Create properties that only apply on design time - wpf

Question

I am using visual studio dark theme. As a result when designing my views I cannot see the font if its black. A fix will be to set the background of the view to white. But our application has different themes so I cannot hard code that.
There are to great properties that I use when creating an usercontrol:
d:DesignWidth="1110" d:DesignHeight="400"
those properties are only affecting the view at design time. It will be great if I can create a property d:DesignBackground just so that I do not have to be adding and removing the background property every time I run the application.

Answer 1

Not sure if it's exactly what you're looking for, but what I do is just plop a trigger in the app.xaml to invoke using the IsInDesignMode property like;
Namespace (Thanks Tono Nam);
xmlns:componentModel="clr-namespace:System.ComponentModel;assembly=PresentationFramework"
XAML;
<Style TargetType="{x:Type UserControl}">
<Style.Triggers>
<Trigger Property="ComponentModel:DesignerProperties.IsInDesignMode"
Value="True">
<Setter Property="Background"
Value="#FFFFFF" />
</Trigger>
</Style.Triggers>
</Style>
Simple, but works, and sometimes I target other dependency properties like font and stuff too depending on the need. Hope this helps.
PS - You can target other TargetType's with their own properties the same way, like for example, ChildWindows, Popups, Windows, whatever...

Answer 2

You can create a static class with an attached property for design mode:
using System;
using System.ComponentModel;
using System.Diagnostics;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
namespace Helpers.Wpf
{
public static class DesignModeHelper
{
private static bool? inDesignMode;
public static readonly DependencyProperty BackgroundProperty = DependencyProperty
.RegisterAttached("Background", typeof (Brush), typeof (DesignModeHelper), new PropertyMetadata(BackgroundChanged));
private static bool InDesignMode
{
get
{
if (inDesignMode == null)
{
var prop = DesignerProperties.IsInDesignModeProperty;
inDesignMode = (bool) DependencyPropertyDescriptor
.FromProperty(prop, typeof (FrameworkElement))
.Metadata.DefaultValue;
if (!inDesignMode.GetValueOrDefault(false) && Process.GetCurrentProcess().ProcessName.StartsWith("devenv", StringComparison.Ordinal))
inDesignMode = true;
}
return inDesignMode.GetValueOrDefault(false);
}
}
public static Brush GetBackground(DependencyObject dependencyObject)
{
return (Brush) dependencyObject.GetValue(BackgroundProperty);
}
public static void SetBackground(DependencyObject dependencyObject, Brush value)
{
dependencyObject.SetValue(BackgroundProperty, value);
}
private static void BackgroundChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
if (!InDesignMode)
return;
d.SetValue(Control.BackgroundProperty, e.NewValue);
}
}
}
And you can use it like this:
xmlns:wpf="clr-namespace:Helpers.Wpf;assembly=Helpers.Wpf"
<Grid Background="Black"
wpf:DesignModeHelper.Background="White">
<Button Content="Press me!"/>
</Grid>
You can use this approach to implement other property for design mode.

Answer 3

In 2022 you actually can and almost guessed it:
d:Background="White"
Note you can set pretty much any other control properties differently for design-time when prefix them with d:, for example:
<TextBlock Text="{Binding TextFromViewModel}"
Foreground="{StaticResource PrimaryBrush}"
d:Text="Design-time text"
d:Foreground="Black" />
Source: Use Design Time Data with the XAML Designer in Visual Studio