By default, the RotateCenterX / RotateCenterY property is empty. If the RotateCenterX / RotateCenterY property is empty, missing or invalid, the center of the layer ( RotateCenterLayer layer) is considered the rotation center. Use the DefaultLayer(exDefLayerRotateCenterX) property to specify the default value for the RotateCenterX property, before adding the layer. 

You can change the Debug property ( to exDebugLayerDragRotate, for instance ) of the DragInfo object during the DragStart event to show the current rotation point as shown in the following screen shot:

For instance:

• "lwidth/2 + 78", defines the center 78 pixels to the right relative to the center of the layer.

The RotateCenterX property supports the following keywords:

• lwidth keyword, indicates the width in pixels of the layer
• width keyword, specifies the width in pixels of the view / control
• lheight keyword, indicates the height in pixels of the layer
• height keyword, specifies the height in pixels of the view / control

Also, this property supports all constants, operators and functions defined here.

The following properties can be used to specify a different rotation center:

• RotateCenterLayer, indicates the index of the layer the rotation is around.
• RotateCenterX, indicates the expression that determines the x-origin of the rotation point relative to the RotateCenterLayer layer.
• RotateCenterY, indicates the expression that determines the y-origin of the rotation point relative to the RotateCenterLayer layer.

The following picture shows the rotation properties of the Layer, relative to the RotateCenterLayer layer:

Any of the following properties can be used to rotate the layer:

• DefaultRotateAngle, specifies the default angle to rotate the layer.
• RotateAngle, specifies the angle to rotate the layer.
• RotateAngleValid, validates / limits the rotation angle of the layer.
• Value and ValueToRotateAngle, specifies the expression to convert the value to rotating angle. The RotateAngleToValue converts the current rotation angle to a value.

The following properties can be used to change the rotation center, while the layer's OnDrag property is exDoRotamove:

• RotamoveCenterX, specifies the x-position of the layer's center.
• RotamoveCenterY, specifies the y-position of the layer's center. 
• RotamoveOffsetX,  specifies the x-offset of the layer.
• RotamoveOffsetY, specifies the y-offset of the layer.