This direction property determines the direction of the fade:
The default value is OpacityRamp.LeftToRight.
offset : real
Specifies the distance from the starting edge to begin the ramp down. For example, setting offset: 0.75 with direction: OpacityRamp.LeftToRight will begin fading at 75% of the width of the sourceItem.
The default value is 0.5.
slope : real
Specifies the rate at which opacity is reduced. A value of 1.0 will ramp the opacity down to 0 over the full width of the sourceItem. A value of 2.0 will reduce the opacity to 0 over half the width of the sourceItem.
The default value is 2.0.
sourceItem : Item
Specifies the Item to which the effect is applied. The OpacityRampEffect cannot be a child of the sourceItem.