Editor Services

The IEditorService interface, exposed through the WinFormHtmlEditor.EditorService property, is the workhorse API for the editor. It bundles together clipboard commands, undo and redo, find and replace, scrollbar layout, justification, print and page setup, and the low-level ExecCommand dispatcher. Most user-facing toolbar buttons in the bundled sample applications are thin wrappers over methods on this service.

The service is owned by the editor and disposed when the editor is disposed; do not dispose it manually. Calls must happen after the document is ready - the simplest way to guarantee that is to call methods from event handlers raised by the editor itself (for example, WinFormHtmlEditor.DocumentReady).

Search and Replace methods operate against the rendered text and return success flags or counts you can surface in your UI. The ExecCommand method is an escape hatch into the underlying browser command engine and accepts any of the documented MSHTML execCommand identifiers. In all examples below, htmlEditor1 is a WinFormHtmlEditor placed on the form at design time.

AdjustEditorSize Method

Resizes both the width and the height of the editor so the entire document fits without needing scrollbars. Useful for "auto-grow" layouts where the editor should expand to its content rather than scroll.

Syntax

public void AdjustEditorSize()

Example

private void htmlEditor1_DocumentReady(object sender, EventArgs e)
{
    // Make the editor large enough to show the whole document at once.
    htmlEditor1.EditorService.AdjustEditorSize();
}

AdjustEditorWidth Method

Resets the control width so the horizontal scrollbar is not needed; the editor expands or shrinks based on the widest visible content. Height is left unchanged.

Syntax

public void AdjustEditorWidth()

Example

private void widenButton_Click(object sender, EventArgs e)
{
    htmlEditor1.EditorService.AdjustEditorWidth();
}

AdjustEditorHeight Method

Resets the control height so the vertical scrollbar is not needed; the editor expands or shrinks based on visible content. Width is left unchanged.

Syntax

public void AdjustEditorHeight()

Example

private void heightFitButton_Click(object sender, EventArgs e)
{
    htmlEditor1.EditorService.AdjustEditorHeight();
}

GetScrollBarSetting Method

Returns the current scrollbar visibility policy as a ScrollBarVisibility enum value. Useful when you need to toggle scrollbars and want to restore the prior setting.

Syntax

public ScrollBarVisibility GetScrollBarSetting()

Returns

ScrollBarVisibility — the current scrollbar policy.

Example

ScrollBarVisibility prior = htmlEditor1.EditorService.GetScrollBarSetting();
htmlEditor1.EditorService.SetScrollBarSetting(ScrollBarVisibility.None);
PrintEditor();
htmlEditor1.EditorService.SetScrollBarSetting(prior); // restore

SetScrollBarSetting Method

Applies a scrollbar visibility policy to the editor. The policy controls whether each scrollbar is always shown, never shown, shown only when needed, or driven by the document body style.

Syntax

public void SetScrollBarSetting(ScrollBarVisibility scrollbarValue)

Parameters

Remarks

Choose Custom when you want full control through the BodyStyle CSS overflow attribute - the editor will not overwrite your custom value in that mode.

Example

// Show scrollbars only when content overflows.
htmlEditor1.EditorService.SetScrollBarSetting(ScrollBarVisibility.Auto);

GetScrollPosition Method

Returns the current scroll offset of the editor viewport as a System.Drawing.Point. X is the horizontal scroll position and Y is the vertical scroll position, both in pixels.

Syntax

public Point GetScrollPosition()

Returns

System.Drawing.Point — the current scroll offset in pixels.

Example

Point savedScroll = htmlEditor1.EditorService.GetScrollPosition();
htmlEditor1.LoadHtml(updatedHtml);
htmlEditor1.EditorService.SetScrollPosition(savedScroll.X, savedScroll.Y);

SetScrollPosition Method

Scrolls the editor viewport to the absolute pixel coordinates supplied. Coordinates outside the scrollable range are clamped. Combine with GetScrollPosition to save and restore scroll state across page reloads.

Syntax

public void SetScrollPosition(int x, int y)

Parameters

Example

// Jump to the top of the document.
htmlEditor1.EditorService.SetScrollPosition(0, 0);

IsMsWordContentInClipboard Method

Determines whether the Windows clipboard currently holds content that originated from Microsoft Word. Use this to decide whether to enable a "Paste from Word" UI affordance.

Syntax

public bool IsMsWordContentInClipboard()

Returns

System.Boolean — true if the clipboard holds Word content; otherwise false.

Example

pasteFromWordToolStripButton.Enabled =
    htmlEditor1.EditorService.IsMsWordContentInClipboard();

PasteFromMsWord Method

Pastes clipboard content into the editor while stripping Word-specific noise (mso classes, conditional comments, redundant span wrappers). Produces cleaner HTML than a raw Paste when the source is Word.

Syntax

public void PasteFromMsWord()

Example

if (htmlEditor1.EditorService.IsMsWordContentInClipboard())
    htmlEditor1.EditorService.PasteFromMsWord();
else
    htmlEditor1.EditorService.Paste();

Cut Method

Performs a clipboard Cut: the current selection is copied to the clipboard and removed from the document. Equivalent to pressing Ctrl+X.

Syntax

public void Cut()

Example

private void cutToolStripButton_Click(object sender, EventArgs e)
{
    htmlEditor1.EditorService.Cut();
}

Copy Method

Copies the current selection to the clipboard without modifying the document. Equivalent to pressing Ctrl+C.

Syntax

public void Copy()

Example

private void copyToolStripButton_Click(object sender, EventArgs e)
{
    htmlEditor1.EditorService.Copy();
}

Delete Method

Deletes the current selection in the editor. If there is no selection, deletes the character to the right of the caret.

Syntax

public void Delete()

Example

private void deleteToolStripButton_Click(object sender, EventArgs e)
{
    htmlEditor1.EditorService.Delete();
}

Paste Method

Pastes the current clipboard content at the caret position. For Word-sourced content, prefer PasteFromMsWord which produces cleaner markup.

Syntax

public void Paste()

Example

private void pasteToolStripButton_Click(object sender, EventArgs e)
{
    htmlEditor1.EditorService.Paste();
}

Undo Method

Reverses the most recent edit. Calls are no-ops when the undo stack is empty.

Syntax

public void Undo()

Example

private void undoToolStripButton_Click(object sender, EventArgs e)
{
    htmlEditor1.EditorService.Undo();
}

Redo Method

Re-applies the most recent edit that was undone. Calls are no-ops when the redo stack is empty.

Syntax

public void Redo()

Example

private void redoToolStripButton_Click(object sender, EventArgs e)
{
    htmlEditor1.EditorService.Redo();
}

ToggleOverWriteMode Method

Toggles between insert mode and overwrite mode for the editor. In overwrite mode, typing replaces the character to the right of the caret instead of inserting before it.

Syntax

public void ToggleOverWriteMode()

Example

private void insertKey_Pressed(object sender, EventArgs e)
{
    htmlEditor1.EditorService.ToggleOverWriteMode();
}

Print Method

Prints the editor's HTML content. When showDialog is true the standard Print dialog is shown so the user can pick printer and copies; otherwise the document is sent directly to the default printer.

Syntax

public void Print(bool showDialog)

Parameters

Remarks

If no printer is installed a message box is shown using the caption from NoPrinterMessageCaption.

Example

private void printToolStripButton_Click(object sender, EventArgs e)
{
    // Show the Print dialog so the user can choose printer and copies.
    htmlEditor1.EditorService.Print(showDialog: true);
}

ExecCommand Method

Dispatches an arbitrary command to the underlying browser command engine. This is the escape hatch for advanced scenarios where the strongly typed services do not expose what you need. Identifiers follow the legacy MSHTML execCommand set (for example "InsertHTML", "FontName", "ForeColor").

Syntax

public void ExecCommand(string cmdId, bool showUi = false, object? value = null)

Parameters

Example

// Insert a horizontal rule at the caret using the underlying engine.
htmlEditor1.EditorService.ExecCommand("InsertHTML", false, "<hr/>");

ShowPrintPreviewDialog Method

Opens the browser Print Preview dialog so the user can review pagination and print settings before printing.

Syntax

public void ShowPrintPreviewDialog()

Example

private void printPreviewToolStripButton_Click(object sender, EventArgs e)
{
    htmlEditor1.EditorService.ShowPrintPreviewDialog();
}

ShowPageSetupDialog Method

Opens the browser Page Setup dialog so the user can change margins, orientation, headers and footers used when printing.

Syntax

public void ShowPageSetupDialog()

Example

private void pageSetupToolStripButton_Click(object sender, EventArgs e)
{
    htmlEditor1.EditorService.ShowPageSetupDialog();
}

JustifyLeft Method

Toggles left justification on the block element containing the caret or selection. Calling it again on an already-left-justified block removes the alignment.

Syntax

public void JustifyLeft()

Example

private void alignLeftToolStripButton_Click(object sender, EventArgs e)
{
    htmlEditor1.EditorService.JustifyLeft();
}

JustifyRight Method

Toggles right justification on the block element containing the caret or selection.

Syntax

public void JustifyRight()

Example

private void alignRightToolStripButton_Click(object sender, EventArgs e)
{
    htmlEditor1.EditorService.JustifyRight();
}

JustifyCenter Method

Toggles center justification on the block element containing the caret or selection.

Syntax

public void JustifyCenter()

Example

private void alignCenterToolStripButton_Click(object sender, EventArgs e)
{
    htmlEditor1.EditorService.JustifyCenter();
}

Search Method

Searches for text within the editor and selects the next match. The search direction, whole-word matching, and case sensitivity are all caller-controlled. When useCaretPosition is true and there is no current selection, the search begins at the caret rather than at the document origin.

Syntax

public bool Search(string text, bool forward, bool matchWholeWord, bool matchCase, bool useCaretPosition = false)

Parameters

Returns

System.Boolean — true if a match was found and selected; otherwise false.

Example

bool found = htmlEditor1.EditorService.Search(
    text: "TODO",
    forward: true,
    matchWholeWord: false,
    matchCase: false);

if (!found)
    MessageBox.Show("No more matches.");

Replace Method

Replaces the currently selected text with replacement if (and only if) the selection equals searchString under the supplied matching options. Use this for "Find next, then Replace" interactive workflows.

Syntax

public bool Replace(string searchString, string replacement, bool matchWholeWord, bool matchCase)

Parameters

Returns

System.Boolean — true if the selection was replaced; otherwise false.

Example

// Interactive workflow: Find, then Replace on user click.
if (htmlEditor1.EditorService.Search("colour", true, false, false))
{
    htmlEditor1.EditorService.Replace(
        searchString: "colour",
        replacement:  "color",
        matchWholeWord: false,
        matchCase: false);
}

ReplaceAll Method

Replaces every occurrence of replaceWhat in the document with replaceWith. The returned count tells you how many replacements were applied so you can surface a "Replaced N occurrences" message.

Syntax

public int ReplaceAll(string replaceWhat, string replaceWith, bool matchWholeWord, bool matchCase)

Parameters

Returns

System.Int32 — the number of occurrences that were replaced.

Example

int count = htmlEditor1.EditorService.ReplaceAll(
    replaceWhat: "color",
    replaceWith: "colour",
    matchWholeWord: false,
    matchCase: false);

MessageBox.Show($"Replaced {count} occurrence(s).");

SearchWithDefaultIeDialog Method

Pops up the browser's built-in Find dialog inside the editor surface. Useful when you want to defer Find UI to the browser instead of building your own.

Syntax

public void SearchWithDefaultIeDialog()

Example

private void findToolStripButton_Click(object sender, EventArgs e)
{
    htmlEditor1.EditorService.SearchWithDefaultIeDialog();
}

DeleteText Method

Deletes length characters of rendered text starting at startIndex. The caret is collapsed to the deletion point afterwards. Use when you need surgical, index-based removal without selecting first.

Syntax

public void DeleteText(int startIndex, int length)

Parameters

Example

// Remove the first 10 characters of plain text.
htmlEditor1.EditorService.DeleteText(startIndex: 0, length: 10);

ReplaceText Method

Replaces length characters of rendered text starting at startIndex with replacementText. Equivalent to a DeleteText followed by an insertion, but performed atomically so a single undo step reverses the change.

Syntax

public void ReplaceText(int startIndex, int length, string replacementText)

Parameters

Example

// Replace the 4 characters starting at offset 12 with a new word.
htmlEditor1.EditorService.ReplaceText(12, 4, "Hello");

PrintPageSetup Method (Uniform Margin)

Sets all four print margins to the same value, in inches. Convenient when you want uniform margins without specifying each side.

Syntax

public void PrintPageSetup(double margin)

Parameters

Example

// One-inch margins on all four sides.
htmlEditor1.EditorService.PrintPageSetup(margin: 1.0);
htmlEditor1.EditorService.Print(showDialog: false);

PrintPageSetup Method (Per-Side Margins)

Sets each print margin individually, in inches. Use this overload when the four margins differ - for example, a wider left margin for binding.

Syntax

public void PrintPageSetup(double topMargin, double bottomMargin, double rightMargin, double leftMargin)

Parameters

Example

// Wider left margin to leave room for binding.
htmlEditor1.EditorService.PrintPageSetup(
    topMargin:    1.0,
    bottomMargin: 1.0,
    rightMargin:  0.75,
    leftMargin:   1.25);

ClearUndoStack Method

Discards the entire undo history. Subsequent Undo calls will be no-ops until new edits are recorded. Useful after loading a fresh document to ensure the user cannot "undo back into" the previous document's state.

Syntax

public void ClearUndoStack()

Example

// After loading a brand-new document, prevent undo across documents.
htmlEditor1.LoadHtml(freshHtml);
htmlEditor1.EditorService.ClearUndoStack();

HasHorizontalScrollbar Property

Indicates whether the editor is currently displaying a horizontal scrollbar. Read-only; the value reflects layout, not policy - it can be false even when SetScrollBarSetting was called with Both if the content fits horizontally.

Syntax

public bool HasHorizontalScrollbar { get; }

Returns

System.Boolean — true if a horizontal scrollbar is currently visible.

Example

if (htmlEditor1.EditorService.HasHorizontalScrollbar)
    htmlEditor1.EditorService.AdjustEditorWidth(); // grow to fit

HasVerticalScrollbar Property

Indicates whether the editor is currently displaying a vertical scrollbar. Read-only.

Syntax

public bool HasVerticalScrollbar { get; }

Returns

System.Boolean — true if a vertical scrollbar is currently visible.

Example

if (htmlEditor1.EditorService.HasVerticalScrollbar)
    htmlEditor1.EditorService.AdjustEditorHeight();

NoPrinterMessageCaption Property

Gets or sets the caption used for the message box shown when Print is invoked and no printer is installed. Localize this string at startup if your application targets non-English locales.

Syntax

public string NoPrinterMessageCaption { get; set; }

Returns

System.String — the caption of the "no printer" message box.

Example

// Localise the caption shown when no printer is installed.
htmlEditor1.EditorService.NoPrinterMessageCaption = "Printer not available";