WPF自定义控件之列表滑动特效 PowerListBox

来源:转载


列表控件是应用程序中常见的控件之一,对其做一些绚丽的视觉特效,可以让软件增色不少。

本人网上看过一个视频,是windows phone 7系统上的一个App的列表滚动效果,效果非常炫

现在在WPF上用ListBox重现此效果

首先我们来分析一下,这种实时滚动的效果是如何实现的,有哪些步骤

1.获取ListBox模板内部的ScrollViewer和ItemsPanel

2.监听ScrollViewer的滚动事件ScrollChange, 获取ItemsPanel的布局方向

3.在滚动事件发生时计算当前可视化区域中的第一项和最后一项,这是此滑动效果的核心算法所在,算法的效率决定了滑动效果的流畅性

4.根据滚动的方向和布局的方向依次对指定的Item做动画效果。

 

重写ListBoxItem

public class PowerListBoxItem : ListBoxItem

声明构造函数并赋初始值

 static PowerListBoxItem() { DefaultStyleKeyProperty.OverrideMetadata(typeof(PowerListBoxItem), new FrameworkPropertyMetadata(typeof(PowerListBoxItem))); } public PowerListBoxItem() { ItemStatus = ItemStatusEnum.Out; //默认Item状态为"退出" duration = new TimeSpan(0, 0, 0, 0, 300); //easingFunction = new PowerEase() { EasingMode = EasingMode.EaseIn, Power = 4 }; easingFunction = new CircleEase() { EasingMode = EasingMode.EaseInOut }; }

定义PowerListBoxItem的成员属性

 /// <summary> /// PowerListBoxItem模板中的内容控件 /// </summary> private FrameworkElement contentControl; /// <summary> /// 动画间隔时间 /// </summary> private TimeSpan duration; private IEasingFunction easingFunction; //动画缓动函数 private IList<AnimationModel> DownInAnimationList; //定义Item从下往上运动的动画内容集合 private IList<AnimationModel> UpInAnimationList; //定义Item从上往下运动的动画内容集合 /// <summary> /// 项枚举状态,指明Item运动的方向 /// </summary> internal enum ItemStatusEnum { UpIn, DownIn, RightIn, LeftIn, Out } private ItemStatusEnum _itemStatus; internal ItemStatusEnum ItemStatus { get { return _itemStatus; } set { if (_itemStatus == value) //状态相同时不再刷新状态 return; _itemStatus = value; PlayAnimation(); //执行动画 } }

重写ListBox 

 [StyleTypedProperty(Property = "ItemContainerStyle", StyleTargetType = typeof(PowerListBoxItem))] public class PowerListBox : ListBox { static PowerListBox() { DefaultStyleKeyProperty.OverrideMetadata(typeof(PowerListBox), new FrameworkPropertyMetadata(typeof(PowerListBox))); } public PowerListBox() { DefaultStyleKey = typeof(PowerListBox); } } protected override DependencyObject GetContainerForItemOverride() { return new PowerListBoxItem(); //指定PowerListBox的项为PowerListBoxItem } protected override bool IsItemItsOwnContainerOverride(object item) { return item is PowerListBoxItem; }

定义PowerList的成员属性

 /// <summary> /// ListBox内部的滚动试图 /// </summary> private ScrollViewer _scrollView; /// <summary> /// 容器的布局方向 /// </summary> private Orientation _panelOrientation; /// <summary> /// 当前可视化视图的第一项 /// </summary> private int firstVisibleIndex; /// <summary> /// 当前可视化视图的最后一项 /// </summary> private int lastVisibleIndex; /// <summary> /// 上次滚动时可视化视图的第一项 /// </summary> private int oldFirstVisibleIndex; /// <summary> /// 上次滚动时可视化视图的最后一项 /// </summary> private int oldLastVisibleIndex; /// <summary> /// 标识,是否已找到第一项 /// </summary> private bool isFindFirst; /// <summary> /// 当前累计已遍历过的Item高度或宽度的值,用于寻找第一项和最后一项 /// </summary> private double cumulativeNum;

获取PowerListBox内部的ScrollViewer和ItemsPanel,并监听滚动事件

 public override void OnApplyTemplate() { _scrollView = VisualHelper.FindFirstVisualChild<ScrollViewer>(this); if (_scrollView == null) return; _scrollView.CanContentScroll = false; //不按Item为步长滚动 _scrollView.PanningMode = PanningMode.Both; _scrollView.ScrollChanged += _scrollView_ScrollChanged; //监听滚动事件 var panel = this.ItemsPanel.LoadContent(); //读取布局容器 if (panel is StackPanel) _panelOrientation = (panel as StackPanel).Orientation; else if (panel is VirtualizingPanel) _panelOrientation = (panel as VirtualizingStackPanel).Orientation; base.OnApplyTemplate(); } private void _scrollView_ScrollChanged(object sender, ScrollChangedEventArgs e) { //Console.WriteLine("itemCount:{0} VerticalOffset:{1} ViewportHeight:{2} ContentVerticalOffset:{3}", //Items.Count, _scrollView.VerticalOffset, _scrollView.ViewportHeight, _scrollView.ContentVerticalOffset);
//每次滚动时都计算当前可视化区域的首尾项 calculationIndex(); refreshItemStatus(); //刷新Item状态 }

计算可视化区域的第一项和最后一项

 private void calculationIndex() { oldFirstVisibleIndex = firstVisibleIndex; oldLastVisibleIndex = lastVisibleIndex; isFindFirst = false; if (_panelOrientation == Orientation.Vertical) { cumulativeNum = 0.0; for (int i = 0; i < Items.Count; i++) { var _item = this.ItemContainerGenerator.ContainerFromIndex(i) as PowerListBoxItem; cumulativeNum += _item.ActualHeight + _item.Margin.Top + _item.Margin.Bottom; //遍历Items, 累计Item高度,第一个超过滚动条垂直偏移量的Item就是当前可视化区域中的第一项 if (!isFindFirst && cumulativeNum >= _scrollView.VerticalOffset) { firstVisibleIndex = i; isFindFirst = true; } //累计Item高度超过滚动条垂直偏移量和滚动区显示高度的和,就是当前可视化区域的最后一项 if (cumulativeNum >= (_scrollView.VerticalOffset + _scrollView.ViewportHeight)) { lastVisibleIndex = i; break; } } } }

确定当前可视化区域的首尾项之后,刷新Item的状态

 private void refreshItemStatus() { Console.WriteLine("firstIndex: {0} lastIndex: {1} oldFirstIndex: {2} oldLastIndex: {3} {4}", firstVisibleIndex, lastVisibleIndex, oldFirstVisibleIndex, oldLastVisibleIndex, firstVisibleIndex > oldFirstVisibleIndex ? "Down In" : firstVisibleIndex < oldFirstVisibleIndex ? "UpIn" : "normal"); if ((firstVisibleIndex == oldFirstVisibleIndex && lastVisibleIndex == oldLastVisibleIndex) || oldFirstVisibleIndex == 0 && oldLastVisibleIndex == 0) return; //Console.WriteLine("firstVisibleIndex:{0} oldFirstVisibleIndex:{1}", firstVisibleIndex, oldFirstVisibleIndex); //判断滚动方向 if (firstVisibleIndex > oldFirstVisibleIndex) { //垂直 滚动条往下,内容网上 //水平 滚动条往右,内容往左 for (var i = oldLastVisibleIndex; i <= lastVisibleIndex; i++) { var _item = this.ItemContainerGenerator.ContainerFromIndex(i) as PowerListBoxItem; _item.ItemStatus = _panelOrientation == Orientation.Vertical ? PowerListBoxItem.ItemStatusEnum.DownIn : PowerListBoxItem.ItemStatusEnum.RightIn; //Console.WriteLine("DownIn {0}", i); } } else if (lastVisibleIndex < oldLastVisibleIndex) { //垂直 滚动条往上,内容网下 //水平 滚动条往左,内容往右 for (var i = oldFirstVisibleIndex; i >= firstVisibleIndex; i--) { var _item = this.ItemContainerGenerator.ContainerFromIndex(i) as PowerListBoxItem; _item.ItemStatus = _panelOrientation == Orientation.Vertical ? PowerListBoxItem.ItemStatusEnum.UpIn : PowerListBoxItem.ItemStatusEnum.LeftIn; //Console.WriteLine("UpIn {0}", i); } } }

定义PowerListBox的默认外观

 <Style TargetType="{x:Type local:PowerListBox}"> <Setter Property="Background" Value="Transparent"/> <Setter Property="BorderThickness" Value="0"/> <Setter Property="BorderBrush" Value="Transparent"/> <Setter Property="Padding" Value="0"/> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="{x:Type local:PowerListBox}"> <ScrollViewer x:Name="ScrollViewer" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Foreground="{TemplateBinding Foreground}" Padding="{TemplateBinding Padding}"> <ItemsPresenter/> </ScrollViewer> </ControlTemplate> </Setter.Value> </Setter> </Style> <Style TargetType="{x:Type local:PowerListBoxItem}"> <Setter Property="Background" Value="Transparent"/> <Setter Property="BorderThickness" Value="0"/> <Setter Property="BorderBrush" Value="Transparent"/> <Setter Property="Padding" Value="0"/> <Setter Property="HorizontalContentAlignment" Value="Stretch"/> <Setter Property="VerticalContentAlignment" Value="Stretch"/> <Setter Property="Margin" Value="0,8"/> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="{x:Type local:PowerListBoxItem}"> <Border x:Name="LayoutRoot" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" HorizontalAlignment="{TemplateBinding HorizontalAlignment}" VerticalAlignment="{TemplateBinding VerticalAlignment}"> <ContentControl x:Name="ContentContainer" ContentTemplate="{TemplateBinding ContentTemplate}" Content="{TemplateBinding Content}" Foreground="{TemplateBinding Foreground}" HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}" Margin="{TemplateBinding Padding}" VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}" RenderTransformOrigin="0.5,0.5"> <ContentControl.RenderTransform> <TransformGroup> <TranslateTransform/> </TransformGroup> </ContentControl.RenderTransform> </ContentControl> </Border> </ControlTemplate> </Setter.Value> </Setter> </Style>

调用 PowerListBox

 <local:PowerListBox ItemsSource="{Binding TestModelList}" > <local:PowerListBox.ItemTemplate> <DataTemplate> <Grid> <Grid.ColumnDefinitions> <ColumnDefinition Width="150"/> <ColumnDefinition/> </Grid.ColumnDefinitions> <TextBlock Text="{Binding Name}" VerticalAlignment="Center" FontSize="20"/> <Border Width="100" Height="120" Background="#FF4949D3" Grid.Column="1" HorizontalAlignment="Left"> <TextBlock Text="{Binding Id}" VerticalAlignment="Center" HorizontalAlignment="Center" FontSize="40" Foreground="Black"/> </Border> </Grid> </DataTemplate> </local:PowerListBox.ItemTemplate></local:PowerListBox>

效果图

 

 由于gif录制帧数的原因,效果图不是很流畅,但实际运行情况动画效果是非常流畅的



分享给朋友:
您可能感兴趣的文章:
随机阅读: