如何将 ResourceDictionary 样式应用于代码隐藏文件中的控件

Question

我在自己的文件中有如下定义的 ResourceDictionary：

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

<Style x:Key="labelStyle">
        <Setter Property="Label.Foreground" Value="#8860D0"/>
    </Style>

</ResourceDictionary>

在我的代码隐藏文件中，我有一个标签列表，其中包含一些标签控件。

private List<Label> labels;

有什么方法可以将 ResourceDisctionary 中的样式应用于我的所有标签？到目前为止，我已经做到了这一点，但没有应用样式：

ResourceDictionary skin = Application.LoadComponent(new Uri("BrightTheme.xaml", UriKind.Relative)) as ResourceDictionary;
            Resources.MergedDictionaries.Add(skin);

            for (int i = 0; i < labels.Count; i++)
            {
                labels[i].Style = (Style)skin["labelStyle"];
            }

Answer 1

正如我在回答之前的评论中所说，如果最终目标是主题化，那么您的标签是由程序自动生成还是在 xaml 中硬编码都没有关系。您想要采取的方法是交换您的 ResourceDictionary 主题，看起来您正在尝试这样做，尽管我看到您只是添加而不是删除。

另外，您不需要将每个标签的样式设置为键。因为要由 ResourceDictionary 来应用 Label 的整体样式。

这是一个例子：

Dictionary1.xaml：这是一个主题。请注意，第二种样式是将 labelStyle 应用于所有标签的样式

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <Style x:Key="labelStyle" TargetType="Label">
        <Setter Property="Foreground" Value="#8860D0"/>
    </Style>
    <Style TargetType="{x:Type Label}" BasedOn="{StaticResource labelStyle}"/>
</ResourceDictionary>

Dictionary2.xaml：这是另一个主题

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:local="clr-namespace:ApplyLabelStyleOnUserControl">
    <Style x:Key="labelStyle" TargetType="Label">
        <Setter Property="Foreground" Value="DarkGreen"/>
    </Style>
    <Style TargetType="{x:Type Label}" BasedOn="{StaticResource labelStyle}"/>
</ResourceDictionary>

MainWindow.xaml

    <Grid>
        <StackPanel>
            <Button Content="Swap Theme" Click="Button_Click" Margin="15"/>
            <local:UserControl1 x:Name="userControl1" Margin="5"/>
        </StackPanel>
    </Grid

MainWindow.xaml.cs

        private bool useSecondTheme;

        public MainWindow()
        {
            InitializeComponent();
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            useSecondTheme = !useSecondTheme;
            userControl1.SwapTheme(useSecondTheme);
        }

UserControl1.xaml

    <Grid>
        <StackPanel>
            <ListBox ItemsSource="{Binding MyLabels}">
                <ListBox.ItemContainerStyle>
                    <Style TargetType="ListBoxItem">
                        <Setter Property="Template">
                            <Setter.Value>
                                <ControlTemplate TargetType="ListBoxItem">
                                    <Border>
                                        <Label Margin="5" Content="{Binding}"/>
                                    </Border>
                                </ControlTemplate>
                            </Setter.Value>
                        </Setter>
                    </Style>
                </ListBox.ItemContainerStyle>
            </ListBox>
            <Button Click="Button_Click" Content="Add Random Label" Margin="5"/>
        </StackPanel>
    </Grid>

UserControl1.xaml.cs：具体看SwapTheme

using System;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Linq;
using System.Windows;
using System.Windows.Controls;

namespace ApplyLabelStyleOnUserControl
{
    /// <summary>
    /// Interaction logic for UserControl1.xaml
    /// </summary>
    public partial class UserControl1 : UserControl, INotifyPropertyChanged
    {
        private ObservableCollection<string> myLabels;

        public ObservableCollection<string> MyLabels
        {
            get
            {
                if (this.myLabels == null)
                    this.myLabels = new ObservableCollection<string>();
                return this.myLabels;
            }
        }
        private static Random random = new Random();
        public string RandomString(int length)
        {
            const string chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
            return new string(Enumerable.Repeat(chars, length)
              .Select(s => s[random.Next(s.Length)]).ToArray());
        }

        public UserControl1()
        {
            InitializeComponent();
            this.DataContext = this;
            this.Loaded += OnLoaded;
        }

        private void OnLoaded(object sender, RoutedEventArgs e)
        {
            // Initialize it with 5 random strings, but allow more labels to be added with a button on the UI.
            MyLabels.Add(RandomString(25));
            MyLabels.Add(RandomString(25));
            MyLabels.Add(RandomString(25));
            MyLabels.Add(RandomString(25));
            MyLabels.Add(RandomString(25));
        }

        public event PropertyChangedEventHandler PropertyChanged;

        /// <summary>
        /// Swaps between two themes
        /// </summary>
        /// <param name="useSecondTheme">when true it uses Dictionary2.xaml resource dictionary, otherwise it uses Dictionary1.xaml</param>
        internal void SwapTheme(bool useSecondTheme)
        {
            if (useSecondTheme)
            {
                // Remove the old theme
                ResourceDictionary oldSkin = Application.LoadComponent(new Uri("Dictionary1.xaml", UriKind.Relative)) as ResourceDictionary;
                Resources.MergedDictionaries.Remove(oldSkin);

                // Add the new theme
                ResourceDictionary newSkin = Application.LoadComponent(new Uri("Dictionary2.xaml", UriKind.Relative)) as ResourceDictionary;
                Resources.MergedDictionaries.Add(newSkin);
            }
            else
            {
                // Remove the old theme
                ResourceDictionary oldSkin = Application.LoadComponent(new Uri("Dictionary2.xaml", UriKind.Relative)) as ResourceDictionary;
                Resources.MergedDictionaries.Remove(oldSkin);

                // Add the new theme
                ResourceDictionary newSkin = Application.LoadComponent(new Uri("Dictionary1.xaml", UriKind.Relative)) as ResourceDictionary;
                Resources.MergedDictionaries.Add(newSkin);
            }
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            MyLabels.Add(RandomString(25));
        }
    }
}

每当我点击“交换主题”按钮时，它都会在我定义的两个 ResourceDictionaries 之间切换：

Answer 2

尝试创建一个实际的ResourceDictionary 并设置它的Source 而不是调用Application.LoadComponent：

ResourceDictionary skin = new ResourceDictionary() 
{ 
    Source = new Uri("BrightTheme.xaml", UriKind.Relative) 
};

for (int i = 0; i < labels.Count; i++)
{
    labels[i].Style = (Style) skin["labelStyle"];
}