Xamarin Forms Frame not expanding with content - user-interface

Question

I'm new to Xamarin Forms, and I've met my first challenge. I want a Frame around my Stacklayout within a Listview. When the user selects an item in the Listview I want some controls to appear. This works fine without the Frame, but the Frame does not expand when the controls appear. How can I change or get around this behavior?
Code below.
XAML:
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:local="clr-namespace:MVVMTest"
x:Class="MVVMTest.MainPage">
<StackLayout>
<ListView HasUnevenRows="True" SelectedItem="{Binding SelectedViewItem, Mode=TwoWay}" ItemsSource="{Binding Items}" >
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Frame BackgroundColor="White" BorderColor="Black">
<StackLayout>
<Label Text="{Binding Name}"></Label>
<Entry Text="{Binding Details}" IsVisible="{Binding ShowDetails}"></Entry>
</StackLayout>
</Frame>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackLayout>
XAML.cs
namespace MVVMTest
{
public partial class MainPage : ContentPage
{
public MainPage()
{
BindingContext = new ViewModel()
{
Items = new List<ViewModelItem>()
{
new ViewModelItem()
{
Name = "Test",
Details = "details"
},
new ViewModelItem()
{
Name = "Test2",
Details = "details2"
}
}
};
InitializeComponent();
}
}
}
Model:
namespace MVVMTest
{
public class ViewModel : INotifyPropertyChanged
{
private ViewModelItem _selectedViewItem;
private List<ViewModelItem> _items;
public event PropertyChangedEventHandler PropertyChanged;
void OnPropertyChanged([CallerMemberName] string propertyName = "")
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
public ViewModelItem SelectedViewItem
{
get
{
return _selectedViewItem;
}
set
{
_selectedViewItem = value;
OnPropertyChanged();
if (value != null)
{
value.ShowDetails = !value.ShowDetails;
SelectedViewItem = null;
}
}
}
public List<ViewModelItem> Items
{
get
{
return _items;
}
set
{
_items = value;
OnPropertyChanged();
}
}
public ViewModel()
{
}
}
public class ViewModelItem : INotifyPropertyChanged
{
private bool _showDetails;
private string _details;
private string _name;
public event PropertyChangedEventHandler PropertyChanged;
void OnPropertyChanged([CallerMemberName] string propertyName = "")
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
public string Name
{
get
{
return _name;
}
set
{
_name = value;
OnPropertyChanged();
}
}
public bool ShowDetails
{
get
{
return _showDetails;
}
set
{
_showDetails = value;
OnPropertyChanged();
}
}
public string Details
{
get
{
return _details;
}
set
{
_details = value;
OnPropertyChanged();
}
}
}
}

Answer 1

I ended up using the PropertyChanged event to react to when the ListView was displayed or hidden. In the eventhandler, I set the HeightRequest of the Frame and this forces it to resize itself.
Alternative solution/help can be found here:
https://forums.xamarin.com/discussion/comment/366577
XAML:
<StackLayout>
<ListView HasUnevenRows="True" SelectedItem="{Binding SelectedViewItem, Mode=TwoWay}" ItemsSource="{Binding Items}" >
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Frame BackgroundColor="White" BorderColor="Black" Margin="2" Padding="2" VerticalOptions="FillAndExpand" HorizontalOptions="FillAndExpand">
<StackLayout>
<Label Text="{Binding Name}"></Label>
<ListView HasUnevenRows="True" Margin="2" ItemsSource="{Binding DetailObjects}" IsVisible="{Binding ShowDetails}" PropertyChanged="ListView_PropertyChanged">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Entry Text="{Binding Details}"></Entry>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackLayout>
</Frame>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackLayout>
Code behind:
public partial class MainPage : ContentPage
{
public MainPage()
{
BindingContext = new ViewModel()
{
Items = new List<ViewModelItem>()
{
new ViewModelItem()
{
Name = "Test",
DetailObjects = new List<ViewModelItemDetails>
{
new ViewModelItemDetails
{
Details = "details1"
},
new ViewModelItemDetails
{
Details = "details2"
}
}
},
new ViewModelItem()
{
Name = "Test2",
DetailObjects = new List<ViewModelItemDetails>
{
new ViewModelItemDetails
{
Details = "details1"
},
new ViewModelItemDetails
{
Details = "details2"
}
}
}
}
};
InitializeComponent();
}
private void ListView_PropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
{
if (!(sender is ListView list)) return;
if (e.PropertyName == ListView.IsVisibleProperty.PropertyName)
{
Element parent = list;
Frame frame = null;
while (frame == null && parent != null)
{
if (parent is Frame) frame = parent as Frame;
parent = parent.Parent;
}
if (list.IsVisible)
{
list.HeightRequest = list.ItemsSource.Cast<ViewModelItemDetails>().Count() * 50;
if (frame != null) frame.HeightRequest = list.HeightRequest + 50;
}
else
{
if (frame != null) frame.HeightRequest = 50;
}
}
}
}