WPF 如何流畅地滚动ScrollViewer

看了看原生UWP的ScrollViewer，滑动很流畅(例如 开始菜单)，但是WPF自带的ScrollViewer滚动十分生硬..

突发奇想，今天来实现一个流畅滚动的ScrollViewer.

01效果预览

流畅地滚动ScrollViewer_哔哩哔哩_bilibili

效果预览（更多效果请下载源码体验）：

02代码如下

一、ScrollViewerBehavior.cs 代码如下

using System.Windows;
using System.Windows.Controls;

namespace WPFDevelopers.Controls
{
    public static class ScrollViewerBehavior
    {
        public static readonly DependencyProperty VerticalOffsetProperty = DependencyProperty.RegisterAttached("VerticalOffset", typeof(double), typeof(ScrollViewerBehavior), new UIPropertyMetadata(0.0, OnVerticalOffsetChanged));
        public static void SetVerticalOffset(FrameworkElement target, double value) => target.SetValue(VerticalOffsetProperty, value);
        public static double GetVerticalOffset(FrameworkElement target) => (double)target.GetValue(VerticalOffsetProperty);
        private static void OnVerticalOffsetChanged(DependencyObject target, DependencyPropertyChangedEventArgs e) => (target as ScrollViewer)?.ScrollToVerticalOffset((double)e.NewValue);
    }
}

二、ScrollViewerAnimation.cs 代码如下 

using System;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media.Animation;

namespace WPFDevelopers.Controls
{
    public class ScrollViewerAnimation : ScrollViewer
    {
        //记录上一次的滚动位置
        private double LastLocation = 0;
        //重写鼠标滚动事件
        protected override void OnMouseWheel(MouseWheelEventArgs e)
        {
            double WheelChange = e.Delta;
            //可以更改一次滚动的距离倍数 (WheelChange可能为正负数!)
            double newOffset = LastLocation - (WheelChange * 2);
            //Animation并不会改变真正的VerticalOffset(只是它的依赖属性) 所以将VOffset设置到上一次的滚动位置 (相当于衔接上一个动画)
            ScrollToVerticalOffset(LastLocation);
            //碰到底部和顶部时的处理
            if (newOffset < 0)
                newOffset = 0;
            if (newOffset > ScrollableHeight)
                newOffset = ScrollableHeight;

            AnimateScroll(newOffset);
            LastLocation = newOffset;
            //告诉ScrollViewer我们已经完成了滚动
            e.Handled = true;
        }
        private void AnimateScroll(double ToValue)
        {
            //为了避免重复，先结束掉上一个动画
            BeginAnimation(ScrollViewerBehavior.VerticalOffsetProperty, null);
            DoubleAnimation Animation = new DoubleAnimation();
            Animation.EasingFunction = new CubicEase() { EasingMode = EasingMode.EaseOut };
            Animation.From = VerticalOffset;
            Animation.To = ToValue;
            //动画速度
            Animation.Duration = TimeSpan.FromMilliseconds(800);
            //考虑到性能，可以降低动画帧数
            //Timeline.SetDesiredFrameRate(Animation, 40);
            BeginAnimation(ScrollViewerBehavior.VerticalOffsetProperty, Animation);
        }
    }
}

使用方法:直接创建

如果是在ListBox中，可以通过修改模板的方式，把换成ScrollViewerAnimation即可.

三、ScrollViewerAnimationExample.xaml 代码如下