15、导航滑动动画

　　在触屏设备上，手指滑动页面，或者单击导航选项时，增加导航下横线滑动的效果：

　　这个版本有点简单粗暴，同事在项目中优化了一下算法。这里只是简单记录一下大致思路：

1、导航使用 ListView 控件，下面使用 Pivot 控件

　　大致结构为：

页面中的 ListView：

<ListView x:Name="listview" VerticalAlignment="Top" Margin="0,40,0,0" Background="White" ScrollViewer.HorizontalScrollBarVisibility="Hidden" ScrollViewer.HorizontalScrollMode="Enabled" ScrollViewer.VerticalScrollBarVisibility="Disabled" ScrollViewer.VerticalScrollMode="Disabled" SelectionChanged="listView_SelectionChanged">
            <ListView.ItemContainerStyle>
                <Style TargetType="ListViewItem">
                    <Setter Property="Template">
                        <Setter.Value>
                            <ControlTemplate TargetType="ListViewItem">
                                <!--选中色设置为 红色-->
                                <ListViewItemPresenter CheckBrush="{x:Null}" ContentMargin="{TemplateBinding Padding}" CheckMode="Inline" ContentTransitions="{x:Null}" CheckBoxBrush="{x:Null}" DragForeground="{x:Null}" DragOpacity="0" DragBackground="{x:Null}" DisabledOpacity="0" FocusBorderBrush="{x:Null}" FocusSecondaryBorderBrush="{x:Null}" HorizontalContentAlignment="Center" PointerOverForeground="{ThemeResource SystemControlHighlightAltBaseHighBrush}" PressedBackground="{x:Null}" PlaceholderBackground="{ThemeResource ListViewItemPlaceholderBackgroundThemeBrush}" PointerOverBackground="{x:Null}" ReorderHintOffset="{ThemeResource ListViewItemReorderHintThemeOffset}" SelectionCheckMarkVisualEnabled="True" SelectedForeground="Red" SelectedPointerOverBackground="{x:Null}" SelectedBackground="{x:Null}" VerticalContentAlignment="Center" SelectedPressedBackground="{x:Null}" Foreground="Black"/>
                            </ControlTemplate>
                        </Setter.Value>
                    </Setter>
                </Style>
            </ListView.ItemContainerStyle>
            <ListView.ItemsPanel>
                <ItemsPanelTemplate>
                    <ItemsStackPanel Orientation="Horizontal"/>
                </ItemsPanelTemplate>
            </ListView.ItemsPanel>
            <ListView.ItemTemplate>
                <DataTemplate>
                    <Grid>
                        <Grid.RowDefinitions>
                            <RowDefinition Height="Auto"/>
                            <RowDefinition Height="Auto"/>
                        </Grid.RowDefinitions>
                        <TextBlock Text="{Binding Text}" FontSize="20" Margin="20,10"/>

　　　　　　　　　　　　　　<!--作为位移指示条-->
                        <Rectangle x:Name="rect" Fill="Red" Height="2" HorizontalAlignment="Stretch" Grid.Row="1" Opacity="0" Loaded="rect_Loaded">
                            <Rectangle.RenderTransform>
                                <CompositeTransform/>
                            </Rectangle.RenderTransform>
                        </Rectangle>
                    </Grid>
                </DataTemplate>
            </ListView.ItemTemplate>
        </ListView>

选中时，播放的位移动画：

<Page.Resources>
        <!--#region 导航下划线位移动画-->
        <Storyboard x:Name="SB_Slide" Completed="SB_Slide_Completed">
            <DoubleAnimationUsingKeyFrames x:Name="SB_Slide_TransX" Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.TranslateX)" >
                <!--Storyboard.TargetName="rect1"-->
                <EasingDoubleKeyFrame KeyTime="0" Value="0"/>
                <EasingDoubleKeyFrame KeyTime="0:0:0.5" Value="600">
                    <EasingDoubleKeyFrame.EasingFunction>
                        <!--回弹效果-->
                        <!--<BackEase EasingMode="EaseOut" Amplitude="0.3"/>-->
                        <QuarticEase EasingMode="EaseOut"/>
                    </EasingDoubleKeyFrame.EasingFunction>
                </EasingDoubleKeyFrame>
            </DoubleAnimationUsingKeyFrames>
        </Storyboard>
        <!--#endregion-->
</Page.Resources>

Pivot 中，重写 Template，去掉 Header 等多余对象：

     <Pivot x:Name="pivot" Grid.Row="1" SelectedItem="{Binding SelectedItem,ElementName=listview,Mode=TwoWay}">
            <Pivot.ItemContainerStyle>
                <Style TargetType="PivotItem">
                    <!--默认 Item 两侧有大约20px 的 Margin-->
                    <Setter Property="Margin" Value="0"/>
                </Style>
            </Pivot.ItemContainerStyle>
            <Pivot.ItemTemplate>
                <DataTemplate>
                    <Grid Background="LightBlue">
                        <TextBlock FontSize="30" Text="{Binding Text}" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="20"/>
                    </Grid>
                </DataTemplate>
            </Pivot.ItemTemplate>
            <Pivot.Template>
                <!--去掉模板中多余的 UI（Header 等）和动画-->
                <ControlTemplate TargetType="Pivot">
                    <Grid x:Name="RootElement" Background="{TemplateBinding Background}" HorizontalAlignment="{TemplateBinding HorizontalAlignment}" VerticalAlignment="{TemplateBinding VerticalAlignment}">
                        <Grid.Resources>
                            <Style x:Key="BaseContentControlStyle" TargetType="ContentControl">
                                <Setter Property="FontFamily" Value="Segoe UI"/>
                                <Setter Property="FontWeight" Value="SemiBold"/>
                                <Setter Property="FontSize" Value="15"/>
                                <Setter Property="Template">
                                    <Setter.Value>
                                        <ControlTemplate TargetType="ContentControl">
                                            <ContentPresenter ContentTemplate="{TemplateBinding ContentTemplate}" ContentTransitions="{TemplateBinding ContentTransitions}" Content="{TemplateBinding Content}" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" Margin="{TemplateBinding Padding}" OpticalMarginAlignment="TrimSideBearings" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
                                        </ControlTemplate>
                                    </Setter.Value>
                                </Setter>
                            </Style>
                            <Style x:Key="TitleContentControlStyle" BasedOn="{StaticResource BaseContentControlStyle}" TargetType="ContentControl">
                                <Setter Property="FontFamily" Value="{ThemeResource PivotTitleFontFamily}"/>
                                <Setter Property="FontWeight" Value="{ThemeResource PivotTitleThemeFontWeight}"/>
                                <Setter Property="FontSize" Value="{ThemeResource PivotTitleFontSize}"/>
                            </Style>
                        </Grid.Resources>
                        <Grid.RowDefinitions>
                            <RowDefinition Height="Auto"/>
                            <RowDefinition Height="*"/>
                        </Grid.RowDefinitions>
                        <VisualStateManager.VisualStateGroups>
                            <VisualStateGroup x:Name="Orientation">
                                <VisualState x:Name="Portrait">
                                    <!--<Storyboard>
                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Margin" Storyboard.TargetName="TitleContentControl">
                                                <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource PivotPortraitThemePadding}"/>
                                            </ObjectAnimationUsingKeyFrames>
                                        </Storyboard>-->
                                </VisualState>
                                <VisualState x:Name="Landscape">
                                    <!--<Storyboard>
                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Margin" Storyboard.TargetName="TitleContentControl">
                                                <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource PivotLandscapeThemePadding}"/>
                                            </ObjectAnimationUsingKeyFrames>
                                        </Storyboard>-->
                                </VisualState>
                            </VisualStateGroup>
                            <VisualStateGroup x:Name="NavigationButtonsVisibility">
                                <VisualState x:Name="NavigationButtonsHidden"/>
                                <VisualState x:Name="NavigationButtonsVisible">
                                    <!--<Storyboard>
                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Opacity" Storyboard.TargetName="NextButton">
                                                <DiscreteObjectKeyFrame KeyTime="0" Value="1"/>
                                            </ObjectAnimationUsingKeyFrames>
                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="IsEnabled" Storyboard.TargetName="NextButton">
                                                <DiscreteObjectKeyFrame KeyTime="0" Value="True"/>
                                            </ObjectAnimationUsingKeyFrames>
                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Opacity" Storyboard.TargetName="PreviousButton">
                                                <DiscreteObjectKeyFrame KeyTime="0" Value="1"/>
                                            </ObjectAnimationUsingKeyFrames>
                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="IsEnabled" Storyboard.TargetName="PreviousButton">
                                                <DiscreteObjectKeyFrame KeyTime="0" Value="True"/>
                                            </ObjectAnimationUsingKeyFrames>
                                        </Storyboard>-->
                                </VisualState>
                            </VisualStateGroup>
                            <VisualStateGroup x:Name="HeaderStates">
                                <VisualState x:Name="HeaderDynamic"/>
                                <VisualState x:Name="HeaderStatic">
                                    <!--<Storyboard>
                                           <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility" Storyboard.TargetName="Header">
                                                <DiscreteObjectKeyFrame KeyTime="0" Value="Collapsed"/>
                                            </ObjectAnimationUsingKeyFrames>
                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility" Storyboard.TargetName="StaticHeader">
                                                <DiscreteObjectKeyFrame KeyTime="0" Value="Visible"/>
                                            </ObjectAnimationUsingKeyFrames>
                                        </Storyboard>-->
                                </VisualState>
                            </VisualStateGroup>
                        </VisualStateManager.VisualStateGroups>
                        <ContentControl x:Name="TitleContentControl" ContentTemplate="{TemplateBinding TitleTemplate}" Content="{TemplateBinding Title}" IsTabStop="False" Margin="{StaticResource PivotPortraitThemePadding}" Style="{StaticResource TitleContentControlStyle}" Visibility="Collapsed"/>
                        <Grid Grid.Row="1">
                            <!--<Grid.Resources>
                                    <ControlTemplate x:Key="NextTemplate" TargetType="Button">
                                        <Border x:Name="Root" BorderBrush="{ThemeResource SystemControlForegroundTransparentBrush}" BorderThickness="{ThemeResource PivotNavButtonBorderThemeThickness}" Background="{ThemeResource SystemControlBackgroundBaseMediumLowBrush}">
                                            <VisualStateManager.VisualStateGroups>
                                                <VisualStateGroup x:Name="CommonStates">
                                                    <VisualState x:Name="Normal"/>
                                                    <VisualState x:Name="PointerOver">
                                                        <Storyboard>
                                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Background" Storyboard.TargetName="Root">
                                                                <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightBaseMediumBrush}"/>
                                                            </ObjectAnimationUsingKeyFrames>
                                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Foreground" Storyboard.TargetName="Arrow">
                                                                <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightAltAltMediumHighBrush}"/>
                                                            </ObjectAnimationUsingKeyFrames>
                                                        </Storyboard>
                                                    </VisualState>
                                                    <VisualState x:Name="Pressed">
                                                        <Storyboard>
                                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Background" Storyboard.TargetName="Root">
                                                                <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightBaseMediumHighBrush}"/>
                                                            </ObjectAnimationUsingKeyFrames>
                                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Foreground" Storyboard.TargetName="Arrow">
                                                                <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightAltAltMediumHighBrush}"/>
                                                            </ObjectAnimationUsingKeyFrames>
                                                        </Storyboard>
                                                    </VisualState>
                                                </VisualStateGroup>
                                            </VisualStateManager.VisualStateGroups>
                                            <FontIcon x:Name="Arrow" Foreground="{ThemeResource SystemControlForegroundAltMediumHighBrush}" FontSize="12" FontFamily="{ThemeResource SymbolThemeFontFamily}" Glyph="&#xE0E3;" HorizontalAlignment="Center" MirroredWhenRightToLeft="True" UseLayoutRounding="False" VerticalAlignment="Center"/>
                                        </Border>
                                    </ControlTemplate>
                                    <ControlTemplate x:Key="PreviousTemplate" TargetType="Button">
                                        <Border x:Name="Root" BorderBrush="{ThemeResource SystemControlForegroundTransparentBrush}" BorderThickness="{ThemeResource PivotNavButtonBorderThemeThickness}" Background="{ThemeResource SystemControlBackgroundBaseMediumLowBrush}">
                                            <VisualStateManager.VisualStateGroups>
                                                <VisualStateGroup x:Name="CommonStates">
                                                    <VisualState x:Name="Normal"/>
                                                    <VisualState x:Name="PointerOver">
                                                        <Storyboard>
                                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Background" Storyboard.TargetName="Root">
                                                                <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightBaseMediumBrush}"/>
                                                            </ObjectAnimationUsingKeyFrames>
                                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Foreground" Storyboard.TargetName="Arrow">
                                                                <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightAltAltMediumHighBrush}"/>
                                                            </ObjectAnimationUsingKeyFrames>
                                                        </Storyboard>
                                                    </VisualState>
                                                    <VisualState x:Name="Pressed">
                                                        <Storyboard>
                                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Background" Storyboard.TargetName="Root">
                                                                <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightBaseMediumHighBrush}"/>
                                                            </ObjectAnimationUsingKeyFrames>
                                                            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Foreground" Storyboard.TargetName="Arrow">
                                                                <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightAltAltMediumHighBrush}"/>
                                                            </ObjectAnimationUsingKeyFrames>
                                                        </Storyboard>
                                                    </VisualState>
                                                </VisualStateGroup>
                                            </VisualStateManager.VisualStateGroups>
                                            <FontIcon x:Name="Arrow" Foreground="{ThemeResource SystemControlForegroundAltMediumHighBrush}" FontSize="12" FontFamily="{ThemeResource SymbolThemeFontFamily}" Glyph="&#xE0E2;" HorizontalAlignment="Center" MirroredWhenRightToLeft="True" UseLayoutRounding="False" VerticalAlignment="Center"/>
                                        </Border>
                                    </ControlTemplate>
                                </Grid.Resources>-->
                            <ScrollViewer x:Name="ScrollViewer" BringIntoViewOnFocusChange="False" HorizontalSnapPointsAlignment="Center" HorizontalSnapPointsType="MandatorySingle" HorizontalScrollBarVisibility="Hidden" Margin="{TemplateBinding Padding}" Template="{StaticResource ScrollViewerScrollBarlessTemplate}" VerticalSnapPointsType="None" VerticalScrollBarVisibility="Disabled" VerticalScrollMode="Disabled" VerticalContentAlignment="Stretch" ZoomMode="Disabled"
                                          ViewChanging="ScrollViewer_ViewChanging" DirectManipulationStarted="ScrollViewer_DirectManipulationStarted" >
                                <PivotPanel x:Name="Panel" VerticalAlignment="Stretch">
                                    <Grid x:Name="PivotLayoutElement">
                                        <Grid.ColumnDefinitions>
                                            <ColumnDefinition Width="Auto"/>
                                            <ColumnDefinition Width="*"/>
                                            <ColumnDefinition Width="Auto"/>
                                        </Grid.ColumnDefinitions>
                                        <Grid.RowDefinitions>
                                            <RowDefinition Height="Auto"/>
                                            <RowDefinition Height="*"/>
                                        </Grid.RowDefinitions>
                                        <Grid.RenderTransform>
                                            <CompositeTransform x:Name="PivotLayoutElementTranslateTransform"/>
                                        </Grid.RenderTransform>
                                        <!--<ContentPresenter x:Name="LeftHeaderPresenter" ContentTemplate="{TemplateBinding LeftHeaderTemplate}" Content="{TemplateBinding LeftHeader}" HorizontalAlignment="Stretch" VerticalAlignment="Stretch"/>-->
                                        <ContentControl x:Name="HeaderClipper" Grid.Column="1" HorizontalContentAlignment="Stretch" UseSystemFocusVisuals="True" Visibility="Collapsed">
                                            <ContentControl.Clip>
                                                <RectangleGeometry x:Name="HeaderClipperGeometry"/>
                                            </ContentControl.Clip>
                                            <Grid Background="Transparent">
                                                <PivotHeaderPanel x:Name="StaticHeader" Visibility="Collapsed"/>
                                                <PivotHeaderPanel x:Name="Header">
                                                    <PivotHeaderPanel.RenderTransform>
                                                        <TransformGroup>
                                                            <CompositeTransform x:Name="HeaderTranslateTransform"/>
                                                            <CompositeTransform x:Name="HeaderOffsetTranslateTransform"/>
                                                        </TransformGroup>
                                                    </PivotHeaderPanel.RenderTransform>
                                                </PivotHeaderPanel>
                                            </Grid>
                                        </ContentControl>
                                        <!--<Button x:Name="PreviousButton" Background="Transparent" Grid.Column="1" HorizontalAlignment="Left" Height="36" IsTabStop="False" IsEnabled="False" Margin="{ThemeResource PivotNavButtonMargin}" Opacity="0" Template="{StaticResource PreviousTemplate}" UseSystemFocusVisuals="False" VerticalAlignment="Top" Width="20"/>
                                            <Button x:Name="NextButton" Background="Transparent" Grid.Column="1" HorizontalAlignment="Right" Height="36" IsTabStop="False" IsEnabled="False" Margin="{ThemeResource PivotNavButtonMargin}" Opacity="0" Template="{StaticResource NextTemplate}" UseSystemFocusVisuals="False" VerticalAlignment="Top" Width="20"/>
                                        <ContentPresenter x:Name="RightHeaderPresenter" ContentTemplate="{TemplateBinding RightHeaderTemplate}" Content="{TemplateBinding RightHeader}" Grid.Column="2" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" />-->
                                        <ItemsPresenter x:Name="PivotItemPresenter" Grid.ColumnSpan="3" Grid.Row="1">
                                            <ItemsPresenter.RenderTransform>
                                                <TransformGroup>
                                                    <TranslateTransform x:Name="ItemsPresenterTranslateTransform"/>
                                                    <CompositeTransform x:Name="ItemsPresenterCompositeTransform"/>
                                                </TransformGroup>
                                            </ItemsPresenter.RenderTransform>
                                        </ItemsPresenter>
                                    </Grid>
                                </PivotPanel>
                            </ScrollViewer>
                        </Grid>
                    </Grid>
                </ControlTemplate>
            </Pivot.Template>
        </Pivot>

2、事件操作

1）大致思路是，当手指滑动屏幕时，通过 Pivot 中 ScrollViewer 的 ViewChanging 事件，来横向移动选中 Item 中红色的矩形（Rectangle），当动画结束时，再重置当前的 Rectangle 的位移。

如果单击 ListView 中的 Item，则直接在它的 SelectionChanged 事件中，计算前一个 Rectangle 和新 Rectangle 的相对位置，来播放位移动画。

2） code behind 中的代码：

   public sealed partial class MainPage : Page
    {
        public MainPage()
        {
            this.InitializeComponent();
            this.Loaded += MainPage_Loaded;
        }

        private void MainPage_Loaded(object sender, RoutedEventArgs e)
        {
            this.Loaded -= MainPage_Loaded;

            // 绑定到匿名类型上
            pivot.ItemsSource = listview.ItemsSource = new []{ new { Text = "军事" } , new { Text = "科技" }, new { Text = "国内新闻" },new { Text = "娱乐" }, new { Text = "国际新闻" }, new { Text = "相声" }, new { Text = "体育赛事" },  new { Text = "综艺" } };

            listview.SelectedIndex = 0;            
        }

        #region 横向 Rectangle 的位移
        Rectangle rect_old; // 上一次选中的 Rectangle
        Rectangle rect_current; // 当前选中的 Rectangle
        double posi_previous; // 手指点击屏幕时，记录当前的 pivot 中 ScrollViewer.HorizontalOffset
        ScrollViewer pivot_sv;
        bool IsMoving = false;//手指是否在滑动中
        private void listView_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            if (firstRectInited == false) return;

            // 如果是当前显示项，则显示“下横线”
            for (int i = 0; i < listview.Items.Count; i++)
            {
                if (listview.ContainerFromIndex(i) != null)
                {
                    var grid = (listview.ContainerFromIndex(i) as ListViewItem).ContentTemplateRoot as Grid;
                    var rect = grid.FindName("rect") as Rectangle;
                    (rect.RenderTransform as CompositeTransform).TranslateX = 0;// 重置横向位移为 0

                    if (listview.SelectedIndex == i) // 当前选中项
                    {
                        listview.ScrollIntoView(listview.SelectedItem);//当滑动 pivot 时，如果 ListView选中项不在视图内，则显示
                        rect_old = rect_current;
                        rect_current = rect;
                        if (IsMoving == false) // 非手指划动 pivot
                        {
                            Rect_Slide();
                            listview.IsHitTestVisible = false; // 当“划动动画”在播放的时候，不再接受单击事件
                        }
                    }

                    if (IsMoving)
                        rect.Opacity = listview.SelectedIndex == i ? 1 : 0;//选中项显示下横向，否则隐藏
                }
            }

            IsMoving = false;
        }

        //播放划动动画
        void Rect_Slide()
        {
            if (rect_old != null && rect_current != null)
            {
                // 如果设置 Width 属性，可能会导致列表宽度发生变化，所以这里使用 Scale来缩放下横线
                (rect_old.RenderTransform as CompositeTransform).ScaleX = rect_current.ActualWidth / rect_old.ActualWidth;
                var old_rect = GetBounds(rect_old, listview);
                var new_rect = GetBounds(rect_current, listview);

                // 获取 ListView 单击后，两个 Item之间的距离
                SB_Slide_TransX.KeyFrames[1].Value = new_rect.X - old_rect.X;

                Storyboard.SetTarget(SB_Slide_TransX, rect_old);
                SB_Slide.Begin();
            }
        }

        // 获取子元素相对于父元素的左边
        public Rect GetBounds(FrameworkElement childElement, FrameworkElement parentElement)
        {
            GeneralTransform transform = childElement.TransformToVisual(parentElement);
            return transform.TransformBounds(new Rect(0, 0, childElement.ActualWidth, childElement.ActualHeight));
        }

        // 滑动动画结束时，重置参数
        private void SB_Slide_Completed(object sender, object e)
        {
            listview.IsHitTestVisible = true;
            rect_old.Opacity = 0;
            (rect_old.RenderTransform as CompositeTransform).ScaleX = 1;
            rect_current.Opacity = 1;
            SB_Slide.Stop();
        }

        // 手指横向移动 Pivot 时，更改下横向的位移
        private void ScrollViewer_ViewChanging(object sender, ScrollViewerViewChangingEventArgs e)
        {
            if (IsMoving && rect_current != null && pivot_sv != null)
                (rect_current.RenderTransform as CompositeTransform).TranslateX = (pivot_sv.HorizontalOffset - posi_previous) / pivot_sv.ActualWidth * rect_current.ActualWidth;
        }

        // 手指开始触摸屏幕时
        private void ScrollViewer_DirectManipulationStarted(object sender, object e)
        {
            IsMoving = true;
            pivot_sv = sender as ScrollViewer;
            posi_previous = pivot_sv.HorizontalOffset;
        }

        // 查找第一个 Rectangle
        bool firstRectInited = false;
        private void rect_Loaded(object sender, RoutedEventArgs e)
        {
            var r = sender as Rectangle;
            r.Loaded -= rect_Loaded;

            if (!firstRectInited  && listview.ContainerFromIndex(0) != null)
            {
                var grid = (listview.ContainerFromIndex(0) as ListViewItem).ContentTemplateRoot as Grid;
                rect_current = grid.FindName("rect") as Rectangle;
                rect_current.Opacity = 1;
                firstRectInited = true;
            }
        }
        #endregion
        
    }

 demo 工程源码