/// <summary>
/// 通过表达式指定动画开始的值。
/// </summary>
/// <param name="expression"></param>
/// <returns></returns>
public EasyTransitionAnimationFluentContext <T> FromExpression(String expression)
{
if (FromKeyFrameContext != null)
{
throw new InvalidOperationException("From 已经被指定。");
}
FromKeyFrameContext = new ExpressionKeyFrameFluentContext
{
Value = expression,
Progress = 0
};
return(this);
}
protected override void InsertExpressionKeyFrame(ExpressionKeyFrameFluentContext keyFrameContext)
{
switch (AnimationKind)
{
case TransitionAnimationKind.Relative:
(CompositionAnimation as KeyFrameAnimation).InsertExpressionKeyFrame(keyFrameContext.Progress, $"this.StartingValue + {keyFrameContext.Value}", keyFrameContext.EasingFunction);
break;
case TransitionAnimationKind.Absolute:
(CompositionAnimation as KeyFrameAnimation).InsertExpressionKeyFrame(keyFrameContext.Progress, keyFrameContext.Value, keyFrameContext.EasingFunction);
break;
default:
throw new ArgumentOutOfRangeException();
}
}
protected override void InsertExpressionKeyFrame(ExpressionKeyFrameFluentContext keyFrameContext)
{
(CompositionAnimation as KeyFrameAnimation).InsertExpressionKeyFrame(keyFrameContext.Progress, keyFrameContext.Value, keyFrameContext.EasingFunction);
}
protected abstract void InsertExpressionKeyFrame(ExpressionKeyFrameFluentContext keyFrameContext);
