private static void ConvertContentTo(HtmlNode node, TextWriter outText, PrecedingDomTextInfo textInfo)
{
foreach (HtmlNode subnode in node.ChildNodes)
{
ConvertTo(subnode, outText, textInfo);
}
}
private static void ConvertTo(HtmlNode node, TextWriter outText, PrecedingDomTextInfo textInfo)
{
string html;
switch (node.NodeType)
{
case HtmlNodeType.Comment:
// don't output comments
break;
case HtmlNodeType.Document:
ConvertContentTo(node, outText, textInfo);
break;
case HtmlNodeType.Text:
// script and style must not be output
string parentName = node.ParentNode.Name;
if ((parentName == "script") || (parentName == "style"))
{
break;
}
// get text
html = ((HtmlTextNode)node).Text;
// is it in fact a special closing node output as text?
if (HtmlNode.IsOverlappedClosingElement(html))
{
break;
}
// check the text is meaningful and not a bunch of whitespaces
if (html.Length == 0)
{
break;
}
if (!textInfo.WritePrecedingWhiteSpace || textInfo.LastCharWasSpace)
{
html = html.TrimStart();
if (html.Length == 0)
{
break;
}
textInfo.IsFirstTextOfDocWritten.Value = textInfo.WritePrecedingWhiteSpace = true;
}
outText.Write(HtmlEntity.DeEntitize(Regex.Replace(html.TrimEnd(), @"\s{2,}", " ")));
if (textInfo.LastCharWasSpace = char.IsWhiteSpace(html[html.Length - 1]))
{
outText.Write(' ');
}
break;
case HtmlNodeType.Element:
string?endElementString = null;
bool isInline;
bool skip = false;
int listIndex = 0;
switch (node.Name)
{
case "nav":
skip = true;
isInline = false;
break;
case "body":
case "section":
case "article":
case "aside":
case "header":
case "footer":
case "address":
case "main":
case "div":
case "p": // stylistic - adjust as you tend to use
if (textInfo.IsFirstTextOfDocWritten)
{
outText.Write("\r\n");
}
endElementString = "\r\n";
isInline = false;
break;
case "em":
if (textInfo.IsFirstTextOfDocWritten)
{
outText.Write("_");
}
endElementString = "_";
isInline = true;
break;
case "strong":
if (textInfo.IsFirstTextOfDocWritten)
{
outText.Write("__");
}
endElementString = "__";
isInline = true;
break;
case "h1":
case "h2":
case "h3":
case "h4":
case "h5":
case "h6":
if (textInfo.IsFirstTextOfDocWritten)
{
outText.Write("\r\n");
int level = int.Parse(node.Name.Substring(1));
outText.Write(new string('#', level));
outText.Write(" ");
}
endElementString = "\r\n";
isInline = false;
break;
case "br":
outText.Write("\r\n");
skip = true;
textInfo.WritePrecedingWhiteSpace = false;
isInline = true;
break;
case "a":
if (node.Attributes.Contains("href"))
{
string href = node.Attributes["href"].Value?.Trim() ?? "";
if (!string.IsNullOrEmpty(href) && !href.StartsWith("data:"))
{
outText.Write("[");
endElementString = $"]({href})";
}
}
isInline = true;
break;
case "code":
if (textInfo.IsFirstTextOfDocWritten)
{
outText.Write("`");
}
endElementString = "`";
isInline = true;
break;
case "li":
if (textInfo.ListIndex > 0)
{
outText.Write("\r\n{0}.\t", textInfo.ListIndex++);
}
else
{
outText.Write(
"\r\n*\t"); //using '*' as bullet char, with tab after, but whatever you want eg "\t->", if utf-8 0x2022
}
isInline = false;
break;
case "ol":
listIndex = 1;
goto case "ul";
case "ul"
: //not handling nested lists any differently at this stage - that is getting close to rendering problems
endElementString = "\r\n";
isInline = false;
break;
case "img": //inline-block in reality
if (node.Attributes.Contains("alt"))
{
outText.Write('[' + node.Attributes["alt"].Value);
endElementString = "]";
}
if (node.Attributes.Contains("src"))
{
outText.Write('<' + node.Attributes["src"].Value + '>');
}
isInline = true;
break;
default:
isInline = true;
break;
}
if (!skip && node.HasChildNodes)
{
ConvertContentTo(node, outText,
isInline
? textInfo
: new PrecedingDomTextInfo(textInfo.IsFirstTextOfDocWritten)
{
ListIndex = listIndex
});
}
if (endElementString != null)
{
outText.Write(endElementString);
}
break;
}
}