自定义WPF控件是否可以实现IsDefault属性

Question

我有一个自定义按钮控件,不是从Button派生的.我是否可以实现IsDefault的等价物,以便调用与我的控件关联的命令.我希望这是一个附加属性,我可以添加到任何控件,但据我所知,它似乎不是.如果我的控件不是来自Button,或者至少有一个合理的解决方法,我是不是运气不好？

更新: 我刚刚看了一下反射器,看看它是如何在Button下进行的,我必须说它不是我见过的最自我解释的代码.看来,为了处理Button默认的概念,至少有3个自定义类型的自定义类型.由于似乎没有现成的借用IsDefault功能的方法,我想我必须缩小我想要实现的目标,这样我至少可以获得默认焦点和访问键处理工作而忽略Button.IsDefault实现中隐藏的复杂性.

更新: 添加了以下代码示例,显示了我尝试itowlson的建议的不必要的尝试.

MyButton.xaml

<UserControl x:Class="IsDefault.MyButton"
             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"
             Height="28"
             Width="117">

    <Grid>
        <Button Click="Button_Click">
            <Button.Template>
                <ControlTemplate>
                    <Border BorderThickness="2"
                            CornerRadius="12"
                            Background="DarkSlateBlue">
                        <TextBlock Foreground="WhiteSmoke"
                                   HorizontalAlignment="Center"
                                   VerticalAlignment="Center">Some Text</TextBlock>
                    </Border>
                </ControlTemplate>
            </Button.Template>
        </Button>
    </Grid>
</UserControl>

MyButton.xaml.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace IsDefault
{
    /// <summary>
    /// Interaction logic for MyButton.xaml
    /// </summary>
    public partial class MyButton : UserControl
    {


        // Provide CLR accessors for the event
        public event RoutedEventHandler Click
        {
            add { AddHandler(ClickEvent, value); }
            remove { RemoveHandler(ClickEvent, value); }
        }

        // Using a RoutedEvent
        public static readonly RoutedEvent ClickEvent = EventManager.RegisterRoutedEvent(
            "Click", RoutingStrategy.Bubble, typeof(RoutedEventHandler), typeof(MyButton));



        public bool IsDefault
        {
            get { return (bool)GetValue(IsDefaultProperty); }
            set { SetValue(IsDefaultProperty, value); }
        }

        public static readonly DependencyProperty IsDefaultProperty =
            DependencyProperty.Register(
                "IsDefault", 
                typeof(bool),
                typeof(MyButton),
                new PropertyMetadata(false, IsDefault_PropertyChangedCallback, null));


        public MyButton()
        {
            InitializeComponent();
        }

        protected override void OnAccessKey(AccessKeyEventArgs e)
        {
            base.OnAccessKey(e);

            if (e.Key == "\r")
            {
                if (e.IsMultiple)
                {
                    // There are multiple controls that are currently handling the Enter key
                    MessageBox.Show("there are multiple controls handling the Enter key.");
                }
                else
                {
                    RaiseEvent(new RoutedEventArgs(ClickEvent, this));
                }
            }
        }

        private static void IsDefault_PropertyChangedCallback(
            DependencyObject d,
            DependencyPropertyChangedEventArgs e)
        {
            var button = d as MyButton;

            var isDefault = (bool)e.NewValue;

            if (isDefault)
            {
                AccessKeyManager.Register("\r", button);
            }
            else
            {
                AccessKeyManager.Unregister("\r", button);
            }
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            RaiseEvent(new RoutedEventArgs(ClickEvent));
        }
    }
}

MainWindow.xaml

<Window x:Class="IsDefault.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525"
        xmlns:my="clr-namespace:IsDefault">
    <Grid>
        <Button Content="Button"
                Height="23"
                HorizontalAlignment="Left"
                Margin="224,24,0,0"
                Name="button1"
                VerticalAlignment="Top"
                Width="75" />
        <TextBox Height="23"
                 HorizontalAlignment="Left"
                 Margin="208,94,0,0"
                 Name="textBox1"
                 VerticalAlignment="Top"
                 Width="120" />
        <my:MyButton Height="28"
                     HorizontalAlignment="Left"
                     Margin="232,154,0,0"
                     x:Name="myButton1"
                     VerticalAlignment="Top"
                     Width="117"
                     Click="myButton1_Click"
                     IsDefault="True"/>
    </Grid>
</Window>

MainWindow.xaml.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace IsDefault
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private void myButton1_Click(object sender, RoutedEventArgs e)
        {
            MessageBox.Show("My button was clicked, yay!");
        }
    }
}

Answer 1

所有设置Button.IsDefault都是调用AccessKeyManager.Register("\r", this)(如果设置为false,则取消注册).(实际上,它在焦点管理方面做了一些额外的工作,但这对你来说可能并不重要.)

所以要自己实现类似的效果:

• 以通常的方式创建IsDefault依赖项属性.
• 在IsDefault PropertyChangedCallback中,根据新值调用AccessKeyManager.Register或AccessKeyManager.Unregister,传递"\r"(输入字符串)作为键,控制实例作为元素.
• 覆盖OnAccessKey以指定控件如何响应Enter键.(例如,ButtonBase会覆盖它以调用OnClick.您也可以处理AccessKeyManager.AccessKeyPressed附加事件,但由于您正在定义自定义控件,因此覆盖OnAccessKey更整洁.)