/// <summary>
/// Gets HTML from a text string, wrapping lines in the given default block element.
/// </summary>
/// <param name="text">The plain text to convert into HTML</param>
/// <returns>The HTML</returns>
public static string GetHTMLFromText(string text, bool addLinks, DefaultBlockElement defaultBlockElement)
{
text = EscapeHtmlEntitiesAndAddLinks(text, addLinks);
text = NormalizeText(text);
return ConvertTextToHtml(text, defaultBlockElement);
}
private static string ConvertTextToHtml(string text, DefaultBlockElement defaultBlockElement)
{
if (defaultBlockElement == null)
{
return text.Replace("\r\n", "<br />");
}
if (!text.Contains("\r\n"))
{
return text;
}
bool insideBlockElement = false;
bool blockElementIsEmpty = true;
// Replace each occurrence of a sequence of non-CRLF characters followed by 0 or more CRLFs with the
// non-CRLF characters wrapped in an HTML block element:
// line1\r\nline2\r\n\r\nline3 => <p>line1<br />line2</p><p>line3</p>
// (the <br /> is added because ParagraphDefaultBlockElement.NumberOfNewLinesToReplace == 2)
string htmlFromText = Regex.Replace(text, @"(?<plainText>[^\r\n]+)?(?<succeedingNewLines>(\r\n){0," + defaultBlockElement.NumberOfNewLinesToReplace + "})",
delegate (Match match)
{
Group plainText = match.Groups["plainText"];
Group succeedingNewLines = match.Groups["succeedingNewLines"];
if (plainText.Length == 0 && succeedingNewLines.Length == 0)
{
return string.Empty;
}
StringBuilder html = new StringBuilder();
if (!insideBlockElement)
{
html.Append(defaultBlockElement.BeginTag);
insideBlockElement = true;
blockElementIsEmpty = true;
}
if (plainText.Length > 0)
{
html.Append(plainText.Value);
blockElementIsEmpty = false;
}
// The length of succeedingNewLines is the number of characters captured and each newline is two characters: \r\n.
int numberOfSucceedingNewLines = succeedingNewLines.Length / 2;
if (numberOfSucceedingNewLines == defaultBlockElement.NumberOfNewLinesToReplace)
{
if (blockElementIsEmpty)
{
// Manually inflate the element, otherwise it won't be rendered.
html.Append(" ");
}
html.AppendLine(defaultBlockElement.EndTag);
insideBlockElement = false;
}
else
{
for (int i = 0; i < numberOfSucceedingNewLines; i++)
{
html.AppendLine("<br />");
blockElementIsEmpty = false;
}
}
return html.ToString();
});
return insideBlockElement ? htmlFromText + defaultBlockElement.EndTag : htmlFromText;
}
public BasicHtmlGenerationService(DefaultBlockElement defaultBlockElement)
{
_defaultBlockElement = defaultBlockElement;
}
