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authorStephane Delcroix <stephane@delcroix.org>2016-11-15 20:39:48 +0100
committerJason Smith <jason.smith@xamarin.com>2016-11-15 11:39:48 -0800
commita6bbed029c64d2d64b74eeb67e27a099abf70664 (patch)
tree551c3924c055e2d39592b3f1c726cca46924dd73 /Xamarin.Forms.Core/TypedBinding.cs
parent14e21dcebd4a706aaa5eed384b142957d84df002 (diff)
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[XamlC] TypedBindings, some tests, a compiler, ... (#489)
Diffstat (limited to 'Xamarin.Forms.Core/TypedBinding.cs')
-rw-r--r--Xamarin.Forms.Core/TypedBinding.cs291
1 files changed, 291 insertions, 0 deletions
diff --git a/Xamarin.Forms.Core/TypedBinding.cs b/Xamarin.Forms.Core/TypedBinding.cs
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+#define DO_NOT_CHECK_FOR_BINDING_REUSE
+
+using System;
+using System.ComponentModel;
+using System.Globalization;
+using System.Collections.Generic;
+
+namespace Xamarin.Forms.Internals
+{
+ //FIXME: need a better name for this, and share with Binding, so we can share more unittests
+ public abstract class TypedBindingBase : BindingBase
+ {
+ IValueConverter _converter;
+ object _converterParameter;
+ object _source;
+ string _updateSourceEventName;
+
+ public IValueConverter Converter {
+ get { return _converter; }
+ set {
+ ThrowIfApplied();
+ _converter = value;
+ }
+ }
+
+ public object ConverterParameter {
+ get { return _converterParameter; }
+ set {
+ ThrowIfApplied();
+ _converterParameter = value;
+ }
+ }
+
+ public object Source {
+ get { return _source; }
+ set {
+ ThrowIfApplied();
+ _source = value;
+ }
+ }
+
+ internal string UpdateSourceEventName {
+ get { return _updateSourceEventName; }
+ set {
+ ThrowIfApplied();
+ _updateSourceEventName = value;
+ }
+ }
+
+ internal TypedBindingBase()
+ {
+ }
+ }
+
+ public sealed class TypedBinding<TSource, TProperty> : TypedBindingBase
+ {
+ readonly Func<TSource, TProperty> _getter;
+ readonly Action<TSource, TProperty> _setter;
+ readonly PropertyChangedProxy [] _handlers;
+
+ public TypedBinding(Func<TSource, TProperty> getter, Action<TSource, TProperty> setter, Tuple<Func<TSource, object>, string> [] handlers)
+ {
+ if (getter == null)
+ throw new ArgumentNullException(nameof(getter));
+
+ _getter = getter;
+ _setter = setter;
+
+ if (handlers == null)
+ return;
+
+ _handlers = new PropertyChangedProxy [handlers.Length];
+ for (var i = 0; i < handlers.Length; i++)
+ _handlers [i] = new PropertyChangedProxy(handlers [i].Item1, handlers [i].Item2, this);
+ }
+
+ readonly WeakReference<object> _weakSource = new WeakReference<object>(null);
+ readonly WeakReference<BindableObject> _weakTarget = new WeakReference<BindableObject>(null);
+ BindableProperty _targetProperty;
+
+ // Applies the binding to a previously set source and target.
+ internal override void Apply(bool fromTarget = false)
+ {
+ base.Apply(fromTarget);
+
+ BindableObject target;
+#if DO_NOT_CHECK_FOR_BINDING_REUSE
+ if (!_weakTarget.TryGetTarget(out target))
+ throw new InvalidOperationException();
+#else
+ if (!_weakTarget.TryGetTarget(out target) || target == null) {
+ Unapply();
+ return;
+ }
+#endif
+ object source;
+ if (_weakSource.TryGetTarget(out source) && source != null)
+ ApplyCore(source, target, _targetProperty, fromTarget);
+ }
+
+ // Applies the binding to a new source or target.
+ internal override void Apply(object context, BindableObject bindObj, BindableProperty targetProperty)
+ {
+ _targetProperty = targetProperty;
+ var source = Source ?? Context ?? context;
+
+#if (!DO_NOT_CHECK_FOR_BINDING_REUSE)
+ base.Apply(source, bindObj, targetProperty);
+
+ BindableObject prevTarget;
+ if (_weakTarget.TryGetTarget(out prevTarget) && !ReferenceEquals(prevTarget, bindObj))
+ throw new InvalidOperationException("Binding instances can not be reused");
+
+ object previousSource;
+ if (_weakSource.TryGetTarget(out previousSource) && !ReferenceEquals(previousSource, source))
+ throw new InvalidOperationException("Binding instances can not be reused");
+#endif
+ _weakSource.SetTarget(source);
+ _weakTarget.SetTarget(bindObj);
+
+ ApplyCore(source, bindObj, targetProperty);
+ }
+
+ internal override BindingBase Clone()
+ {
+ Tuple<Func<TSource, object>, string> [] handlers = _handlers == null ? null : new Tuple<Func<TSource, object>, string> [_handlers.Length];
+ if (handlers != null) {
+ for (var i = 0; i < _handlers.Length; i++)
+ handlers [i] = new Tuple<Func<TSource, object>, string>(_handlers [i].PartGetter, _handlers [i].PropertyName);
+ }
+ return new TypedBinding<TSource, TProperty>(_getter, _setter, handlers) {
+ Mode = Mode,
+ Converter = Converter,
+ ConverterParameter = ConverterParameter,
+ StringFormat = StringFormat,
+ Source = Source,
+ UpdateSourceEventName = UpdateSourceEventName,
+ };
+ }
+
+ internal override object GetSourceValue(object value, Type targetPropertyType)
+ {
+ if (Converter != null)
+ value = Converter.Convert(value, targetPropertyType, ConverterParameter, CultureInfo.CurrentUICulture);
+
+ //return base.GetSourceValue(value, targetPropertyType);
+ if (StringFormat != null)
+ return string.Format(StringFormat, value);
+
+ return value;
+ }
+
+ internal override object GetTargetValue(object value, Type sourcePropertyType)
+ {
+ if (Converter != null)
+ value = Converter.ConvertBack(value, sourcePropertyType, ConverterParameter, CultureInfo.CurrentUICulture);
+
+ //return base.GetTargetValue(value, sourcePropertyType);
+ return value;
+ }
+
+ internal override void Unapply()
+ {
+#if (!DO_NOT_CHECK_FOR_BINDING_REUSE)
+ base.Unapply();
+#endif
+ if (_handlers != null)
+ Unsubscribe();
+
+#if (!DO_NOT_CHECK_FOR_BINDING_REUSE)
+ _weakSource.SetTarget(null);
+ _weakTarget.SetTarget(null);
+#endif
+ }
+
+ // ApplyCore is as slim as it should be:
+ // Setting 100000 values : 17ms.
+ // ApplyCore 100000 (w/o INPC, w/o unnapply) : 20ms.
+ internal void ApplyCore(object sourceObject, BindableObject target, BindableProperty property, bool fromTarget = false)
+ {
+ var isTSource = sourceObject != null && sourceObject is TSource;
+ var mode = this.GetRealizedMode(property);
+ if (mode == BindingMode.OneWay && fromTarget)
+ return;
+
+ var needsGetter = (mode == BindingMode.TwoWay && !fromTarget) || mode == BindingMode.OneWay;
+
+ if (isTSource && (mode == BindingMode.OneWay || mode == BindingMode.TwoWay) && _handlers != null)
+ Subscribe((TSource)sourceObject);
+
+ if (needsGetter) {
+ var value = property.DefaultValue;
+ if (isTSource) {
+ try {
+ value = GetSourceValue(_getter((TSource)sourceObject), property.ReturnType);
+ } catch (Exception ex) when (ex is NullReferenceException || ex is KeyNotFoundException) {
+ }
+ }
+ if (!TryConvert(ref value, property, property.ReturnType, true)) {
+ Log.Warning("Binding", "{0} can not be converted to type '{1}'", value, property.ReturnType);
+ return;
+ }
+ target.SetValueCore(property, value, BindableObject.SetValueFlags.ClearDynamicResource, BindableObject.SetValuePrivateFlags.Default | BindableObject.SetValuePrivateFlags.Converted);
+ return;
+ }
+
+ var needsSetter = (mode == BindingMode.TwoWay && fromTarget) || mode == BindingMode.OneWayToSource;
+ if (needsSetter && _setter != null && isTSource) {
+ var value = GetTargetValue(target.GetValue(property), typeof(TProperty));
+ if (!TryConvert(ref value, property, typeof(TProperty), false)) {
+ Log.Warning("Binding", "{0} can not be converted to type '{1}'", value, typeof(TProperty));
+ return;
+ }
+ _setter((TSource)sourceObject, (TProperty)value);
+ }
+ }
+
+ static bool TryConvert(ref object value, BindableProperty targetProperty, Type convertTo, bool toTarget)
+ {
+ if (value == null)
+ return true;
+ if ((toTarget && targetProperty.TryConvert(ref value)) || (!toTarget && convertTo.IsInstanceOfType(value)))
+ return true;
+
+ object original = value;
+ try {
+ value = Convert.ChangeType(value, convertTo, CultureInfo.InvariantCulture);
+ return true;
+ } catch (Exception ex ) when (ex is InvalidCastException || ex is FormatException||ex is OverflowException) {
+ value = original;
+ return false;
+ }
+ }
+
+ class PropertyChangedProxy
+ {
+ public Func<TSource, object> PartGetter { get; }
+ public string PropertyName { get; }
+ public BindingExpression.WeakPropertyChangedProxy Listener { get; }
+ WeakReference<INotifyPropertyChanged> _weakPart = new WeakReference<INotifyPropertyChanged>(null);
+ readonly BindingBase _binding;
+
+ public INotifyPropertyChanged Part {
+ get {
+ INotifyPropertyChanged target;
+ if (_weakPart.TryGetTarget(out target))
+ return target;
+ return null;
+ }
+ set {
+ _weakPart.SetTarget(value);
+ Listener.SubscribeTo(value, OnPropertyChanged);
+ }
+ }
+
+ public PropertyChangedProxy(Func<TSource, object> partGetter, string propertyName, BindingBase binding)
+ {
+ PartGetter = partGetter;
+ PropertyName = propertyName;
+ _binding = binding;
+ Listener = new BindingExpression.WeakPropertyChangedProxy();
+ }
+
+ void OnPropertyChanged(object sender, PropertyChangedEventArgs e)
+ {
+ if (!string.IsNullOrEmpty(e.PropertyName) && string.CompareOrdinal(e.PropertyName, PropertyName) != 0)
+ return;
+ Device.BeginInvokeOnMainThread(() => _binding.Apply(false));
+ }
+ }
+
+ void Subscribe(TSource sourceObject)
+ {
+ for (var i = 0; i < _handlers.Length; i++) {
+ var part = _handlers [i].PartGetter(sourceObject);
+ if (part == null)
+ break;
+ var inpc = part as INotifyPropertyChanged;
+ if (inpc == null)
+ continue;
+ _handlers [i].Part = (inpc);
+ }
+ }
+
+ void Unsubscribe()
+ {
+ for (var i = 0; i < _handlers.Length; i++)
+ _handlers [i].Listener.Unsubscribe();
+ }
+ }
+} \ No newline at end of file