I'm currently working on a map application, which allows users to create differently sized polygons on a Google Map and manipulate them. One such manipulation is rotation, and I'm having trouble figuring out how to give the user effective controls to rotate a polygon. Right now, I'm using a slider that pops up over the polygon that can be dragged left or right to rotate the polygon clockwise or counterclockwise, but this doesn't give the user fine-tuned control, and can be difficult to use at times. Is there a standard for controls for rotating polygons (or objects in general)? What is generally used in this type of situation? Thanks!
Solution for this from photo editing tools is:
When you select polygon, it is marked with think square, all corners are small selectable squares. If you mousover that squares / edges, mouse cursor can change to rotate icon. If you move it up or left it is rotating counter clockwise, if you move it bottom right it is rotating clockwise.
While rotating at each time small marker is available showing angle of rotation. i.e. 23%
If you press shift, incremental rotation is started for 25% or so..
You can maybe use some of this logic.