/// <summary>
/// Returns a <see cref="Brush"/> which serves as a zero-value for an additive animation.
/// The exact type of the brush is dependent on the first key frame in the animation.
/// </summary>
/// <returns>A new <see cref="Brush"/> which serves as a zero-value.</returns>
protected override sealed Brush GetZeroValue()
{
if (KeyFrames.Count == 0)
{
throw new InvalidOperationException(
"Creating a zero-brush requires at least one registered key frame.");
}
var firstFrame = KeyFrames.First();
var brushType = firstFrame.Value.GetType();
return(BrushAnimationHelper.Instance.GetZeroValue());
}
/// <summary>
/// Called when the <see cref="ExtendedVisualStateManager"/> transitions to the element.
/// The timeline which gets returned by this method is then used as a transitioning animation.
/// </summary>
/// <param name="toTimeline">
/// The input timeline, for which a visual transition timeline should be generated.
/// The VisualStateManager wants to transition to this timeline.
/// </param>
/// <param name="easingFunction">
/// An easing function to be applied to the resulting timeline.
/// Can be null.
/// </param>
/// <returns>
/// A <see cref="Timeline"/> which displays a visual transition to this element.
/// </returns>
public Timeline CreateToTransitionTimeline(
Timeline toTimeline, IEasingFunction easingFunction)
{
var result = new BrushAnimation()
{
EasingFunction = easingFunction
};
if (KeyFrames.Count > 0)
{
result.To = KeyFrames.First().Value;
}
return(result);
}
public override float GetFrameValue(float frame, float startFrame = 0)
{
if (InterpolationType == STInterpoaltionType.Constant)
{
return(Constant);
}
if (KeyFrames.Count == 0)
{
return(0);
}
if (KeyFrames.Count == 1)
{
return(KeyFrames[0].Value);
}
STKeyFrame LK = KeyFrames.First();
STKeyFrame RK = KeyFrames.Last();
float Frame = frame - startFrame;
foreach (STKeyFrame keyFrame in KeyFrames)
{
if (keyFrame.Frame <= Frame)
{
LK = keyFrame;
}
if (keyFrame.Frame >= Frame && keyFrame.Frame < RK.Frame)
{
RK = keyFrame;
}
}
if (LK.Frame != RK.Frame)
{
float FrameDiff = Frame - LK.Frame;
float Weight = FrameDiff / (RK.Frame - LK.Frame);
switch (InterpolationType)
{
case STInterpoaltionType.Constant: return(LK.Value);
case STInterpoaltionType.Step: return(LK.Value);
case STInterpoaltionType.Linear: return(InterpolationHelper.Lerp(LK.Value, RK.Value, Weight));
case STInterpoaltionType.Bezier:
{
return(InterpolationHelper.Lerp(LK.Value, RK.Value, Weight));
STBezierKeyFrame bezierKeyLK = (STBezierKeyFrame)LK;
STBezierKeyFrame bezierKeyRK = (STBezierKeyFrame)RK;
float length = RK.Frame - LK.Frame;
return(InterpolationHelper.BezierInterpolate(frame,
bezierKeyLK.Frame,
bezierKeyRK.Frame,
bezierKeyLK.SlopeIn,
bezierKeyRK.SlopeOut,
bezierKeyLK.Value,
bezierKeyRK.Value));
}
case STInterpoaltionType.Hermite:
{
STHermiteKeyFrame hermiteKeyLK = (STHermiteKeyFrame)LK;
STHermiteKeyFrame hermiteKeyRK = (STHermiteKeyFrame)RK;
float length = RK.Frame - LK.Frame;
return(InterpolationHelper.HermiteInterpolate(frame,
hermiteKeyLK.Frame,
hermiteKeyRK.Frame,
hermiteKeyLK.TangentIn,
hermiteKeyLK.TangentOut,
hermiteKeyLK.Value,
hermiteKeyRK.Value));
}
}
}
return(LK.Value);
}