How to Create a curved header layout and making a button that overlaps the header???

Here im using stacklayout as header,How to create a curved header layout?????

<Grid.RowDefinitions>


</Grid.RowDefinitions>

  <!-- header background -->
        <StackLayout Grid.Row="0" BackgroundColor="White">
            <Grid ColumnSpacing="0" RowSpacing="0">
                <Grid.RowDefinitions>
                    <RowDefinition Height="Auto"/>
                    <RowDefinition Height="Auto"/>
                </Grid.RowDefinitions>
                <StackLayout Grid.Row="0" HorizontalOptions="Center" VerticalOptions="Start"  Padding="0,50,0,00">
                    <Label Text="Name" HorizontalOptions="Start"/>
                    <Entry Placeholder="Enter Your Name" HorizontalOptions="Center" HorizontalTextAlignment="Center" />
                </StackLayout>
                <StackLayout Grid.Row="1" HorizontalOptions="Center" VerticalOptions="Start" Padding="0,50,0,00">
                    <Label Text="Place" HorizontalOptions="Start"/>
                    <Entry Placeholder="place" HorizontalOptions="Center" HorizontalTextAlignment="Center"  />
                </StackLayout>
            </Grid>
        </StackLayout>

  <Image Source="ProfilePic.jpg" Margin="0,0,0,-50" HeightRequest="50" WidthRequest="50" HorizontalOptions="Center" VerticalOptions="EndAndExpand"/>

Sample output will be like this...