Thanks everyone for the extensive feedback and discussion!
I will implement the Drawing Page with the Y-axis pointing upwards from the bottom left.
In the end this isn't really a huge problem because it's only really used for the absolute position of views. Using QGraphicsView we get SVG for free, so I believe the coordinates will be transformed automatically if we wanted SVG for output.
In the case of units - my method before uses FreeCAD Units . If I read correctly, you can explicitly set the units used within QGraphicsView so we shouldn't have to worry about resolution independence.
jriegel wrote:Selection mean you can select lines points and so on in the drawing view (SVG elements).
Associativity mean you can add a "DatumFeature" to a selected line and points. This feature knows the "names" of the 2D SVG element they belong to and can be updated after a regeneration of the drawing view ( if the elements still exists).
That was the original plan, never got the time to do it...
Hopefully that is what I will achieve in the end - just not using SVG for the GUI.
TBH I wish we had someone implement a robust method for HLR - Hidden Line Removal so we could do the projection ourselves and have associativity with every edge and vertex of a part.
yorik wrote:One related thing I've been scratching my head with since a little time, one of the most-asked questions we hear here is certainly "how do I put dimensions on my drawing?". It is already possible, draft dimensions work fairly well now, but the problem is obviously that you must use the Draft tool instead of the normal Drawing tool to place them on the drawing sheet, which is far from obvious. But we absolutely can't make the Drawing module depend on something from the Draft module. So what could be a good solution to that? Any idea?
On this matter, I think we need to look at a more unified approach to 'dimensions' within FreeCAD. These might be 'strong' - lengths of edges in sketches or pads or 'weak' dimensions such as Annotations.
Eventually I would hope we can get the Drawing module to find automatically 'useful' datum dimensions within sketches aswell as with user made annotations. Similarly what would be useful is if we could collect all dimensions so that they could be referenced in equations (a bit like Pro/E Creo) or be used with optimisation problems. Perhaps maybe worthwhile discussing in another topic?