2014-04-25 8:57 GMT+02:00 Papoj Thamjaroenporn <pt2277@...3110...>:

Hi,

I’m writing here for the first time so nice to meet you all!

I started playing with Inkscape since a few weeks ago and one thing I
haven’t really understood is the way coordinate system works on Inkscape.
First of all, in the UI, the origin lies at the bottom-left corner of the
canvas, with y-axis pointing upward (based on what Inkscape displayed when I
moved my mouse around the canvas). However, when I created a path through an
LPE and printed anchor positions as the path was moved around, I found that
the internal coordinate system had y-axis pointing downward, with the origin
(0,0) lying somewhere above the canvas instead. Is this an expected
behavior? Is there a transformation matrix that transforms the internal
positions to the canvas positions?

There are several coordinate systems in Inkscape:

- The standard SVG coordinate system, denoted in the source as
"document coordinate system", starts in the top left corner and Y
grows downwards;
- The Inkscape "desktop coordinate system" starts in the bottom left
corner and Y grows upwards
- Window coordinates start in the top left corner of the visible area.
- World coordinates are offset with respect to the window coordinates
so that they start in top left corner of the document, but preserve
the ratio of 1 unit = 1 screen pixel.

Describe in more detail what exactly did you print and I can describe
what is happening.

Regards, Krzysztof