在写一个看新闻软件的时候，用到了SemanticZoom控件，遇到了一些问题，比如如何根据首字母分类，以及放大视图中有数据的和没数据的通过背景色或前景色区分，幸运的是，all solved。
先来个效果图
![[UWP] 使用SemanticZoom控件](https://image.shishitao.com:8440/aHR0cHM6Ly9iYnNtYXguaWthZmFuLmNvbS9zdGF0aWMvTDNCeWIzaDVMMmgwZEhCekwybHRZV2RsY3pJd01UVXVZMjVpYkc5bmN5NWpiMjB2WW14dlp5ODJOalUwTlRrdk1qQXhOakF5THpZMk5UUTFPUzB5TURFMk1ESXhOVEUzTVRFek5ESTVPQzB4TlRFeU5qZzFOekEyTG1kcFpnPT0uanBn.jpg?w=700 "[UWP] 使用SemanticZoom控件")
主要是参考了msdn的一篇博客，地址已经放在参考链接里了。
首先是一个SemanticZoom控件，这个控件有ZoomedInView和ZoomedOutView两种视图。
ZoomedOutView视图就是这个
![[UWP] 使用SemanticZoom控件](https://image.shishitao.com:8440/aHR0cHM6Ly9iYnNtYXguaWthZmFuLmNvbS9zdGF0aWMvTDNCeWIzaDVMMmgwZEhCekwybHRZV2RsY3pJd01UVXVZMjVpYkc5bmN5NWpiMjB2WW14dlp5ODJOalUwTlRrdk1qQXhOakF5THpZMk5UUTFPUzB5TURFMk1ESXhOVEUzTVRVeU5Ua3dOeTB4TkRNNE1EZ3pNRFV4TG5CdVp3PT0uanBn.jpg?w=700 "[UWP] 使用SemanticZoom控件")
而ZoomedInView视图就是一个带有列表头的列表的样子，还是上个图好了，我个人不喜欢看一大段的纯文字
![[UWP] 使用SemanticZoom控件](https://image.shishitao.com:8440/aHR0cHM6Ly9iYnNtYXguaWthZmFuLmNvbS9zdGF0aWMvTDNCeWIzaDVMMmgwZEhCekwybHRZV2RsY3pJd01UVXVZMjVpYkc5bmN5NWpiMjB2WW14dlp5ODJOalUwTlRrdk1qQXhOakF5THpZMk5UUTFPUzB5TURFMk1ESXhOVEUzTVRnME56a3dOeTAzTWpjMk1Ea3lOREl1Y0c1bi5qcGc%3D.jpg?w=700 "[UWP] 使用SemanticZoom控件")
首先弄个Model，这里叫Picture
public class Picture
{
public string ImageUri { get; set; }
public string Title { get; set; }
}
然后再加个ViewModel，叫MainPageViewModel，类里写一个数据集合和加载数据的方法
public ObservableCollection<AlphaKeyGroup<Picture>> AllPictures { get; set; }
关于加载数据的方法，很显然，我们要把数据按照Title的首字母分组，按首字母分组说实话我不会，然后我在msdn找到了一个类叫AlphaKeyGroup，这个类可以用来按首字母分组
public class AlphaKeyGroup<T> : List<T>
{
/// <summary>
/// The delegate that is used to get the key information.
/// </summary>
/// <param name="item">An object of type T</param>
/// <returns>The key value to use for this object</returns>
public delegate string GetKeyDelegate(T item); /// <summary>
/// The Key of this group.
/// </summary>
public string Key { get; private set; } /// <summary>
/// Public constructor.
/// </summary>
/// <param name="key">The key for this group.</param>
public AlphaKeyGroup(string key)
{
Key = key;
} /// <summary>
/// Create a list of AlphaGroup<T> with keys set by a SortedLocaleGrouping.
/// </summary>
/// <param name="slg">The </param>
/// <returns>Theitems source for a LongListSelector</returns>
private static List<AlphaKeyGroup<T>> CreateGroups(SortedLocaleGrouping slg)
{
List<AlphaKeyGroup<T>> list = new List<AlphaKeyGroup<T>>(); foreach (string key in slg.GroupDisplayNames)
{
list.Add(new AlphaKeyGroup<T>(key));
} return list;
} /// <summary>
/// Create a list of AlphaGroup<T> with keys set by a SortedLocaleGrouping.
/// </summary>
/// <param name="items">The items to place in the groups.</param>
/// <param name="ci">The CultureInfo to group and sort by.</param>
/// <param name="getKey">A delegate to get the key from an item.</param>
/// <param name="sort">Will sort the data if true.</param>
/// <returns>An items source for a LongListSelector</returns>
public static List<AlphaKeyGroup<T>> CreateGroups(IEnumerable<T> items, CultureInfo ci, GetKeyDelegate getKey, bool sort)
{
SortedLocaleGrouping slg = new SortedLocaleGrouping(ci);
List<AlphaKeyGroup<T>> list = CreateGroups(slg); foreach (T item in items)
{
int index = ;
if (slg.SupportsPhonetics)
{
//check if your database has yomi string for item
//if it does not, then do you want to generate Yomi or ask the user for this item.
//index = slg.GetGroupIndex(getKey(Yomiof(item)));
}
else
{
index = slg.GetGroupIndex(getKey(item));
}
if (index >= && index < list.Count)
{
list[index].Add(item);
}
} if (sort)
{
foreach (AlphaKeyGroup<T> group in list)
{
group.Sort((c0, c1) => { return ci.CompareInfo.Compare(getKey(c0), getKey(c1)); });
}
} return list;
} }
AlphaKeyGroup
使用的时候这样，CreateGroups方法有三个参数，第一个是要分组的数据，第二个参数是分组的方法，第三个参数是是否排序，该方法返回了一个List<AlphaKeyGroup<Picture>>类型的数据，
//按拼音分组
List<AlphaKeyGroup<Picture>> groupData = AlphaKeyGroup<Picture>.CreateGroups(
picturesList, (Picture s) => s.Title, true); foreach (var item in groupData)
{
AllPictures.Add(item);
}
当然首先要在picturesList里加一些示例数据
picturesList.Add(new Picture { ImageUri = "http://t3.gstatic.com/images?q=tbn:ANd9GcQ_ih-aN2gxUz435mPC733IFDNhk1vqFQSVKshWMHEtzxKfKqbs", Title = "OOO" });
picturesList.Add(new Picture { ImageUri = "http://4.bp.blogspot.com/-v4cAAv3ViZk/T3w0jsZocUI/AAAAAAAACE0/l21tSjKnSUI/s640/Cool_facebook_timeline_covers+%252814%2529.jpg", Title = "ZZZ" });
picturesList.Add(new Picture { ImageUri = "http://t3.gstatic.com/images?q=tbn:ANd9GcTv1Kx5oic3I39RTIoAMrFOKQxaIKNtXSNSr5B5bUGsX5mRMMBl_Q", Title = "DDD" });
picturesList.Add(new Picture { ImageUri = "http://t0.gstatic.com/images?q=tbn:ANd9GcRFzgy_qOhDZ3GAQVxIOi1oTg8VSToo8hX_0cxoD6ZqUW9K-r9p", Title = "BBB" });
然后开始写UI部分，当然要先把Page的DataContext设置到MainPageViewModel的实例，比较简单这里就不写了， 再在Xaml里加上一个CollectionViewSource，用来给SemanticZoom提供数据，ItemsPath填的是集合属性的名字，至于为什么填这个，看看AlphaKeyGroup类的源码就知道了，里面有个List<T>类型的 InternalList，数据就是被存在这里的，IsSourceGrouped意思是要把AllPictures分组
<CollectionViewSource x:Key="CollectionViewSource" IsSourceGrouped="True"
ItemsPath="InternalList"
Source="{Binding AllPictures}"/>
开始写SemanticZoom
<SemanticZoom >
<SemanticZoom.Style>
<Style TargetType="SemanticZoom">
<Setter Property="HorizontalContentAlignment" Value="Stretch"/>
</Style>
</SemanticZoom.Style>
<!--数据列表-->
<SemanticZoom.ZoomedInView>
<ListView ItemsSource="{Binding Source={StaticResource CollectionViewSource}}"
SelectionMode="None"
ShowsScrollingPlaceholders="True"
IsItemClickEnabled="True"
ItemClick="ListView_ItemClick">
<ListView.ItemTemplate>
<DataTemplate>
<Grid Padding="0,8"
BorderThickness="{StaticResource BorderThickness}"
BorderBrush="{StaticResource BorderBrush}" >
<Grid.ColumnDefinitions>
<ColumnDefinition Width="2*"/>
<ColumnDefinition Width="3*"/>
<ColumnDefinition Width="Auto"/>
</Grid.ColumnDefinitions>
<Image Grid.Column="0" Stretch="Fill" HorizontalAlignment="Left" >
<Image.Source>
<BitmapImage UriSource="{Binding imageUri}"/>
</Image.Source>
</Image>
<Grid Grid.Column="1" Margin="5,2">
<TextBlock Text="{Binding Title}" VerticalAlignment="Top" TextWrapping="Wrap"/>
</Grid>
</Grid>
</DataTemplate>
</ListView.ItemTemplate>
<ListView.ItemContainerStyle>
<Style TargetType="ListViewItem">
<Setter Property="HorizontalContentAlignment" Value="Stretch"/>
<Setter Property="Margin" Value="0"/>
</Style>
</ListView.ItemContainerStyle>
<!--列表头-->
<ListView.GroupStyle>
<GroupStyle HidesIfEmpty="True" >
<GroupStyle.HeaderTemplate>
<DataTemplate>
<TextBlock Text="{Binding Key}" FontSize="25" Foreground="Red"/>
</DataTemplate>
</GroupStyle.HeaderTemplate>
</GroupStyle>
</ListView.GroupStyle>
</ListView>
</SemanticZoom.ZoomedInView>
<!--排序列表-->
<SemanticZoom.ZoomedOutView>
<GridView ItemsSource="{Binding Source={StaticResource CollectionViewSource},Path=CollectionGroups}">
<GridView.ItemsPanel>
<ItemsPanelTemplate>
<WrapGrid MaximumRowsOrColumns="4" VerticalAlignment="Top" Orientation="Horizontal"/>
</ItemsPanelTemplate>
</GridView.ItemsPanel>
<GridView.ItemTemplate>
<DataTemplate>
<Border Background="{Binding Converter={StaticResource BackgroundConverter}}">
<TextBlock Text="{Binding Group.Key}" HorizontalAlignment="Center"
VerticalAlignment="Center"
Foreground="{Binding Converter={StaticResource ForegroundConverter}}"/>
</Border>
</DataTemplate>
</GridView.ItemTemplate> <GridView.ItemContainerStyle>
<Style TargetType="GridViewItem">
<Setter Property="HorizontalAlignment" Value="Center"/>
<Setter Property="HorizontalContentAlignment" Value="Stretch"/>
<Setter Property="VerticalAlignment" Value="Center"/>
<Setter Property="VerticalContentAlignment" Value="Stretch"/>
</Style>
</GridView.ItemContainerStyle>
<GridView.Template>
<ControlTemplate>
<ScrollViewer ScrollViewer.VerticalScrollMode="Enabled">
<Viewbox Stretch="Uniform" Margin="8" VerticalAlignment="Top"
ScrollViewer.VerticalScrollMode="Enabled" StretchDirection="Both" >
<ItemsPresenter />
</Viewbox>
</ScrollViewer>
</ControlTemplate>
</GridView.Template>
</GridView>
</SemanticZoom.ZoomedOutView>
</SemanticZoom>
SemanticZoom
注意到排序列表的GridView.ItemTemplate ,用到了两个Converter，即BackgroundConverter和ForegroundConverter
<Border Background="{Binding Converter={StaticResource BackgroundConverter}}">
<TextBlock Text="{Binding Group.Key}" HorizontalAlignment="Center"
VerticalAlignment="Center"
Foreground="{Binding Converter={StaticResource ForegroundConverter}}"/>
</Border>
我一直想实现在ZoomedOutView里那种有数据的和没数据的用颜色区分的功能，自己写Converter没写出来，然后发现了这个
这两个Converter是系统自带的，用的时候设置好Enabled和Disabled的颜色，有数据的时候显示Enabled的颜色，没有就显示Disabled的颜色
<JumpListItemBackgroundConverter x:Key="BackgroundConverter" Enabled="Red"
Disabled="Transparent"/>
<JumpListItemBackgroundConverter x:Key="ForegroundConverter" Enabled="White" Disabled="Black"/>
附上demo
还有一个待解决的问题，在ZoomOutView中如何将无数据的项变成不可点击状态？既然那两个Converter能知道哪个是没数据的，说明一定有办法，Pending……
参考链接