Using WPF background from resource dictionary

Question

My WPF application has several windows and I want to use the same background image for all of them. I've defined the bitmap and image brush in a resource dictionary as follows.

<BitmapImage x:Key="BackgroundImage" UriSource="/Resources/BackPlate.png"/>
<ImageBrush x:Key="BackgroundBrush" ImageSource="{StaticResource BackgroundImage}" TileMode="Tile" ViewportUnits="Absolute" Viewport="0,0,128,128"/>

When I set the background property in the Window description, the background changes successfully in Visual Studio, but when I run the application, I get a parsing exception, I assume because the window resources haven't actually been read yet?

<Window x:Class="MyApp.Test"
...
    Background="{StaticResource BackgroundBrush}">
<Window.Resources>
...

Is there another way to specify the background after the resources have been read? I've tried the Window.Background approach, but I can't figure out how to get it to work w/o specifying the whole image brush definition.

 <Window.Background>
    <ImageBrush ?>
</Window.Background>

Is there a way to specify the image brush by reference when using this approach?

Have you tried a Style Template with the background added to it to be inherited to each instance? What's the exception you get? — Chris W.
The exception is "A first chance exception of type 'System.Windows.Markup.XamlParseException' occurred in PresentationFramework.dll Additional information: 'Provide value on 'System.Windows.StaticResourceExtension' threw an exception.' Line number '5' and line position '35'." — user7134019

mm8 mm8 · Accepted Answer · 2017-03-14T19:19:10

It should work provided that you merge the ResourceDictionary into your App.xaml file:

<Application x:Class="WpfApp1.App"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:local="clr-namespace:WpfApp1"
             StartupUri="MainWindow.xaml">
    <Application.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <ResourceDictionary Source="YourResourceDictionary.xaml" />
            </ResourceDictionary.MergedDictionaries>
        </ResourceDictionary>
    </Application.Resources>
</Application>

Using WPF background from resource dictionary

1 Answers