Background image of a winrt universal application - windows-phone-8.1

Question

I have two images, one for windows phone and second for windows project. and I want these images on every page of their respective platform.
What currently I am doing is setting background from app.cs in if windows phone and if windows app code snippets.
I want any xaml method if any for this.

Answer 1

Set the background of each page to a common resource and then set that resource to your image. By default the page's background will be set to
Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
You can set the ApplicationPageBackgroundThemeBrush to an ImageBrush in your app.xaml's Resources, but since you want different images for Windows and for Windows Phone add another level of indirection. Create a ResourceDictionary of the same name in both projects and then merge that dictionary into Application.Resources.
In app.xaml:
<Application.Resources>
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="PlatformDictionary.xaml" />
</ResourceDictionary.MergedDictionaries>
</ResourceDictionary>
</Application.Resources>
Then set the actual brush in PlatformDictionary.xaml files in the Windows and Windows Phone projects. Generally you'll fall back to defaults in HighContrast modes, but if you have important information in the image you can provide a high contrast version of the image as PhonePageBackground.contrast-high.png using the contrast resource qualifiers:
<ResourceDictionary.ThemeDictionaries>
<ResourceDictionary x:Name="Default">
<ImageBrush x:Key="ApplicationPageBackgroundThemeBrush" ImageSource="Assets/PhonePageBackground.png"/>
</ResourceDictionary>
<ResourceDictionary x:Name="HighContrast">
<SolidColorBrush x:Key="ApplicationPageBackgroundThemeBrush" Color="{ThemeResource PhoneBackgroundColor}"/>
</ResourceDictionary>
</ResourceDictionary.ThemeDictionaries>
The Windows version will be the same except for your Windows page background image in the default theme and SystemColorWindowColor in the HighContrast theme.