与动态资源一起使用时出现前台问题

Question

对于我的自定义控件，我正在使用动态资源来设置 Foreground 属性。最初，当我运行应用程序时，前景属性未设置为我的控件。当我动态更改值时，前景已正确应用。如何解决此问题？

PS：简单的示例 Wpf应用程序4

MainWindow.xaml

<Window x:Class="WpfApplication4.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="MainWindow"
    Width="300"
    Height="200">
<Window.Resources>
    <SolidColorBrush x:Key="ForegroundBrush" Color="Red" />
    <SolidColorBrush x:Key="BackgroundBrush" Color="Yellow" />
    <Style x:Key="MyStyle" TargetType="ContentControl">
        <Setter Property="Foreground" Value="{DynamicResource ForegroundBrush}" />
        <Setter Property="Background" Value="{DynamicResource BackgroundBrush}" />
    </Style>
</Window.Resources>
<Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="Auto" />
        <RowDefinition Height="*" />
    </Grid.RowDefinitions>
    <StackPanel>
        <Button Click="ButtonBase_OnClick" Content="Create and Add Custom Control With Style" />
        <Button Click="ButtonBase_OnClick_1" Content="Change Color" />
    </StackPanel>
    <StackPanel x:Name="myPanel" Grid.Row="1" />
</Grid>

MainWindow.xaml.cs

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }
    private void ButtonBase_OnClick(object sender, RoutedEventArgs e)
    {
        var control = new MyControl {Style = this.Resources["MyStyle"] as Style};
        control.CreateContent(string.Format("My Control {0}", myPanel.Children.Count + 1));
        myPanel.Children.Add(control);
    }
    private void ButtonBase_OnClick_1(object sender, RoutedEventArgs e)
    {
        var brush = (SolidColorBrush)Resources["ForegroundBrush"];
        Resources["ForegroundBrush"] = new SolidColorBrush(Color.Add(brush.Color, Color.FromRgb(0, 100, 100)));
        var brush1 = (SolidColorBrush)Resources["BackgroundBrush"];
        Resources["BackgroundBrush"] = new SolidColorBrush(Color.Add(brush1.Color, Color.FromRgb(0, 100, 100)));
    }
}
public class MyControl : ContentControl
{
    public MyControl()
    {
        DefaultStyleKey = typeof(MyControl);
    }
    public void CreateContent(string text)
    {
        this.Content = new TextBlock() {Text = text};
    }
}

通用.xaml

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                xmlns:local="clr-namespace:WpfApplication4">
<Style TargetType="local:MyControl">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="local:MyControl">
                <Border Background="{TemplateBinding Background}">
                    <ContentPresenter Content="{TemplateBinding Content}" />
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

Answer 1

如果要将Style应用于控件，则必须将Style应用于该控件（在提供的代码示例中尚未执行此操作）。你在这里有两个选择...请尝试以下操作（无论在哪里使用该控件）：

<local:MyControl Style="{StaticResource MyStyle}" />

或者像这样定义Style，这将影响范围内控件的所有实例：

<Style TargetType="ContentControl">
    <Setter Property="Foreground" Value="{DynamicResource ForegroundBrush}" />
    <Setter Property="Background" Value="{DynamicResource BackgroundBrush}" />
</Style>