Converting from APNG to WebP caused an error about timestamp being a float

[singpolyma]

Helps #7015

Changes proposed in this pull request:

• cast timestamp to int in WebPImagePlugin so that APNG conversion works instead of crashing

[hugovk]

Please can you include a test case that fails without the fix and passes with it?

[radarhere]

To demonstrate that this problem at least doesn't exist with all APNG files, using https://github.com/python-pillow/Pillow/blob/main/Tests/images/iss634.apng, the following code runs with Pillow 9.4.0 without an error.

from PIL import Image
im = Image.open('iss634.apng')
im.save('out.webp')

[radarhere]

if you feel uncomfortable writing a test case, just posting a self-contained example here would still be helpful.

[singpolyma]

This WIP test includes an image from https://signalstickers.com/pack/2ef10d945db55e0712773e18b24febe0 so it may not be properly redistributable as part of your suite, but it reproduces the issue when my patch is not applied

[radarhere]

Thanks. I see now that I missed the obvious fact that I needed to use save_all in my previous comment.

If I replace your test with

def test_float_duration(tmp_path):
    temp_file = str(tmp_path / "temp.webp")
    with Image.open("Tests/images/iss634.apng") as im:
        assert im.info["duration"] == 70.0

        im.save(temp_file, save_all=True)

    with Image.open(temp_file) as reloaded:
        reloaded.load()
        assert reloaded.info["duration"] == 70

does that sound good to you? It uses one of our existing test images.

[radarhere]

What do you think about using round instead of int, here and below?

[radarhere]

Suggested change

	enc.add(None, int(timestamp), 0, 0, "", lossless, quality, 0)
	enc.add(None, round(timestamp), 0, 0, "", lossless, quality, 0)

[radarhere]

Suggested change

	int(timestamp),
	round(timestamp),

[radarhere]

I've created PR #6996 with my two suggestions.

[hugovk]

Thanks for the PR, #6996 has been merged instead.