Fix issue with scale height `65536` used as "flexible height"

[petschki]

In Plone 6 there are image scales with height 65536 in order to make the height calculated flexible when scaling down to the width. This is a problem in cropping editor, because there the flag can_scale checks if width and height of scaled image is larger than the original image.

To make these scales croppable here's my solution proposal:

• can_scale only checks that the width of the scaled image is lower equal to the original width.
• if the scaled image height is 65536 we calculate the height for the editor by the ratio of the original width/height.

I'm not really happy with the hard coded pixel value though. I also thought about a checkbox in the settings to discard the maximum check for the editor and leave it up to the integrator to constrain the scales to the valid one.

feedback welcome...

see #130

[MrTango]

I added a test to verify the desired behavior. Currently the last assert fails, because we allow a height higher than original image, even if it is under the max value of 65536. That does not make sense.

[MrTango]

but also the test_create_new_hashkey_for_cropped_images is still failing and i think not without reason.

[laulaz]

🙏