Question

I created a silverlight template control. Thouse control consist 4 elements: 2 textbox and 2 textblock.
markup (in generic.xaml):

<Style TargetType="local:InputForm">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="local:InputForm">
                    <Border Background="{TemplateBinding Background}"
                            BorderBrush="{TemplateBinding BorderBrush}"
                            BorderThickness="{TemplateBinding BorderThickness}">
                        <Grid>
                            <Grid.RowDefinitions>
                                <RowDefinition />
                                <RowDefinition />
                            </Grid.RowDefinitions>
                            <Grid.ColumnDefinitions>
                                <ColumnDefinition/>
                                <ColumnDefinition/>
                            </Grid.ColumnDefinitions>
                            <TextBlock Text="Login" Grid.Column="0" Grid.Row="0"/>
                            <TextBlock Text="Password" Grid.Column="0" Grid.Row="1"/>
                            <TextBox x:Name="LoginTextBox" Grid.Column="1" Grid.Row="0" Text="Login..."/>
                            <TextBox x:Name="PasswordTextBox" Grid.Column="1" Grid.Row="1" Text="Password..."/>
                        </Grid>
                    </Border>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

In code file I get the textbox from template and set Foreground.Opacity property equels 0.5.
code:

public class InputForm : Control
{
    private TextBox _loginTextBox;
    private TextBox _passwordTextBox;

    public InputForm()
    {
        this.DefaultStyleKey = typeof(InputForm);
    }

    public override void OnApplyTemplate()
    {
        base.OnApplyTemplate();

        _loginTextBox = this.GetTemplateChild("LoginTextBox") as TextBox;
        _passwordTextBox = this.GetTemplateChild("PasswordTextBox") as TextBox;

        SetInActive();
    }

    private void SetInActive()
    {
        _loginTextBox.Foreground.Opacity = .5;
        _passwordTextBox.Foreground.Opacity = .5;
    }
}

When I added this control in my silverlight application all textboxs element began represent text with Foreground.Opacity = 0.5
Start application:

Select “Login” tab:

Back to “Some infromation” tab:

Sample located here: http://perpetuumsoft.com/Support/silverlight/SilverlightApplicationOpacity.zip
Is it silverlight bug or I do something wrong?

Answer 1

The problem is that the Foreground property is of type Brush which is a reference type (a class).

When you assign .Opacity = 0.5 you are changing the opacity value of the referenced Brush. All other elements that are referencing the same brush will be affected.

Ordinarily we would use a Storyboard in VisualStateManager in the control template to specify the visual appearance of a control in different “states”.

However a quick fix for your code would be:

private void SetInActive()     
{     
    Brush brush = new SolidColorBrush(Colors.Black) { Opacity = 0.5 };
    _loginTextBox.Foreground = brush    
    _passwordTextBox.Foreground= brush
}