diff options
Diffstat (limited to 'Xamarin.Forms.Core/Setter.cs')
| -rw-r--r-- | Xamarin.Forms.Core/Setter.cs | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/Xamarin.Forms.Core/Setter.cs b/Xamarin.Forms.Core/Setter.cs new file mode 100644 index 00000000..b260e8f0 --- /dev/null +++ b/Xamarin.Forms.Core/Setter.cs @@ -0,0 +1,88 @@ +using System; +using System.Reflection; +using System.Runtime.CompilerServices; +using System.Xml; +using Xamarin.Forms.Internals; +using Xamarin.Forms.Xaml; + +namespace Xamarin.Forms +{ + [ContentProperty("Value")] + public sealed class Setter : IValueProvider + { + readonly ConditionalWeakTable<BindableObject, object> _originalValues = new ConditionalWeakTable<BindableObject, object>(); + + public BindableProperty Property { get; set; } + + public object Value { get; set; } + + object IValueProvider.ProvideValue(IServiceProvider serviceProvider) + { + if (Property == null) + { + var lineInfoProvider = serviceProvider.GetService(typeof(IXmlLineInfoProvider)) as IXmlLineInfoProvider; + IXmlLineInfo lineInfo = lineInfoProvider != null ? lineInfoProvider.XmlLineInfo : new XmlLineInfo(); + throw new XamlParseException("Property not set", lineInfo); + } + var valueconverter = serviceProvider.GetService(typeof(IValueConverterProvider)) as IValueConverterProvider; + + Func<MemberInfo> minforetriever = + () => + (MemberInfo)Property.DeclaringType.GetRuntimeProperty(Property.PropertyName) ?? (MemberInfo)Property.DeclaringType.GetRuntimeMethod("Get" + Property.PropertyName, new[] { typeof(BindableObject) }); + + object value = valueconverter.Convert(Value, Property.ReturnType, minforetriever, serviceProvider); + Value = value; + return this; + } + + internal void Apply(BindableObject target, bool fromStyle = false) + { + if (target == null) + throw new ArgumentNullException("target"); + if (Property == null) + return; + + object originalValue = target.GetValue(Property); + if (!Equals(originalValue, Property.DefaultValue)) + { + _originalValues.Remove(target); + _originalValues.Add(target, originalValue); + } + + var dynamicResource = Value as DynamicResource; + var binding = Value as BindingBase; + if (binding != null) + target.SetBinding(Property, binding.Clone(), fromStyle); + else if (dynamicResource != null) + target.SetDynamicResource(Property, dynamicResource.Key, fromStyle); + else + target.SetValue(Property, Value, fromStyle); + } + + internal void UnApply(BindableObject target, bool fromStyle = false) + { + if (target == null) + throw new ArgumentNullException("target"); + if (Property == null) + return; + + object actual = target.GetValue(Property); + if (!fromStyle && !Equals(actual, Value)) + { + //Do not reset default value if the value has been changed + _originalValues.Remove(target); + return; + } + + object defaultValue; + if (_originalValues.TryGetValue(target, out defaultValue)) + { + //reset default value, unapply bindings and dynamicResource + target.SetValue(Property, defaultValue, fromStyle); + _originalValues.Remove(target); + } + else + target.ClearValue(Property); + } + } +}
\ No newline at end of file |