Поскольку вы использовали привязку данных, было бы лучше обрабатывать все logi c в ViewModel.
в коде за
Определить настраиваемую запись
public class MyEntry:Entry
{
public static readonly BindableProperty IsFocusProperty =BindableProperty.Create("IsFocus", typeof(bool), typeof(MyEntry), false,propertyChanged: OnChanged);
static void OnChanged(BindableObject bindable, object oldValue, object newValue)
{
var entry = bindable as MyEntry;
var focus = (bool)newValue;
if(focus)
{
entry.Focus();
}
else
{
entry.Unfocus();
}
}
public bool IsFocus
{
get { return (bool)GetValue(IsFocusProperty); }
set {
SetValue(IsFocusProperty, value);
}
}
public MyEntry()
{
this.Focused += MyEntry_Focused;
this.Unfocused += MyEntry_Unfocused;
}
private void MyEntry_Unfocused(object sender, FocusEventArgs e)
{
this.IsFocus = false;
}
private void MyEntry_Focused(object sender, FocusEventArgs e)
{
this.IsFocus = true;
}
}
в модели
public class CrossingUIModel : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
public int Id { get; set; }
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
string fieldValue;
public string FieldValue
{
get
{
return fieldValue;
}
set
{
if (fieldValue != value)
{
fieldValue = value;
OnPropertyChanged("FieldValue");
}
}
}
bool isFocus = false;
public bool IsFocus
{
get
{
return isFocus;
}
set
{
if (isFocus != value)
{
isFocus = value;
OnPropertyChanged("IsFocus");
}
}
}
}
в ViewModel
public class MyViewModel
{
public ObservableCollection<CrossingUIModel> BindCrossingUIModel { get; set; }
public MyViewModel()
{
BindCrossingUIModel = new ObservableCollection<CrossingUIModel>();
for (int i = 1; i < 21; i++)
{
CrossingUIModel model = new CrossingUIModel();
model.Id = i;
BindCrossingUIModel.Add(model);
}
foreach (CrossingUIModel model in BindCrossingUIModel)
{
model.PropertyChanged += Model_PropertyChanged;
}
}
private void Model_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
if(e.PropertyName== "FieldValue")
{
var model = sender as CrossingUIModel;
if(model.FieldValue.Length==1)
{
model.FieldValue = model.FieldValue.Substring(0, 1);
model.IsFocus = false;
int id = model.Id;
BindCrossingUIModel[id].IsFocus = true;
}
}
}
}
в xaml
Теперь нам не нужно устанавливать MaxLength и TextChanged больше.
<StackLayout HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand">
<CollectionView x:Name="CrossingView" ItemsSource="{Binding BindCrossingUIModel, Mode=TwoWay}" SelectionMode="Multiple">
<CollectionView.ItemsLayout>
<GridItemsLayout Orientation="Vertical" Span="10" />
</CollectionView.ItemsLayout>
<CollectionView.ItemTemplate>
<DataTemplate>
<StackLayout WidthRequest="100" HeightRequest="30" HorizontalOptions="FillAndExpand">
<local:MyEntry WidthRequest="80" BackgroundColor="LightBlue" HeightRequest="30" x:Name="Fields" Text="{Binding FieldValue, Mode=TwoWay}"
IsFocus="{Binding IsFocus, Mode=TwoWay}"
ReturnType="Next" Keyboard="Numeric"
></local:MyEntry>
</StackLayout>
</DataTemplate>
</CollectionView.ItemTemplate>
</CollectionView>
</StackLayout>
Кстати, вы можете использовать Grid вместо StackLayout в качестве родительского макета записи.
введите описание изображения здесь