Cms: [FR] Add option to customise image editor constraints

[leevigraham]

Description

It would be nice if we could add or even fully customise the cropping aspect ratios in the image editor. Adding a new custom value could easily be implemented with a hook or a config setting:

Requested here: https://github.com/craftcms/cms/issues/4359#issuecomment-557728635

My use case which involves additional requirements is to show the user a "safe zone" in the "cropperGrid" by adding additional grid lines. I wonder if this would also be possible as an advanced custom config for the cropping aspect ratio.

Example: The blue guides would be the "cropperGrid" lines with an aspect ratio of 32:9

[andris-sevcenko]

My use case which involves additional requirements is to show the user a "safe zone" in the "cropperGrid" by adding additional grid lines. I wonder if this would also be possible as an advanced custom config for the cropping aspect ratio.

@leevigraham can you post that as a separate issue, please?

[andris-sevcenko]

Just added this for Craft 3.5.