Issue with skew attribute in component transform in Glyphs3-merge branch

[roberto-arista]

Consider the following code

import pprint

from fontTools.pens.recordingPen import RecordingPen
from glyphsLib import GSFont

if __name__ == "__main__":
    gs_font = GSFont("example.glyphs")
    layer = gs_font.glyphs["bitcoin"].layers[0]
    recording_pen = RecordingPen()
    layer.draw(recording_pen)
    pprint.pp(recording_pen.value)

When running the code from the main branch, the output is:

[('moveTo', ((249, 650),)),
 ('lineTo', ((297, 650),)),
 ('lineTo', ((324, 800),)),
 ('lineTo', ((276, 800),)),
 ('closePath', ()),
 ('moveTo', ((364, 650),)),
 ('lineTo', ((412, 650),)),
 ('lineTo', ((439, 800),)),
 ('lineTo', ((391, 800),)),
 ('closePath', ()),
 ('moveTo', ((115, -110),)),
 ('lineTo', ((163, -110),)),
 ('lineTo', ((191, 50),)),
 ('lineTo', ((143, 50),)),
 ('closePath', ()),
 ('moveTo', ((230, -110),)),
 ('lineTo', ((278, -110),)),
 ('lineTo', ((307, 50),)),
 ('lineTo', ((259, 50),)),
 ('closePath', ()),
 ('addComponent', ('B', <affine transformation 1 0 0.0 0.94 5 21>))]

Instead, when running the code from Glyphs3-merge, the output is:

[('moveTo', ((249, 650),)),
 ('lineTo', ((297, 650),)),
 ('lineTo', ((324, 800),)),
 ('lineTo', ((276, 800),)),
 ('closePath', ()),
 ('moveTo', ((364, 650),)),
 ('lineTo', ((412, 650),)),
 ('lineTo', ((439, 800),)),
 ('lineTo', ((391, 800),)),
 ('closePath', ()),
 ('moveTo', ((115, -110),)),
 ('lineTo', ((163, -110),)),
 ('lineTo', ((191, 50),)),
 ('lineTo', ((143, 50),)),
 ('closePath', ()),
 ('moveTo', ((230, -110),)),
 ('lineTo', ((278, -110),)),
 ('lineTo', ((307, 50),)),
 ('lineTo', ((259, 50),)),
 ('closePath', ()),
 ('addComponent',
  ('B', <affine transformation 1.0 0.0 -0.8422883804630793 0.94 5.0 21.0>))]

Attached you can find the .glyphs file.

example.glyphs.zip

cc @schriftgestalt

[schriftgestalt]

As fare as I can see, both transforms are not correct. In the .glyphs source is this:

{
pos = (5,21);
ref = B;
scale = (1,0.94);
slant = (-0.7,0);
}

transfrom from main:

1 0 0.0 0.94 5 21

and from Glyphs3 branch:

1 0 -0.8422883804630793 0.94 5 21

and from Glyphs 3.app

1 0 -0.011484837902484654 0.94 5 21

from what I can tell, the version from Glyphs.app seem to be correct. The calculation of the transform from scale, rotation and slant was done in a different order than in Glyphs.app (and the skew needed to be converted to radians). I fixed that. Thanks for the test case.

[roberto-arista]

Hey Georg, thanks for the fix. I cannot see the code on remote, let me know when you'll push it (and on which branch) so I can test it on my end.

[schriftgestalt]

the type cast is still relevant. Remove the change with the active property.

[roberto-arista]

done!