Interactive cropping

[AlexSauer]

This commit addresses issue #42.
The user can click with the left mouse to set the top right corner of the crop and a right click sets the bottom right corner

[haesleinhuepf]

Hi @AlexSauer ,
this is super cool! Thanks for working on this. Two questions:

• Do you think it would be easy to draw a red frame while dragging the mouse? It might increase user-convenience a lot.
• I'm not sure if it works correctly. Maybe X and Y are mixed up? See this video:

haase-17-05-2024-10-38-29.mp4

Thanks again for working on this! This can be a game changer for cropping people :-)

[haesleinhuepf]

see comment above

[AlexSauer]

Hi @haesleinhuepf,

thanks a lot for starting the project! It saved me a lot of time to be able to view large 3D stacks that are saved on a remote cluster :) Very happy to contribute something.

I decided against something like a red frame as it would require the user to keep pressing down the mouse while selecting the rectangle and I thought that would not work well for selecting the 3D crops as you would have use the mouse the change the slice (see the video below). But if you disagree, I can change it.

Regarding the X-Y crop, I am slightly confused what is happening here as it works fine for me:
https://github.com/haesleinhuepf/stackview/assets/22394318/e1cf6db6-1d1a-46a5-adee-c621b3b0fa63

Do you have an idea what could cause this? I have to admit that I am not the most knowledgable when it comes to ipywidgets.
So if we can't resolve this easily, feel free to reject the PR. I do not want to create extra work for you