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.