使用ControlTemplate

Question

我用ControlTemplate创建了一个自定义按钮。
我使用ControlTemplate来绑定UserControl的默认属性，例如Background或Foreground。

但是，如果我添加自定义依赖项属性（例如CornerRadius），则会出现两个错误：

1. “成员'CornerRadius'无法识别或无法访问。”
2. “在类型'UserControl'上找不到静态成员'CornerRadiusProperty'。”

Xaml：

<UserControl x:Class="MyProject.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" 
         d:DesignHeight="50" d:DesignWidth="50"
         BorderThickness="1" BorderBrush="White" Background="Black"
         Content="OK" Foreground="White">
    <UserControl.Template>
        <ControlTemplate TargetType="UserControl">
            <Border Name="ground"
                    BorderThickness="{TemplateBinding BorderThickness}"
                    BorderBrush="{TemplateBinding BorderBrush}"
                    Background="{TemplateBinding Background}"
                    CornerRadius="{TemplateBinding CornerRadius}">
                <Label Name="content"
                       VerticalContentAlignment="Center" 
                       HorizontalContentAlignment="Center"
                       Content="{TemplateBinding Content}"
                       Foreground="{TemplateBinding Foreground}"
                       FontFamily="{TemplateBinding FontFamily}"
                       FontWeight="{TemplateBinding FontWeight}"
                       FontSize="{TemplateBinding FontSize}"/>
            </Border>
        </ControlTemplate>
    </UserControl.Template>
</UserControl>

代码背后：

namespace MyProject
{
    public partial class MyButton : UserControl
    {
        public static readonly DependencyProperty CornerRadiusProperty =
            DependencyProperty.Register("CornerRadius", typeof(CornerRadius), typeof(MyButton));

        public CornerRadius CornerRadius
        {
            get => (CornerRadius)GetValue(CornerRadiusProperty);
            set => SetValue(CornerRadiusProperty, value);
        }


        public MyButton() => InitializeComponent();
    }
}

如果我使用此处User control with custom properties指定的解决方案，则会遇到此问题Wpf - Custom control: How to override default properties?。

那么，有一种解决方案可以避免这两个问题？

Answer 1

自定义Button不应是UserControl，而应直接从Button派生。

向您的Visual Studio项目添加“自定义控件（WPF）”并按如下所示对其进行修改：

public class MyButton : Button
{
    static MyButton()
    {
        DefaultStyleKeyProperty.OverrideMetadata(
            typeof(MyButton),
            new FrameworkPropertyMetadata(typeof(MyButton)));
    }

    public static readonly DependencyProperty CornerRadiusProperty =
        DependencyProperty.Register(
            nameof(CornerRadius), typeof(CornerRadius), typeof(MyButton));

    public CornerRadius CornerRadius
    {
        get => (CornerRadius)GetValue(CornerRadiusProperty);
        set => SetValue(CornerRadiusProperty, value);
    }
}

然后在生成的Themes\Generic.xaml文件中更改其默认样式：

<Style TargetType="local:MyButton">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="local:MyButton">
                <Border Name="ground"
                        BorderThickness="{TemplateBinding BorderThickness}"
                        BorderBrush="{TemplateBinding BorderBrush}"
                        Background="{TemplateBinding Background}"
                        CornerRadius="{TemplateBinding CornerRadius}">
                    <Label Name="content"
                           VerticalContentAlignment="Center" 
                           HorizontalContentAlignment="Center"
                           Content="{TemplateBinding Content}"
                           Foreground="{TemplateBinding Foreground}"
                           FontFamily="{TemplateBinding FontFamily}"
                           FontWeight="{TemplateBinding FontWeight}"
                           FontSize="{TemplateBinding FontSize}"/>
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

有关详细信息，请参见Control Authoring Overview。