On 2015-08-25 08:15+0100 Phil Rosenberg wrote: > Hi Alan > >> Instead of multiplying the MM values by 72/25.4 within drivers like >> svg whose length units are pts, I intend instead to simply #define >> PLPLOT_DEFAULT_PTPI, PLPLOT_DEFAULT_WIDTH_PT, and >> PLPLOT_DEFAULT_HEIGHT_PT in plplotP.h and use those values in pt devices. > > Works for me, I have no strong feelings here. > >> >> It is also becoming pretty clear to me that plsc->xdpi and plsc->ydpi >> are misnomers since dots per inch normally would refer to pixels only. >> Thus, I will probably change those to plsc->xupi and plsc->yupi where >> "upi" stands for units per inch where units could be pixels, pts, mm, >> or whatever length unit is appropriate to the device. > > In the documentation it says that dpi will only be used by raster > drivers and drivers which use real world units will ignore the dpi > measurements. I don't know if svg or ps or pdf drivers actually use > the dpi value at all, but given that statement in the docs then > leaving it as dpi or using ppi might be a better description. > In the API these variables are called xp and yp, which are not very > descriptive This is somewhere it might be worth making a change, where > I would suggest changing them to dpi or ppi.
Hi Phil: Actually, that remark about dpi being ignored by "real-world" drivers is something you included in your recent changes to the plspage documentation which was probably based on an earlier e-mail remark by me. I am not sure this is actually true at the moment for our "real-world" drivers, but I certainly believe it is a worthwhile goal for them since changing the number of mm per inch or pts per inch should do very little other than to cause mass confusion. At the same time, though, I see nothing wrong with real-world devices calling plspage with the units per inch that they use so that plsc->xupi and plsc->yupi will reflect that in case those values are of some use to the user. Therefore, I am still leaning strongly toward the above rename from dpi to upi. Also, I plan to change PLPLOT_DEFAULT_MMPI ==> PLPLOT_MMPI PLPLOT_DEFAULT_PTPI ==> PLPLOT_PTPI (i.e., drop DEFAULT from the name) since there is nothing "default" about these values). But I will retain the PLPLOT_DEFAULT_PIXPI name since that really is a default value that is only adopted if the user does not select some other value. Finally, I have to say that making all devices follow the same set of rules for getting and setting upi and length values (with well-established variations for each general kind of device length unit) is long overdue, and we are still very early in the stages of the whole process. So our current ideas about what the rules should be are mostly theoretical and will likely require revision as we gain practical experience with this change for more and more of our devices. 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 __________________________ ------------------------------------------------------------------------------ _______________________________________________ Plplot-devel mailing list Plplot-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/plplot-devel
