OSError: invalid argument when draw stroke with specific font

[mirusu400]

What did you do?

I make a simple image, draw with Image, ImageFont, ImageDraw class.

What did you expect to happen?

I just want to add stroke.

What actually happened?

It gets error with specific font when I add stroke width.

What are your OS, Python and Pillow versions?

• OS: Windows-10-10.0.17763-SP0
• Python: 3.9.7 (tags/v3.9.7:1016ef3, Aug 30 2021, 20:19:38) [MSC v.1929 64 bit (AMD64)]
• Pillow: 8.3.2

from PIL import Image, ImageDraw, ImageFont, ImageOps

img = Image.new("RGBA", (100, 100), color=(255, 255, 255, 255))
fnt = ImageFont.truetype("C:/Windows/Fonts/calibriz.ttf", 16)

draw = ImageDraw.Draw(img)
text="a"
for i in text:
    draw.text(
        (0, 0),
        i,
        fill=(255,255,0,255),
        font=fnt,
        anchor="la",
        stroke_width=2,
        stroke_fill=(255,255,255,255)
    )

img.save("test.png")

Traceback (most recent call last):
  File "C:\Users\User\Documents\_github\drawfontimage\core.py", line 180, in create
    draw.text(
  File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\PIL\ImageDraw.py", line 457, in text
    draw_text(stroke_ink, stroke_width)
  File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\PIL\ImageDraw.py", line 408, in draw_text
    mask, offset = font.getmask2(
  File "C:\Users\User\AppData\Local\Programs\Python\Python39\lib\site-packages\PIL\ImageFont.py", line 676, in getmask2
    self.font.render(
OSError: invalid argument

The OSError is not happen when we remove option stroke_width and stroke_fill .

---

Pillow version 7.2.0 PERPECTLY resolve this issue, but after 8.0.0 it gets error.

I make simple repo for test / explain this issue.

https://github.com/mirusu400/pillow-stroke-error

Only some of fonts get this error, but I don't know the reason.

[nulano]

I have found this is related to the bitmap font fix - for obvious reasons FreeType is failing to stroke bitmap glyphs.

The failing fonts have bundled bitmap glyphs that are loaded by default - adding FT_LOAD_NO_BITMAP prevents this and fixes the issue.

Edit: I'm not sure I have time to put together a PR before the release in two days. I think this will require changing both the font_render and text_layout functions, the latter getting a new parameter stroke_width to be passed from the Python layer.