在自定义控制代码中处理事件

Question

好的，这可能是一个非常愚蠢的问题，但我已经搜索了很长时间，但找不到可行的解决方案......

我有一个继承自 Control 的自定义控件，其中应包含自动化代码。

例如，在选中时选择控件 TextBox 的所有文本，或者在更改 TextBox 的内容时生成紧密匹配列表。

public class vokDataGridEdit : Control
{
    static vokDataGridEdit()
    {
        DefaultStyleKeyProperty.OverrideMetadata(typeof(vokDataGridEdit), new FrameworkPropertyMetadata(typeof(vokDataGridEdit)));

        // Events internal to control (??? found on some how-to's)
        EventManager.RegisterClassHandler(typeof(vokDataGridEdit), UIElement.GotKeyboardFocusEvent, new RoutedEventHandler(OnSelectContent), true);
    }

    // Dependecy Properties ...

    // The Event that shall Fire when the TextBox gets Focus / Editing Mode
    public static void SelectContent(object sender, RoutedEventArgs e)
    {
        if (sender is TextBox tb)
        {
            tb.SelectAll();
        }
    }
}

以及控件样式模板：

<ResourceDictionary xmlns       = "http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x     = "http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:ccont = "clr-namespace:App.Controls">

    <!-- Default style for the Validation Buttons -->
    <Style TargetType="{x:Type ccont:vokDataGridEdit}">

        <Setter Property="SnapsToDevicePixels"  Value="true" />

        <Setter Property="Template">
            <Setter.Value>

                <ControlTemplate TargetType="{x:Type ccont:vokDataGridEdit}">

                    <TextBox Text                               = "{Binding Text, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged, RelativeSource={RelativeSource AncestorType=ccont:vokDataGridEdit}}"
                             BorderThickness                    = "0"
                             ContextMenuService.Placement       = "Right"
                             ContextMenuService.PlacementTarget = "{Binding Path=., RelativeSource={RelativeSource Self}}"
                             GotKeyboardFocus                   = "SelectContent">

                        <TextBox.ContextMenu>
                            <ContextMenu>
                                <ContextMenu.Template>
                                    <ControlTemplate>

                                        <Border CornerRadius    = "5"
                                                Background      = "LightGray"
                                                BorderThickness = "1" 
                                                BorderBrush     = "Gray"
                                                Padding         = "2">

                                            <StackPanel Orientation="Vertical">

                                                <!-- Title -->
                                                <TextBlock Text="Test" />

                                                <!-- TODO: List of matches -->
                                                <TextBox Text               = "{Binding Text, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged, RelativeSource={RelativeSource AncestorType=ccont:vokDataGridEdit}}" 
                                                         BorderThickness    = "0" />

                                            </StackPanel>

                                        </Border>

                                    </ControlTemplate>
                                </ContextMenu.Template>
                            </ContextMenu>
                        </TextBox.ContextMenu>

                    </TextBox>

                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

</ResourceDictionary>

问题 1： 如何绑定事件SelectContent（在获得焦点时选择所有TextBox 内容，注意：它是CellEditingTemplate 的DataGrid 的一部分) 到GotKeyboardFocus?事件在应用程序代码中通常很好，但对于自定义控件，它们不起作用，因为样式没有真正的“代码隐藏”......

问题 2： 假设我有一个包含单词数组的依赖属性。根据TextBox的内容，我想从依赖属性中的数组中选择几个词，并将它们传递给自定义控件中的ListBox（ListBox的内容只能由自定义控件，而不是使用该控件的任何人。是否有关于如何实现此功能的首选/规范 MVVM 架构？

Answer 1

通常您应该只发布一个问题，而不是多个问题。关于第一个，您可以使用 EventSetter 例如在UserControl 的资源中隐含的Style：

<Style TargetType="TextBox">
    <EventSetter Event="GotKeyboardFocus" Handler="SelectContent"/>
</Style>

关于第二个问题 - 实现一个属性，它是您列表的子集并相应地更新它，例如如果更改了依赖属性（请参阅属性更改回调）或更改了子集所依赖的其他值。

或者，您可以使用TextBox 的行为并在那里处理您需要的事件。参见例如选择所有行为：

public class SelectAllBehavior : Behavior<TextBox>
{
    private bool _doSelectAll = false;
    protected override void OnAttached()
    {
        base.OnAttached();
        AssociatedObject.GotFocus += AssociatedObject_GotFocus;
        AssociatedObject.PreviewMouseUp += AssociatedObject_MouseUp;
        AssociatedObject.PreviewMouseDown += AssociatedObject_MouseDown;
    }

    private void AssociatedObject_MouseUp(object sender, System.Windows.Input.MouseButtonEventArgs e)
    {
        if (_doSelectAll)
        {
            AssociatedObject.Dispatcher.BeginInvoke((Action) (()=>{ AssociatedObject.SelectAll(); }));
        }
        _doSelectAll = false;
    }

    private void AssociatedObject_MouseDown(object sender, System.Windows.Input.MouseButtonEventArgs e)
    {
        _doSelectAll = !AssociatedObject.IsFocused;
    }

    private void AssociatedObject_GotFocus(object sender, System.Windows.RoutedEventArgs e)
    {
        AssociatedObject.SelectAll();
    }

    protected override void OnDetaching()
    {
        AssociatedObject.GotFocus -= AssociatedObject_GotFocus;
        AssociatedObject.PreviewMouseUp -= AssociatedObject_MouseUp;
        AssociatedObject.PreviewMouseDown -= AssociatedObject_MouseDown;
        base.OnDetaching();
    }
}

在 XAML 中使用此行为：

xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
<TextBox Text="Some text">
    <i:Interaction.Behaviors>
        <local:SelectAllBehavior/>
    </i:Interaction.Behaviors>
</TextBox>

Answer 2

部分解决方案：

最后我得到了关于直接控制工作的事件（ContextMenu 中的控制仍然没有得到 EventHandlers...）。

显然，重点是使用GetTemplateChild() 按名称获取文本框，然后关联事件处理程序：

<ResourceDictionary xmlns       = "http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x     = "http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:ccont = "clr-namespace:App.Controls">

    <!-- Default style for the Validation Buttons -->
    <Style TargetType="{x:Type ccont:vokDataGridEdit}">

        <Setter Property="SnapsToDevicePixels"  Value="true" />

        <Setter Property="Template">
            <Setter.Value>

                <ControlTemplate TargetType="{x:Type ccont:vokDataGridEdit}">

                    <TextBox Text                               = "{Binding Text, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged, RelativeSource={RelativeSource AncestorType=ccont:vokDataGridEdit}}"
                             BorderThickness                    = "0"
                             ContextMenuService.Placement       = "Right"
                             ContextMenuService.PlacementTarget = "{Binding Path=., RelativeSource={RelativeSource Self}}"
                             x:Name                             = "TextBox">

                        <TextBox.ContextMenu>
                            <ContextMenu x:Name="Menu">
                                <ContextMenu.Template>
                                    <ControlTemplate>

                                        <Border CornerRadius    = "5"
                                                Background      = "LightGray"
                                                BorderThickness = "1" 
                                                BorderBrush     = "Gray"
                                                Padding         = "2">

                                            <StackPanel Orientation="Vertical">

                                                <!-- Title -->
                                                <TextBlock Text="Test" x:Name = "Test" />

                                                <!-- TODO: List of matches -->
                                                <TextBox Text               = "{Binding Text, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged, RelativeSource={RelativeSource AncestorType=ccont:vokDataGridEdit}}" 
                                                         BorderThickness    = "0" />

                                            </StackPanel>

                                        </Border>

                                    </ControlTemplate>
                                </ContextMenu.Template>
                            </ContextMenu>
                        </TextBox.ContextMenu>

                    </TextBox>

                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

</ResourceDictionary>

和代码（依赖属性未显示）：

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media;

namespace App.Controls
{
    /// <summary>
    /// DataGrid Edit control (see: https://www.c-sharpcorner.com/article/wpf-routed-events/ for RoutedEvents)
    /// </summary>
    public class vokDataGridEdit : Control
    {
        static vokDataGridEdit()
        {
            DefaultStyleKeyProperty.OverrideMetadata(typeof(vokDataGridEdit), new FrameworkPropertyMetadata(typeof(vokDataGridEdit)));
        }

        public override void OnApplyTemplate()
        {
            base.OnApplyTemplate();

            // Demo purpose only, check for previous instances and remove the handler first  
            if (this.GetTemplateChild("TextBox") is TextBox button)
            {
                button.PreviewMouseLeftButtonDown   += this.SelectContentPreparation;
                button.GotKeyboardFocus             += this.SelectContent;
                button.MouseDoubleClick             += this.SelectContent;
                //button.GotFocus                     += this.SelectContent;
            }
        }

        /// <summary>
        /// Prepare the Control to ensure it has focus before subsequent event fire
        /// </summary>
        private void SelectContentPreparation(object sender, MouseButtonEventArgs e)
        {
            if (sender is TextBox tb)
            {
                if (!tb.IsKeyboardFocusWithin)
                {
                    e.Handled = true;
                    tb.Focus();
                }
            }
        }

        private void SelectContent(object sender, RoutedEventArgs e)
        {
            if (sender is TextBox tb)
            {
                e.Handled = true;
                tb.SelectAll();
            }
        }
    }
}