Curve widget with three points

A widget that can be initialized on a DOM element of an image to create a curve with three points:
- The user specifies two points, between which a straight line is automatically drawn. The third point is located in the middle of this line.
- The user can change the position of the middle point by dragging (drag-and-drop).
- All points are editable: their positions can be changed by dragging.
- This widget provides intuitive interaction and allows for easy creation and editing of three-point curves.

#javascript