ImageDraw.line and Coords typing issue

[Andrej730]

ImageDraw.line is currently using Coords for xy argument.

Pillow/src/PIL/ImageDraw.py

Line 237 in c7ed097

xy: Coords,

Pillow/src/PIL/_typing.py

Line 40 in c7ed097

Coords = Union[Sequence[float], Sequence[Sequence[float]]]

Coords allows Sequence[Sequence], so it should support both tuple[tuple] and list[list] but currently it doesn't seem to be the case with ImageDraw.line - it fails with list[list] at runtime though there are no typing errors.

See example below.

from PIL import Image, ImageDraw
import numpy as np

img_size = (200, 200)
scale = 1.0

img = Image.new("RGB", img_size, "white")
draw = ImageDraw.Draw(img)

verts = np.array(
    [
        [[22.0, 105.0], [114.0, 105.0]],
        [[22.0, 105.0], [22.0, 23.0]],
        [[114.0, 105.0], [114.0, 113.0]],
        [[114.0, 113.0], [14.0, 113.0]],
        [[14.0, 113.0], [14.0, 15.0]],
        [[14.0, 15.0], [114.0, 15.0]],
        [[114.0, 15.0], [114.0, 23.0]],
        [[114.0, 23.0], [22.0, 23.0]],
    ]
)

for verts_ in verts:
    lst: list[list[float]]
    lst = verts_.tolist()
    # No typing errors but fails at runtime.
    # Traceback (most recent call last):
    # File "second_test.py", line 28, in <module>
    #     draw.line(verts_.tolist(), fill="black", width=2)
    # File "\Lib\site-packages\PIL\ImageDraw.py", line 249, in line
    #     self.draw.draw_lines(xy, ink, width)
    # ValueError: incorrect coordinate type
    # draw.line(lst, fill="black", width=2)

    # Works fine.
    tple = tuple(tuple(i) for i in verts_)
    draw.line(tple, fill="black", width=2)

# Show the image
img.show()

[radarhere]

Hi. Prior to adding type hints, the idea of a sequence of lists for co-ordinates was discussed in #3738, and declined.

However, I suppose the fact that we have existing type hints that suggest this is a new argument. I've created #8800