src/Tizen.NUI/src/internal/XamlBinding/Interactivity/BindingCondition.cs

   1 using System;
   2 using Tizen.NUI.Xaml;
   3
   4 namespace Tizen.NUI.Binding
   5 {
   6         // [ProvideCompiled("Xamarin.Forms.Core.XamlC.PassthroughValueProvider")]
   7         [AcceptEmptyServiceProvider]
   8         internal sealed class BindingCondition : Condition, IValueProvider
   9         {
  10                 readonly BindableProperty _boundProperty;
  11
  12                 BindingBase _binding;
  13                 object _triggerValue;
  14
  15                 public BindingCondition()
  16                 {
  17                         _boundProperty = BindableProperty.CreateAttached("Bound", typeof(object), typeof(BindingCondition), null, propertyChanged: OnBoundPropertyChanged);
  18                 }
  19
  20                 public BindingBase Binding
  21                 {
  22                         get { return _binding; }
  23                         set
  24                         {
  25                                 if (_binding == value)
  26                                         return;
  27                                 if (IsSealed)
  28                                         throw new InvalidOperationException("Can not change Binding once the Condition has been applied.");
  29                                 _binding = value;
  30                         }
  31                 }
  32
  33                 public object Value
  34                 {
  35                         get { return _triggerValue; }
  36                         set
  37                         {
  38                                 if (_triggerValue == value)
  39                                         return;
  40                                 if (IsSealed)
  41                                         throw new InvalidOperationException("Can not change Value once the Condition has been applied.");
  42                                 _triggerValue = value;
  43                         }
  44                 }
  45
  46                 object IValueProvider.ProvideValue(IServiceProvider serviceProvider)
  47                 {
  48                         //This is no longer required
  49                         return this;
  50                 }
  51
  52                 internal override bool GetState(BindableObject bindable)
  53                 {
  54                         object newValue = bindable.GetValue(_boundProperty);
  55                         return EqualsToValue(newValue);
  56                 }
  57
  58                 internal override void SetUp(BindableObject bindable)
  59                 {
  60                         if (Binding != null)
  61                                 bindable.SetBinding(_boundProperty, Binding.Clone());
  62                 }
  63
  64                 internal override void TearDown(BindableObject bindable)
  65                 {
  66                         bindable.RemoveBinding(_boundProperty);
  67                         bindable.ClearValue(_boundProperty);
  68                 }
  69
  70                 static IValueConverterProvider s_valueConverter = DependencyService.Get<IValueConverterProvider>();
  71
  72                 bool EqualsToValue(object other)
  73                 {
  74                         if ((other == Value) || (other != null && other.Equals(Value)))
  75                                 return true;
  76
  77                         object converted = null;
  78                         if (s_valueConverter != null)
  79                                 converted = s_valueConverter.Convert(Value, other != null ? other.GetType() : typeof(object), null, null);
  80                         else
  81                                 return false;
  82
  83                         return (other == converted) || (other != null && other.Equals(converted));
  84                 }
  85
  86                 void OnBoundPropertyChanged(BindableObject bindable, object oldValue, object newValue)
  87                 {
  88                         bool oldState = EqualsToValue(oldValue);
  89                         bool newState = EqualsToValue(newValue);
  90
  91                         if (newState == oldState)
  92                                 return;
  93
  94                         if (ConditionChanged != null)
  95                                 ConditionChanged(bindable, oldState, newState);
  96                 }
  97         }
  98 }