WPF 嵌套列表性能问题

Question

下面的代码与第二个组合框存在性能问题...当我更改第一个组合框然后打开第二个组合框时它很好。但是，如果我第二次更改第一个组合框并尝试打开 第二个组合框有很多性能问题....

公共部分类 MainWindow ：窗口， INotifyPropertyChanged {

    public MainWindow()
    {
        InitializeComponent();

        Books = new List<Book>();
        Books.Add(new Book("Abc"));
        Books.Add(new Book("Cde"));
        Books.Add(new Book("Xyz"));
        Books.Add(new Book("Min"));
        this.DataContext = this;
        SelectedBook = Books[0];
    }

    Book _selctedBook;
    public Book SelectedBook
    {
        get { return _selctedBook; }
        set
        {
            _selctedBook = value;
            raiseChange("SelectedBook");
        }
    }

    List<Book> _books = new List<Book>();
    public List<Book> Books { get { return _books; } set { _books = value; raiseChange("Books"); } }

    void raiseChange(string name)
    {
        if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(name));
    }

    public event PropertyChangedEventHandler PropertyChanged;

}

public class Book : INotifyPropertyChanged
{
    public string Name { get; set; }
    public ObservableCollection<BookType> BookTypes { get; set; }

    BookType _selectedBookType;
    public BookType SelectedBookType { get { return _selectedBookType; } set { _selectedBookType = value; raiseChange("SelectedBookType"); } }

    public Book(string name)
    {
        Name = name;
        BookTypes = new ObservableCollection<BookType>();


        if (name == "Abc")
            BookTypes.Add(BookType.Action);

        BookTypes.Add(BookType.Comedy);
        BookTypes.Add(BookType.Drama);
        BookTypes.Add(BookType.Friction);
        BookTypes.Add(BookType.Thriller);

        SelectedBookType = BookTypes[0];
    }


      void raiseChange(string name)
    {
        if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(name));
    }

    public event PropertyChangedEventHandler PropertyChanged;
}

public enum BookType
{
    Friction,
    Drama,
    Action,
    Thriller,
    Comedy,
}

<Grid>
    <Grid.Resources>
        <DataTemplate x:Key="ItemTemplate2">
            <StackPanel>
                <TextBlock Text="{Binding .}"/>
            </StackPanel>
        </DataTemplate>
    </Grid.Resources>
    <Grid.RowDefinitions>
        <RowDefinition></RowDefinition>
        <RowDefinition></RowDefinition>
    </Grid.RowDefinitions>
        <ComboBox Height="23" Name="comboBox1"   Grid.Row="0"
              SelectedItem="{Binding SelectedBook,Mode=TwoWay}"
              ItemsSource="{Binding Books}" 
              DisplayMemberPath="Name" 
               Width="386" />
    <ComboBox Height="23"  Name="comboBox2" Grid.Row="1" DataContext="{Binding SelectedItem, ElementName=comboBox1}" 
              ItemsSource="{Binding BookTypes}"  SelectedItem="{Binding SelectedBookType,Mode=TwoWay}" 
               Width="386" ItemTemplate="{DynamicResource ItemTemplate2}">

    </ComboBox>

</Grid>

Answer 1

我怀疑这与每次第一个框更改时重新绑定第二个枚举有关。

相反，将第二个框绑定一次；

        <Grid.Resources>
            <DataTemplate x:Key="ItemTemplate2">
                <StackPanel>
                    <TextBlock Text="{Binding .}"/>
                </StackPanel>
            </DataTemplate>

            <ObjectDataProvider x:Key="BookTypeEnum" MethodName="GetValues" ObjectType="{x:Type System:Enum}">
                <ObjectDataProvider.MethodParameters>
                    <x:Type TypeName="local:BookType"/>
                </ObjectDataProvider.MethodParameters>
            </ObjectDataProvider>

        </Grid.Resources>


  <ComboBox Height="23"  Name="comboBox2" Grid.Row="1" DataContext="{Binding SelectedItem, ElementName=comboBox1}" 
          ItemsSource="{Binding Source={StaticResource BookTypeEnum}}"  SelectedItem="{Binding SelectedBookType,Mode=TwoWay}" 
           Width="386" />