By default, the ValueToRotateAngle property is empty. If the ValueToRotateAngle property is empty, missing or invalid it has no effect. If the ValueToRotateAngle property is valid, the result of evaluation of it, indicates the value of the RotateAngle property, while the OnDrag property is exDoRotate or exDoRotamove. The RotateAngleValid property limits / validates the rotation angle of the layer. The RotateAngle property specifies the angle to rotate the layer. The Change event occurs when the layer's Value property is changed. During the Change event, you can change values of other layers as well. For instance, if the second-hand of the clock is rotated, you can rotate the hour and the minute-hands of the clock as well. Use the DefaultLayer(exDefLayerValueToRotateAngle) property to specify the default value for the ValueToRotateAngle property, before adding the layer. The RotateAngleToValue converts the current rotation angle to a value.

For instance:

• the control displays a clock, the value could be the current-time
• the control displays a gauge, so the value could be the value on the gauge pointed by the needle

For instance:

• "0", no rotation, or assigns always 0 to RotateAngle property 
• "value / 2", specifies half of the layer's Value
• "value / 100 * 360", Value percent from 360 degree. For instance, if the value is 50, the expression returns 180, and if 100, the expression returns 360
• "value < 50 ? (270 + value/50*90) : (value - 50)/50 * 90", for a value less than 50 returns the angle between 270 and 360, and for a value grater than 50, from 0 to 90 
• "2 * 360 * ( (0:=(value < 0 ? floor(value) + 1 - value : value - floor(value))) < 0.5 ? =:0 : (0:= (=:0 - 0.5)) )", indicates the position ( rotation angle ) of the clock's hours-hand giving the time value.
• "((1:=( ( (0:=(value < 0 ? floor(value) + 1 - value : value - floor(value))) < 0.5 ? =:0 : (0:= (=:0 - 0.5)) ) * 24 )) - floor(=:1)) * 360", indicates the position ( rotation angle ) of the clock's minutes-hand giving the time value.
• "((2:=(((1:=( ( (0:=(value < 0 ? floor(value) + 1 - value : value - floor(value))) < 0.5 ? =:0 : (0:= (=:0 - 0.5)) ) * 24 )) - floor(=:1)) * 60 )) - floor(=:2) ) * 360", indicates the position ( rotation angle ) of the clock's seconds-hand giving the time value.

The ValueToRotateAngle property supports the following keywords:

• value keyword indicates the layer's Value property.

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

The Value property indicates the value keyword in the following properties:

• ValueToRotateAngle, Specifies the expression to convert the value to rotating angle. The layer's RotateAngle property is the result of evaluating the ValueToRotateAngle expression, while the OnDrag property is exDoRotate or exDoRotamove. The RotateAngleToValue converts the current rotation angle to a value.
• ValueToOffsetX, Specifies the expression to convert the value to x-offset. The layer's OffsetX property is the result of evaluating the ValueToOffsetX expression, while the OnDrag property is exDoMove. The OffsetToValue converts the current offset to a value.
• ValueToOffsetY, Specifies the expression to convert the value to y-offset. The layer's OffsetY property is the result of evaluating the ValueToOffsetY expression, while the OnDrag property is exDoMove. The OffsetToValue converts the current offset to a value.

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 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 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.