how can I change font color during runtime in wpf?

I am using VS2010 - WPF - C# and I am building a securities ticker that show some values to the user in a listview.

My listview looks like this:

<ListView Height="325" Margin="开发者_如何学Go8,8,8,0" x:Name="listView1" VerticalAlignment="Top" BorderThickness="3" FontWeight="Bold" FontSize="12" Foreground="White" Background="{x:Null}" BorderBrush="{x:Null}" Style="{DynamicResource ListViewStyle1}">
  <ListView.View>
    <GridView>
      <GridViewColumn Header="name" DisplayMemberBinding="{Binding company_name}" Width="200" />
      <GridViewColumn Header="symbol" DisplayMemberBinding="{Binding symbol}" Width="50" />
      <GridViewColumn Header="price"  DisplayMemberBinding="{Binding price}" Width="75" />
      <GridViewColumn Header="percent " DisplayMemberBinding="{Binding change_percent}" Width="50" />
    </GridView>
  </ListView.View>
</ListView>

I would like some rows in my listview to be coloured in red, others in green, depending on the percent value at runtime, but I don't know how.

Best Regards

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To do what you're looking for, H.B's answer is it.

However consider this from a usability standpoint. Some people are colour-blind and will find certain font/background colour combinations difficult or impossible to read. You might be better considering having a colour ellipse in a new first column, and keeping the standard background/foreground colours as per the users' selections in Windows. The approach to setting the background brush of the ellipse would be the same as H.B's answer for the font.

Even for people who aren't colour-blind, trying to read bright green text on a white background might be challenging (imagine those people sat with a window behind them, for example).

Just a thought.

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Bind the Foreground of your control to the change_percent and use a ValueConverter to turn it into a Brush.

Here would be a basic converter which changes from red to yellow to green:

public class PercentToBrushConverter : IValueConverter
{
    //http://stackoverflow.com/questions/3722307/is-there-an-easy-way-to-blend-two-system-drawing-color-values/3722337#3722337
    private Color Blend(Color color, Color backColor, double amount)
    {
        byte r = (byte)((color.R * amount) + backColor.R * (1 - amount));
        byte g = (byte)((color.G * amount) + backColor.G * (1 - amount));
        byte b = (byte)((color.B * amount) + backColor.B * (1 - amount));
        return Color.FromRgb(r, g, b);
    }

    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        //Assumes the percent property to be an int.
        int input = (int)value;
        Color red = Colors.Red;
        Color yellow = Colors.Yellow;
        Color green = Colors.Green;
        Color color;
        if (input <= 50)
        {
            color = Blend(yellow, red, (double)input/50);
        }
        else
        {
            color = Blend(green, yellow, (double)(input - 50) / 50);
        }
        return new SolidColorBrush(color);
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        throw new NotSupportedException();
    }
}

Which you could use like this:

<ListView>
    <ListView.Resources>
        <vc:PercentToBrushConverter x:Key="PercentToBrushConverter"/>
    </ListView.Resources>
    <ListView.View>
        <GridView>
            <GridViewColumn Header="Progress">
                <GridViewColumn.CellTemplate>
                    <DataTemplate>
                        <StackPanel Orientation="Horizontal">
                            <!-- An indicator ellipse as suggested by Neil Barnwell -->
                            <Ellipse Height="16" Width="16" Fill="{Binding change_percent, Converter={StaticResource PercentToBrushConverter}}"/>
                            <TextBlock Margin="5,0,0,0" Text="{Binding change_percent}"/>
                        </StackPanel>
                    </DataTemplate>
                </GridViewColumn.CellTemplate>
            </GridViewColumn>
            <!-- ... -->
        </GridView>
    </ListView.View>
</ListView>

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How to do the xmlns declaration:

You need to define the class in some namespace:

namespace MySolution.ValueConverters
{
    public class PercentToBrushConverter : IValueConverter { /*...*/ }
}

This namespace can be mapped in the Window or any other parent control:

<Window ...
    xmlns:vc="clr-namespace:MySolution.ValueConverters">

This maps the MySolution.ValueConverters namespace to the vc prefix. For some more reference see MSDN.