// ---------------------------------------------------------------------
//
// Internal Methods
//
// ---------------------------------------------------------------------
/// <summary>
/// Main entry point for Xaml-to-Html converter.
/// Converts a xaml string into html string.
/// </summary>
/// <param name="xamlString">
/// Xaml strinng to convert.
/// </param>
/// <param name="context">Conversion context</param>
/// <returns>
/// Html string produced from a source xaml.
/// </returns>
public static string ConvertXamlToHtml(string xamlString, HtmlFromXamlContext context)
{
using (var xamlReader = XmlReader.Create(new StringReader(xamlString), new XmlReaderSettings {
DtdProcessing = DtdProcessing.Ignore, IgnoreWhitespace = true
}))
{
Preprocess(xamlReader, context);
}
using (var xamlReader = XmlReader.Create(new StringReader(xamlString), new XmlReaderSettings {
DtdProcessing = DtdProcessing.Ignore, IgnoreWhitespace = true
}))
{
var htmlStringBuilder = new StringBuilder(256);
using (var sw = new StringWriter(htmlStringBuilder))
{
using (var htmlWriter = XmlWriter.Create(sw, new XmlWriterSettings {
OmitXmlDeclaration = true
}))
{
if (!WriteFlowDocument(xamlReader, htmlWriter, context))
{
return(string.Empty);
}
}
}
return(htmlStringBuilder.ToString());
}
}
// ---------------------------------------------------------------------
//
// Private Methods
//
// ---------------------------------------------------------------------
#region Private Methods
private static void Preprocess(XmlReader xamlReader, HtmlFromXamlContext context)
{
if (!xamlReader.IsEmptyElement)
{
while (ReadNextToken(xamlReader) && xamlReader.NodeType != XmlNodeType.EndElement)
{
if (xamlReader.NodeType == XmlNodeType.Element)
{
if (xamlReader.Name == "Table")
{
context.AddTable();
}
else if (xamlReader.Name == "TableCell")
{
while (xamlReader.MoveToNextAttribute())
{
if (xamlReader.Name == "BorderThickness")
{
context.CurrentTable.AddBorder(GetThickness(xamlReader.Value));
}
}
xamlReader.MoveToElement();
}
Preprocess(xamlReader, context);
}
}
// Debug.Assert(xamlReader.NodeType == XmlNodeType.EndElement);
}
}
private static void WriteElementWithContent(XmlReader xamlReader, XmlWriter htmlWriter, string htmlElementName, StringBuilder inlineStyle, HtmlFromXamlContext context)
{
var subElements = new List <string>();
var elementName = xamlReader.LocalName;
if (!string.IsNullOrEmpty(elementName))
{
context.AddReaderElement(elementName);
}
if (!string.IsNullOrEmpty(htmlElementName))
{
htmlWriter.WriteStartElement(htmlElementName);
}
WriteFormattingProperties(xamlReader, htmlWriter, inlineStyle, subElements, context);
foreach (var element in subElements)
{
htmlWriter.WriteStartElement(element);
}
WriteElementContent(xamlReader, string.IsNullOrEmpty(htmlElementName) ? null : htmlWriter, inlineStyle, context);
foreach (var element in subElements)
{
htmlWriter.WriteEndElement();
}
if (!string.IsNullOrEmpty(htmlElementName))
{
htmlWriter.WriteEndElement();
}
if (!string.IsNullOrEmpty(elementName))
{
context.RemoveReaderElement(elementName);
}
}
/// <summary>
/// Converts a xaml element into an appropriate html element.
/// </summary>
/// <param name="xamlReader">
/// On entry this XTextReader must be on Element start tag;
/// on exit - on EndElement tag.
/// </param>
/// <param name="htmlWriter">
/// May be null, in which case we are skipping xaml content
/// without producing any html output
/// </param>
/// <param name="inlineStyle">
/// StringBuilder used for collecting css properties for inline STYLE attributes on every level.
/// </param>
/// <param name="context">Conversion context</param>
private static void WriteElement(XmlReader xamlReader, XmlWriter htmlWriter, StringBuilder inlineStyle, HtmlFromXamlContext context)
{
Debug.Assert(xamlReader.NodeType == XmlNodeType.Element);
if (htmlWriter == null)
{
// Skipping mode; recurse into the xaml element without any output
WriteElementContent(xamlReader, /*htmlWriter:*/ null, null, context);
}
else
{
string htmlElementName = null;
switch (xamlReader.LocalName)
{
case "Run":
case "Span":
htmlElementName = "span";
break;
case "InlineUIContainer":
htmlElementName = "span";
break;
case "Bold":
htmlElementName = "b";
break;
case "Italic":
htmlElementName = "i";
break;
case "Paragraph":
htmlElementName = "p";
break;
case "BlockUIContainer":
htmlElementName = "div";
break;
case "Section":
htmlElementName = "div";
break;
case "Table":
htmlElementName = "table";
context.TableMove();
break;
case "Table.Columns":
htmlElementName = "colgroup";
break;
case "TableColumn":
htmlElementName = "col";
break;
case "TableRowGroup":
htmlElementName = "tbody";
break;
case "TableRow":
htmlElementName = "tr";
break;
case "TableCell":
htmlElementName = "td";
break;
case "List":
string marker = xamlReader.GetAttribute("MarkerStyle");
if (marker == null || marker == "None" || marker == "Disc" || marker == "Circle" || marker == "Square" || marker == "Box")
{
htmlElementName = "ul";
}
else
{
htmlElementName = "ol";
}
break;
case "ListItem":
htmlElementName = "li";
break;
default:
if (context.OnGetHtmlElementName != null)
{
// Custom handling of the element
htmlElementName = context.OnGetHtmlElementName(xamlReader.LocalName);
}
else
{
htmlElementName = null;
}
break;
}
if (htmlWriter != null && htmlElementName != null)
{
WriteElementWithContent(xamlReader, htmlWriter, htmlElementName, inlineStyle, context);
}
else
{
// Skip this unrecognized xaml element
WriteElementContent(xamlReader, /*htmlWriter:*/ null, null, context);
}
}
}
/// <summary>
/// Conberts an element notation of complex property into
/// </summary>
/// <param name="xamlReader">
/// On entry this XTextReader must be on Element start tag;
/// on exit - on EndElement tag.
/// </param>
/// <param name="htmlWriter">
/// May be null, in which case we are skipping xaml content
/// without producing any html output
/// </param>
/// <param name="inlineStyle">
/// StringBuilder containing a value for STYLE attribute.
/// </param>
/// <param name="context">Conversion context</param>
private static bool HandleComplexProperty(XmlReader xamlReader, XmlWriter htmlWriter, StringBuilder inlineStyle, HtmlFromXamlContext context)
{
Debug.Assert(xamlReader.NodeType == XmlNodeType.Element);
// ship Table.Columns (unhandled)
if (!xamlReader.Name.Contains(".") || xamlReader.Name == "Table.Columns")
{
return(false);
}
if (xamlReader.Name.EndsWith(".TextDecorations"))
{
var level = 1;
var decorations = new List <string>();
while (ReadNextToken(xamlReader))
{
if (xamlReader.NodeType == XmlNodeType.Element)
{
if (!xamlReader.IsEmptyElement)
{
level++;
}
if (xamlReader.Name == "TextDecoration")
{
if (xamlReader.HasAttributes && xamlReader.MoveToAttribute("Location"))
{
if (xamlReader.Value == "Strikethrough")
{
decorations.Add("line-through");
}
else if (xamlReader.Value == "Underline")
{
decorations.Add("underline");
}
}
}
}
else if (xamlReader.NodeType == XmlNodeType.EndElement)
{
level--;
}
if (level <= 0)
{
if (decorations.Any())
{
inlineStyle?.Append($"text-decoration:{string.Join(" ", decorations)};");
}
break;
}
}
return(false);
}
else
{
// Skip the element representing the unhandled complex property
WriteElementContent(xamlReader, /*htmlWriter:*/ null, /*inlineStyle:*/ null, context);
return(true);
}
}
private static void WriteElementInnerContent(XmlReader xamlReader, XmlWriter htmlWriter, StringBuilder inlineStyle, HtmlFromXamlContext context, ref bool elementContentStarted)
{
while (ReadNextToken(xamlReader) && xamlReader.NodeType != XmlNodeType.EndElement)
{
switch (xamlReader.NodeType)
{
case XmlNodeType.Element:
if (!HandleComplexProperty(xamlReader, htmlWriter, inlineStyle, context))
{
if (htmlWriter != null && !elementContentStarted && inlineStyle.Length > 0)
{
// Output STYLE attribute and clear inlineStyle buffer.
htmlWriter.WriteAttributeString("style", inlineStyle.ToString());
inlineStyle.Clear();
}
elementContentStarted = true;
if (xamlReader.NodeType == XmlNodeType.Element)
{
WriteElement(xamlReader, htmlWriter, inlineStyle, context);
}
else
{
WriteElementInnerContent(xamlReader, htmlWriter, inlineStyle, context, ref elementContentStarted);
return;
}
}
Debug.Assert(xamlReader.NodeType == XmlNodeType.EndElement || xamlReader.NodeType == XmlNodeType.Element && xamlReader.IsEmptyElement);
break;
case XmlNodeType.Comment:
if (htmlWriter != null)
{
if (!elementContentStarted && inlineStyle.Length > 0)
{
htmlWriter.WriteAttributeString("style", inlineStyle.ToString());
}
htmlWriter.WriteComment(xamlReader.Value);
}
elementContentStarted = true;
break;
case XmlNodeType.CDATA:
case XmlNodeType.Text:
case XmlNodeType.SignificantWhitespace:
if (htmlWriter != null)
{
if (!elementContentStarted && inlineStyle.Length > 0)
{
htmlWriter.WriteAttributeString("style", inlineStyle.ToString());
}
var text = xamlReader.Value;
context.OnWriteText?.Invoke(xamlReader, htmlWriter, inlineStyle, context, ref text);
htmlWriter.WriteString(text);
}
elementContentStarted = true;
break;
}
}
}
/// <summary>
/// Reads a content of current xaml element, converts it
/// </summary>
/// <param name="xamlReader">
/// XTextReader which is expected to be at XmlNodeType.Element
/// (opening element tag) position.
/// </param>
/// <param name="htmlWriter">
/// May be null, in which case we are skipping the xaml element;
/// witout producing any output to html.
/// </param>
/// <param name="inlineStyle">
/// StringBuilder used for collecting css properties for inline STYLE attribute.
/// </param>
/// <param name="context">Conversion context</param>
private static void WriteElementContent(XmlReader xamlReader, XmlWriter htmlWriter, StringBuilder inlineStyle, HtmlFromXamlContext context)
{
Debug.Assert(xamlReader.NodeType == XmlNodeType.Element);
bool elementContentStarted = false;
if (xamlReader.IsEmptyElement)
{
if (htmlWriter != null && !elementContentStarted && inlineStyle.Length > 0)
{
// Output STYLE attribute (if still on element) and clear inlineStyle buffer
if (htmlWriter.WriteState == WriteState.Element)
{
htmlWriter.WriteAttributeString("style", inlineStyle.ToString());
}
inlineStyle.Clear();
}
elementContentStarted = true;
}
else
{
WriteElementInnerContent(xamlReader, htmlWriter, inlineStyle, context, ref elementContentStarted);
Debug.Assert(xamlReader.NodeType == XmlNodeType.EndElement);
}
}
/// <summary>
/// Reads attributes of the current xaml element and converts
/// them into appropriate html attributes or css styles.
/// </summary>
/// <param name="xamlReader">
/// XTextReader which is expected to be at XmlNodeType.Element
/// (opening element tag) position.
/// The reader will remain at the same level after function complete.
/// </param>
/// <param name="htmlWriter">
/// TextWriter for output html, which is expected to be in
/// after WriteStartElement state.
/// </param>
/// <param name="inlineStyle">
/// String builder for collecting css properties for inline STYLE attribute.
/// </param>
/// <param name="subElements"></param>
/// <param name="context">Conversion context</param>
private static void WriteFormattingProperties(XmlReader xamlReader, XmlWriter htmlWriter, StringBuilder inlineStyle, IList <string> subElements, HtmlFromXamlContext context)
{
Debug.Assert(xamlReader.NodeType == XmlNodeType.Element);
var elementName = xamlReader.LocalName;
// Clear string builder for the inline style
inlineStyle.Clear();
bool borderSet = false;
bool borderColorSet = false;
string fontSizeStyle = null;
var fontSizeIgnore = false;
if (xamlReader.HasAttributes)
{
while (xamlReader.MoveToNextAttribute())
{
string css = null;
switch (xamlReader.Name)
{
// Character fomatting properties
// ------------------------------
case "Background":
css = "background-color:" + ParseXamlColor(xamlReader.Value) + ";";
break;
case "FontFamily":
css = "font-family:" + xamlReader.Value + ";";
break;
case "FontStyle":
css = "font-style:" + xamlReader.Value.ToLower() + ";";
break;
case "FontWeight":
css = "font-weight:" + xamlReader.Value.ToLower() + ";";
break;
case "FontStretch":
break;
case "FontSize":
double size;
if (double.TryParse(xamlReader.Value, out size))
{
fontSizeStyle = "font-size:" + Math.Round(size, 1, MidpointRounding.AwayFromZero).ToString(CultureInfo.InvariantCulture) + "px;";
}
else
{
fontSizeStyle = "font-size:" + xamlReader.Value + "px;";
}
break;
case "Foreground":
css = "color:" + ParseXamlColor(xamlReader.Value) + ";";
break;
case "TextDecorations":
css = "text-decoration:underline;";
break;
case "TextEffects":
break;
case "Emphasis":
break;
case "StandardLigatures":
break;
case "Variants":
break;
case "Capitals":
break;
case "Fraction":
break;
case "BaselineAlignment":
if (xamlReader.Value == "Subscript")
{
subElements.Add("sub");
fontSizeIgnore = true;
}
else if (xamlReader.Value == "Superscript")
{
subElements.Add("sup");
fontSizeIgnore = true;
}
break;
// Paragraph formatting properties
// -------------------------------
case "Padding":
css = "padding:" + ParseXamlThickness(xamlReader.Value) + ";";
break;
case "Margin":
css = "margin:" + ParseXamlThickness(xamlReader.Value) + ";";
break;
case "BorderThickness":
var t = GetThickness(xamlReader.Value);
var bw = PrintThickness(t);
css = $"border-width:{bw};";
borderSet = true;
break;
case "BorderBrush":
css = "border-color:" + ParseXamlColor(xamlReader.Value) + ";";
borderColorSet = true;
break;
case "LineHeight":
break;
case "TextIndent":
css = "text-indent:" + xamlReader.Value + ";";
break;
case "TextAlignment":
css = "text-align:" + xamlReader.Value + ";";
break;
case "IsKeptTogether":
break;
case "IsKeptWithNext":
break;
case "ColumnBreakBefore":
break;
case "PageBreakBefore":
break;
case "FlowDirection":
break;
// Table attributes
// ----------------
case "Width":
css = "width:" + ParseXamlSize(xamlReader.Value) + ";";
break;
case "ColumnSpan":
htmlWriter.WriteAttributeString("COLSPAN", xamlReader.Value);
break;
case "RowSpan":
htmlWriter.WriteAttributeString("ROWSPAN", xamlReader.Value);
break;
case "CellSpacing":
if (xamlReader.Value == "0")
{
css = "border-collapse:collapse;";
}
break;
default:
context.OnWriteCustomProperty?.Invoke(xamlReader, htmlWriter, inlineStyle, context, xamlReader.Name);
break;
}
if (context.OnWriteElementAttribute != null)
{
css = context.OnWriteElementAttribute(elementName, xamlReader.Name, xamlReader.Value, css);
}
if (css != null)
{
inlineStyle.Append(css);
}
}
if (!fontSizeIgnore && fontSizeStyle != null)
{
inlineStyle.Append(fontSizeStyle);
}
}
if (elementName == "Table")
{
if (!borderSet && context.CurrentTable != null)
{
var t = context.CurrentTable.CommonBorder;
var thickness = PrintThickness(new HtmlThickness(0, t.Top, t.Right, 0));
inlineStyle.Append($"border-width:{thickness};");
borderSet = true;
}
}
if (borderSet || borderColorSet)
{
inlineStyle.Append("border-style:solid;");
}
context.OnWriteElementStyle?.Invoke(xamlReader, htmlWriter, inlineStyle, context, elementName);
// Return the xamlReader back to element level
xamlReader.MoveToElement();
Debug.Assert(xamlReader.NodeType == XmlNodeType.Element);
}
/// <summary>
/// Processes a root level element of XAML (normally it's FlowDocument element).
/// </summary>
/// <param name="xamlReader">
/// XTextReader for a source xaml.
/// </param>
/// <param name="htmlWriter">
/// TextWriter producing resulting html
/// </param>
/// <param name="context">Conversion context</param>
private static bool WriteFlowDocument(XmlReader xamlReader, XmlWriter htmlWriter, HtmlFromXamlContext context)
{
if (!ReadNextToken(xamlReader))
{
// Xaml content is empty - nothing to convert
return(false);
}
if (xamlReader.NodeType != XmlNodeType.Element || (xamlReader.Name != "FlowDocument" && xamlReader.Name != "Section"))
{
// Root FlowDocument elemet is missing
return(false);
}
// Create a buffer StringBuilder for collecting css properties for inline STYLE attributes
// on every element level (it will be re-initialized on every level).
var inlineStyle = new StringBuilder();
if (context.Options.OuterElement != string.Empty)
{
htmlWriter.WriteStartElement(context.Options.OuterElement);
}
WriteElementWithContent(xamlReader, htmlWriter, context.Options.InnerElement, inlineStyle, context);
if (context.Options.OuterElement != string.Empty)
{
htmlWriter.WriteEndElement();
}
return(true);
}
