新增

GridLengthAnimation继承自AnimationTimeline

public class GridLengthAnimation : AnimationTimeline

    {

        public static readonly DependencyProperty FromProperty;

        public static readonly DependencyProperty ToProperty;

        public static readonly DependencyProperty EasingFunctionProperty;

        static GridLengthAnimation()

        {

            FromProperty = DependencyProperty.Register("From", typeof(GridLength), typeof(GridLengthAnimation));

            ToProperty = DependencyProperty.Register("To", typeof(GridLength), typeof(GridLengthAnimation));

            EasingFunctionProperty = DependencyProperty.Register("EasingFunction", typeof(IEasingFunction), typeof(GridLengthAnimation));

        }

        protected override Freezable CreateInstanceCore()

        {

            return new GridLengthAnimation();

        }

        public override Type TargetPropertyType

        {

            get { return typeof(GridLength); }

        }

        public IEasingFunction EasingFunction

        {

            get

            {

                return (IEasingFunction)GetValue(GridLengthAnimation.EasingFunctionProperty);

            }

            set

            {

                SetValue(GridLengthAnimation.EasingFunctionProperty, value);

            }

        }

        public GridLength From

        {

            get

            {

                return (GridLength)GetValue(GridLengthAnimation.FromProperty);

            }

            set

            {

                SetValue(GridLengthAnimation.FromProperty, value);

            }

        }

        public GridLength To

        {

            get

            {

                return (GridLength)GetValue(GridLengthAnimation.ToProperty);

            }

            set

            {

                SetValue(GridLengthAnimation.ToProperty, value);

            }

        }

        public override object GetCurrentValue(object defaultOriginValue, object defaultDestinationValue, AnimationClock animationClock)

        {

            double fromValue = ((GridLength)GetValue(GridLengthAnimation.FromProperty)).Value;

            double toValue = ((GridLength)GetValue(GridLengthAnimation.ToProperty)).Value;

            IEasingFunction easingFunction = this.EasingFunction;

            double progress = (easingFunction != null) ? easingFunction.Ease(animationClock.CurrentProgress.Value) : animationClock.CurrentProgress.Value;

            if (fromValue > toValue)

            {

                return new GridLength((1 - progress) * (fromValue - toValue) + toValue, this.To.IsStar ? GridUnitType.Star : GridUnitType.Pixel);

            }

            else

            {

                return new GridLength((progress) * (toValue - fromValue) + fromValue, this.To.IsStar ? GridUnitType.Star : GridUnitType.Pixel);

            }

        }

    }

            <RowDefinition Height="40"></RowDefinition>

            <RowDefinition></RowDefinition>

            <RowDefinition Height="0.1*"></RowDefinition>

        </Grid.RowDefinitions>

        <Grid.ColumnDefinitions>

            <ColumnDefinition x:Name="grid" Width="0.06*"></ColumnDefinition>

            <ColumnDefinition ></ColumnDefinition>

        </Grid.ColumnDefinitions>

GridLengthAnimation d = new GridLengthAnimation();

d.From = new GridLength(0.06, GridUnitType.Star);

d.To = new GridLength(0.2, GridUnitType.Star);

d.Duration = TimeSpan.FromSeconds(0.2);

grid.BeginAnimation(ColumnDefinition.WidthProperty, d);

   <Storyboard x:Key="showColumn" Duration="0:0:1" Storyboard.TargetName="grid" Storyboard.TargetProperty="Width" Completed="Storyboard_Completed">

            <local:GridLengthAnimation From="0" To="300">

                <local:GridLengthAnimation.EasingFunction>

                    <BounceEase EasingMode="EaseOut"/>

                </local:GridLengthAnimation.EasingFunction>

            </local:GridLengthAnimation>

        </Storyboard>

        <Storyboard x:Key="hideColumn" Duration="0:0:1" Storyboard.TargetName="grid" Storyboard.TargetProperty="Width" Completed="Storyboard_Completed">

            <local:GridLengthAnimation From="300" To="0">

                <local:GridLengthAnimation.EasingFunction>

                    <BounceEase EasingMode="EaseOut"/>

                </local:GridLengthAnimation.EasingFunction>

            </local:GridLengthAnimation>

        </Storyboard>

  BeginStoryboard((grid.Width.Value == 300) ? FindResource("hideColumn") as Storyboard : FindResource("showColumn") as Storyboard);