【WPF】GridLengthAnimation

参考 : http://zhidao.baidu.com

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);
            }
        }
    }

调用

GridLengthAnimation d = new GridLengthAnimation();
d.From = new GridLength(0, GridUnitType.Pixel);
d.To = new GridLength(100, GridUnitType.Pixel);
d.Duration = TimeSpan.FromSeconds(0.2);
grid_main.RowDefinitions[0].BeginAnimation(RowDefinition.HeightProperty, d);