方法1：两个层，内层与外层用背景颜色差，padding设置边框
<StackLayout BackgroundColor="White"> <StackLayout BackgroundColor="Black" Padding="1"> <Editor BackgroundColor="White" /> </StackLayout> ... </StackLayout>
方法2：Frame 可以套在外面设置边框也可以设置圆边
1 <Frame Grid.Row="1" MinimumHeightRequest="200" BorderColor="Black" CornerRadius="20" HasShadow="True" BackgroundColor="#cfe2f3"> 2 <StackLayout BackgroundColor="Transparent" VerticalOptions="FillAndExpand"> 3 <radialView:RadialProgressView VerticalOptions="FillAndExpand" BindingContext="{Binding radialProgressViewModel}" /> 4 <Label FontSize="Large" Text="实时数据" TextColor="#3399CC" VerticalOptions="End" HorizontalTextAlignment="Center"></Label> 5 </StackLayout> 6 </Frame>
原文：https://www.cnblogs.com/Xamarin-Oz/p/11069183.html