On Wed, 2013-09-25 at 11:23 -0700, Bryce Harrington wrote:
On Wed, Sep 25, 2013 at 02:39:46AM -0700, ian_bruce@...2136... wrote:
On Tue, 24 Sep 2013 23:27:50 +0200 Johan Engelen <jbc.engelen@...2592...> wrote:
On 24-9-2013 22:16, Krzysztof Kosi\u0144ski wrote:
So it seems that 1px should ideally correspond to 1in / dpi of the monitor. E.g. the units are supposed to map 1:1 to the real world when the document is displayed at 100% zoom.
It is surely unsurprising that if somebody chooses to dimension their drawing in inches, millimetres, or kilometres, that these units are supposed to relate to the real world.
However, it is not clear that every drawing needs to be displayed at a real-world scale of 1:1 .
Really, there are (at least) three different ways the unit system touches the real world.
First is the physical measurements of the page. For instance, if you're going to fold a 8.5"x11" paper into forths and want a logo to appear in the middle of the cover, you're going to care about seeing position in document inches.
Second is the physical measurement of the monitor. If you're making assets for a website or buttons for a cell phone UI, you'll care about display pixels, display mm's, etc. and probably don't care about paper at all. It's possible you care about the dpi of some product display that you don't have access to (so don't just assume the attached monitor's dpi is the one the user cares about.)
Third is the physical measurement of the thing the drawing is conceiving. If you're drawing a map, then you'll care about km's and miles. You may care about how many printed page inches or cm's correspond to how many miles or km's.
Personally, this third use case is the one I care about, but when I was doing the original units system it became clear that the SVG spec cared mostly about the first one, and somewhat the second, and it wasn't at all clear how to handle the third. Indeed, it seems there is even difficulty in trying to make it handle #1 and #2 in a user-intuitive way. At the least, it all made me very confused.
I wonder if perhaps what we should do here is ignore SVG's units and consider the three (or more) use cases that users have, and think from their POV what would work best. Establish different unit systems "modes" and let the user toggle which units mode to use in the Inkscape UI while drawing.
With SVG 2 there is the possibility to improve the unit situation. Can someone come up with a concrete proposal? I can then bring it to the working group. (I will also be thinking about this when I get a chance.)
A couple of notes:
I believe that we require "px" explicitly when writing out "font-size". There is a note in the code about this.
The whole concept of "px" is confused by the various screen resolutions out there. I know that the CSS working group is struggling with this.
Tav