c# - 如何找到 RibbonComboBox 的子元素

Question

我已经在我的 XAML 中声明了一个 RibbonComboBox。

<RibbonGroup Header="Category">
    <RibbonComboBox Name="cboCategory" Label="Category" HorizontalContentAlignment="Left">
        <RibbonGallery Name="galCategory">
            <RibbonGalleryCategory Name="catCategory" DisplayMemberPath="Text">
            </RibbonGalleryCategory>
        </RibbonGallery>
    </RibbonComboBox>
    <RibbonComboBox Name="cboSubcategory" Label="Subcategory:" HorizontalContentAlignment="Left">
        <RibbonGallery Name="galSubcategory">
            <RibbonGalleryCategory Name="catSubcategory" DisplayMemberPath="Text">
            </RibbonGalleryCategory>
        </RibbonGallery>
    </RibbonComboBox>
</RibbonGroup>

由于我不完全理解的原因，为了操作组合框中的项目，我需要 RibbonComboBox 的一些成员，我需要 RibbonGallery 的其他成员和一些任务需要 RibbonGalleryCategory 的成员。

那么，根据我的 RibbonComboBox 实例，我如何找到子 RibbonGallery 和 RibbonGalleryCategory 元素？没有 Controls 或 Children 属性。

我在网上找到了以下用于查找控件子元素的代码:

protected T GetChildOfType<T>(DependencyObject depObj) where T : DependencyObject
{
    if (depObj == null)
        return null;

    for (int i = 0; i < VisualTreeHelper.GetChildrenCount(depObj); i++)
    {
        var child = VisualTreeHelper.GetChild(depObj, i);
        var result = (child as T) ?? GetChildOfType<T>(child);
        if (result != null)
            return result;
    }
    return null;
}

但是，在编译此代码时，VisualTreeHelper.GetChildrenCount() 在我传递组合框时始终返回 0。因此无法找到控件的子控件。

编辑:

根据名称 VisualTreeHelper，我假设此类是用于查找视觉元素的，并且图库可能不是一个单独的视觉元素。所以我想我需要知道如何遍历不可视的子元素？

Answer 1

我采用了两种不同的方法。一个包含您的嵌套元素，另一个包含一个简单的 ComboBox。按钮填充并读取 ComboBox 和 RibbonGalleryCategory

XAML

  <StackPanel>
            <Button Content="Fill me :)" Width="80" Height="20" Click="FillMe_OnClick"/>
            <Ribbon>
                <RibbonGroup Header="Category">
                    <RibbonComboBox Name="cboCategory" Label="Category" HorizontalContentAlignment="Left">
                        <ComboBoxItem>Item 1</ComboBoxItem>
                        <ComboBoxItem>Item 2</ComboBoxItem>
                        <ComboBoxItem>Item 3</ComboBoxItem>
                        <ComboBoxItem>Item 4</ComboBoxItem>
                    </RibbonComboBox>
                    <RibbonComboBox Name="cboSubcategory" Label="Subcategory:" HorizontalContentAlignment="Left">
                        <RibbonGallery Name="galSubcategory">
                            <RibbonGalleryCategory Name="catSubcategory" DisplayMemberPath="Text">
                            </RibbonGalleryCategory>
                        </RibbonGallery>
                    </RibbonComboBox>
                </RibbonGroup>
            </Ribbon>
            <Button Content="Read me" Width="80" Height="20" Click="ReadMeCat_OnClick"></Button>
            <Button Content="Read me too" Width="80" Height="20" Click="ReadMeCombo_OnClick"></Button>
</StackPanel>

代码隐藏

public MainWindow()
        {

            InitializeComponent();
        }

        private void FillMe_OnClick(object sender, RoutedEventArgs e)
        {
            this.catSubcategory.Items.Add(new { Text = "Hello" });
            this.catSubcategory.Items.Add(new { Text = "World" });
            this.catSubcategory.Items.Add(new { Text = "Hello" });
            this.catSubcategory.Items.Add(new { Text = "Moon" });
        }

        private void ReadMeCat_OnClick(object sender, RoutedEventArgs e)
        {
            var result = catSubcategory.Items.Cast<dynamic>().Aggregate("", (current, xx) => (string) (current + (xx.Text + "\n")));
            MessageBox.Show(result);
        }

        private void ReadMeCombo_OnClick(object sender, RoutedEventArgs e)
        {
            var result = cboCategory.Items.Cast<ComboBoxItem>().Aggregate("", (current, xx) => current + (xx.Content.ToString() + "\n"));
            MessageBox.Show(result);
        }

注意

我认为这不需要太多解释。如果您还需要，请调用 ;)

请注意，这不是应该做的。 WPF 通过绑定(bind)和 MVVM 释放它真正的力量。我也可以给你举个这样的例子。

编辑

是的，你是对的。 ComboBox-Items 将显示但无法选择，除非您使用 RibbonGalleryCategory-Approach。

关于这东西的另一个愚蠢的事情是，RibbonGallery 实际上不是真正的 控件。它只是一个带有 ControlTemplate 的 ItemsControl，VisualTreeHelper 无法找到它。

在我看来，如果您不从一开始就使用 MVVM 和 DataBinding，那么使用该控件会使一切变得更加复杂。

有了 DataBinding，一切都像魅力一样运作。不幸的是，您仍然需要使用 RibbonGallery 和 RibbonGalleryCategory。或者你只是在那里放置一个 Ribbon 风格的普通 ComboBox

EDIT 2 - 一个简单的 MVVM 方法

代码

public partial class MainWindow : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void OnPropertyChanged(string propertyName)
    {
        this.PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }

    public MainWindow()
    {

        InitializeComponent();
        this.Ponies.Add(new Pony() { Id = 0, Color = Brushes.DeepSkyBlue, Name = "Slayer" });
        this.Ponies.Add(new Pony() { Id = 1, Color = Brushes.DeepPink, Name = "Murder" });
        this.Ponies.Add(new Pony() { Id = 2, Color = Brushes.Yellow, Name = "Brutal" });
        this.DataContext = this;
    }

    private ObservableCollection<Pony> _ponies = new ObservableCollection<Pony>();
    private Pony _selectedPony;
    public ObservableCollection<Pony> Ponies => this._ponies;


    public Pony SelectedPony {
        get { return _selectedPony; }
        set {
            if (this._selectedPony == value) return;
            _selectedPony = value;
            this.OnPropertyChanged("SelectedPony");
        }
    }
}

public class Pony : INotifyPropertyChanged
{
    public int Id { get; set; }
    private string _name;

    public string Name {
        get { return this._name; }
        set {
            this._name = value;
            this.OnPropertyChanged("Name");
        }
    }

    public Brush Color { get; set; }

    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void OnPropertyChanged(string propertyName)
    {
        this.PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

XAML

<Window x:Class="MyNameSpace.MainWindow"
        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:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        x:Name="root"
        Title="Try WPF!"
        mc:Ignorable="d">

    <Grid >
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"></RowDefinition>
            <RowDefinition></RowDefinition>
        </Grid.RowDefinitions>
        <Ribbon>
            <RibbonGroup Header="Category">
                <RibbonComboBox Label="Category" HorizontalContentAlignment="Left" >
                    <RibbonGallery SelectedItem="{Binding SelectedPony}">
                        <RibbonGalleryCategory ItemsSource="{Binding Ponies}" >
                            <RibbonGalleryCategory.ItemTemplate>
                            <DataTemplate>
                                <TextBlock Name="tb" Text="{Binding Name}" Background="{Binding Color}"/>
                            </DataTemplate>
                            </RibbonGalleryCategory.ItemTemplate>
                        </RibbonGalleryCategory>
                    </RibbonGallery>
                </RibbonComboBox>                
            </RibbonGroup>
        </Ribbon>

    </Grid>
</Window>

如您所见，功能更强大，代码更少:)