Я использую базовую систему государственного управления, найденную здесь: (код ниже)
https://github.com/xDelivered-Patrick/Xamarin.Forms.Essentials/blob/master/Essentials/Controls/State/StateContainer.cs
При реализации мой XAML View выглядит следующим образом.
Проблема в том, что StackLayout CenterAndExpand не работает. Все виды при визуализации просто свернуты вверху.
Если я вытащу конкретный раздел из StateContainer и исключу его использование, он будет правильно отображаться. Это проблема с тем, как View отображается внутри Содержимого StateContainer?
РЕДАКТИРОВАТЬ: Вот минимальный пример: https://github.com/aherrick/StateManagementDemo
XAML:
<ContentPage.Content>
<StackLayout x:Name="layoutWrap" VerticalOptions="FillAndExpand"
HorizontalOptions="FillAndExpand">
<controls:StateContainer State="{Binding State}">
<controls:StateCondition Is="Loading">
<StackLayout Orientation="Vertical" HorizontalOptions="CenterAndExpand" VerticalOptions="CenterAndExpand">
<ActivityIndicator x:Name="loadingIndicator"
IsVisible="{Binding IsBusy}"
IsRunning="{Binding IsBusy}"
VerticalOptions="FillAndExpand"
HorizontalOptions="FillAndExpand" />
</StackLayout>
</controls:StateCondition>
<controls:StateCondition Is="Loaded">
<!-- actual content here -->
</controls:StateCondition>
<controls:StateCondition Is="Error">
<StackLayout Orientation="Vertical" HorizontalOptions="CenterAndExpand" VerticalOptions="CenterAndExpand">
<Label FontAttributes="Bold" Text="Oops! There was a problem." VerticalOptions="CenterAndExpand" HorizontalOptions="CenterAndExpand" />
<Button Text="Tap to Retry" Command="{Binding LoadVenuesCommand}" CommandParameter="true" HorizontalOptions="CenterAndExpand" TextColor="White" Padding="15" BackgroundColor="#26265E" />
</StackLayout>
</controls:StateCondition>
</controls:StateContainer>
</StackLayout>
</ContentPage.Content>
C #
[ContentProperty("Content")]
[Preserve(AllMembers = true)]
public class StateCondition : View
{
public object Is { get; set; }
public object IsNot { get; set; }
public View Content { get; set; }
}
[ContentProperty("Conditions")]
[Preserve(AllMembers = true)]
public class StateContainer : ContentView
{
public List<StateCondition> Conditions { get; set; } = new List<StateCondition>();
// https://forums.xamarin.com/discussion/102024/change-bindableproperty-create-to-bindableproperty-create
//public static readonly BindableProperty StateProperty = BindableProperty.Create(nameof(State), typeof(object), typeof(StateContainer), propertyChanged: StateChanged);
public static readonly BindableProperty StateProperty = BindableProperty.Create<StateContainer, object>(x => x.State, null, propertyChanged: StateChanged);
public static void Init()
{
}
private static void StateChanged(BindableObject bindable, object oldValue, object newValue)
{
var parent = bindable as StateContainer;
parent?.ChooseStateProperty(newValue);
}
public object State
{
get { return GetValue(StateProperty); }
set { SetValue(StateProperty, value); }
}
private void ChooseStateProperty(object newValue)
{
foreach (StateCondition stateCondition in Conditions)
{
if (stateCondition.Is != null)
{
if (stateCondition.Is.ToString().Equals(newValue.ToString()))
{
Content = stateCondition.Content;
}
}
else if (stateCondition.IsNot != null)
{
if (!stateCondition.IsNot.ToString().Equals(newValue.ToString()))
{
Content = stateCondition.Content;
}
}
}
}
}