Xamarin.Froms Frame BackgroudColor change not showing - xaml

Question

Ihave this scenario: A ListView and every Cell is a frame. When showing the list all frames backgroudcolor is white when i click on frame i want the color to change in blie. I change the color but not refreshing. This is my code:
In xaml page
<pages:PopupPage.Resources>
<local1:ChangeFrameBackgroudColor x:Key="ChangeFrameBackgroudColor" />
</ResourceDictionary>-->
</pages:PopupPage.Resources>
<ListView x:Name="IzberiFirmaListView" HasUnevenRows="True" ItemsSource="{Binding KorisnikFirmi}" SelectedItem="{Binding IzbranaFirmaId } " Header="{Binding}" ItemTapped="IzberiFirmaListView_ItemTapped">
<ListView.ItemTemplate >
<DataTemplate>
<local:ExtendedViewCell SelectedBackgroundColor="#2188ff" >
<StackLayout Padding="20, 10" >
<Frame x:Name="frameLabel" BorderColor="#2188ff" BackgroundColor="{Binding IsActive, Converter={StaticResource ChangeFrameBackgroudColor}}">
<Label FontAttributes="Bold" FontSize="18" TextColor="Black" Text="{Binding Naziv}" ></Label>
</Frame>
</StackLayout>
</local:ExtendedViewCell>
</DataTemplate>
</ListView.ItemTemplate>
<ListView.HeaderTemplate>
<DataTemplate>
<ContentView BackgroundColor="#006BE6" >
<Label Margin="10" HorizontalOptions="CenterAndExpand" Text="ОДБЕРЕТЕ ФИРМА" TextColor="White" FontSize="20" FontAttributes="Bold"/>
</ContentView>
</DataTemplate>
</ListView.HeaderTemplate>
</ListView>
In xaml.cs Page:
private void IzberiFirmaListView_ItemTapped(object sender, ItemTappedEventArgs e)
{
var vm = BindingContext as OdberiFirmaPopupViewModel;
var firm = e.Item as SysDashFirma;
vm.ChangeColorOnItemSelected(firm);
}
In viewModel
public List<SysDashFirma> KorisnikFirmi
{
get { return korisnikFirmi; }
set
{
if (korisnikFirmi != value)
{
korisnikFirmi = value;
SetProperty(ref korisnikFirmi, value);
OnPropertyChanged("KorisnikFirmi");
}
}
}
public void ChangeColorOnItemSelected(SysDashFirma firm)
{
if (_oldFirmSelected == firm)
{
//firm.BackColor = "#2188ff";
firm.IsActive = true;
UpdateSelectedFirmItemColor(firm);
}
else
{
if(_oldFirmSelected != null)
{
//_oldFirmSelected.BackColor = "#f5f5f5";
_oldFirmSelected.IsActive = false;
UpdateSelectedFirmItemColor(_oldFirmSelected);
}
// firm.BackColor = "#2188ff";
firm.IsActive = true;
UpdateSelectedFirmItemColor(firm);
}
_oldFirmSelected = firm;
}
private void UpdateSelectedFirmItemColor(SysDashFirma firm)
{
var index = KorisnikFirmi.IndexOf(firm);
KorisnikFirmi.Remove(firm);
KorisnikFirmi.Insert(index,firm);
}
Changes are made in the list ,flag is changed, probably cant refresh the bidning context to converter read all from start.

Answer 1

Use OnPropertyChanged for the IsActive property to notify the UI about its change.
public class Firm : INotifyPropertyChanged
{
private string name = "Unknown";
public string Name
{
get
{
return name;
}
set
{
name = value;
OnPropertyChanged();
}
}
private bool isActive;
public bool IsActive
{
get
{
return isActive;
}
set
{
isActive = value;
OnPropertyChanged();
}
}
protected void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
public event PropertyChangedEventHandler PropertyChanged;
}
I would suggest changing the IsActive property alone as removing and adding the item is not necessary.
<ListView
ItemTapped="ListView_ItemTapped"
ItemsSource="{Binding FirmCollection}">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Frame
Padding="2"
BackgroundColor="{Binding IsActive, Converter={StaticResource converterTest}}">
<Label Text="{Binding Name}"/>
</Frame>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
ViewModel
public class ViewModel : INotifyPropertyChanged
{
....
....
private Firm oldSelectedFirm;
public Firm OldSelectedFirm
{
get
{
return oldSelectedFirm;
}
set
{
oldSelectedFirm = value;
OnPropertyChanged();
}
}
...
...
}
Xaml.cs
void ListView_ItemTapped(System.Object sender, Xamarin.Forms.ItemTappedEventArgs e)
{
var tappedFirm = (e.Item as Firm);
var vm = (BindingContext as ViewModel);
if (vm.OldSelectedFirm != null)
vm.OldSelectedFirm.IsActive = false;
tappedFirm.IsActive = true;
vm.OldSelectedFirm = tappedFirm;
}