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Control points are shape points, which can be used for the interactive modification of different shape geometry aspects. The control points of a shape are contained in an instance of the NControlPointCollection class, which can be obtained from the ControlPoints property of the NShape class. Control points are one of the optional shape elements and may not be available by default for each shape (see Shapes for more information).
Control points are represented by an instance of the NControlPoint class. Following is a brief description of the most important control point features:
Location
You can get/set the location of a control point in model and scene coordinates of the shape to which the control point belongs. This is done with the help of the
ModelLocation and
Location properties. The location of a control point is actually stored in model coordinates of the shape - in this way when the shape is transformed the control point will adopt the shape transformation to scene coordinates.
Tooltip
Each control point has a tooltip which is used to inform the user about the actual action being performed with the shape, through a specific control point. The tooltip is controlled by the
Tooltip property.
Control point logic
It is up to the shape to implement the specific action implemented by a control point. In general this is done by overriding the
UpdateFromControlPoint method of the
NShape class, which receives as argument the control point, whose location has changed.
See Also