How to make a semi-transparent background image on xamarin - xamarin.forms

Question

I have to opacify (make semi-transparent) the background image with a colored veil, I tried adding a frame but I don't get the desired effect`
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:d="http://xamarin.com/schemas/2014/forms/design"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:viewmodels="clr-namespace:GET_SOUND_V2.ViewModels" x:DataType="viewmodels:LoginViewModel"
mc:Ignorable="d"
x:Class="GET_SOUND_V2.Views.LoginPage"
BackgroundImage="maco.jpg">
<ContentPage.Content>
<Frame BorderColor="Transparent" Opacity="0.7">
<Frame.Background>
<LinearGradientBrush StartPoint="0,0"
EndPoint="1,0">
<GradientStop Color="#1d57a8"
Offset="0.1"/>
<GradientStop Color="#1d57a8"
Offset="1.0"/>
</LinearGradientBrush>
</Frame.Background>
<StackLayout Orientation="Vertical" Padding="30" Spacing="40">
<BoxView HeightRequest="30"/>
<StackLayout Orientation="Vertical">
<Entry x:Name="txtUserName" Text="{Binding UserName}" HorizontalTextAlignment="Center" Placeholder="UserName"
PlaceholderColor="White" HeightRequest="40"
Keyboard="Email"
TextColor="White"
Focused="BiometricCredentials" />
<Entry x:Name="txtPassword" Text="{Binding Password}" HorizontalTextAlignment="Center" Placeholder="Password"
PlaceholderColor="White" HeightRequest="40"
IsPassword="True"
TextColor="White"/>
</StackLayout>
<Button Command="{Binding SubmitCommand}" Text="Accedi" TextColor="White" CornerRadius="50"
FontAttributes="Bold" FontSize="Large" HorizontalOptions="FillAndExpand" VerticalOptions="EndAndExpand"
Margin="0,0,0,150" BackgroundColor="#EF7F1A" />
</StackLayout>
</Frame>
</ContentPage.Content>
</ContentPage>
I would like the elements, however, not to be affected by the opacity value (still be fully opaque), any advice on how I could do?

Answer 1

One approach is to "overlay" two elements over each other, using a single-cell Grid.
The "underneath" item is the image (with opacity applied).
The "top" item is the rest of your layout.
.
<Grid>
<Frame ...>
...
</Frame>
<StackLayout ...>
...
</StackLayout>
</Grid>
Notice that StackLayout is no longer inside Frame. Because no Grid.Row or Grid.Column is specified on these two elements, they both are at Row=0, Column=0. Hence, overlaid one on top of the other.
May need to add properties to <Grid> element, to get desired size, etc. But start with what I show, see what happens.