private void SetCurrentCumulativeModifier(IAnimationClock animationClock)
{
if (IsCumulative)
{
double factor = animationClock.CurrentIteration.GetValueOrDefault() - 1;
if (factor > 0d)
{
T toFromDistance = SubtractValues(_actualTo, _actualFrom);
_cumulativeModifier = ScaleValue(toFromDistance, factor);
_useCumulativeModifier = true;
}
}
}
/// <summary>
/// Returns the current value of the animation.
/// </summary>
/// <param name="defaultOriginValue">
/// The origin value provided to the animation if the animation does not have its
/// own start value. If this animation is the first in a composition chain it will
/// be the base value of the property being animated; otherwise it will be the value
/// returned by the previous animation in the chain.
/// </param>
/// <param name="defaultDestinationValue">
/// The destination value provided to the animation if the animation does not have
/// its own destination value.
/// </param>
/// <param name="animationClock">
/// A non-specific <see cref="IAnimationClock"/> which can generate the <see cref="IClock.CurrentTime"/>
/// or <see cref="IClock.CurrentProgress"/> value to be used by the
/// animation to generate its output value.
/// </param>
/// <returns>The value this animation believes should be the current value for the property.</returns>
public virtual T GetCurrentValue(
object defaultOriginValue, object defaultDestinationValue, IAnimationClock animationClock)
{
ReadPreamble();
if (animationClock == null)
{
throw new ArgumentNullException(nameof(animationClock));
}
if (!(defaultOriginValue is T) && !(defaultOriginValue is null))
{
ThrowForInvalidAnimationValueType(nameof(defaultOriginValue));
}
if (!(defaultDestinationValue is T) && !(defaultDestinationValue is null))
{
ThrowForInvalidAnimationValueType(nameof(defaultDestinationValue));
}
return(GetCurrentValueCore(
(T)defaultOriginValue, (T)defaultDestinationValue, animationClock));
}
protected override double GetCurrentValueCore(
double from,
double to,
IAnimationClock animationClock)
{
double progress = animationClock.CurrentProgress.Value;
// Perform a very simple animation.
// Return a scaled value between from and to, depending on the current progress.
if (progress == 0)
{
return(from);
}
else if (progress == 1)
{
return(to);
}
else
{
return(from + (to - from) * progress);
}
}
private void SetDynamicAnimationValues(T defaultOrigin, T defaultDestination, IAnimationClock animationClock)
{
SetActualFromAndTo(defaultOrigin, defaultDestination);
SetCurrentAdditiveModifier(defaultOrigin);
SetCurrentCumulativeModifier(animationClock);
}
/// <summary>
/// Returns the value which represents the current value of the animation.
/// </summary>
/// <param name="defaultOriginValue">
/// The suggested origin value, used if <see cref="From"/> is not set.
/// </param>
/// <param name="defaultDestinationValue">
/// The suggested origin value, used if <see cref="To"/> is not set.
/// </param>
/// <param name="animationClock">
/// The <see cref="IAnimationClock"/> to be used by the animation to generate its output value.
/// </param>
/// <returns>The value which this animation believes to be the current one.</returns>
protected override T GetCurrentValueCore(T defaultOriginValue, T defaultDestinationValue, IAnimationClock animationClock)
{
SetConstantAnimationValues();
SetDynamicAnimationValues(defaultOriginValue, defaultDestinationValue, animationClock);
ValidateAnimationValues(_actualFrom, _actualTo);
double progress = animationClock.CurrentProgress.Value;
T interpolatedValue;
interpolatedValue = InterpolateValue(_actualFrom, _actualTo, progress);
if (_useCumulativeModifier)
{
interpolatedValue = AddValues(interpolatedValue, _cumulativeModifier);
}
if (_useAdditiveModifier)
{
interpolatedValue = AddValues(interpolatedValue, _additiveModifier);
}
return(interpolatedValue);
}
/// <summary>
/// Calculates a value that represents the current value of the property being animated,
/// as determined by the host animation.
/// </summary>
/// <param name="defaultOriginValue">
/// The suggested origin value, used if the animation
/// does not have its own explicitly set start value.
/// </param>
/// <param name="defaultDestinationValue">
/// The suggested destination value, used if the animation
/// does not have its own explicitly set end value.
/// </param>
/// <param name="animationClock">
/// An <see cref="IAnimationClock"/> which can generate the <see cref="IClock.CurrentTime"/>
/// or <see cref="IClock.CurrentProgress"/> value to be used by the
/// animation to generate its output value.
/// </param>
/// <returns>The value this animation believes should be the current value for the property.</returns>
protected abstract T GetCurrentValueCore(
T defaultOriginValue,
T defaultDestinationValue,
IAnimationClock animationClock);
