WPF用户控件内绑定 [英] Bindings inside WPF user control

问题描述

为了进入世界WPF和习惯绑定，我做了用来定义搜索过滤器的用户控件。根据通缉过滤器，用户可以输入文字，选择一个日期，或者选择在组合框中的项目。下面是与创建的搜索控制的三个实例，不同类型的每个就是一个例子：

In order to get into the WPF world and getting used to bindings, I've made a user control used to define a search filter. Depending on the wanted filter, the user can either enter a text, pick a date or select an item in a combo box. Here's an example with three instances of the created search control, each being of different type:

可喜的是，一切工作正常，但我不知道，如果按预期一切都已经完成。

The good news is, everything is working but I'm not sure if everything has been done as intended.

SearchUserControl.xaml：

SearchUserControl.xaml:

<UserControl x:Class="Zefix.View.UserControls.SearchUserControl"
             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="82" 
             d:DesignWidth="300" 
             Height="Auto"
             x:Name="SearchUserControlRoot">
    <Grid>
        <StackPanel>
            <Label Name="LabelHeaderText" Content="{Binding HeaderText, ElementName=SearchUserControlRoot}" />
            <TextBox Name="TextBoxSearchText" Text="{Binding SearchValue, ElementName=SearchUserControlRoot}" Visibility="{Binding TextBoxVisiblity, ElementName=SearchUserControlRoot}" />
            <DatePicker Name="DatePickerSearch" SelectedDate="{Binding SearchValue, ElementName=SearchUserControlRoot}" Visibility="{Binding DatePickerVisiblity, ElementName=SearchUserControlRoot}" />
            <ComboBox Name="ComboBoxSearch" Text="{Binding SearchValue, ElementName=SearchUserControlRoot}" ItemsSource="{Binding AvailableValues, ElementName=SearchUserControlRoot}" Visibility="{Binding ComboBoxVisiblity, ElementName=SearchUserControlRoot}" IsEditable="True" />
        </StackPanel>
    </Grid>
</UserControl>

SearchUserControl.xaml.cs：

SearchUserControl.xaml.cs:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Windows;
using Zefix.DataAccess;

namespace Zefix.View.UserControls {
    /// <summary>
    ///     Interaction logic for SearchUserControl.xaml
    /// </summary>
    public partial class SearchUserControl {

        #region Public Dependency Properties

        /// <summary>
        /// The search value property
        /// </summary>
        public static readonly DependencyProperty SearchValueProperty =
            DependencyProperty.Register("SearchValue", typeof (object), typeof (SearchUserControl));

        /// <summary>
        /// The available values property
        /// </summary>
        public static readonly DependencyProperty AvailableValuesProperty =
            DependencyProperty.Register("AvailableValues", typeof (IEnumerable<object>), typeof (SearchUserControl));

        /// <summary>
        /// The search type property
        /// </summary>
        public static readonly DependencyProperty SearchTypeProperty =
            DependencyProperty.Register("SearchType", typeof (SearchType), typeof (SearchUserControl));

        /// <summary>
        /// The header text property
        /// </summary>
        public static readonly DependencyProperty HeaderTextProperty =
            DependencyProperty.Register("HeaderText", typeof (string), typeof (SearchUserControl));

        #endregion

        #region Private Dependency Properties

        /// <summary>
        /// The combo box visiblity property
        /// </summary>
        private static readonly DependencyProperty ComboBoxVisiblityProperty =
            DependencyProperty.Register("ComboBoxVisiblity", typeof (Visibility), typeof (SearchUserControl));

        /// <summary>
        /// The text box visiblity property
        /// </summary>
        private static readonly DependencyProperty TextBoxVisiblityProperty =
            DependencyProperty.Register("TextBoxVisiblity", typeof (Visibility), typeof (SearchUserControl));

        /// <summary>
        /// The date picker visiblity property
        /// </summary>
        private static readonly DependencyProperty DatePickerVisiblityProperty =
            DependencyProperty.Register("DatePickerVisiblity", typeof (Visibility), typeof (SearchUserControl));

        #endregion

        #region Public Properties

        /// <summary>
        ///     Gets or sets the type of the search.
        /// </summary>
        /// <value>
        ///     The type of the search.
        /// </value>
        public SearchType SearchType {
            get { return (SearchType) GetValue(SearchTypeProperty); }
            set { SetValue(SearchTypeProperty, value); }
        }

        /// <summary>
        ///     Gets or sets the header text.
        /// </summary>
        /// <value>
        ///     The header text.
        /// </value>
        public string HeaderText {
            get { return (string) GetValue(HeaderTextProperty); }
            set { SetValue(HeaderTextProperty, value); }
        }

        /// <summary>
        /// Gets or sets the available values.
        /// </summary>
        /// <value>
        /// The available values.
        /// </value>
        public IEnumerable<object> AvailableValues {
            get { return (IEnumerable<object>) GetValue(AvailableValuesProperty); }
            set { SetValue(AvailableValuesProperty, value); }
        }

        /// <summary>
        /// Gets or sets the search value.
        /// </summary>
        /// <value>
        /// The search value.
        /// </value>
        public object SearchValue {
            get { return GetValue(SearchValueProperty); }
            set { SetValue(SearchValueProperty, value); }
        }

        #endregion

        #region Private Properties

        /// <summary>
        /// Gets or sets the combo box visiblity.
        /// </summary>
        /// <value>
        /// The combo box visiblity.
        /// </value>
        private Visibility ComboBoxVisiblity {
            get { return (Visibility) GetValue(ComboBoxVisiblityProperty); }
            set { SetValue(ComboBoxVisiblityProperty, value); }
        }

        /// <summary>
        /// Gets or sets the date picker visiblity.
        /// </summary>
        /// <value>
        /// The date picker visiblity.
        /// </value>
        private Visibility DatePickerVisiblity {
            get { return (Visibility) GetValue(DatePickerVisiblityProperty); }
            set { SetValue(DatePickerVisiblityProperty, value); }
        }

        /// <summary>
        /// Gets or sets the text box visiblity.
        /// </summary>
        /// <value>
        /// The text box visiblity.
        /// </value>
        private Visibility TextBoxVisiblity {
            get { return (Visibility) GetValue(TextBoxVisiblityProperty); }
            set { SetValue(TextBoxVisiblityProperty, value); }
        }

        #endregion

        #region Constructor

        /// <summary>
        ///     Initializes a new instance of the <see cref="SearchUserControl" /> class.
        /// </summary>
        public SearchUserControl() {
            InitializeComponent();

            DependencyPropertyDescriptor pd = DependencyPropertyDescriptor.FromProperty(SearchTypeProperty, typeof (SearchUserControl));
            pd.AddValueChanged(this, OnSearchTypePropertyChanged);

            // Initialize default parameters
            SearchType = SearchType.Unknown;
        }

        #endregion

        #region Private Methods

        /// <summary>
        /// Called when the search type property has changed.
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="e">The <see cref="EventArgs"/> instance containing the event data.</param>
        private void OnSearchTypePropertyChanged(object sender, EventArgs e) {

            // Hide all editors
            DatePickerVisiblity = Visibility.Collapsed;
            ComboBoxVisiblity = Visibility.Collapsed;
            TextBoxVisiblity = Visibility.Collapsed;

            // Make the correct editor visible
            switch (SearchType) {
                case SearchType.Date:
                    DatePickerVisiblity = Visibility.Visible;
                    break;
                case SearchType.TextSelection:
                    ComboBoxVisiblity = Visibility.Visible;
                    break;
                case SearchType.Text:
                    TextBoxVisiblity = Visibility.Visible;
                    break;
            }
        }

        #endregion
    }
}

从父控件的搜索控件实例化：

Instantiation of the search controls from the parent control:

        <ribbon:Tab Label="Search">
            <ribbon:Group Padding="0,5,0,5">
                <customcontrols:SearchUserControl x:Name="SearchUserControlCompanyName" HeaderText="company name" Margin="5,0,0,0" SearchType="Text" VerticalAlignment="Center" VerticalContentAlignment="Center" />
                <customcontrols:SearchUserControl x:Name="SearchUserControlCompanyNationality" HeaderText="company nationality (ISO3 code)" Margin="5,0,0,0" SearchType="TextSelection" AvailableValues="{Binding Path=CompaniesViewModel.ISO3Codes}" VerticalAlignment="Center" />
                <customcontrols:SearchUserControl x:Name="SearchUserControlDateFounded" HeaderText="date founded" Margin="5,0,0,0" SearchType="Date" VerticalAlignment="Center" VerticalContentAlignment="Center" />
                <ribbon:Button Context="StatusBarItem" Name="ButtonApplyFilter" Label="Search" ImageSourceSmall="/Resources/search_magnifying_glass_find.png" Margin="5,0,0,0" VerticalAlignment="Center" Click="OnButtonApplyFilterClicked" Command="{Binding Path=ApplyFilterCommand}" ScreenTipHeader="Apply the search filter" VerticalContentAlignment="Center" VariantSize="Large" />
            </ribbon:Group>
        </ribbon:Tab>

在SearchControl我根据所设定的检索类别想显示正确的组件（文本，日期选择器或ComboBox）。对于这一点，xxxVisibility依赖属性和属性已创建（当SearchTypeProperty通知一个属性更改事件，他们正在建立）。由于没有理由将它们公开为公共的（它们被用作只有SearchControl内），我做了他们私有的; MSDN指出绑定属性必须是公共虽然。该项目编译和无的问题上运行，但带出的讯息预计公共成员'绑定xxxVisibility性错误（不知道它是Visual Studio或ReSharper的告诉我）。

In the SearchControl I wanted to display the correct component (textbox, datepicker or combobox) according to the set SearchType. For this the, xxxVisibility dependency properties and properties have been created (they are being set when the SearchTypeProperty notifies a property changed event). As there is no reason to expose them as public (they are being used only inside the SearchControl), I've made them private; MSDN states that bound properties MUST be public though. The project compiles and runs without an issue, but errors are being shown for the bound xxxVisibility properties with the message 'Public member expected' (can't tell if it's visual studio or resharper telling me that).

是我的方法来创建此用户控件对于WPF的概念是否正确？
如果xxxVisibility属性是公共的（事件虽然我不希望暴露他们）？

Is my approach to create this user control correct in respect to the WPF concepts? Should the xxxVisibility properties be public (event though I don't want to expose them)?

推荐答案

这是答案，而不是仅仅评论一个非常困难的问题。我个人认为，你的用户控件已写得好而据我可以看到不破坏任何规则。虽然我看不出声明私人 的DependencyProperty ，它的是的不寻常的任何问题。在这种情况下，开发商往往选择实施公共 只读的DependencyProperty 与私人 由其DependencyPropertyKey 而不是：

This is a very difficult question to 'answer', rather than just 'comment' on. In my personal opinion, your UserControl has been written well and as far as I can see doesn't break any rules. Although I don't see any problem with declaring a private DependencyProperty, it is unusual. In this situation, developers often chose to implement a public Read Only DependencyProperty with a private DependencyPropertyKey instead:

private static readonly DependencyPropertyKey ComboBoxVisiblityPropertyKey
    = DependencyProperty.RegisterReadOnly("ComboBoxVisiblity", typeof(int), 
    typeof(SearchUserControl), new PropertyMetadata(Visibility.Collapsed));

public static readonly DependencyProperty ComboBoxVisiblityProperty
    = ComboBoxVisiblityPropertyKey.DependencyProperty;

public int ComboBoxVisiblity
{
    get { return (int)GetValue(ComboBoxVisiblityProperty); }
    protected set { SetValue(ComboBoxVisiblityPropertyKey, value); }
}

一些开发商的可能的也认为这不寻常的，你正在创建类型的属性能见度，而不是结合 BOOL 与 BoolToVisibilityConverter 的价值观，但再次...这是你的prerogative。总体而言，做得好！ ：）

Some developers may also think it unusual that you are creating properties of type Visibility rather than binding bool values with BoolToVisibilityConverters, but again... that is your prerogative. Overall, well done! :)

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