how to insert a background image in a grid of Xamarin forms pcl

Question

I need to put a background to a grid, a PNG image. I can not find concrete solutions online, you can add it from xaml? or necessarily must act through c #?

Thank you.

    <StackLayout VerticalOptions="FillAndExpand" x:Name="allContent" HorizontalOptions="FillAndExpand" Orientation="Vertical" Spacing="0">    
<Grid Grid.Row="1">
              <Grid.ColumnDefinitions>
                <ColumnDefinition Width="2*"></ColumnDefinition>
                <ColumnDefinition Width="6*"></ColumnDefinition>
                <ColumnDefinition Width="2*"></ColumnDefinition>
              </Grid.ColumnDefinitions>
              <Grid.RowDefinitions>
                <RowDefinition Height="1*"></RowDefinition>
                <RowDefinition Height="2*"></RowDefinition>
                <RowDefinition Height="2*"></RowDefinition>
                <RowDefinition Height="2*"></RowDefinition>
                <RowDefinition Height="2*"></RowDefinition>
              </Grid.RowDefinitions>
              <ActivityIndicator x:Name="loading" Grid.Row="0" Grid.Column="1" IsVisible="false" Color="#008ECC" IsRunning="true" />
              <Label TextColor="#fff" Grid.Row="1" Grid.Column="1" Text="" />
              <Entry FontSize="24" Grid.Row="1" Grid.Column="1" Placeholder="Username" x:Name="UsernameEntry" Text="" />
              <Label TextColor="#fff" Grid.Row="2" Grid.Column="1" Text="" />
              <Entry FontSize="24" Grid.Row="2" Grid.Column="1" Placeholder="Password" IsPassword="True" x:Name="PasswordEntry" Text="" />
              <Button x:Name="LoginButton" Grid.Row="3" Grid.Column="1" Text="Accedi" Clicked="Login_OnClicked"/>
              <Label TextColor="#fff" Text="Ricorda accesso" Grid.Row="3" Grid.Column="1"></Label>
              <Switch x:Name="switchRememberPassword" Grid.Row="4" Grid.Column="1"></Switch>              
              <Label x:Name="recuperaPassword" Grid.Row="4" Grid.Column="1" TextColor="#fff" Text="Recupera credenziali di accesso" FontSize="12"></Label>
            </Grid>
</StackLayout>

Answer 1

You can add it as a child of your Grid, and add the properties Grid.ColumnSpan and Grid.RowSpan to span to all your grid. For example:

     <Grid>
        <Image HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand" Aspect="AspectFill" Source="" Grid.Row="6" Grid.Column="4" Grid.RowSpan="2" Grid.ColumnSpan="2"/>
            <!-- My other properties here code here-->
     </Grid>

(Also if your Grid is on a ContentPage and it occupies the full screen you can use the property BackgroundImage of your page)

Answer 2

<RelativeLayout>
<Image Aspect="Fill" Source="Jupiter.png" Opacity="0.3"
            RelativeLayout.WidthConstraint=
              "{ConstraintExpression Type=RelativeToParent, Property=Width}"
            RelativeLayout.HeightConstraint=
              "{ConstraintExpression Type=RelativeToParent, Property=Height}"/>
<Grid RelativeLayout.WidthConstraint=
          "{ConstraintExpression Type=RelativeToParent, Property=Width}"
        RelativeLayout.HeightConstraint=
          "{ConstraintExpression Type=RelativeToParent, Property=Height}">

  <Label Text="Hello world from XAML" VerticalOptions="Center"
     HorizontalOptions="Center" FontSize="30"/>
</Grid>