diff options
Diffstat (limited to 'Xamarin.Forms.Core/View.cs')
-rw-r--r-- | Xamarin.Forms.Core/View.cs | 114 |
1 files changed, 114 insertions, 0 deletions
diff --git a/Xamarin.Forms.Core/View.cs b/Xamarin.Forms.Core/View.cs new file mode 100644 index 00000000..d03c74bb --- /dev/null +++ b/Xamarin.Forms.Core/View.cs @@ -0,0 +1,114 @@ +using System; +using System.Collections.Generic; +using System.Collections.ObjectModel; +using System.Collections.Specialized; +using System.Linq; + +namespace Xamarin.Forms +{ + public class View : VisualElement, IViewController + { + public static readonly BindableProperty VerticalOptionsProperty = BindableProperty.Create("VerticalOptions", typeof(LayoutOptions), typeof(View), LayoutOptions.Fill, + propertyChanged: (bindable, oldvalue, newvalue) => ((View)bindable).InvalidateMeasure(InvalidationTrigger.VerticalOptionsChanged)); + + public static readonly BindableProperty HorizontalOptionsProperty = BindableProperty.Create("HorizontalOptions", typeof(LayoutOptions), typeof(View), LayoutOptions.Fill, + propertyChanged: (bindable, oldvalue, newvalue) => ((View)bindable).InvalidateMeasure(InvalidationTrigger.HorizontalOptionsChanged)); + + public static readonly BindableProperty MarginProperty = BindableProperty.Create("Margin", typeof(Thickness), typeof(View), default(Thickness), propertyChanged: MarginPropertyChanged); + + readonly ObservableCollection<IGestureRecognizer> _gestureRecognizers = new ObservableCollection<IGestureRecognizer>(); + + protected internal View() + { + _gestureRecognizers.CollectionChanged += (sender, args) => + { + switch (args.Action) + { + case NotifyCollectionChangedAction.Add: + foreach (IElement item in args.NewItems.OfType<IElement>()) + { + ValidateGesture(item as IGestureRecognizer); + item.Parent = this; + } + break; + case NotifyCollectionChangedAction.Remove: + foreach (IElement item in args.OldItems.OfType<IElement>()) + item.Parent = null; + break; + case NotifyCollectionChangedAction.Replace: + foreach (IElement item in args.NewItems.OfType<IElement>()) + { + ValidateGesture(item as IGestureRecognizer); + item.Parent = this; + } + foreach (IElement item in args.OldItems.OfType<IElement>()) + item.Parent = null; + break; + case NotifyCollectionChangedAction.Reset: + foreach (IElement item in _gestureRecognizers.OfType<IElement>()) + item.Parent = this; + break; + } + }; + } + + public IList<IGestureRecognizer> GestureRecognizers + { + get { return _gestureRecognizers; } + } + + public LayoutOptions HorizontalOptions + { + get { return (LayoutOptions)GetValue(HorizontalOptionsProperty); } + set { SetValue(HorizontalOptionsProperty, value); } + } + + public Thickness Margin + { + get { return (Thickness)GetValue(MarginProperty); } + set { SetValue(MarginProperty, value); } + } + + public LayoutOptions VerticalOptions + { + get { return (LayoutOptions)GetValue(VerticalOptionsProperty); } + set { SetValue(VerticalOptionsProperty, value); } + } + + protected override void OnBindingContextChanged() + { + var gotBindingContext = false; + object bc = null; + + for (var i = 0; i < GestureRecognizers.Count; i++) + { + var bo = GestureRecognizers[i] as BindableObject; + if (bo == null) + continue; + + if (!gotBindingContext) + { + bc = BindingContext; + gotBindingContext = true; + } + + SetInheritedBindingContext(bo, bc); + } + + base.OnBindingContextChanged(); + } + + static void MarginPropertyChanged(BindableObject bindable, object oldValue, object newValue) + { + ((View)bindable).InvalidateMeasure(InvalidationTrigger.MarginChanged); + } + + void ValidateGesture(IGestureRecognizer gesture) + { + if (gesture == null) + return; + if (gesture is PinchGestureRecognizer && _gestureRecognizers.GetGesturesFor<PinchGestureRecognizer>().Count() > 1) + throw new InvalidOperationException($"Only one {nameof(PinchGestureRecognizer)} per view is allowed"); + } + } +}
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