C# 如何在c中更改ResourceDictionary上的setter属性#

我有

和一些setter，当我检查天气状况时，我想在

MainPage.xaml.cs

中的c代码中将字体颜色从白色更改为黑色，xaml页面中的代码如下所示：

<ContentPage.Resources>
    <ResourceDictionary>
        <Style x:Key="labelStyle"
               TargetType="Label">
            <Setter Property="FontSize" 
                    Value="Medium" />
            <Setter Property="Margin" 
                    Value="0,0,0,0" />
            <Setter Property="FontAttributes" 
                    Value="Bold" />
            <Setter Property="TextColor" 
                    Value="White"/>
        </Style>

        <local:LongToDateTimeConverter x:Key="longToDateTimeConverter" />
    </ResourceDictionary>
</ContentPage.Resources>

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="StyleColorChange.MainPage"
             x:Name="MyPage">
    <ContentPage.Resources>
        <ResourceDictionary>
            <Style x:Key="labelStyle"
               TargetType="Label">
                <Setter Property="FontSize" 
                    Value="Medium" />
                <Setter Property="Margin" 
                    Value="0,0,0,0" />
                <Setter Property="FontAttributes" 
                    Value="Bold" />
                <Setter Property="TextColor" Value="White" />
                <Style.Triggers>
                    <DataTrigger TargetType="Label"
                                 Binding="{Binding isWeatherConditionChecked}"
                                 Value="True">
                        <Setter Property="TextColor" Value="{Binding labelStyleTextColor}" />
                    </DataTrigger>
                </Style.Triggers>
            </Style>
        </ResourceDictionary>
    </ContentPage.Resources>
    
    <!--This part is only to create a sample app-->
    <StackLayout BackgroundColor="Gray">
        <Button Text="Go!" Clicked="Button_Clicked" />
        <Label x:Name="MyLabel" Text="This is a label" Style="{StaticResource labelStyle}"/>
    </StackLayout>

</ContentPage>

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Xamarin.Forms;

namespace StyleColorChange
{
    public partial class MainPage : ContentPage
    {
        public string labelStyleTextColor { get; set; } = "White";
        private bool _isWeatherConditionChecked;
        public bool isWeatherConditionChecked
        {
            get { return _isWeatherConditionChecked; }
            set { _isWeatherConditionChecked = value; OnPropertyChanged("isWeatherConditionChecked"); }
        }
        public MainPage()
        {
            InitializeComponent();
            BindingContext = this;
        }
        private void Button_Clicked(object sender, EventArgs e)
        {            
            labelStyleTextColor = "Black";
            isWeatherConditionChecked = !isWeatherConditionChecked;
        }
    }
}

---

如何获取

以及如何在c#中将其颜色更改为黑色？

没有足够的信息，但我假设您可以使用来实现最终目标，即基于某些数据（属性）动态更改

文本颜色

如果您想从
MainPage.xaml.cs
更改颜色，可以使用稍微更改的@Cfun建议的建议，而不是在xaml中硬编码值，您可以向
Setter.value
添加绑定对象，如下所示：

<ContentPage.Resources>
    <ResourceDictionary>
        <Style x:Key="labelStyle"
               TargetType="Label">
            <Setter Property="FontSize" 
                    Value="Medium" />
            <Setter Property="Margin" 
                    Value="0,0,0,0" />
            <Setter Property="FontAttributes" 
                    Value="Bold" />
            <Setter Property="TextColor" 
                    Value="White"/>
        </Style>

        <local:LongToDateTimeConverter x:Key="longToDateTimeConverter" />
    </ResourceDictionary>
</ContentPage.Resources>

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="StyleColorChange.MainPage"
             x:Name="MyPage">
    <ContentPage.Resources>
        <ResourceDictionary>
            <Style x:Key="labelStyle"
               TargetType="Label">
                <Setter Property="FontSize" 
                    Value="Medium" />
                <Setter Property="Margin" 
                    Value="0,0,0,0" />
                <Setter Property="FontAttributes" 
                    Value="Bold" />
                <Setter Property="TextColor" Value="White" />
                <Style.Triggers>
                    <DataTrigger TargetType="Label"
                                 Binding="{Binding isWeatherConditionChecked}"
                                 Value="True">
                        <Setter Property="TextColor" Value="{Binding labelStyleTextColor}" />
                    </DataTrigger>
                </Style.Triggers>
            </Style>
        </ResourceDictionary>
    </ContentPage.Resources>
    
    <!--This part is only to create a sample app-->
    <StackLayout BackgroundColor="Gray">
        <Button Text="Go!" Clicked="Button_Clicked" />
        <Label x:Name="MyLabel" Text="This is a label" Style="{StaticResource labelStyle}"/>
    </StackLayout>

</ContentPage>


using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Xamarin.Forms;

namespace StyleColorChange
{
    public partial class MainPage : ContentPage
    {
        public string labelStyleTextColor { get; set; } = "White";
        private bool _isWeatherConditionChecked;
        public bool isWeatherConditionChecked
        {
            get { return _isWeatherConditionChecked; }
            set { _isWeatherConditionChecked = value; OnPropertyChanged("isWeatherConditionChecked"); }
        }
        public MainPage()
        {
            InitializeComponent();
            BindingContext = this;
        }
        private void Button_Clicked(object sender, EventArgs e)
        {            
            labelStyleTextColor = "Black";
            isWeatherConditionChecked = !isWeatherConditionChecked;
        }
    }
}


我添加了
isWeatherConditionChecked
和
labelStyleTextColor
仅作为示例，但我想您的代码中也有类似的东西可以使用。
如果它回答了您的问题或您觉得它很有帮助，请让我知道，否则您可能会给我留下反馈/评论。