Content Services

The IContentService interface is the primary entry point for programmatically reading, writing, and otherwise manipulating the HTML document hosted by a WinFormHtmlEditor control. Access it through htmlEditor1.Content. Members fall into three groups: bulk content I/O (get/set body, document, files), targeted insertion (HTML at caret, head injection, scripts), and document inspection (element lookup, attribute access, link and image enumeration). Two sub-services are reachable through this interface: TableAuthoringService for table row/column/cell authoring and MailMerge for host-registered placeholder fields.

All methods operate against the currently active document and fire the editor's normal change notifications. Callers should not invoke these methods from non-UI threads. Methods that depend on a live MSHTML document require the editor to be in WYSIWYG design mode; calls made from source-edit mode are either ignored or return last-loaded data depending on the method.

GetBodyText Method

Returns the plain-text content of the document body, with HTML markup stripped. Use this for indexing, comparison, or display in a non-HTML surface.

Syntax

string GetBodyText();

Returns

string -- the plain-text body content.

Example

string body = htmlEditor1.Content.GetBodyText();
Console.WriteLine($"Plain body has {body.Length} chars");

Dim body As String = htmlEditor1.Content.GetBodyText()
Console.WriteLine($"Plain body has {body.Length} chars")

GetFormattedPlainText Method

Similar to GetBodyText but preserves block-level layout cues such as paragraph line breaks. Try both algorithms and pick the one whose output best matches the host application's expectations.

Syntax

string GetFormattedPlainText();

Returns

string -- the formatted plain-text body.

Example

string formatted = htmlEditor1.Content.GetFormattedPlainText();
File.WriteAllText(@"C:\temp\export.txt", formatted);

Dim formatted As String = htmlEditor1.Content.GetFormattedPlainText()
File.WriteAllText("C:\temp\export.txt", formatted)

SetBodyText Method

Replaces the document body with the supplied plain text. HTML metacharacters (<, >, &) in the input are escaped automatically.

Syntax

void SetBodyText(string text);

Parameters

Example

htmlEditor1.Content.SetBodyText("Quarterly report draft - 2026 Q1");

GetBodyHtml Method

Returns the HTML markup contained in the document body. The getInXhtml parameter controls whether the output is normalized to XHTML (self-closing void tags, lowercase names, quoted attributes).

Syntax

string GetBodyHtml(bool getInXhtml);

Parameters

Returns

string -- the body HTML.

Example

string xhtml = htmlEditor1.Content.GetBodyHtml(getInXhtml: true);
XDocument doc = XDocument.Parse("<root>" + xhtml + "</root>");

Dim xhtml As String = htmlEditor1.Content.GetBodyHtml(getInXhtml:=True)
Dim doc As XDocument = XDocument.Parse("<root>" & xhtml.ToString() & "</root>")

SetBodyHtml Method

Replaces the document body markup with the supplied HTML. Equivalent to assigning the WinFormHtmlEditor.BodyHtml property.

Syntax

void SetBodyHtml(string bodyHtml);

Parameters

Example

htmlEditor1.Content.SetBodyHtml("<h1>Welcome</h1><p>Edit me.</p>");

GetDocumentHtml Method

Returns the full HTML document including the DOCTYPE, head, and body. Use this when the host needs the complete file payload for save or upload.

Syntax

string GetDocumentHtml();

Returns

string -- the complete document HTML.

Example

string fullDoc = htmlEditor1.Content.GetDocumentHtml();
File.WriteAllText(@"C:\temp\out.html", fullDoc, Encoding.UTF8);

Dim fullDoc As String = htmlEditor1.Content.GetDocumentHtml()
File.WriteAllText("C:\temp\out.html", fullDoc, Encoding.UTF8)

SetDocumentHtml Method

Replaces the entire document with the supplied HTML, including DOCTYPE, head, and body. Equivalent to assigning the WinFormHtmlEditor.DocumentHtml property.

Syntax

void SetDocumentHtml(string docHtml);

Parameters

Example

string template = File.ReadAllText(@"C:\templates\letter.html");
htmlEditor1.Content.SetDocumentHtml(template);

Dim template As String = File.ReadAllText("C:\templates\letter.html")
htmlEditor1.Content.SetDocumentHtml(template)

GetDocumentXml Method

Returns the document content serialized as XML. Useful when the host needs to persist or interchange the document through an XML pipeline.

Syntax

string GetDocumentXml();

Returns

string -- XML representation of the document.

Example

string xml = htmlEditor1.Content.GetDocumentXml();
XDocument.Parse(xml).Save(@"C:\temp\doc.xml");

Dim xml As String = htmlEditor1.Content.GetDocumentXml()
XDocument.Parse(xml).Save("C:\temp\doc.xml")

GetBodyStyleAsDom Method

Returns the body element's style as an mshtml.IHTMLStyle COM pointer. Use this to read or mutate individual CSS properties without parsing the style string. Returns null when no body element is available (e.g. source-edit mode).

Syntax

IHTMLStyle GetBodyStyleAsDom();

Returns

mshtml.IHTMLStyle -- the body style DOM wrapper.

Example

IHTMLStyle style = htmlEditor1.Content.GetBodyStyleAsDom();
if (style != null)
{
    style.backgroundColor = "#fafafa";
    style.color = "#222";
}

Dim style As IHTMLStyle = htmlEditor1.Content.GetBodyStyleAsDom()

If style IsNot Nothing Then
    style.backgroundColor = "#fafafa"
    style.color = "#222"
End If

GetBodyStyle Method

Returns the value of the body element's style attribute as a CSS declaration string.

Syntax

string GetBodyStyle();

Returns

string -- the inline CSS string.

Example

string css = htmlEditor1.Content.GetBodyStyle();
Debug.WriteLine($"Body inline CSS = {css}");

Dim css As String = htmlEditor1.Content.GetBodyStyle()
Debug.WriteLine($"Body inline CSS = {css}")

SetBodyStyle Method

Writes the supplied CSS declaration string to the body element's style attribute, replacing any existing value.

Syntax

void SetBodyStyle(string styleValue);

Parameters

Example

htmlEditor1.Content.SetBodyStyle("font-family:Segoe UI; padding:12px; color:#222;");

GetBodyClassName Method

Returns the body element's class attribute, or empty string when no class is set.

Syntax

string GetBodyClassName();

Returns

string -- the body class name.

Example

if (htmlEditor1.Content.GetBodyClassName() != "dark")
    htmlEditor1.Content.SetBodyClassName("dark");

If htmlEditor1.Content.GetBodyClassName() IsNot "dark" Then htmlEditor1.Content.SetBodyClassName("dark")

SetBodyClassName Method

Sets the body element's class attribute. Pair this with an InsertHtmlBetweenHead call that injects the matching <style> block to switch the document's theme at runtime.

Syntax

void SetBodyClassName(string className);

Parameters

Example

htmlEditor1.Content.SetBodyClassName("print-preview");

GetAllLinkHrefs Method

Returns the list of href attribute values for every anchor (<a>) in the document body. Use this to validate or rewrite outgoing URLs before publication.

Syntax

string[] GetAllLinkHrefs();

Returns

string[] -- array of hyperlink URLs.

Example

foreach (string href in htmlEditor1.Content.GetAllLinkHrefs())
{
    if (!Uri.IsWellFormedUriString(href, UriKind.Absolute))
        Debug.WriteLine($"Broken link: {href}");
}

For Each href As String In htmlEditor1.Content.GetAllLinkHrefs()
    If Not Uri.IsWellFormedUriString(href, UriKind.Absolute) Then Debug.WriteLine($"Broken link: {href}")
Next

GetAllImageSources Method

Returns the list of src attribute values for every <img> element in the body, in document order.

Syntax

string[] GetAllImageSources();

Returns

string[] -- array of image source URLs.

Example

string[] images = htmlEditor1.Content.GetAllImageSources();
MessageBox.Show($"Document references {images.Length} image(s).");

Dim images As String() = htmlEditor1.Content.GetAllImageSources()
MessageBox.Show($"Document references {images.Length} image(s).")

InsertHtml Method

Inserts an HTML fragment at the caret position without disturbing focus. The canonical way to plug arbitrary markup into the document from a custom toolbar button. Script blocks are filtered out by this method; use InsertScript for those.

Syntax

void InsertHtml(string htmlText, bool keepSelected);

Parameters

Example

htmlEditor1.Content.InsertHtml("<p>Hello, <b>world</b></p>", keepSelected: false);

htmlEditor1.Content.InsertHtml("<p>Hello, <b>world</b></p>", keepSelected:=False)

InsertText Method

Inserts a plain-text fragment at the caret. HTML metacharacters in the input are escaped (so < becomes <).

Syntax

void InsertText(string text);

Parameters

Example

htmlEditor1.Content.InsertText(DateTime.Now.ToString("yyyy-MM-dd HH:mm"));

InsertHorizontalRule Method

Inserts an <hr> horizontal-rule element at the caret position.

Syntax

void InsertHorizontalRule();

Example

private void DividerButton_Click(object sender, EventArgs e)
{
    htmlEditor1.Content.InsertHorizontalRule();
}

Private Sub DividerButton_Click(sender As Object, e As EventArgs)
    htmlEditor1.Content.InsertHorizontalRule()
End Sub

InsertScript Method

Inserts a script block at the caret position. InsertHtml strips <script> tags; use this method instead when the script must be preserved in the document.

Syntax

void InsertScript(string scriptMarkUp);

Parameters

Example

htmlEditor1.Content.InsertScript("<script>console.log('hi');</script>");

InsertHtmlBetweenHead Method

Inserts the supplied HTML inside the document's <head> section. Useful for injecting <style>, <link>, <meta>, or <script> elements that should live in the head rather than in the body.

Syntax

void InsertHtmlBetweenHead(string insertingHtml);

Parameters

Example

htmlEditor1.Content.InsertHtmlBetweenHead(

    "<style id='theme'>body { background:#222; color:#eee; }</style>");

RemoveHtmlElementFromHeadByTag Method

Removes every element inside <head> whose tag name matches tagName. Tag matching is case-insensitive.

Syntax

void RemoveHtmlElementFromHeadByTag(string tagName);

Parameters

Example

// Clear all stylesheet links before reapplying a fresh theme.

htmlEditor1.Content.RemoveHtmlElementFromHeadByTag("link");

RemoveHtmlElementFromHeadById Method

Removes the element inside <head> whose id attribute matches the supplied value. No-op when no matching element exists.

Syntax

void RemoveHtmlElementFromHeadById(string id);

Parameters

Example

htmlEditor1.Content.RemoveHtmlElementFromHeadById("theme");

RemoveHtmlElementById Method

Removes the element anywhere in the document whose id attribute matches the supplied value.

Syntax

void RemoveHtmlElementById(string id);

Parameters

Example

htmlEditor1.Content.RemoveHtmlElementById("legacyBanner");

ChangeElementId Method

Renames the id attribute of the element from oldId to newId. Useful when restructuring a document programmatically.

Syntax

void ChangeElementId(string oldId, string newId);

Parameters

Example

htmlEditor1.Content.ChangeElementId("intro", "introduction");

ElementExists Method

Returns true if an element with the supplied id exists anywhere in the document.

Syntax

bool ElementExists(string elementId);

Parameters

Returns

bool -- true if found.

Example

if (!htmlEditor1.Content.ElementExists("footer"))
    htmlEditor1.Content.InsertHtml("<div id='footer'>(c) 2026</div>", false);

If Not htmlEditor1.Content.ElementExists("footer") Then htmlEditor1.Content.InsertHtml("<div id='footer'>(c) 2026</div>", False)

GetAttributeValueOfAnElement Method

Returns the value of the named attribute on the element with the given id.

Syntax

string GetAttributeValueOfAnElement(string elementId, string attributeName);

Parameters

Returns

string -- attribute value, or empty string when not set.

Example

string href = htmlEditor1.Content.GetAttributeValueOfAnElement("mainLink", "href");

Dim href As String = htmlEditor1.Content.GetAttributeValueOfAnElement("mainLink", "href")

SetAttributeValueOfAnElement Method

Sets the value of the named attribute on the element with the given id.

Syntax

void SetAttributeValueOfAnElement(string elementId, string attributeName, string value);

Parameters

Example

htmlEditor1.Content.SetAttributeValueOfAnElement("logo", "alt", "Company logo");

GetOuterHtmlOfAnElement Method

Returns the outer HTML (including the element's own tag) of the element with the given id.

Syntax

string GetOuterHtmlOfAnElement(string elementId);

Parameters

Returns

string -- outer HTML.

Example

string outerHtml = htmlEditor1.Content.GetOuterHtmlOfAnElement("intro");
Debug.WriteLine(outerHtml);

Dim outerHtml As String = htmlEditor1.Content.GetOuterHtmlOfAnElement("intro")
Debug.WriteLine(outerHtml)

GetInnerHtmlOfAnElement Method

Returns the inner HTML (the markup between the element's open and close tags) of the element with the given id.

Syntax

string GetInnerHtmlOfAnElement(string elementId);

Parameters

Returns

string -- inner HTML.

Example

string innerHtml = htmlEditor1.Content.GetInnerHtmlOfAnElement("sidebar");

Dim innerHtml As String = htmlEditor1.Content.GetInnerHtmlOfAnElement("sidebar")

UpdateInnerHtmlOfAnElement Method

Replaces the inner HTML of the element with the given id. Existing children are discarded.

Syntax

void UpdateInnerHtmlOfAnElement(string elementId, string newHtml);

Parameters

Example

htmlEditor1.Content.UpdateInnerHtmlOfAnElement("status", "<b>Updated</b>");

GetHtmlElements Method

Returns a snapshot of every element in the document (or just the body, depending on the argument) as a System.Windows.Forms.HtmlElementCollection, which the host can enumerate to inspect or mutate elements.

Syntax

HtmlElementCollection GetHtmlElements(bool onlyBodyElements);

Parameters

Returns

System.Windows.Forms.HtmlElementCollection -- the element collection.

Example

var elements = htmlEditor1.Content.GetHtmlElements(onlyBodyElements: true);
foreach (HtmlElement el in elements)
{
    if (el.TagName == "IMG")
        Debug.WriteLine(el.GetAttribute("src"));
}

Dim elements = htmlEditor1.Content.GetHtmlElements(onlyBodyElements:=True)

For Each el As HtmlElement In elements
    If el.TagName Is "IMG" Then Debug.WriteLine(el.GetAttribute("src"))
Next

GetBodyIHtmlElements Method

Returns the body elements as an mshtml.IHTMLElementCollection COM pointer. Use this when an MSHTML-style API surface is required (for example, when calling COM methods that expect MSHTML interfaces).

Syntax

IHTMLElementCollection GetBodyIHtmlElements();

Returns

mshtml.IHTMLElementCollection -- the body element collection.

Example

IHTMLElementCollection coll = htmlEditor1.Content.GetBodyIHtmlElements();
foreach (IHTMLElement el in coll)
    Debug.WriteLine(el.tagName);

Dim coll As IHTMLElementCollection = htmlEditor1.Content.GetBodyIHtmlElements()

For Each el As IHTMLElement In coll
    Debug.WriteLine(el.tagName)
Next

GetHtmlElementAt Method

Returns the topmost element under the supplied document coordinate as an mshtml.IHTMLElement. Useful for hit-testing custom commands or drag-and-drop targeting.

Syntax

IHTMLElement GetHtmlElementAt(Point caretPosition);

Parameters

Returns

mshtml.IHTMLElement -- the element at that point, or null.

Example

IHTMLElement hit = htmlEditor1.Content.GetHtmlElementAt(new Point(120, 80));
if (hit != null)
    Debug.WriteLine($"Hit: {hit.tagName}#{hit.id}");

Dim hit As IHTMLElement = htmlEditor1.Content.GetHtmlElementAt(New Point(120, 80))
If hit IsNot Nothing Then Debug.WriteLine($"Hit: {hit.tagName}#{hit.id}")

EmbedLocalImagesAsBase64 Method

Walks the document looking for <img> elements whose src resolves to a local file and rewrites each one into a Base64-encoded data: URI. After this call the document is self-contained -- safe to email or save as a single HTML file.

Syntax

void EmbedLocalImagesAsBase64();

Example

htmlEditor1.Content.EmbedLocalImagesAsBase64();
string portable = htmlEditor1.Content.GetDocumentHtml();
File.WriteAllText(@"C:\temp\portable.html", portable);

htmlEditor1.Content.EmbedLocalImagesAsBase64()
Dim portable As String = htmlEditor1.Content.GetDocumentHtml()
File.WriteAllText("C:\temp\portable.html", portable)

GetEmailMessageWithLocalImagesEmbedded Method

Builds and returns a System.Net.Mail.MailMessage whose HTML body is the current document with all local images converted to linked resources. Use this when sending the document as an email without writing your own MIME packaging.

Syntax

MailMessage GetEmailMessageWithLocalImagesEmbedded();

Returns

System.Net.Mail.MailMessage -- the constructed message ready to hand to SmtpClient.Send.

Example

using (MailMessage msg = htmlEditor1.Content.GetEmailMessageWithLocalImagesEmbedded())
{
    msg.From = new MailAddress("you@example.com");
    msg.To.Add("customer@example.com");
    msg.Subject = "Monthly report";
    new SmtpClient("smtp.example.com").Send(msg);
}

Using msg As MailMessage = htmlEditor1.Content.GetEmailMessageWithLocalImagesEmbedded()
    msg.From = New MailAddress("you@example.com")
    msg.[To].Add("customer@example.com")
    msg.Subject = "Monthly report"
    Call New SmtpClient("smtp.example.com").Send(msg)
End Using

LoadBodyHtmlFromFile Method

Loads an HTML fragment from filePath using the given encoding and replaces the body content with it. The document head and DOCTYPE are preserved.

Syntax

void LoadBodyHtmlFromFile(string filePath, Encoding encoding);

Parameters

Example

htmlEditor1.Content.LoadBodyHtmlFromFile(@"C:\templates\body.html", Encoding.UTF8);

LoadDocumentHtmlFromFile Method

Loads a complete HTML document from filePath using the given encoding and replaces the entire document.

Syntax

void LoadDocumentHtmlFromFile(string filePath, Encoding encoding);

Parameters

Example

htmlEditor1.Content.LoadDocumentHtmlFromFile(@"C:\templates\letter.html", Encoding.UTF8);

SaveBodyHtmlToFile Method

Writes the body HTML to filePath. Existing files are overwritten.

Syntax

void SaveBodyHtmlToFile(string filePath);

Parameters

Example

htmlEditor1.Content.SaveBodyHtmlToFile(@"C:\out\fragment.html");

SaveDocumentHtmlToFile Method

Writes the complete HTML document (DOCTYPE, head, body) to filePath.

Syntax

void SaveDocumentHtmlToFile(string filePath);

Parameters

Example

htmlEditor1.Content.SaveDocumentHtmlToFile(@"C:\out\full.html");

SaveEditorContentAsXml Method

Serializes the document HTML as XML and writes it to the supplied file. Provided for host apps that store editor content as XML.

Syntax

void SaveEditorContentAsXml(string fileName);

Parameters

Example

htmlEditor1.Content.SaveEditorContentAsXml(@"C:\out\snapshot.xml");

OpenFile Method

Opens an HTML file from filePath and loads it into the editor. Encoding is detected automatically. Fires the editor's FileOpened event on success.

Syntax

void OpenFile(string filePath);

Parameters

Example

using (var dlg = new OpenFileDialog
{
    Filter = "HTML files|*.html;*.htm"
}

)
{
    if (dlg.ShowDialog() == DialogResult.OK)
        htmlEditor1.Content.OpenFile(dlg.FileName);
}

    Using dlg = New OpenFileDialog With {
.Filter = "HTML files|*.html;*.htm"
    }
        If dlg.ShowDialog() Is DialogResult.OK Then htmlEditor1.Content.OpenFile(dlg.FileName)
    End Using

ClearContent Method

Clears the document body. The document's head, DOCTYPE, and configured base URL are preserved.

Syntax

void ClearContent();

Example

private void NewDocumentButton_Click(object sender, EventArgs e)
{
    htmlEditor1.Content.ClearContent();
}

Private Sub NewDocumentButton_Click(sender As Object, e As EventArgs)
    htmlEditor1.Content.ClearContent()
End Sub

UpdateBaseUrl Method

Updates the <base href> element of the document. Equivalent to assigning the WinFormHtmlEditor.BaseUrl property.

Syntax

void UpdateBaseUrl(string baseUrl);

Parameters

Example

htmlEditor1.Content.UpdateBaseUrl("https://cdn.example.com/assets/");

GetRightToLeft Method

Returns the document's right-to-left setting.

Syntax

RightToLeft GetRightToLeft();

Returns

System.Windows.Forms.RightToLeft -- the RTL mode (Yes, No, or Inherit).

Example

RightToLeft rtl = htmlEditor1.Content.GetRightToLeft();

Debug.WriteLine($"Current RTL mode = {rtl}");

SetRightToLeft Method

Sets the document's right-to-left direction. Use this for languages such as Arabic or Hebrew.

Syntax

void SetRightToLeft(RightToLeft rightToLeftValue);

Parameters

Example

htmlEditor1.Content.SetRightToLeft(RightToLeft.Yes);

ResetTableManipulator Method

Resets the table-authoring helper attached to the current document. Call this after restructuring tables programmatically so the next user interaction sees a fresh manipulator state.

Syntax

void ResetTableManipulator();

Example

htmlEditor1.Content.SetBodyHtml(rebuiltHtml);

htmlEditor1.Content.ResetTableManipulator();

Dispose Method (inherited from IDisposable)

Releases unmanaged resources held by the content service. The control disposes its services automatically when the control itself is disposed; host applications normally do not call this directly.

Syntax

void Dispose();

Example

// The host control owns disposal -- only call this if you took ownership of the service.

htmlEditor1.Content.Dispose();

TableAuthoringService Property

Gets or sets the table-authoring sub-service. The sub-service offers row/column/cell operations (insert before/after, delete, merge), zero-border guideline visibility, and selected-cell background color.

Syntax

ITableAuthoringService TableAuthoringService { get; set; }

Property value

ITableAuthoringService -- the table-authoring service.

Remarks

Common members: InsertColumn(InsertPositions), DeleteColumn(), InsertRow(InsertPositions), DeleteRow(), MergeSelectedCells(), CanMergeCells(), ShowGuidelinesForTablesWithZeroBorder(bool), HideGuidelinesOfTablesWithZeroBorder(bool), IsTableBorderZero(IHTMLElement), SelectedCellBackgroundColor, EnableTableCellMerging, GetTableManipulator(), ResetTableManipulator().

Example

var tas = htmlEditor1.Content.TableAuthoringService;
tas.InsertRow(InsertPositions.Below);
if (tas.CanMergeCells())
    tas.MergeSelectedCells();

Dim tas = htmlEditor1.Content.TableAuthoringService
tas.InsertRow(InsertPositions.Below)
If tas.CanMergeCells() Then tas.MergeSelectedCells()

MailMerge Property

Gets the mail-merge placeholder insertion sub-service (Feature 2.5.5). The host application registers a list of PlaceholderField entries, and the editor lets the end user insert any of them as a placeholder span -- useful for building templates that are later filled per-record at send time.

Syntax

IMailMergeService MailMerge { get; }

Property value

IMailMergeService -- the mail-merge service.

Remarks

Members: IList<PlaceholderField> PlaceholderFields { get; set; } -- fields registered for end-user insertion; void InsertPlaceholder(PlaceholderField field) -- inserts a placeholder span at the caret (ignored in source-edit mode); event EventHandler<PlaceholderInsertedEventArgs> PlaceholderInserted -- fires after a span is inserted with the field and emitted HTML.

Example

htmlEditor1.Content.MailMerge.PlaceholderFields = new List<PlaceholderField>
{
    new PlaceholderField
    {
        Name = "FirstName",
        DisplayLabel = "First Name"
    },
    new PlaceholderField
    {
        Name = "OrderTotal",
        DisplayLabel = "Order Total"
    }
};
htmlEditor1.Content.MailMerge.PlaceholderInserted += (s, e) => Debug.WriteLine($"Inserted {e.Field.Name}: {e.InsertedHtml}");

    htmlEditor1.Content.MailMerge.PlaceholderFields = New List(Of PlaceholderField) From {
    New PlaceholderField With {
    .Name = "FirstName",
    .DisplayLabel = "First Name"
},
    New PlaceholderField With {
    .Name = "OrderTotal",
    .DisplayLabel = "Order Total"
}
    }
    htmlEditor1.Content.MailMerge.PlaceholderInserted += Function(s, e) Debug.WriteLine($"Inserted {e.Field.Name}: {e.InsertedHtml}")

Remarks

The member SetAttributeValueOfAnElementFromBODY appeared in older releases but has been removed; use SetAttributeValueOfAnElement for both head and body elements. Methods that depend on a live MSHTML document require the editor to be in WYSIWYG design mode -- calls made in source-edit mode are either ignored or return last-loaded data. All calls must be made on the UI thread.