WPF Grid Sliding Animation

http://www.codeproject.com/Articles/18379/WPF-Tutorial-Part-2-Writing-a-custom-animation-cla
에 있는 클래스를 조금 수정하여 Grid 패널을 숨기고 보여주는 기능을 애니메이션으로 구현.
기존 클래스를 사용하면 Grid Column/Row 의 GridLength 속성이 Pixel 인 경우 제대로 동작하지 않는 문제와 애니메이션후 동작하지않는 문제가 있었고 위 주소를 참조하여 이를 해결.

< GridLengthAnimation.cs >

namespace GridAnimationDemo
{
    internal class GridLengthAnimation : AnimationTimeline
    {
        static GridLengthAnimation()
        {
            FromProperty = DependencyProperty.Register("From", typeof(GridLength),
                typeof(GridLengthAnimation));

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

        public override Type TargetPropertyType
        {
            get
            {
                return typeof(GridLength);
            }
        }

        protected override System.Windows.Freezable CreateInstanceCore()
        {
            return new GridLengthAnimation();
        }

        public static readonly DependencyProperty FromProperty;
        public GridLength From
        {
            get
            {
                return (GridLength)GetValue(GridLengthAnimation.FromProperty);
            }
            set
            {
                SetValue(GridLengthAnimation.FromProperty, value);
            }
        }

        public static readonly DependencyProperty ToProperty;
        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 fromVal = ((GridLength)GetValue(GridLengthAnimation.FromProperty)).Value;
            double toVal = ((GridLength)GetValue(GridLengthAnimation.ToProperty)).Value;

            if (fromVal > toVal)
            {
                return new GridLength((1 - animationClock.CurrentProgress.Value) * (fromVal - toVal) + toVal,
                ((GridLength)GetValue(GridLengthAnimation.FromProperty)).GridUnitType);
            }

            return new GridLength(animationClock.CurrentProgress.Value * (toVal - fromVal) + fromVal,
            ((GridLength)GetValue(GridLengthAnimation.ToProperty)).GridUnitType);
        }
    }
}

< Show/Hide 애니메이션 >

GridLength orgGridWidth = gridMain.ColumnDefinitions[0].Width;

int minPanelWidth = 30;

        private void btnSlidePanel_Click(object sender, RoutedEventArgs e)

        {

            if (gridMain.ColumnDefinitions[0].Width.Value > minPanelWidth)  // hide grid

            {

                orgGridWidth = gridMain.ColumnDefinitions[0].Width;                

                GridLengthAnimation gla = new GridLengthAnimation();

                gla.From = gridMain.ColumnDefinitions[0].Width;

                gla.To = new GridLength(minPanelWidth, GridUnitType.Pixel);

                gla.Duration = new TimeSpan(0, 0, 0, 0, 300);

                gla.FillBehavior = FillBehavior.HoldEnd;

                gla.Completed += delegate(object o, EventArgs evt)

                {

                    gridMain.ColumnDefinitions[0].Width = new GridLength(minPanelWidth, GridUnitType.Pixel);

                    gridMain.ColumnDefinitions[0].BeginAnimation(ColumnDefinition.WidthProperty, null);

                    gla.FillBehavior = FillBehavior.Stop;

                };

                gridMain.ColumnDefinitions[0].BeginAnimation(ColumnDefinition.WidthProperty, gla);

            }

            else // show grid

            {

                GridLengthAnimation gla = new GridLengthAnimation();

                gla.From = gridMain.ColumnDefinitions[0].Width;

                gla.To = orgGridWidth;

                gla.Duration = new TimeSpan(0, 0, 0, 0, 300);

                gla.FillBehavior = FillBehavior.HoldEnd;

                gla.Completed += delegate(object o, EventArgs evt)

                {

                    gridMain.ColumnDefinitions[0].Width = orgGridWidth;

                    gridMain.ColumnDefinitions[0].BeginAnimation(ColumnDefinition.WidthProperty, null);

                    gla.FillBehavior = FillBehavior.Stop;

                };

                gridMain.ColumnDefinitions[0].BeginAnimation(ColumnDefinition.WidthProperty, gla);

            }

        }