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authorJason Smith <jason.smith@xamarin.com>2016-03-22 13:02:25 -0700
committerJason Smith <jason.smith@xamarin.com>2016-03-22 16:13:41 -0700
commit17fdde66d94155fc62a034fa6658995bef6fd6e5 (patch)
treeb5e5073a2a7b15cdbe826faa5c763e270a505729 /Xamarin.Forms.Core/Interactivity/BindingCondition.cs
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Initial import
Diffstat (limited to 'Xamarin.Forms.Core/Interactivity/BindingCondition.cs')
-rw-r--r--Xamarin.Forms.Core/Interactivity/BindingCondition.cs100
1 files changed, 100 insertions, 0 deletions
diff --git a/Xamarin.Forms.Core/Interactivity/BindingCondition.cs b/Xamarin.Forms.Core/Interactivity/BindingCondition.cs
new file mode 100644
index 00000000..88b7cf36
--- /dev/null
+++ b/Xamarin.Forms.Core/Interactivity/BindingCondition.cs
@@ -0,0 +1,100 @@
+using System;
+using Xamarin.Forms.Xaml;
+
+namespace Xamarin.Forms
+{
+ public sealed class BindingCondition : Condition, IValueProvider
+ {
+ readonly BindableProperty _boundProperty;
+
+ BindingBase _binding;
+ object _triggerValue;
+
+ public BindingCondition()
+ {
+ _boundProperty = BindableProperty.CreateAttached("Bound", typeof(object), typeof(DataTrigger), null, propertyChanged: OnBoundPropertyChanged);
+ }
+
+ public BindingBase Binding
+ {
+ get { return _binding; }
+ set
+ {
+ if (_binding == value)
+ return;
+ if (IsSealed)
+ throw new InvalidOperationException("Can not change Binding once the Trigger has been applied.");
+ _binding = value;
+ }
+ }
+
+ public object Value
+ {
+ get { return _triggerValue; }
+ set
+ {
+ if (_triggerValue == value)
+ return;
+ if (IsSealed)
+ throw new InvalidOperationException("Can not change Value once the Trigger has been applied.");
+ _triggerValue = value;
+ }
+ }
+
+ internal IServiceProvider ServiceProvider { get; set; }
+
+ internal IValueConverterProvider ValueConverter { get; set; }
+
+ object IValueProvider.ProvideValue(IServiceProvider serviceProvider)
+ {
+ ValueConverter = serviceProvider.GetService(typeof(IValueConverterProvider)) as IValueConverterProvider;
+ ServiceProvider = serviceProvider;
+
+ return this;
+ }
+
+ internal override bool GetState(BindableObject bindable)
+ {
+ object newValue = bindable.GetValue(_boundProperty);
+ return EqualsToValue(newValue);
+ }
+
+ internal override void SetUp(BindableObject bindable)
+ {
+ if (Binding != null)
+ bindable.SetBinding(_boundProperty, Binding.Clone());
+ }
+
+ internal override void TearDown(BindableObject bindable)
+ {
+ bindable.RemoveBinding(_boundProperty);
+ bindable.ClearValue(_boundProperty);
+ }
+
+ bool EqualsToValue(object other)
+ {
+ if ((other == Value) || (other != null && other.Equals(Value)))
+ return true;
+
+ object converted = null;
+ if (ValueConverter != null)
+ converted = ValueConverter.Convert(Value, other != null ? other.GetType() : typeof(object), null, ServiceProvider);
+ else
+ return false;
+
+ return (other == converted) || (other != null && other.Equals(converted));
+ }
+
+ void OnBoundPropertyChanged(BindableObject bindable, object oldValue, object newValue)
+ {
+ bool oldState = EqualsToValue(oldValue);
+ bool newState = EqualsToValue(newValue);
+
+ if (newState == oldState)
+ return;
+
+ if (ConditionChanged != null)
+ ConditionChanged(bindable, oldState, newState);
+ }
+ }
+} \ No newline at end of file