如何将静态类属性绑定到 XAML/Xamarin 中的 UI 组件

Question

在 Xamarin 应用程序中，我无法将 C# 用户定义的静态类属性 (Colors.BackgroundColor) 的静态属性绑定到 XAML。我需要通过静态类中定义的静态值设置网格颜色的背景。

但我收到错误

在 xmlns 中找不到类型UserInterfaceDefinitions

在此 XAML 上

BackgroundColor = "{Binding Source = {x:Static MyNamespace.Mobile:UserInterfaceDefinitions.Colors} }"

静态类代码

namespace MyNamespace.Mobile
{
    public static class UserInterfaceDefinitions
    {
        public static class Colors
        {
            public static string BackgroundColor = "#DCECE";
        }

        
    }
}

XAML代码

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
              xmlns:buttons="clr-namespace:MyNamespace.Mobile.UI.Buttons" 
              xmlns:Status="clr-namespace:MyNamespace.Mobile.UI.StatusDetails"     
             x:Class="MyNamespace.Mobile.UI.TestAndDemoSelection">
    <ContentPage.Content  Margin="0,0,0,0" BackgroundColor="White">

    
 <Grid x:Name="ChildGrid" Grid.Row="1" Grid.Column="0"  ColumnSpacing="10" BackgroundColor="White" >
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="*"></ColumnDefinition> 
                </Grid.ColumnDefinitions>
            
            <!-- I am getting the error as Type UserInterfaceDefinitions not found in xmlns-->

            <BoxView Grid.Column="0" BackgroundColor = "{Binding Source = {x:Static MyNamespace.Mobile:UserInterfaceDefinitions.Colors} }" /> 
         
 </Grid>     
 
    </ContentPage.Content>
</ContentPage>

代码隐藏.cs

using MyNamespace.Mobile.UI.Models;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

using Xamarin.Forms;
using Xamarin.Forms.Xaml;

namespace MyNamespace.Mobile.UI
{
    [XamlCompilation(XamlCompilationOptions.Compile)]
    public partial class TestAndDemoSelection : ContentPage
    {
        public TestAndDemoSelection()
        {
            InitializeComponent();
        }
 
    }
}

如何将静态类属性绑定到 XAML？

Answer 1

我已经有了决心。这是因为嵌套静态类在 XAML 中无法访问，正确的代码如下。

用户定义的静态类：

namespace MyNamespace.Mobile
{
    [XamlCompilation(XamlCompilationOptions.Compile)]
    public static class UserInterfaceDefinitions
    {
        public static string BackgroundColor { get; } = "#DCECEC";
    }
}

XAML 文件：

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" 
              xmlns:local="clr-namespace:MyNamespace.Mobile"   
             x:Class="MyNamespace.Mobile.UI.TestAndDemoSelection">
    <ContentPage.Content  Margin="0,0,0,0" BackgroundColor="White">


 <Grid x:Name="ChildGrid" Grid.Row="1" Grid.Column="0"  ColumnSpacing="10" BackgroundColor="White" >
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="*"></ColumnDefinition> 
                </Grid.ColumnDefinitions>


           <BoxView Grid.Column="0" BackgroundColor = "{Binding Source = {x:Static local:UserInterfaceDefinitions.BackgroundColor}}" />

 </Grid>     

    </ContentPage.Content>
</ContentPage>

Answer 2

为了绑定静态属性：

1) 使用 xmlns 声明要导入的命名空间

2) 在源中相应地使用 xmlns

=>

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
              xmlns:buttons="clr-namespace:MyNamespace.Mobile.UI.Buttons" 
              xmlns:Status="clr-namespace:MyNamespace.Mobile.UI.StatusDetails" 
             xmnlns:local="clr-namespace:MyNamespace.Mobile" 
             x:Class="MyNamespace.Mobile.UI.TestAndDemoSelection">
    <ContentPage.Content  Margin="0,0,0,0" BackgroundColor="White">


         <Grid x:Name="ChildGrid" Grid.Row="1" Grid.Column="0"  ColumnSpacing="10" BackgroundColor="White" >
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="*"></ColumnDefinition> 
                </Grid.ColumnDefinitions>


            <BoxView Grid.Column="0" BackgroundColor = "{x:Static local:UserInterfaceDefinitions.Colors.BackgroundColor}" /> 

         </Grid>     

    </ContentPage.Content>
</ContentPage>

此外，BackgroundColor 应该是一个属性以便可访问：

public static string BackgroundColor {get;} = "#DCECE";