SvgUriReference.cs :  » GUI » SharpVectorGraphics » SharpVectors » Dom » Svg » C# / CSharp Open Source

using System;
using System.Xml;
using System.IO;
using System.Net;
using SharpVectors.Net;
using SharpVectors.Dom.Css;

namespace SharpVectors.Dom.Svg{
  public class SvgURIReference : ISvgURIReference
  {
    public SvgURIReference(SvgElement ownerElement)
    {
      this.ownerElement = ownerElement;
      this.ownerElement.attributeChangeHandler += new NodeChangeHandler(AttributeChange);
    }

    #region Private fields
    private SvgElement ownerElement;
    #endregion

    #region Update handling
    private void AttributeChange(Object src, XmlNodeChangedEventArgs args)
    {
      XmlAttribute attribute = src as XmlAttribute;

      if(attribute.NamespaceURI == SvgDocument.XLinkNamespace &&
        attribute.LocalName == "href")
      {
        href = null;
        referencedNode = null;
        referencedResource = null;
        absoluteUri = null;
      }
    }

    public NodeChangeHandler referencedNodeChangeHandler;
    private void ReferencedNodeChange(Object src, XmlNodeChangedEventArgs args) 
    {
      if (referencedNodeChangeHandler != null) 
      {
        referencedNodeChangeHandler(src, args);
      }
    }
    #endregion

    #region Implementation of ISvgURIReference
    private ISvgAnimatedString href;
    public ISvgAnimatedString Href
    {
      get
      {
        if(href == null)
        {
          href = new SvgAnimatedString(ownerElement.GetAttribute("href", SvgDocument.XLinkNamespace));
        }
        return href;
      }
    }
    #endregion

    #region And you get these extras for free!
    private string absoluteUri;
    public string AbsoluteUri
    {
      get
      {
        if(absoluteUri == null)
        {
          if(ownerElement.HasAttribute("href", SvgDocument.XLinkNamespace))
          {
            string href = Href.AnimVal.Trim();

            if(href.StartsWith("#"))
            {
              return href;
            }
            else
            {
              string baseUri = ownerElement.BaseURI;
              if(baseUri.Length == 0)
              {
                absoluteUri = new Uri(Href.AnimVal).ToString();

              }
              else
              {
                absoluteUri = new Uri(new Uri(ownerElement.BaseURI), Href.AnimVal).ToString();
              }
            }
          }
        }
        return absoluteUri;
      }
    }

    private XmlNode referencedNode;
    public XmlNode ReferencedNode
    {
      get
      {
        if(referencedNode == null)
        {
          if(ownerElement.HasAttribute("href", SvgDocument.XLinkNamespace))
          {
            referencedNode = ownerElement.OwnerDocument.GetNodeByUri(AbsoluteUri);

            if(referencedNode == null && ownerElement is ISvgExternalResourcesRequired)
            {
              ISvgExternalResourcesRequired extReqElm = (ISvgExternalResourcesRequired)ownerElement;
              
              if(extReqElm.ExternalResourcesRequired.AnimVal)
              {
                throw new SvgExternalResourcesRequiredException();
              }
            } 
            else if (referencedNode is CssXmlElement)
            {
              CssXmlElement cssRef = (CssXmlElement)referencedNode;
              cssRef.attributeChangeHandler += new NodeChangeHandler(ReferencedNodeChange);
              cssRef.elementChangeHandler += new NodeChangeHandler(ReferencedNodeChange);
              cssRef.parentNodeChangeHandler += new NodeChangeHandler(ReferencedNodeChange);
              cssRef.childNodeChangeHandler += new NodeChangeHandler(ReferencedNodeChange);
            }
          }
          else
          {
            referencedNode = null; 
          }
        }
        return referencedNode;
      }
    }

    private WebResponse referencedResource;
    public WebResponse ReferencedResource
    {
      get
      {
        if(referencedResource == null)
        {
          if(ownerElement.HasAttribute("href", SvgDocument.XLinkNamespace))
          {

            referencedResource = ownerElement.OwnerDocument.GetResource(new Uri(AbsoluteUri));

            if(referencedResource == null && ownerElement is ISvgExternalResourcesRequired)
            {
              ISvgExternalResourcesRequired extReqElm = (ISvgExternalResourcesRequired)ownerElement;
              
              if(extReqElm.ExternalResourcesRequired.AnimVal)
              {
                throw new SvgExternalResourcesRequiredException();
              }
            }
          }
          else
          {
            referencedResource = null; 
          }
        }
        return referencedResource;
      }
    }
    #endregion
  }
}