was > fixed when it wasn't. And 4 years have passed since, nothing happened. > - I will replace "dashpattern(on 1cm)" with "dashpattern()" for > linetype 0 and -2 in mp-gnuplot.mp. Can you please confirm if that > works? > - After ConTeXt Meeting/EuroTeX is over, we could discuss with Taco > what MetaPost should do when it gets "(on 1cm)" or "(off 1cm)" as an > argument. If nothing else, the manual should clearly describe the > behaviour. Are you willing to open a ticket at > http://tracker.luatex.org? I'm not sure what to put in the ticket. I guess it is more appropriate if you can open a ticket, since you know the details of the matter. Best, Xiaoyong > Mojca > ___________________________________________________________________________________ > If your question is of interest to others as well, please add an entry to the > Wiki! > > maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context > webpage : http://www.pragma-ade.nl / http://tex.aanhet.net > archive : http://foundry.supelec.fr/projects/contextrev/ > wiki : http://contextgarden.net > ___________________________________________________________________________________ ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://tex.aanhet.net archive : http://foundry.supelec.fr/projects/contextrev/ wiki : http://contextgarden.net ___________________________________________________________________________________
