WPF后台动画DoubleAnimation讲解

WPF后台动画，使用DoubleAnimation做的。

1.移动动画

需要参数（目标点离最上边的位置，目标点离最左边的位置，元素名称）

Image mImage = new Image();

FloatInElement(100,100,mImage);

/// <summary>
        /// 移动动画 
        /// </summary>
        /// <param name="top">目标点相对于上端的位置</param>
        /// <param name="left">目标点相对于左端的位置</param>
        /// <param name="elem">移动元素</param>
        public static void FloatInElement(double top, double left, UIElement elem)
        {
            try
            {
                DoubleAnimation floatY = new DoubleAnimation()
                {
                    To = TransValueFromHeight(top),
                    Duration = new TimeSpan(0, 0, 0, 1, 0),
                };
                DoubleAnimation floatX = new DoubleAnimation()
                {
                    To = TransValueFromWidth(left),
                    Duration = new TimeSpan(0, 0, 0, 1, 0),
                };
                
                elem.BeginAnimation(Canvas.TopProperty, floatY);
                elem.BeginAnimation(Canvas.LeftProperty, floatX);
            }
            catch (Exception)
            {

                throw;
            }
        }

2.透明度动画

需要参数（元素名称,需要到达的透明度）

Image mImage = new Image();

FloatInElement(mImage,0);

/// <summary>
        /// 透明度动画 
        /// </summary>
        /// <param name="elem"></param>
        /// <param name="to"></param>
        public static void FloatElement(UIElement elem, double to)
        {
            lock (elem)
            {
                if (to == 1)
                {
                    elem.Visibility = Visibility.Visible;
                }
                DoubleAnimation opacity = new DoubleAnimation()
                {
                    To = to,
                    Duration = new TimeSpan(0, 0, 0, 1, 0)
                };
                EventHandler handler = null;
                opacity.Completed += handler = (s, e) =>
                {
                    opacity.Completed -= handler;
                    if (to == 0)
                    {
                        elem.Visibility = Visibility.Collapsed;
                    }
                    opacity = null;
                };
                elem.BeginAnimation(UIElement.OpacityProperty, opacity);
            }
        }

3.缓动动画-缩放动画

需要参数（控件名称,元素开始的位置，开始大小，目标大小）

Image mImage = new Image();

ScaleEasingAnimationShow(mImage,new Point(0.5,0.5),1,0);

元素开始的位置是从new Point（0，0）到new Point（1，1），左上角为（0，0）、右下角为（1，1），控件大小范围为（1，0） 1为控件本身大小，0 为控件缩放完，不显示。

如果要改动画类型，则改EasingMode = EasingMode.EaseOut

/// <summary>
        /// 用户控件是的动画
        /// </summary>
        /// <param name="element">控件名</param>
        /// <param name="point">元素开始动画的位置</param>
        /// <param name="from">元素开始的大小</param>
        /// <param name="from">元素到达的大小</param>
        public static void ScaleEasingAnimationShow(FrameworkElement element, Point point, double from, double to)
        {
            lock (element)
            {
                ScaleTransform scale = new ScaleTransform();
                element.RenderTransform = scale;
                element.RenderTransformOrigin = point;//定义圆心位置        
                EasingFunctionBase easeFunction = new PowerEase()
                {
                    EasingMode = EasingMode.EaseOut,
                    Power = 5
                };
                DoubleAnimation scaleAnimation = new DoubleAnimation()
                {
                    From = from,                                   //起始值
                    To = to,                                     //结束值
                    EasingFunction = easeFunction,                    //缓动函数
                    Duration = new TimeSpan(0, 0, 0, 1, 0)  //动画播放时间
                };
                AnimationClock clock = scaleAnimation.CreateClock();
                scale.ApplyAnimationClock(ScaleTransform.ScaleXProperty, clock);
                scale.ApplyAnimationClock(ScaleTransform.ScaleYProperty, clock);
            }
        }