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("Tizen.NUI.Xaml.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 }