You should make sure this flare goes to the devel mailing list too. On Thu, 2017-09-14 at 15:11 -0600, brynn wrote:

Suggested reading: https://www.patreon.com/posts/units-part-i-13563546 https://www.patreon.com/posts/units-part-ii-13566508 https://www.patreon.com/posts/units-part-iii-13741251 https://www.patreon.com/posts/units-part-iv-13993147 (Articles written by Marc Jeanmougin, for his patrons on Patreon and for the whole Inkscape community) Maren Am 14.09.2017 um 23:11 schrieb brynn:

Hi Brynn, hi all, Only the third one (SVG) is really useful for this matter :) There are a few settings pertaining to units in the doc properties : Display units, custom size (which should probably be just "size") and "scale". (1) The most important setting is the "(Custom) Size", which will determine what final size your document will be. If you aim for real-world use (like printing/cutting), it will have to be in a realworld unit (mm) to avoid any problem. (2) The "Display Unit" is just a convenience. It will allow you to always see the rulers and size of stuff labeled in that unit, in the *outside* coordinate system (real world size). Whether you plan to use units in the file xml code or not will not affect the values shown and I would recommend setting it to the unit you make your measurements in. (3)The "Scale" is to tell Inkscape what should a user unit be worth in the outside coordinate system. If "the file is using those units" means that you do want to use mm or in or cm IN THE XML CODE[1] (which Inkscape can do, but does not do by default I think), you HAVE TO set it to 1user unit per PIXEL (temporarily set display unit to px, set scale to 1, put display unit back to whatever you need), otherwise a centimeter in the xml code will NOT be worth a centimeter (because… reasons, the details about that are in my article). If you only measure your stuff with the display units (and do not use units in the code, it should not matter (tools "should" take the scale into account, and if some do not it's an bug)) (Also, the "zoom correction factor" in the prefs→ Interface only control the behavior of View→Zoom→1:1 1:2 2:1 so that going to "Zoom 1:1" will show you on screen something worth 1cm at 1cm if you have set it correctly, but does not impact the file in any way.) I hope it's not toooo confusing, -- Marc [1] Like with <rect x="0cm" y="0cm" width="5cm"height="5cm"> vs the "normal" <rect x="0" y="0" width="5"height="5">

On 09/15/2017 10:00 AM, brynn wrote: The "outside coordinate system" is just the length of things upon displaying the file, assuming one respects the given "Size" of the document. "Inside" the file, everything is measured with the "inside" coordinate system. This system's unit is the abstract "user unit": your document may have a rectangle measuring 2 user unit wide and 5 user units tall, and you can tell (in the viewBox) that your complete document is the area between the point of coord (0,0) and the point of coord (20,50), in user units. They're abstract units, like when you do basic geometry in mathematics, without units; only meaning here that 2 user units wide is 10% of the document's width and 5user unit tall is 10% of the document's height. Only the additional data of the "Size" can tell you what the total height is in the "outside world", hence what 10% of it (== my 5uu of height) are worth. Now, the units *inside* the file (like the "cm" in my post-scriptum) are only shortcuts for given, fixed, multiples of the user unit (by definition, "px" is the name of that user unit and "in" is the name given to 96 user units), but if you do not set "1 user unit is one outside-world-pixel", they're not worth what they seem. -- Mc

Sorry for the delay. I think I'm getting it :-) Now, more or less understanding "user units", I'm back at #3 of your first reply. And here in the middle of that paragraph....I think....is the answer I need. to 1, put display unit back to whatever you need), So when someone needs to change the Display units, so that their drawing is as close to real world size as possible, do this: 1 -- set the desired Page Size and units (this sets the viewBox, right?) 2 -- temporarily change Display units to px 3 -- change the Scale to 1 4 -- change the Display units to the desired unit 5 -- the Scale will automatically change to the appropriate value 6 -- leave everything else alone If that's correct then 1 -- I'll make a new FAQ item for it (if no objections) - perhaps link to Marc's article about it - or is there a wiki page for it? 2 -- I'm really thinking Inkscape needs to do all that internally. I think users should be able to simply select the unit they want, the page size they want, and Inkscape does the rest. May I make the bug/feature report, or is it already planned or requested? If that's not correct, please tell me where I'm going wrong. Oh, one last question. your stuff with the display units (and do not use units in the code, it should not matter (tools "should" take the scale into account, and if some do not it's an bug Do you mean to say that it's possible some tools are not respecting the Scale? Or is that more of a theory. Thanks again, brynn -----Original Message----- From: Marc Jeanmougin Sent: Friday, September 15, 2017 2:22 AM To: inkscape-user(a)lists.sourceforge.net Subject: Re: [Inkscape-user] the Scale setting and Display units On 09/15/2017 10:00 AM, brynn wrote: The "outside coordinate system" is just the length of things upon displaying the file, assuming one respects the given "Size" of the document. "Inside" the file, everything is measured with the "inside" coordinate system. This system's unit is the abstract "user unit": your document may have a rectangle measuring 2 user unit wide and 5 user units tall, and you can tell (in the viewBox) that your complete document is the area between the point of coord (0,0) and the point of coord (20,50), in user units. They're abstract units, like when you do basic geometry in mathematics, without units; only meaning here that 2 user units wide is 10% of the document's width and 5user unit tall is 10% of the document's height. Only the additional data of the "Size" can tell you what the total height is in the "outside world", hence what 10% of it (== my 5uu of height) are worth. Now, the units *inside* the file (like the "cm" in my post-scriptum) are only shortcuts for given, fixed, multiples of the user unit (by definition, "px" is the name of that user unit and "in" is the name given to 96 user units), but if you do not set "1 user unit is one outside-world-pixel", they're not worth what they seem. -- Mc ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Inkscape-user mailing list Inkscape-user(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/inkscape-user

Oh, I'm so excited! I don't completely understand everything. But I understand a lot more than before. And what's best is that now I know how to tell other users to set their units. the current behavior of the "default mm" template is that a unitless value in the document (like width="5"), like inkscape sets by default, is in millimeters to be able to "see" it in the xml. (Which also means that width="5mm" will NOT be 5mm) But we could see the unitless "px" in the XML in previous versions. Why can't we see them now? Well, if it can be explained in a very simple way. What is the basis for the change to mm for native/default units? I have a feeling it was something about SVG standards, but not sure. Thank you very, very much! -----Original Message----- From: Marc Jeanmougin Sent: Monday, September 18, 2017 2:52 AM To: inkscape-user(a)lists.sourceforge.net Subject: Re: [Inkscape-user] the Scale setting and Display units Hi, On 09/18/2017 03:19 AM, brynn wrote: Yes We also can control the "scale" because, whether it is practical or not, the current behavior of the "default mm" template is that a unitless value in the document (like width="5"), like inkscape sets by default, is in millimeters to be able to "see" it in the xml. (Which also means that width="5mm" will NOT be 5mm) Technically possible, especially with extensions. ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Inkscape-user mailing list Inkscape-user(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/inkscape-user

Am 24.09.2017 um 11:44 schrieb brynn: Hi brynn, just two notes on the (*): * "It does not correspond to any specific size": As a matter of fact it does (right now it's 1/96 inch). The problem is more that this scale - as pointed out by others in the discussion before - can change at the will of the W3C. If they ever decide to change it again we'd neet to scale documents again (but this time it will be possible to do this fully automatic, i.e. should not require the users interaction anymore) * "It can't be used offline -- for example, you can't print an image in pixels, because the printer doesn't use pixels for a measurement.": That sounds as if the printer would stop working if I tried anyway (which obviously is not true). Printing a px-based document works just as well, what users have to be aware of that a "dot" (as in "dots per inch" or dpi of the printer) does not relate to the px in the SVG document which has a fixed scale. What about dropping the (*) as well as the term "real world units" altogether? I think it's not strictly relevant within the scope of your answer (choosing "px" and "mm" works exactly the same way for users). Regards, Eduard