Click here to Skip to main content
15,867,453 members
Articles / Programming Languages / C#

A Windows Forms based text editor with HTML output

Rate me:
Please Sign up or sign in to vote.
4.91/5 (171 votes)
2 Jul 2013CPOL5 min read 2.7M   72.5K   412   462
A Windows Forms based text editor with HTML output, implemented with a browser control in edit mode.

 

NOTICE: As of 10/28/2017, a new version is available. 

Includes the following features:

  • Requires .NET 4.5.1.
  • Fixes save as and load bugs that fired browser dialogs.
  • Insert inline images either by URL or through the file system. File system images are embedded in the resulting HTML.
  • Full programmatic access to HTML, Body HTML, Body Text
  • Set the background color of the body.
  • Insert images.
  • Resize images.
  • Add and edit hyperlinks from text.
  • Add and edit hyperlinks from images.
  • Support for Windows XP SP2 to Windows 8.
  • Support for all versions of IE. 

 

 

Sample Image - editor.png

 

Introduction

A while ago, I was working on a chat application where one of the chat clients was web based and written with ASP.NET 2.0. The other chat client was a Windows Forms based .NET application written in C#. I needed a rich text editor for my WinForms client that could output HTML, so that the ASP.NET client could display the formatting from the WinForms client. This was ruled out while using the RTF text box.

The solution I worked out was to use a WebBrowser control in edit mode within my WinForms client. Formatting buttons on a toolbar above the web browser are synchronized to the current selection in the WebBrowser control.

This article explains solutions to most of the issues involved in building an editor control from a WebBrowser control. I won't go into everything, as the source code isn't that difficult to browse. But, I do cover some of the tricks necessary to get this to work.

Using the Control

The control is an executable.

You can run it directly with it's main form, or you can embed it as a control in your own app.

To embed it into your own app, simply reference the EXE as if it were a DLL from your app in Visual Studio. 

It should show up in the Toolbox Window in Visual Studio.  

Check the source code for examples of how to access it from your code.

It's a .NET 2.0 control, so it should work in older projects. 

Setting Design Mode 

Applying design mode and establishing an editing template for the document occurs automatically when using the component. But, for reference, here is a brief explanation of how it works.

Applying design mode requires using a COM interface: adding a reference to "Microsoft HTML Object Library", which resolves to MSHTML, and adding a 'using' of 'MSHTML'.

It is necessary to add a body to the control before you can apply changes to the DOM document. To do this, you can simply apply some text to the DocumentText property of the WebBrowser control.

C#
webBrowser1.DocumentText = "<html><body></body></html>"

Next, get a reference to the new DomDocument COM interface, and set the design mode to "On".

C#
IHTMLDocument2 doc =
webBrowser1.Document.DomDocument as IHTMLDocument2;
doc.designMode = "On";

Finally, I replace the context menu for the web browser control so the default IE browser context menu doesn't show up.

C#
webBrowser1.Document.ContextMenuShowing += 
new HtmlElementEventHandler(Document_ContextMenuShowing);

The browser is now in design mode, with a custom method to display the context menu.

Applying Formatting

You can apply formatting and editor functions to a browser control in design mode with the ExecCommand method on browser.Document.

Here are several examples:

C#
public void Cut()
{
    webBrowser1.Document.ExecCommand("Cut", false, null);
}
public void Paste()
{
    webBrowser1.Document.ExecCommand("Paste", false, null);
}
public void Copy()
{
    webBrowser1.Document.ExecCommand("Copy", false, null);
}

Some commands will toggle the formatting state of the current selection.

C#
public void Bold()
{
    webBrowser1.Document.ExecCommand("Bold", false, null);
}

public void Italic()
{
    webBrowser1.Document.ExecCommand("Italic", false, null);
}

Synchronizing Formatting Buttons with Selected Text

This is a bit more tricky than applying formatting commands to the browser control. I literally query the state of the browser editor selection every 200 ms, and set the toolbar formatting buttons based on this.

C#
private void timer_Tick(object sender, EventArgs e)
{
    SetupKeyListener();
    boldButton.Checked = IsBold();
    italicButton.Checked = IsItalic();
    underlineButton.Checked = IsUnderline();
    orderedListButton.Checked = IsOrderedList();
    unorderedListButton.Checked = IsUnorderedList();
    linkButton.Enabled = SelectionType == SelectionType.Text;

    UpdateFontComboBox();
    UpdateFontSizeComboBox();
    if (Tick != null) Tick();
}

You'll notice that there is a Tick event that is fired at the end of the timer's tick event. External components can subscribe to this event to update the state of their GUI. For example, they may update the Enabled state of cut/copy/paste/undo/redo buttons based on the state of the Editor control.

I do this by using the COM document interface retrieved from the WebBrowser control with:

C#
IHTMLDocument2 doc = webBrowser1.Document.DomDocument as IHTMLDocument2;

Then I use queryCommandState to determine the state of the current selection:

C#
public bool IsBold()
{
    return doc.queryCommandState("Bold");
}

public bool IsItalic()
{
    return doc.queryCommandState("Italic");
}

public bool IsUnderline()
{
    return doc.queryCommandState("Underline");
}

The link button and font controls are managed in a similar way, but I'll leave that for you to check out in the code.

Focusing

Focusing the control isn't necessarily simple either. The WebBrowser control itself will not accept focus. Neither will the WebBrowser control's document. But, the body will focus, assuming there is a body element on the control.

C#
private void SuperFocus()
{
    if (webBrowser1.Document != null && 
        webBrowser1.Document.Body != null)
      webBrowser1.Document.Body.Focus();
}

Of course, you never need to call this method directly. Calling the Focus method on the control will place the focus on the editor control containing the WebBrowser control. The editor control will transfer focus to the WebBrowser's document body automatically, when it receives the GotFocus event.

Retrieving Text or HTML

The BodyHtml and BodyText methods retrieve the body HTML and text, respectively.

Linking to the Component Assembly

In Visual Studio 2005, you can link to an assembly (add a reference), even if the assembly is an executable. The editor is written as a component embedded in a form, so you can add this component to the control palette and drag and drop into your application. The control's name is Editor, under namespace Design.

Conclusion

The .NET 2.0 WebBrowser control can effectively be used as a text editor. This is useful when you need an editor control that can be used as an HTML editor. The implementation is not completely straightforward in some areas. This article attempts to show some of the tricks necessary to get it to work.

History

  • 10/04/2006 - various bug fixes and design updates / designer support.
  • 10/19/2006 - more bug fixes and more designer support.
  • 10/28/2017 - Upgrade to .net 4.5.1 and VS 2015

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


Written By
United States United States
This member has not yet provided a Biography. Assume it's interesting and varied, and probably something to do with programming.

Comments and Discussions

 
QuestionA Windows Forms based text editor with HTML output Pin
Christian Torres M31-Oct-16 6:17
Christian Torres M31-Oct-16 6:17 
QuestionHow to use Pin
dnibbo13-Jul-16 23:25
dnibbo13-Jul-16 23:25 
QuestionDRAGDROP_E_NOTREGISTERED Pin
Member 380699628-Jun-16 8:13
Member 380699628-Jun-16 8:13 
QuestionCant find control Pin
dnibbo9-May-16 1:33
dnibbo9-May-16 1:33 
AnswerRe: Cant find control Pin
Member 1313361925-Apr-17 10:38
Member 1313361925-Apr-17 10:38 
GeneralRe: Cant find control Pin
David Coles24-Jan-18 0:26
David Coles24-Jan-18 0:26 
Questionsize of font 7 and unordered list bullets dots size Pin
nighttrain_23-Mar-16 9:23
nighttrain_23-Mar-16 9:23 
Questionissue Pin
Member 1211573929-Jan-16 0:08
Member 1211573929-Jan-16 0:08 
QuestionProblem using VS2015 Pin
susad4-Jan-16 22:07
susad4-Jan-16 22:07 
AnswerRe: Problem using VS2015 Pin
Member 1313361925-Apr-17 10:42
Member 1313361925-Apr-17 10:42 
QuestionControl not supporting rich text editing Pin
Digambar Malla17-Nov-15 23:11
Digambar Malla17-Nov-15 23:11 
AnswerRe: Control not supporting rich text editing Pin
Member 141439387-Feb-19 23:08
Member 141439387-Feb-19 23:08 
Questionto change font size to pixel format? Pin
Member 1214844517-Nov-15 19:40
Member 1214844517-Nov-15 19:40 
QuestionPesky save Dialog fix Pin
Member 1160865517-Nov-15 2:32
Member 1160865517-Nov-15 2:32 
QuestionThe type or namespace name 'LiveSwitch' could not be found Pin
only4ram12-Nov-15 19:21
only4ram12-Nov-15 19:21 
AnswerRe: The type or namespace name 'LiveSwitch' could not be found Pin
Member 188040317-Nov-15 1:15
Member 188040317-Nov-15 1:15 
GeneralRe: The type or namespace name 'LiveSwitch' could not be found Pin
Christian Torres M1-Nov-16 10:24
Christian Torres M1-Nov-16 10:24 
QuestionFinding where the cursor is in the document Pin
elmbrook29-Sep-15 16:30
elmbrook29-Sep-15 16:30 
AnswerRe: Finding where the cursor is in the document Pin
Member 1211573929-Jan-16 0:13
Member 1211573929-Jan-16 0:13 
SuggestionCOM Interface and the dynamic keyword Pin
Paulo Morábito Neto18-Sep-15 6:48
professionalPaulo Morábito Neto18-Sep-15 6:48 
QuestionHello Kevin, excellent, thanks. I had to tweak it as it would not work in my app Pin
Leif Simon Goodwin23-Aug-15 5:32
Leif Simon Goodwin23-Aug-15 5:32 
QuestionWhy don't local images appear Pin
Matt Esterak16-Jun-15 4:15
Matt Esterak16-Jun-15 4:15 
QuestionHow can i disable and enable that editor tooltip Pin
sheelakr12-May-15 20:28
sheelakr12-May-15 20:28 
AnswerRe: How can i disable and enable that editor tooltip Pin
DrDeadCrash21-Jul-15 8:38
DrDeadCrash21-Jul-15 8:38 
QuestionImage is not display in the editor Pin
Member 115717051-May-15 2:23
Member 115717051-May-15 2:23 

General General    News News    Suggestion Suggestion    Question Question    Bug Bug    Answer Answer    Joke Joke    Praise Praise    Rant Rant    Admin Admin   

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.