# Can't skew with Glyphs.drawingTools

**URL:** <https://forum.glyphsapp.com/t/cant-skew-with-glyphs-drawingtools/37387>\
**Category:** Scripting\
**Created:** [October 1, 2026, 8:27am UTC](https://forum.glyphsapp.com/t/cant-skew-with-glyphs-drawingtools/37387 "2026-10-01T08:27:39Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![jkutilek](https://forum.glyphsapp.com/user_avatar/forum.glyphsapp.com/jkutilek/32/29173_2.png) [@jkutilek](https://forum.glyphsapp.com/u/jkutilek)\
**Post date:** [October 1, 2026, 8:27am UTC](https://forum.glyphsapp.com/t/cant-skew-with-glyphs-drawingtools/37387/1 "2026-10-01T08:27:39Z")

</div>

```python
from GlyphsApp.drawingTools import skew
skew(0.1)

```

`Traceback (most recent call last):`  
`File "Macro 2.py", line 3`  
`skew(0.1)`  
` ~~~~ ^^^^^`  
`File "/GlyphsApp/drawingTools.py", line 242, in skew`  
`Transform.shearXBy_yBy_(a, b)`  
`^^^^^^^^^^^^^^^^^^^^^^^`  
`AttributeError: 'NSAffineTransform' object has no attribute 'shearXBy_yBy_'. Did you mean: 'scaleXBy_yBy_'?`

---

<div class="post-metadata">

**Author:** ![thierryc](https://forum.glyphsapp.com/user_avatar/forum.glyphsapp.com/thierryc/32/28231_2.png) [@thierryc](https://forum.glyphsapp.com/u/thierryc)\
**Post date:** [October 1, 2026, 2:03pm UTC](https://forum.glyphsapp.com/t/cant-skew-with-glyphs-drawingtools/37387/2 "2026-10-01T14:03:43Z")

</div>

Maybe a bug. I try that with success on : Glyphs 4.1.1 (4108)

```auto

from AppKit import NSAffineTransform

def skew(a, b=None):
    if b is None:
        b = a
    transform = NSAffineTransform.alloc().init()
    transform.setTransformStruct_((1, b, a, 1, 0, 0))
    transform.concat()

```

I have used the Glyphs MCP server in coding mode to find it.  
I hope that helps.

---

<div class="post-metadata">

**Author:** ![jkutilek](https://forum.glyphsapp.com/user_avatar/forum.glyphsapp.com/jkutilek/32/29173_2.png) [@jkutilek](https://forum.glyphsapp.com/u/jkutilek)\
**Post date:** [October 1, 2026, 4:56pm UTC](https://forum.glyphsapp.com/t/cant-skew-with-glyphs-drawingtools/37387/3 "2026-10-01T16:56:20Z")

</div>

Thanks. There also is

```python
NSAffineTransform.shearXBy_yBy_atCenter_()

```

… which is not listed in Apple’s documentation, but does what I need. It may be deprecated?

---

<div class="post-metadata">

**Author:** ![FlorianPircher](https://forum.glyphsapp.com/user_avatar/forum.glyphsapp.com/florianpircher/32/30457_2.png) [@FlorianPircher](https://forum.glyphsapp.com/u/FlorianPircher)\
**Post date:** [October 1, 2026, 5:20pm UTC](https://forum.glyphsapp.com/t/cant-skew-with-glyphs-drawingtools/37387/4 "2026-10-01T17:20:58Z")

</div>

`NSAffineTransform.shearXBy_yBy_atCenter_` is added by Glyphs to the NSAffineTransform API.