<Viewbox x:Key="A_Name">
// blahh...
</Viewbox>
app.xaml
<Application.Resources>
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<!--Reference xaml file-->
<ResourceDictionary Source="/Resources/Example.xaml" />
</ResourceDictionary.MergedDictionaries>
</ResourceDictionary>
</Application.Resources>
步骤2
YourPage.xaml 中的按钮
<Button Content="{StaticResource Image_KeyName_In_Referenced_XAML_File}" />