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/* $Id: GraphPropertyDescriptor.cs,v 1.3 2009/06/03 01:10:59 ellson Exp $ $Revision: 1.3 $ */
/* vim:set shiftwidth=4 ts=8: */
/**********************************************************
* This software is part of the graphviz package *
* http://www.graphviz.org/ *
* *
* Copyright (c) 1994-2008 AT&T Corp. *
* and is licensed under the *
* Common Public License, Version 1.0 *
* by AT&T Corp. *
* *
* Information and Software Systems Research *
* AT&T Research, Florham Park NJ *
**********************************************************/
using System;
using System.Collections.Generic;
using System.ComponentModel;
namespace Graphviz
{
public class GraphPropertyDescriptor : PropertyDescriptor
{
public GraphPropertyDescriptor(string graphComponent, string name, Attribute[] attrs): base(name, attrs)
{
_graphComponent = graphComponent;
}
public override bool CanResetValue(object component)
{
/* can reset whenever value isn't at default */
return !object.Equals(GetValue(component), DefaultValue);
}
public override Type ComponentType
{
/* property defined on graph components, so we'll say object */
get { return typeof(object); }
}
public override object GetValue(object component)
{
/* return either the set value or the default value */
string value;
GetDictionary(component).TryGetValue(Name, out value);
return value == null ? DefaultValue : value;
}
public override bool IsReadOnly
{
get { return false; }
}
public override Type PropertyType
{
/* property returns strings only */
get { return typeof(string); }
}
public override void ResetValue(object component)
{
SetValue(component, DefaultValue);
}
public override void SetValue(object component, object value)
{
GetDictionary(component)[Name] = (string)value;
}
public override bool ShouldSerializeValue(object component)
{
return CanResetValue(component);
}
private object DefaultValue
{
get
{
/* return default value attribute if any */
DefaultValueAttribute defaultValueAttribute = (DefaultValueAttribute)Attributes[typeof(DefaultValueAttribute)];
return defaultValueAttribute == null ? null : defaultValueAttribute.Value;
}
}
private IDictionary<string, string> GetDictionary(object component)
{
/* if the component is a graph, return the appropriate dictionary */
Graph graph = component as Graph;
if (graph != null)
switch (_graphComponent) {
case "graph":
return graph.GraphAttributes;
case "node":
return graph.DefaultNodeAttributes;
case "edge":
return graph.DefaultEdgeAttributes;
default:
return null;
}
else
return null;
}
private readonly string _graphComponent;
}
}
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