On 2013-01-15 12:47+0800 Hǎiliàng Wáng wrote: > Hello, > > I'm plotting a small PDF graph (128x96) with cairopdf driver, and the > line width looks too thick with line width 1. > > To solve the problem, I modify the code within the cairo driver > (cairo.c) to set the the line width to 0.2 directly, and the result > looks pretty good. > > I have read the thread below so I know there is no plan to change > function plwid's parameter from int to float: > http://www.mail-archive.com/plplot-general@lists.sourceforge.net/msg00429.html > > I'm wondering if it is good idea to add another function to set the > line width with a ratio, e.g. void plwidr(double)? So that the real > line width becomes a product: linewidth*ratio. By default the ratio is > 1.0 so it will not affect the current user, but if the user want finer > line width, just set linewidth=1 and the ratio any floating point > value they want.
Hi Hǎiliàng: I gave you a quick answer on plplot-general, but I think the rest of this discussion should be on plplot-devel. Please subscribe to that list (i.e., the current list) if you would like to participate further in that discussion. @Andrew: most of the rest of this is addressed to you. Since that quick answer I have looked more carefully at what external drawing libraries do. Our two best devices drivers are cairo (based on the pango and cairo external libraries) and qt (based on the Qt4 external libraries. It appears the cairo library uses a floating-point pen width which we currently specify by casting the PLplot integer width appropriately. Also, it appears from our qt code, that we propagate our linewidth to a call the Qt4 setWidth (documented at) http://harmattan-dev.nokia.com/docs/library/html/qt4/qpen.html#width which takes an integer width argument. But right next to that setWidth function they also define setWidthF which takes a floating-point pen width argument. So my guess is the Qt4 library made the same mistake as PLplot has done (integer width argument) but they fixed it later by allowing the setWidthF alternative of specifying a floating-point width. So here is what I suggest we do. 1. Define a new function plwidth just like plwid is done now but with a PLFLT line width argument. (Actually, I like the plwidth name better than plwid.) 2. Wherever plwid is called internally now change that to plwidth with approprate cast of the argument (which allows plwid to be moved to pldeprecated.c below). 3. Define plwid as void plwid(PLINT width) { plwidth( (PLFLT) width); } and move it to pldeprecated. 4. Propagate the floating point line width set by plwidth to each of our device drivers. That would immediately let users specify a 0.2 width for plwidth which would propagate directly to our cairo device driver. With some additional work (i.e., replacing setWidth with setWidthF everywhere) we could propagate floating-point pen widths to our qt device driver as well. @Andrew: do you see any issues with the above four changes? Of course, we would still be stuck with integer line widths for the pllegend, plshade, and plshades API until we changed those width arguments to PLFLT. But making such changes is tougher on our users than the above 4 changes because we don't want to change the pllegend, plshade, and plshades function names. So we could put that change off until later, but if we are going to do the above 4 changes, it is probably a good time to do the pllegend, plshade, and plshades API changes as well (so long as we warn our users about this in the release announcement and do the appropriate SOVERSION bump to force them to recompile their applications/libraries.) But I emphasize this is a separate issue that should not affect what we decide to do for plwid. Alan __________________________ Alan W. Irwin Astronomical research affiliation with Department of Physics and Astronomy, University of Victoria (astrowww.phys.uvic.ca). Programming affiliations with the FreeEOS equation-of-state implementation for stellar interiors (freeeos.sf.net); the Time Ephemerides project (timeephem.sf.net); PLplot scientific plotting software package (plplot.sf.net); the libLASi project (unifont.org/lasi); the Loads of Linux Links project (loll.sf.net); and the Linux Brochure Project (lbproject.sf.net). __________________________ Linux-powered Science __________________________ ------------------------------------------------------------------------------ Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft MVPs and experts. ON SALE this month only -- learn more at: http://p.sf.net/sfu/learnnow-d2d _______________________________________________ Plplot-devel mailing list Plplot-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/plplot-devel
