height=None doesn't work with HorizontalScroll

[lyovushka]

When I put an image that doesn't have height set (i.e. I want to use the image resolution) inside a HorizontalScroll with height=auto, it doesn't show up. Here is an example to reproduce:

from textual.app import App
from textual.widget import Widget
from textual.containers import HorizontalScroll
from textual_image.widget import Image


class TestWidget(Widget):
    DEFAULT_CSS = """
    HorizontalScroll {
        height: auto;
    }
    """

    def compose(self):
        with HorizontalScroll():
            yield Image(".venv/lib/python3.13/site-packages/textual_image/gracehopper.jpg")


class TestApp(App):
    def compose(self):
        yield TestWidget()


TestApp().run()

When I change HorizontalScroll to Horizontal it works fine. The issue happens in both Kitty and foot.

[lyovushka]

As an aside, I think it is more natural to use height=auto for the native height of the image.

[lnqs]

Hey, thanks for the report. When originally implementing it I fought a lot with the sizing. If I remember correctly, a *Scroll doesn't report a size of it's own until it has some content rendered. Therefore picking the size of the parent container to determine the image size results in a size of 0. I don't think there's much to be done about this the way the module is currently implemented.

I'll probably reach out to the Textual team at some point to talk to them if some changes to rich/Textual itself would be possible to better support packages like this (right now it's a bunch of hacks to make it work). At this point this issue could be changed, maybe. But I can't promise when this'll happen. Until then we have to work around it by either don't setting a size to get the original image size or set a size in cells.

As an aside, I think it is more natural to use height=auto for the native height of the image.
I'm unsure about this. To differentiate between "original size" and "fit the image in the parent container
we have "auto" and to set nothing. Having the original size when nothing it set seems natural to me (as this is the same as it would be in HTML/CSS). So for scaling it to the container only leaves auto be used.

[lyovushka]

I think when height/width is not set, textual doesn't like it very much. For a little debugging I did in the above example, Image.get_content_height is not even called by textual I think.

As for scaling to the container - isn't it achieved by "height: 100%" or something similar?