WPF 窗口隐藏内容依赖属性

Question

我想创建一个 Window，它重新声明它自己的 DependencyProperty，名为 Content。

public partial class InfoWindow : Window
{
    public static new readonly DependencyProperty ContentProperty = DependencyProperty.Register("Content", typeof(object), typeof(InfoWindow), new PropertyMetadata(null));
    public object Content
    {
        get { return GetValue(ContentProperty); }
        set { SetValue(ContentProperty, value); }
    }
}

和 XAML 绑定这个属性

<ContentControl Content="{Binding ElementName=_this, Path=Content}" />

它工作正常，只是 Visual Studio 设计器抱怨Logical tree depth exceeded while traversing the tree. This could indicate a cycle in the tree.

有什么方法可以告诉设计者绑定的是InfoWindow.Content 而不是Window.Content？或者隐藏该属性是一个坏主意，我应该重命名我的属性吗？

Answer 1

我在这里尝试实现的是动态定义用于显示不同视图以导航到不同表单的按钮的想法。 （见下文： ） View 和 View Models 之间的链接在 Dictionary View_ViewModel 中设置，用于识别按下按钮时为当前视图设置的视图。 （注：我尽量使用最基本的对象，避免IOC容器之类的，这样代码更容易看懂） 要记住的最重要的事情是正确设置 DataContext 否则您将在遍历树时超出逻辑树深度。错误。您可以在视图后面的代码中或在 XAML 中执行此操作。 示例：

public partial class SetupForm : UserControl
{
    public SetupForm()
    {
        InitializeComponent();
        DataContext = new SetupFormVM();
    }
}

或

<UserControl.DataContext>
    <SaleVM:SalesEntryVM />
</UserControl.DataContext>

这是一个代码 sn-p，它可能会更清楚地解释它并可能回答您的问题。 视图模型定义了主窗口中需要多少按钮和视图。这是通过将 ItemsControl 绑定到 View Model 类中的列表来实现的。 Button 命令绑定到 View Model 类中的 ICommand ChangeViewCommand 属性，该属性评估按下的按钮并调用 ViewChange 方法来更改 CurrentView（这绑定到 XAML 中的内容）

这就是我的主窗口 xaml 的样子。

<Window x:Class="MyNameSpace.Views.ApplicationWindow"
    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"
    xmlns:local="clr-namespace:MyNameSpace.Views"
    mc:Ignorable="d"
    Title="ApplicationWindow" Height="Auto" Width="Auto">
<Grid>
    <Grid.ColumnDefinitions>
        <ColumnDefinition /> -------------------> repeated five times
    </Grid.ColumnDefinitions>
    <Grid.RowDefinitions>
        <RowDefinition /> -------------------------> repeated five times
    </Grid.RowDefinitions>
    <DockPanel Grid.Row="0" Grid.Column="0" Grid.ColumnSpan="5" >
        <!-- Bind to List of Pages -->
        <ItemsControl ItemsSource="{Binding ControlItemsNamesList}" DockPanel.Dock="Top" >
            <!-- Stack the buttons horizontally --> The list contains the labels to assign to the buttons
            <ItemsControl.ItemsPanel>
                <ItemsPanelTemplate>            ---------------------------------------> This to stack the buttons Horizontally
                    <StackPanel Orientation="Horizontal" />
                </ItemsPanelTemplate>
            </ItemsControl.ItemsPanel>
            <!-- This looks at the list items and creates a button with ControlName -->
            <ItemsControl.ItemTemplate>
                <DataTemplate>
                    <Button Content="{Binding ControlName}"
                            Command="{Binding DataContext.ChangeViewCommand, RelativeSource={RelativeSource AncestorType={x:Type Window}}}"  ------> This is important for the Buttons to work Window or ContentControl.
                            CommandParameter="{Binding }"/>
                </DataTemplate>
            </ItemsControl.ItemTemplate>
        </ItemsControl>
    </DockPanel>
    <ContentControl Grid.Row="1" Grid.Column="0" Grid.ColumnSpan="5" Grid.RowSpan="4"  Content="{Binding CurrentView}"/> ---------> This is where I want the new Windows to appear when I click the button
</Grid>

这是我的一个用户控件 xaml 的外观，当我单击主窗口中的按钮时会出现。

<UserControl x:Class="MyNameSpace.Views.SetupForm"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
        mc:Ignorable="d" 
        d:DesignHeight="450" d:DesignWidth="800">
<Grid>
    <Grid.ColumnDefinitions>
        <ColumnDefinition /> ------------------- repeated five times
    </Grid.ColumnDefinitions>
    <Grid.RowDefinitions>
        <RowDefinition/> ------------------- repeated five times
    </Grid.RowDefinitions>
    <DockPanel Grid.Row="0" Grid.Column="0" Grid.RowSpan="5" Background="AliceBlue" Margin="0,0,0,0" >
        <!-- Bind to List of Pages -->
        <ItemsControl ItemsSource="{Binding ControlItemsNamesList}" DockPanel.Dock="Left" >
            <!-- Stack the buttons horizontally -->
            <ItemsControl.ItemsPanel>
                <ItemsPanelTemplate>
                    <StackPanel Orientation="Vertical" />
                </ItemsPanelTemplate>
            </ItemsControl.ItemsPanel>
            <!-- This looks at the list items and creates a button with ControlName -->
            <ItemsControl.ItemTemplate>
                <DataTemplate>
                    <Button Content="{Binding ControlName}"
                            Command="{Binding DataContext.ChangeViewCommand, RelativeSource={RelativeSource AncestorType={x:Type ContentControl}}}"
                            CommandParameter="{Binding }"/>
                </DataTemplate>
            </ItemsControl.ItemTemplate>
        </ItemsControl>
    </DockPanel>
    <ContentControl Grid.Row="0" Grid.Column="1" Grid.ColumnSpan="5" Grid.RowSpan="4"  Content="{Binding CurrentView}"/>
</Grid>
</UserControl>

这是主窗口的 ViewModel：

using Products.MVVMLibrary;
using Products.MVVMLibrary.Interfaces;
using MyNameSpace.Views;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Controls;
using System.Windows.Input;

namespace MyNameSpace.ViewModel
{
public class ApplicationVM : ObservableObject
{
    private MyNameSpace IControlItem currentNavigationItem;
    private MyNameSpace ContentControl currentView;

    private MyNameSpace List<IControlItem> NavigationList;

    private MyNameSpace ICommand changeViewCommand;
    private MyNameSpace ViewConverter viewDictionary;
    private MyNameSpace Dictionary<string, LinkViewToViewModel> View_ViewModel;
    public ApplicationVM()
    {
        viewDictionary = new ViewConverter();
        View_ViewModel = new Dictionary<string, LinkViewToViewModel>();
        NavigationList = new List<IControlItem>();
        InitialiseLists();
    }

    private MyNameSpace void AddControlNavigationItems(string name, ContentControl view, ObservableObject viewModel)
    {
        View_ViewModel.Add(name, new LinkViewToViewModel(view, viewModel));
        IControlItem item = (IControlItem)viewModel;
        NavigationList.Add(item);

    }
    private MyNameSpace void InitialiseLists()
    {
        AddControlNavigationItems("Sales", new SalesForm(), new SalesEntryVM());
        AddControlNavigationItems("Purchases", new PurchaseEntryForm(), new PurchasesVM());
        AddControlNavigationItems("Setup", new SetupForm(), new SetupFormVM());

        //Use the property instead which creates the instance and triggers property change
        CurrentViewModel = (IControlItem)View_ViewModel[View_ViewModel.Keys.ElementAt(0)].ViewModel;
        CurrentView = View_ViewModel[View_ViewModel.Keys.ElementAt(0)].View;
    }

    public List<IControlItem> ControlItemsNamesList
    {
        get => NavigationList;
    }
    /// <summary>
    /// Provides a list of names for Navigation controls to the control item
    /// </summary>
    public Dictionary<string, LinkViewToViewModel> ApplicationViews
    {
        get
        {

            return View_ViewModel;
        }
        set
        {
            View_ViewModel = value;
        }
    }

    public ContentControl CurrentView
    {
        get
        {
            return currentView;
        }
        set
        {
            currentView = value;
            OnPropertyChanged("CurrentView");
        }
    }
    public IControlItem CurrentViewModel
    {
        get
        {
            return currentNavigationItem;
        }
        set
        {
            if (currentNavigationItem != value)
            {
                currentNavigationItem = value;
                OnPropertyChanged("CurrentViewModel");
            }
        }
    }
    /// <summary>
    /// This property is bound to Button Command in XAML.
    /// Calls ChangeViewModel which sets the CurrentViewModel
    /// </summary>
    public ICommand ChangeViewCommand
    {
        get
        {
            if (changeViewCommand == null)
            {
                changeViewCommand = new ButtonClick(
                    p => ViewChange((IControlItem)p), CanExecute);
            }
            return changeViewCommand;
        }
    }

    #region Methods

    private MyNameSpace void ViewChange(IControlItem viewname)
    {
        foreach (KeyValuePair<string, LinkViewToViewModel> item in View_ViewModel)
        {
            if (item.Key == viewname.ControlName)
            {//Set the properties of View and ViewModel so they fire PropertyChange event
                CurrentViewModel = (IControlItem)item.Value.ViewModel;
                CurrentView = item.Value.View;
                break;
            }
        }

    }
    private MyNameSpace bool CanExecute()
    {
        return true;
    }
    #endregion
  }
}

其他类

public class LinkViewToViewModel
{
    public LinkViewToViewModel(ContentControl view, ObservableObject viewModel)
    {
        View = view;
        ViewModel = viewModel;
    }
    public ContentControl View { get; set; }
    public ObservableObject ViewModel { get; set; }
}