The rawproc crop tool is a child of expediency as much as anything; I was writing my image library and I just needed to see how the ApplyCrop() method worked. The big decision was to have a separate window for the tool, and to have it update the display after every modification of the crop rectangle:
The tool is in the Parameters pane, lower left. The crop rectangle is pretty simple; it has two resize targets: the yellow one maintains original aspect, and the red one is free-form. The crop rectangle can be dragged around the image by mouse-dragging anywhere in the rectangle. That’s about it. Oh, the Parameters pane can be drug from the dock and made larger, which I occasionally do in order to have a bigger crop tool with which to work.
Of note about rawproc is that it is a successive application of tools, one working on the previous tool’s output. In this case, the crop tool is the first one in the chain, working on the opened JPEG. The next tool added would be working on the cropped image. When the image is saved to a file, the product of the last tool is used.
I cobbled together the crop tool mainly to get something going, but I find it works really well, so I’m keeping it. It’s not a precision tool, nor does it have the rich selection of aspect ratios, but it gets the crop job done.