use of 'mm' units in specifying the radius (rx) of an ellipse is misinterpreted if the document units are not 'px'

[Alvin Penner]

Normally, when drawing a circle or ellipse, the variables cx, cy, rx, ry are given as dimensionless in the XML editor, and they are normally interpreted as being in units of "inkscape:document-units". However, it is possible to manually override this default in the XML editor, with mixed results.

Attached is a drawing with inkscape:document-units = px. It shows two ellipses. The top ellipse has rx=100, which has been correctly interpreted as 100px, and the bottom ellipse has rx=100mm, which has also been correctly interpreted as mm, so the bottom ellipse is larger as expected.

[Alvin Penner (apenner)]

Attached is a new drawing with inkscape:document-units = mm. The top ellipse has rx=35, which has been correctly interpreted as 35mm, and the bottom ellipse has rx=35mm, which has been misinterpreted. The two ellipses should be the same size, but they are not. The bottom ellipse is about 3 times larger than expected.

[Alvin Penner (apenner)]

attached is a list of all the variables that are impacted by this bug:

circle tag : cx, cy, r
ellipse tag : cx, cy, rx, ry
rect tag : x, y, width, height
text tag : x, y

for all these variables, the data will be misinterpreted if the units are explicitly set to be 'mm' in the individual variable while the document-units is also 'mm'.