Transformation Displace (circular): request more controls

[pierrelabreche]

Would it be possible to:

• have a user-defined rotation center
• identify the rotation center (origin) using a crosshair or other means?
• show a rotation control circle, as an overlay?
• label the center 0 and the arc-defining points 1 and 2 to enable zooming on those points using keyboard shortcuts.
• identify two points on this circle (1) "from" and (2) "to" to define the rotation angle ? The rotation would be shown as a directed edge along the circle: a circular arc between the pair of distinct points #1 and #2, with an arrow pointing at #2.

Thanks

[Robert Schleif]

The above-mentioned additions would make this transformation much more useful to me. If they are implemented, changing the name to "turn" would increase the transformation's visibility (Displacement implies translation and not so much or not at all rotation.)

[jsachs]

I'm not sure why you would want these features, rather than using the Level transformation, unless you are creating special effects and using a mask to control the rotation angle. If you rotate off-center you are likely to lose some slices of the image as they rotate out of bounds, unless you then add a border, at which point this has become a rather different transformation. You can also get this effect currently by using the Composite transformation, placing a rotated image over a background image (using 2-point (shift/rotate) alignment.