最近在做列表头部的Carousel展示，Carousel使用的是FlipView展示，另外使用ListBox显示当前页，如下图
我们先设置一个绑定的数据源
public class GlobalResource : INotifyPropertyChanged
{
private ObservableCollection<string> _items;
public ObservableCollection<string> Items
{
get
{
return _items = _items ?? new ObservableCollection<string>
{
Guid.NewGuid().ToString(),
Guid.NewGuid().ToString(),
Guid.NewGuid().ToString(),
Guid.NewGuid().ToString(),
};
}
set
{
_items = value;
OnPropertyChanged(nameof(Items));
}
} public event PropertyChangedEventHandler PropertyChanged; [NotifyPropertyChangedInvocator]
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
Items作为数据源绑定在FlipView和ListBox上，布局代码如下
<Page x:Class="App1.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="using:App1"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"> <Page.Resources>
<local:GlobalResource x:Key="GlobalResource" />
<Style x:Key="DotListBoxItemStyle" TargetType="ListBoxItem">
<Setter Property="Background" Value="Transparent" />
<Setter Property="TabNavigation" Value="Local" />
<Setter Property="Padding" Value="12,11,12,13" />
<Setter Property="HorizontalContentAlignment" Value="Left" />
<Setter Property="Margin" Value="5" />
<Setter Property="UseSystemFocusVisuals" Value="True" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ListBoxItem">
<Grid x:Name="LayoutRoot"
Background="{TemplateBinding Background}"
BorderThickness="{TemplateBinding BorderThickness}">
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CommonStates">
<VisualState x:Name="Normal" />
<VisualState x:Name="Disabled" />
<VisualState x:Name="PointerOver" />
<VisualState x:Name="Pressed" />
<VisualState x:Name="Selected">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="dotEllipse" Storyboard.TargetProperty="Fill">
<DiscreteObjectKeyFrame KeyTime="0" Value="Blue" />
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="SelectedUnfocused">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="dotEllipse" Storyboard.TargetProperty="Fill">
<DiscreteObjectKeyFrame KeyTime="0" Value="Blue" />
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="SelectedPointerOver">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="dotEllipse" Storyboard.TargetProperty="Fill">
<DiscreteObjectKeyFrame KeyTime="0" Value="Blue" />
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="SelectedPressed">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="dotEllipse" Storyboard.TargetProperty="Fill">
<DiscreteObjectKeyFrame KeyTime="0" Value="Blue" />
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<Ellipse x:Name="dotEllipse"
Width="10"
Height="10"
Control.IsTemplateFocusTarget="True"
Fill="White" />
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Page.Resources> <Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
<ListView>
<ListView.Header>
<Grid Height="200">
<FlipView x:Name="flipView" ItemsSource="{Binding Source={StaticResource GlobalResource}, Path=Items}">
<FlipView.ItemTemplate>
<DataTemplate>
<Rectangle Height="200"
Margin="5,0"
Fill="Red" />
</DataTemplate>
</FlipView.ItemTemplate>
</FlipView> <ListBox x:Name="listBox"
Margin="0,0,0,8"
HorizontalAlignment="Center"
VerticalAlignment="Bottom"
Background="Transparent"
ItemContainerStyle="{StaticResource DotListBoxItemStyle}"
ItemsSource="{Binding Source={StaticResource GlobalResource},
Path=Items}"
SelectedIndex="{Binding ElementName=flipView,
Path=SelectedIndex,
Mode=TwoWay}">
<ListBox.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel HorizontalAlignment="Center" Orientation="Horizontal" />
</ItemsPanelTemplate>
</ListBox.ItemsPanel> <ListBox.ItemTemplate>
<DataTemplate>
<Ellipse Width="10"
Height="10"
Fill="White" />
</DataTemplate>
</ListBox.ItemTemplate> </ListBox>
</Grid> </ListView.Header>
<Button Click="ButtonBase_OnClick">test</Button>
</ListView>
</Grid>
</Page>
MainPage.xaml
一切正常显示
问题：
下面我们需要修改数据源
var globalResource = (GlobalResource) Resources["GlobalResource"];
globalResource.Items.Clear();
for (var i = ; i < ; i++)
{
globalResource.Items.Add(Guid.NewGuid().ToString());
} Debug.WriteLine("flipView.SelectedIndex = {0}", flipView.SelectedIndex);
Debug.WriteLine("listBox.SelectedIndex = {0}", listBox.SelectedIndex);
虽然数据源变了，但是并没有选中当前页（第一个点不为蓝色），通过输出信息发现SelectedIndex都是0，并没有改变
跟踪发现，调用ObservableCollection.Clear方法的时候SelectedIndex都被设为了-1，Add第一个的时候SelectedIndex被置为0，数据源和相关数据都改变了，不知道为什么样式没有出发（VisualState）由于不知道ListView内部实现，我们无法得知具体原因是啥
解决：
对于上面问题，可以通过下面方式解决
重新改变SelectedIndex让ListBox更新样式
var globalResource = (GlobalResource) Resources["GlobalResource"];
globalResource.Items.Clear();
for (var i = ; i < ; i++)
{
globalResource.Items.Add(Guid.NewGuid().ToString());
} flipView.SelectedIndex = -;
flipView.SelectedIndex = ;
Demo: