By Property (PointAnimation)
Gets or sets the total amount by which the animation changes its starting value.
<object By="Point" .../>
value = object.By
object.By = value
The total amount by which the animation changes its starting value.
This property is read/write. The default value is null.
Point parallels a convention that is supported by a type converter, such that properties that take a Point as their value can specify a Point as a formatted string. The type converter generates a new Point value based on processing the string. The type converter functions both for XAML usages and script usages. In both cases, you supply a quoted string. The format of that string is an X,Y value pair. Alternatively, you can use a space rather than a comma as the delimiter betweeen X and Y in the string.
See remarks in Point for details on scripting usages. The properties of PointAnimation are one of the cases where the object model provides access to an actual Point as a return value if you get this property at runtime. This means that you can potentially use the X and Y properties of the returned Point to adjust the animation either before it runs or while it runs.
Use the By property when you want to animate a value "by" a certain amount, rather than specifying a starting or ending value. You may also use the By property with the From property. The following table summarizes how the From, To, and By properties may be used together or separately to determine an animation's target values.
The animation progresses from the value specified by the From property to the base value of the property being animated.
From and To
The animation progresses from the value specified by the From property to the value specified by the To property.
From and By
The animation progresses from the value specified by the From property to the value specified by the sum of the From and By properties.
The animation progresses from the animated property's base value or a previous animation's output value to the value specified by the To property.
The animation progresses from the base value of the property being animated or a previous animation's output value to the sum of that value and the value specified by the By property.
Note If you set both the To and By properties, the To property takes precedence and the By property is ignored.
To use other interpolation methods or animate between more than two target values, use a PointAnimationUsingKeyFrames object.