mono/mcs/class/System/System.ComponentModel/ReflectionPropertyDescriptor.cs

//
// System.ComponentModel.PropertyDescriptor.cs
//
// Author:
//  Lluis Sanchez Gual ([email protected])
//
// (C) Novell, Inc.  
//

//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
// 
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//

using System;
using System.Collections;
using System.Reflection;
using System.Runtime.InteropServices;
using System.ComponentModel.Design;

namespace System.ComponentModel
{
	internal class ReflectionPropertyDescriptor : PropertyDescriptor
	{
		PropertyInfo _member;
		Type _componentType;
		
		public ReflectionPropertyDescriptor (Type componentType, PropertyDescriptor oldPropertyDescriptor, Attribute [] attributes)
		: base (oldPropertyDescriptor, attributes)
		{
			_componentType = componentType;
		}
							 
		public ReflectionPropertyDescriptor (Type componentType, string name, Type type, Attribute [] attributes)
		: base (name, attributes)
		{
			_componentType = componentType;
		}
							 
		public ReflectionPropertyDescriptor (PropertyInfo info)
		: base (info.Name, (Attribute[])info.GetCustomAttributes (true))
		{
			_member = info;
			_componentType = _member.DeclaringType;
		}
		
		PropertyInfo GetPropertyInfo ()
		{
			if (_member == null) {
				_member = _componentType.GetProperty (Name);
				if (_member == null)
					throw new ArgumentException ("Accessor methods for the " + Name + " property are missing");
			}
			return _member;
		}		

		public override Type ComponentType 
		{ 
			get { return _componentType; }
		}

		public override bool IsReadOnly 
		{
			get
			{
				return !GetPropertyInfo ().CanWrite;
			}
		}

		public override Type PropertyType 
		{
			get
			{
				return GetPropertyInfo ().PropertyType;
			}
		}
		
		public override object GetValue (object component)
		{
			return GetPropertyInfo ().GetValue (component, null);
		}
		
		DesignerTransaction CreateTransaction (object obj)
		{
			IComponent com = obj as IComponent;
			if (com == null || com.Site == null)
				return null;
			
			IDesignerHost dh = (IDesignerHost) com.Site.GetService (typeof(IDesignerHost));
			if (dh == null)
				return null;
			
			DesignerTransaction tran = dh.CreateTransaction ();
			IComponentChangeService ccs = (IComponentChangeService) com.Site.GetService (typeof(IComponentChangeService));
			if (ccs != null)
				ccs.OnComponentChanging (com, this);
			return tran;
		}
		
		void EndTransaction (object obj, DesignerTransaction tran, object oldValue, object newValue, bool commit)
		{
			if (tran == null)
				return;
			
			if (commit) {
				IComponent com = obj as IComponent;
				IComponentChangeService ccs = (IComponentChangeService) com.Site.GetService (typeof(IComponentChangeService));
				if (ccs != null)
					ccs.OnComponentChanged (com, this, oldValue, newValue);
				tran.Commit ();
			} else
				tran.Cancel ();
		}
		
		public override void SetValue (object component, object value)
		{
			DesignerTransaction tran = CreateTransaction (component);
			object old = GetValue (component);
			
			try {
				GetPropertyInfo ().SetValue (component, value, null);
				EndTransaction (component, tran, old, value, true);
			} catch {
				EndTransaction (component, tran, old, value, false);
				throw;
			}
		}

		public override void ResetValue (object component)
		{
			DefaultValueAttribute attrib = ((DefaultValueAttribute) Attributes[typeof (DefaultValueAttribute)]);
			if (attrib != null) 
				SetValue (component, attrib.Value); 
			
			DesignerTransaction tran = CreateTransaction (component);
			object old = GetValue (component);
			
			try {
				MethodInfo mi = component.GetType().GetMethod ("Reset" + Name, Type.EmptyTypes);
				if (mi != null)
					mi.Invoke (component, null);
				EndTransaction (component, tran, old, GetValue (component), true);
			} catch {
				EndTransaction (component, tran, old, GetValue (component), false);
				throw;
			}
		}

		public override bool CanResetValue (object component)
		{
			DefaultValueAttribute attrib = ((DefaultValueAttribute) Attributes[typeof (DefaultValueAttribute)]);
			if (attrib != null) {
				object current = GetValue (component);
				if (attrib.Value == null || current == null){
					if (attrib.Value != current)
						return true;
					if (attrib.Value == null && current == null)
						return false;
				}

				return !attrib.Value.Equals (current);
			} else {
				MethodInfo mi = component.GetType().GetMethod ("ShouldPersist" + Name, Type.EmptyTypes);
				if (mi != null)
					return (bool) mi.Invoke (component, null);
				mi = component.GetType().GetMethod ("Reset" + Name, Type.EmptyTypes);
				return mi != null;
			}
		}

		public override bool ShouldSerializeValue (object component)
		{
			DefaultValueAttribute attrib = ((DefaultValueAttribute) Attributes[typeof (DefaultValueAttribute)]);
			if (attrib != null) {
				object current = GetValue (component);
				if ((attrib.Value == null || current == null) && attrib.Value != current)
					return true;
				return !attrib.Value.Equals (current);
			}
			else {
				MethodInfo mi = component.GetType().GetMethod ("ShouldSerialize" + Name, Type.EmptyTypes);
				if (mi != null)
					return (bool) mi.Invoke (component, null);
				return true;
			}
		}
	}
}