以编程方式更改WPF样式的颜色

Question

First off, I have somewhat accomplished what I am about to ask creating different styles with different Foreground/Background colors (for example) and then in the code doing either

Control.Style = new_style

or

this.Resources["MyStyle"] = new_style

I was happy with that until I hit an issue w/ the ComboBox control where I was wanting to programmatically change the color of the arrow on the dropwdown button. This appears to get into Control Template changes to set that so I decided to approach my colors changes from another route -- setting the color values within the Style or Control Template using Binding. So I created a test program starting simple and planning to workup to the Control Template changes but I have yet to get "simple" working. My test program consists of a Textbox and a Button and I am trying to change the foreground color within the text box. The basic XML code is (less some lines):

<Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:Themes="clr-namespace:Microsoft.Windows.Themes;assembly=PresentationFramework.Aero" x:Class="ColorTest4.MainWindow"
        Title="MainWindow" Height="350" Width="525">
    <Window.Resources>
        <SolidColorBrush x:Key="FGColor" Color="{Binding fgColor}"/>
    </Window.Resources>
    <Grid>
        <TextBox HorizontalAlignment="Left" Height="23" Margin="10,10,0,0" TextWrapping="Wrap" Text="TextBox" VerticalAlignment="Top" Width="120" Style="{DynamicResource TextBoxStyle1}">
            <TextBox.Resources>
                <LinearGradientBrush x:Key="TextBoxBorder" EndPoint="0,20" MappingMode="Absolute" StartPoint="0,0">
                    <GradientStop Color="#ABADB3" Offset="0.05"/>
                    <GradientStop Color="#E2E3EA" Offset="0.07"/>
                    <GradientStop Color="#E3E9EF" Offset="1"/>
                </LinearGradientBrush>
                <Style x:Key="TextBoxStyle1" BasedOn="{x:Null}" TargetType="{x:Type TextBox}">
                    <Setter Property="Foreground" Value="{DynamicResource FGColor}"/>
                    <Setter Property="Background" Value="{DynamicResource {x:Static SystemColors.WindowBrushKey}}"/>
                    <Setter Property="BorderBrush" Value="{StaticResource TextBoxBorder}"/>
                    <!--<Some Setter Properties & Style.Triggers removed for conciseness >-->
                </Style>
            </TextBox.Resources>
        </TextBox>
        <Button Content="Button" HorizontalAlignment="Left" Margin="433,10,0,0" VerticalAlignment="Top" Width="75"/>
    </Grid>
</Window>

Then in the code I have:

private Color pvColor = Colors.Green;
private Color fgColor
{
    get { MessageBox.Show("fgColor");  return pvColor; }
}

The idea being that if I want to change the foreground color, pvColor just needs to change within the program.

For whatever reason this is not working. I am hoping I am just overlooking something simple in the code that I have yet to see/find. If I define fgColor in the Window.Resources as below, that works -- I get Pink text:

<Window.Resources>
    <SolidColorBrush x:Key="FGColor" Color="Pink"/>
</Window.Resources>

Any ideas or direction would be greatly appreciate.

Thanks

Update 1: I updated the code snippet to reflect the use of Color rather than Brush. I have also tried Frank J's INotifyPropertyChanged option and also the Dependence Property option but neither have worked yet. The Dependence Property complained that Color was not nullable.

Answer 1

-- Update

I looked at your code again.

The problem that you have is that the color of the SolidColorBrush is changing but not the ressource itself and therefore the change doesn't get propagated.

2 possible solutions:

1) You can change the requirement from having a property set the the brushes color to make the change to changing the ressource itself which will propagate the DynamicResource change (Press the button to see the switch):

<Window x:Class="SOTextBoxForeground.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:SOTextBoxForeground"
    Title="MainWindow" Height="350" Width="525" Name="MyWindow">
<Window.Resources>
      <SolidColorBrush x:Key="FGColor" Color="Green"/>
   </Window.Resources>
   <Grid>
      <Grid.Resources>
         <Style x:Key="TextBoxStyle1" BasedOn="{StaticResource {x:Type TextBox}}" TargetType="{x:Type TextBox}">
            <Setter Property="Foreground" Value="{DynamicResource FGColor}"/>
         </Style>
      </Grid.Resources>
      <TextBox HorizontalAlignment="Left" Height="23" Margin="10,10,0,0" TextWrapping="Wrap" Text="TextBox" VerticalAlignment="Top" Width="120" Style="{StaticResource TextBoxStyle1}" />
      <Button Content="Button" HorizontalAlignment="Left" Margin="433,10,0,0" VerticalAlignment="Top" Width="75" Click="Button_Click"/>
   </Grid>
</Window>

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        this.Resources["FGColor"] = new SolidColorBrush(Colors.Blue);
    }
}

2) Alternatively you bind the styles Foreground directly to the variable via the converter instead of going through the Ressource (again press the button to see the change):

<Window x:Class="SOTextBoxForeground.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:SOTextBoxForeground"
        Title="MainWindow" Height="350" Width="525" Name="MyWindow">
      <Window.Resources>
      <local:ColorToSolidColorBrushConverter x:Key="ColorToSolidColorBrushConverter" />
   </Window.Resources>
   <Grid>
      <Grid.Resources>
         <Style x:Key="TextBoxStyle1" BasedOn="{StaticResource {x:Type TextBox}}" TargetType="{x:Type TextBox}">
            <Setter Property="Foreground" Value="{Binding ElementName=MyWindow, Path=pvColor, Converter={StaticResource ColorToSolidColorBrushConverter}}"/>
         </Style>
      </Grid.Resources>
      <TextBox HorizontalAlignment="Left" Height="23" Margin="10,10,0,0" TextWrapping="Wrap" Text="TextBox" VerticalAlignment="Top" Width="120" Style="{StaticResource TextBoxStyle1}" />
      <Button Content="Button" HorizontalAlignment="Left" Margin="433,10,0,0" VerticalAlignment="Top" Width="75" Click="Button_Click"/>
   </Grid>
</Window>

public class ColorToSolidColorBrushConverter : IValueConverter
{

  public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
  {
     Color? desiredColor = value as Color?;
     if (desiredColor != null)
     {
        return new SolidColorBrush(desiredColor.Value);
     }

     //Return here your default
     return DependencyProperty.UnsetValue;
  }

  public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
  {
     return DependencyProperty.UnsetValue;
  }
}

public partial class MainWindow : Window
{
    public static readonly DependencyProperty pvColorProperty = DependencyProperty.Register("pvColor",
    typeof(Color?), typeof(MainWindow),
    new PropertyMetadata(Colors.Red));

    public Color? pvColor
    {
        get { return (Color?)GetValue(pvColorProperty); }
        set { SetValue(pvColorProperty, value); }
    }

    public MainWindow()
    {
        InitializeComponent();
    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        this.pvColor = Colors.Blue;
    }
}

public class ColorToSolidColorBrushConverter : IValueConverter
{

    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        Color? desiredColor = value as Color?;
        if (desiredColor != null)
        {
            return new SolidColorBrush(desiredColor.Value);
        }

        //Return here your default
        return DependencyProperty.UnsetValue;
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        return DependencyProperty.UnsetValue;
    }
}

For both solutions change the namespace accordingly in the code.

Answer 2

SolidColorBrush.Color expects a Color not another Brush .

private Color pvColor = Colors.Green;
public Color fgColor
{
    get { return pvColor; }
    set
    {
        pvColor = value;
        this.OnPropertyChanged("fgColor"); // Make sure you have INotifyPropertyChanged implemented
    }
}