image_crop_click: Cut out a Subregion of an Image by Mouse Click
In plothelper: New Plots Based on 'ggplot2' and Functions to Create Regular Shapes

This function is a wrapper of magick::image_crop. While the latter asks you to set a geometry parameter, this function enables you to set the four sides of a subregion only by click the mouse. You must click at least 2 times (that is, click on 2 different points to define a rectangle). After clicking, please press Esc on your keyboard. You can also designate an irregular polygon by mouse with at least 3 clicks. If it is irregular, you MUST click on positions in order (something like that, when you draw a polygon in R, you must input the positions of points in order).

1	image_crop_click(x, only_value = FALSE, rectangle = TRUE, trim = FALSE)

`x`	an image read into R by `magick::image_read` or an image modified by functions in the magick package.
`only_value`	the default is FALSE, which will return the subregion. If you set it to TRUE, the result is only four values with the order: left, right, top, bottom.
`rectangle`	whether the cropped area is a rectangle (default is TRUE). If it is FALSE, the subregion can be irregular.
`trim`	this is only used when `rectangle` is FALSE. It decides whether the irregular subregion is to be trimmed. If it is FALSE (default), no trimming will be done. If it is a 0 to 100 value, `magick::image_trim` will be used, whose `fuzz` argument is equal to `trim`. If it is TRUE (not 1), trimming will be done according to the mouse click you have made.