Building a Simple Word Processor Around an Extended RichTextBox Control

• Download source - 52.9 Kb

Introduction

This article describes an easy approach to building a simple word processor around an extended version of the RichTextBox (RTB) control. Microsoft has made available an extended version of the RTB control that greatly eases the requirements for printing the control’s text or RTF content. This article and the sample application will use this extended version of the RTF control to demonstrate the following word processor related functions:

• Opening Text, RTF, HTML, or other text files into a RTB control
• Saving Text, RTF, HTML, or other text files from an RTB control
• Implementation of the Page Setup dialog control
• Implementation of the Print Preview dialog control
• Implementation of the Print dialog control
• Setting font properties on selected text or RTF within the RTB control
• Searching for and highlighting text contained within the RTB control
• Searching for and replacing text contained within the RTB control
• Adding indentation to sections of an RTB’s content
• Adding bullets to sections of an RTB’s content
• Implementing Undo/Redo within an RTB
• Implementing Select All, Cut, Copy, and Paste in an RTB control
• Embedding images into an RTB control
• Setting page and font colors
• Implementing alignment options in an RTB control

Whilst this project will not lead you to drop MS Word, it is a decent little word processor, and to that end, you may find a use for it. I have always kept one of these on hand, and have frequently tailored them to do things like provide a custom tool for viewing reports, error logs, and things of that nature when I wanted to integrate that feature into a product so that I could use it in lieu of doing something like shelling out a text file into Notepad. Doing so allows me to control the appearance of the application, the caption in the title bar of the form, etc.

Figure 1: The editor application in use

Getting Started

In order to get started, unzip the attachment, and load the solution into Visual Studio 2005. Examine the Solution Explorer, and note the files contained in the project:

Figure 2: The Solution Explorer showing the project files

First, note that there are two separate projects contained in the solution. The first project is a class library entitled, “ExtendedRichTextBox”. That library contains a single control class, “RichTextBoxPrintCtrl”. This control class was provided by Microsoft as an alternative to the basic RichTextBox control; the class inherits from the RichTextBox control class but adds to that base class additional support for printing the control’s content. The approach provided by the control is far simpler than the traditional approach used based upon the manipulation of the graphics context of the control.

The second solution is the editor application itself (RichTextEditor). This application uses the extended rich text box control, and then to that, adds in all of the normal document manipulation techniques (such as font selection, indentation, and file IO support). Aside from the main application’s form (frmMain), this project also includes two additional forms, one to search for a string within the RTB’s content, and one to search for and replace strings within the RTB. These forms are frmFind and frmReplace.

Figure 3: Editor application Find dialog

Figure 4: Editor application Find and Replace dialog

In addition to the form classes mentioned, the solution also contains a folder entitled “Graphics”; this folder contains all of the image files used to support the application’s menus and toolbar.

Project References

Aside from the default references, there are a couple of additional references added. Most notably, the extended rich text box control library is added to allow for the use of the extended rich text box control. Figure 5 shows the references as they exist in the project.

Figure 5: Project references

The Code: The Main Form Class

The main form class (frmMain) is pretty easy to follow. It begins with a couple of Imports statements, followed by the class declaration. The code is divided by purpose into four separate regions, which are:

• Declarations
• Menu methods
• Toolbar methods
• Printing

The imports and the class declaration looks like this:

Imports System.Drawing
Imports System.Drawing.Image

Public Class frmMain

The class declaration is plain enough, and does not inherit from or implement any base class or interface. I would emphasis here again that making use of Microsoft’s extended rich text box control greately reduces the amount of code necessary to support all of the methods used within this application.

The declarations section is also very simple; the section contains the variables used throughout the application. The content is as follows:

#Region "Declarations"

    Private currentFile As String
    Private checkPrint As Integer

#End Region

The “currentFile” variable is used to keep track of the path and file name of the file loaded into the extended rich text box control; it is updated whenever the user opens a file, creates and saves a file, or saves a file with a new name and/or file extension.

The “checkPrint” variable is used by the streamlined printing process recommended by Microsoft in the article describing the use of the extended rich text box control. It is used to determine if additional pages exist when the document is sent to the printer (in support of multi-page printing).

The next section of code is the primary block of code used by this application. The “Menu Methods” region contains all of the subroutines evoked in response to the selection of a menu option. The “Toolbar Methods” region follows the “Menu Methods” region, but all of the subroutines in the toolbar controls' section call the subroutines defined in the “Menu Methods” region of the code unless the code is so trivial (one line) that it is just as simple to make the call directly; for that reason, this document will not describe the contents of the “Toolbar Methods” region specifically.

The first block of code in the menu region is used to create a new file:

    Private Sub NewToolStripMenuItem_Click(ByVal sender As _
            System.Object, ByVal e As System.EventArgs) _
            Handles NewToolStripMenuItem.Click

        If rtbDoc.Modified Then
            Dim answer As Integer
            answer = MessageBox.Show("The current document has not" & _ 
                     " been saved, would you like to " & _ 
                     "continue without saving?", "Unsaved Document", _
                     MessageBoxButtons.YesNo, MessageBoxIcon.Question)

            If answer = Windows.Forms.DialogResult.Yes Then
                rtbDoc.Clear()
            Else
                Exit Sub
            End If
        Else
            rtbDoc.Clear()
        End If

        currentFile = ""
        Me.Text = "Editor: New Document"
    End Sub

In this subroutine, prior to clearing the current document, the status of the current document is checked by using the control's “Modified” test; if the document has been modified while it has been open, the test will return true. If the document has been modified, the user is queried with a message box to determine whether or not they want to save (or lose) the modifications made to the current file prior to clearing the file. If they choose to save the changes, the subroutine is exited; else, the document is cleared, and the changes are lost. If the document has not been modified, the subroutine will clear the document without notifying the user. Whenever the document is cleared, the title of the control is updated to indicate that a new (unsaved) document is the current document, and the “currentFile” variable is set to contain an empty string.

Figure 6: Confirmation dialog shown after user requests a new document without saving changes

The next subroutine is used to open an existing file into the rich text box control:

    Private Sub OpenToolStripMenuItem_Click(ByVal sender _
            As System.Object, ByVal e As System.EventArgs) _
            Handles OpenToolStripMenuItem.Click

        If rtbDoc.Modified Then

            Dim answer As Integer
            answer = MessageBox.Show("The current document has not" & _ 
                     " been saved, would you like to continue " & _ 
                     "without saving?", "Unsaved Document", _
                     MessageBoxButtons.YesNo, MessageBoxIcon.Question)

            If answer = Windows.Forms.DialogResult.No Then
                Exit Sub
            Else
                OpenFile()
            End If
        Else
            OpenFile()
        End If

    End Sub

This subroutine works in a manner similar to the “new” subroutine discussed in the previous section. If the file has not been modified or if the user decides not to save the current modifications, the subroutine calls an OpenFile subroutine, which in turn exposes a File Open dialog used to allow the user to navigate to the file they wish to open. The OpenFile subroutine is next, and contains this code:

    Private Sub OpenFile()

        OpenFileDialog1.Title = "RTE - Open File"
        OpenFileDialog1.DefaultExt = "rtf"
        OpenFileDialog1.Filter = "Rich Text Files|*.rtf|" & _ 
                                 "Text Files|*.txt|HTML Files|" & _ 
                                 "*.htm|All Files|*.*"
        OpenFileDialog1.FilterIndex = 1
        OpenFileDialog1.ShowDialog()

        If OpenFileDialog1.FileName = "" Then Exit Sub

        Dim strExt As String
        strExt = System.IO.Path.GetExtension(OpenFileDialog1.FileName)
        strExt = strExt.ToUpper()

        Select Case strExt
            Case ".RTF"
                rtbDoc.LoadFile(OpenFileDialog1.FileName, 
                RichTextBoxStreamType.RichText)
            Case Else
                Dim txtReader As System.IO.StreamReader
                txtReader = New 
                System.IO.StreamReader(OpenFileDialog1.FileName)
                rtbDoc.Text = txtReader.ReadToEnd
                txtReader.Close()
                txtReader = Nothing
                rtbDoc.SelectionStart = 0
                rtbDoc.SelectionLength = 0
        End Select

        currentFile = OpenFileDialog1.FileName
        rtbDoc.Modified = False
        Me.Text = "Editor: " & currentFile.ToString()

    End Sub

Figure 7: Open File dialog

The first part of the FileOpen subroutine is used to configure and display the Open File dialog box; this code sets up the filters for the files types (rich text, text, or HTML), sets the dialog box title, and a selects an extension filter (RTF). Once this is done, the dialog box is displayed. If the user okays the dialog box without specifying a file name, the subroutine will exit. If a file name exists, the code extracts the file extension from the file name, places the extension in a local string variable, converts it to upper case, and does a Select Case statement on the string variable. If the file selected by the user is an RTF file, the subroutine calls the control’s LoadFile method and passes it the file name and format. If the file is not an RTF file, a stream reader is instanced and passed the path to the file, the control is then fed the content of the file by means of the stream reader’s ReadToEnd method. The reader is then closed and disposed of, and the cursor is moved to the beginning of the document and the selection length is set to zero (if you do not do this, the whole document will initialize as entirely selected). After the file is loaded, the “currentFile” variable is updated to contain the current file path and name, the modified property of the control is set to false, and the caption bar is updated to show the name of the file currently under edit in the rich text box control.

The next item up is the “Save” menu option; it contains the following code:

    Private Sub SaveToolStripMenuItem_Click(ByVal sender As _
            System.Object, ByVal e As System.EventArgs) _
            Handles SaveToolStripMenuItem.Click

        If currentFile = "" Then
            SaveAsToolStripMenuItem_Click(Me, e)
            Exit Sub
        End If

        Dim strExt As String
        strExt = System.IO.Path.GetExtension(currentFile)
        strExt = strExt.ToUpper()

        Select Case strExt
            Case ".RTF"
                rtbDoc.SaveFile(currentFile)
            Case Else
                ' to save as plain text

                Dim txtWriter As System.IO.StreamWriter
                txtWriter = New System.IO.StreamWriter(currentFile)
                txtWriter.Write(rtbDoc.Text)
                txtWriter.Close()
                txtWriter = Nothing
                rtbDoc.SelectionStart = 0
                rtbDoc.SelectionLength = 0
                rtbDoc.Modified = False
        End Select

        Me.Text = "Editor: " & currentFile.ToString()

    End Sub

The “Save” function first checks to see if the “currentFile” variable is empty; if it is, the content of the rich text box control has not been saved previously, and the subroutine will call the “Save As” menu option to provide the user with an interface to define a file name and storage location for the current unnamed file. If the file is named (and has a current storage location), the subroutine will check the file extension and, by means of a Select Case statement, determine the appropriate method for storing the file, and will then save the content to the file location. This all works very similar to the approach used to open the file. However, instead of opening a file, the approach is used to call the rich text box control’s SaveFile method if the file is a rich text file, or to instance a stream writer and write the file content out as text to the file location if the file is plain text or HTML.

With both the file open and file save methods used, if the file is anything other than a rich text file, the application will attempt to open or save it with a stream reader or stream writer; this will allow the application to work with any text file, not just RTF, TXT, or HTML files. That would permit you to use it with custom file types, or other things such as license files or error log files.

The next subroutine addresses the “Save As” menu option; its code is as follows:

    Private Sub SaveAsToolStripMenuItem_Click(ByVal sender As _
            System.Object, ByVal e As System.EventArgs) _
            Handles SaveAsToolStripMenuItem.Click

        SaveFileDialog1.Title = "RTE - Save File"
        SaveFileDialog1.DefaultExt = "rtf"
        SaveFileDialog1.Filter = "Rich Text Files|*.rtf|" & _ 
                                 "Text Files|*.txt|HTML Files" & _ 
                                 "|*.htm|All Files|*.*"
        SaveFileDialog1.FilterIndex = 1
        SaveFileDialog1.ShowDialog()

        If SaveFileDialog1.FileName = "" Then Exit Sub

        Dim strExt As String
        strExt = System.IO.Path.GetExtension(SaveFileDialog1.FileName)
        strExt = strExt.ToUpper()

        Select Case strExt
            Case ".RTF"
                rtbDoc.SaveFile(SaveFileDialog1.FileName, _
                       RichTextBoxStreamType.RichText)
            Case Else
                Dim txtWriter As System.IO.StreamWriter
                txtWriter = New 
                System.IO.StreamWriter(SaveFileDialog1.FileName)
                txtWriter.Write(rtbDoc.Text)
                txtWriter.Close()
                txtWriter = Nothing
                rtbDoc.SelectionStart = 0
                rtbDoc.SelectionLength = 0
        End Select

        currentFile = SaveFileDialog1.FileName
        rtbDoc.Modified = False
        Me.Text = "Editor: " & currentFile.ToString()

    End Sub

Figure 8: File menu options

By now, this should look pretty familiar; in the code, a Save as file dialog box is configured and displayed to the user. The dialog will permit the user to save the file as RTF, TXT, or HTML. If the user saves the file as RTF, the control’s SaveFile method is used to store the contents of the file whilst preserving the RTF formatting. If the user selects another option, the file will be saved as plain text using a text writer. In either case, after the file is saved, the “currentFile” variable is updated, the application’s title bar is updated, and the document’s Modified property is set to False.

The next item in the code is the menu’s Exit call. It is used to terminate the application. Prior to closing the application, this subroutine checks to see if the current document has been modified and, if it has, it alerts the user and asks whether or not the document should be saved prior to closing it and the application. The code is as follows:

    Private Sub ExitToolStripMenuItem_Click(ByVal sender As _
            System.Object, ByVal e As System.EventArgs) _
            Handles ExitToolStripMenuItem.Click

        If rtbDoc.Modified Then

            Dim answer As Integer
            answer = MessageBox.Show("The current document has not been" & _ 
                     " saved, would you like to continue without saving?", _
                     "Unsaved Document", MessageBoxButtons.YesNo, _
                     MessageBoxIcon.Question)

            If answer = Windows.Forms.DialogResult.No Then
                Exit Sub
            Else
                Application.Exit()
            End If
        Else
            Application.Exit()
        End If

    End Sub

The next menu option addressed is the edit menu’s “Select All” function. Select All is a method embedded in the rich text box control, and therefore it may be called directly without writing any additional code to make the Select All happen; to use it, just call it as follows:

    Private Sub SelectAllToolStripMenuItem_Click(ByVal sender _
            As System.Object, ByVal e As System.EventArgs) _
            Handles SelectAllToolStripMenuItem.Click

        Try
            rtbDoc.SelectAll()
        Catch exc As Exception
            MessageBox.Show("Unable to select all document content.", _
                            "RTE – Select", MessageBoxButtons.OK, _
                            MessageBoxIcon.Error)
        End Try

    End Sub

Following the edit menu’s “Select All” function, we have the cut, copy, and paste subroutines. Just as the Select All method exists within the rich text box control, so do these, and so you can call them directly in a manner similar to that used in Select All. For that reason, I am not going to show them here, but you can see the calls made in the example application if you’d care to take a look at them.

Figure 9: Edit menu options

Next up is the menu option used to select the current font. This code merely uses a standard font dialog box to set the rich text box control’s SelectionFont property to the font selected by the user through the font dialog. The code used to do this is as follows:

    Private Sub SelectFontToolStripMenuItem_Click(ByVal sender _
            As System.Object, ByVal e As System.EventArgs) _
            Handles SelectFontToolStripMenuItem.Click

        If Not rtbDoc.SelectionFont Is Nothing Then
            FontDialog1.Font = rtbDoc.SelectionFont
        Else
            FontDialog1.Font = Nothing
        End If

        FontDialog1.ShowApply = True
        If FontDialog1.ShowDialog() = Windows.Forms.DialogResult.OK Then
            rtbDoc.SelectionFont = FontDialog1.Font
        End If

    End Sub

Figure 10: Font dialog in use

Similarly, the font color menu option is used to display a standard color dialog to the user; if the user selects a color from the dialog, the ForeColor property of the document will be updated to contain the selected color. As the rich text box control works primarily with selected text (that is, what you change in terms of selecting a font or changing a color), this function will alter the color of the selected text only. If no text is selected, the color at the insertion point will hold the fore color selection, and typing from the insertion point will show text in the newly selected color.

    Private Sub FontColorToolStripMenuItem_Click(ByVal sender _
            As System.Object, ByVal e As System.EventArgs) _
            Handles FontColorToolStripMenuItem.Click

        ColorDialog1.Color = rtbDoc.ForeColor
        If ColorDialog1.ShowDialog = Windows.Forms.DialogResult.OK Then
            rtbDoc.SelectionColor = ColorDialog1.Color
        End If

    End Sub

The next three sections of code are the subroutines used to set the selected text’s bold, italic, or underline properties. Each section is set up to work such that, if the selected text is bold, selecting the bold option will remove the bolding (or italics, or underline). (As they all basically work the same, I am only showing bold here.)

    Private Sub BoldToolStripMenuItem_Click(ByVal sender As _
           System.Object, ByVal e As System.EventArgs) _
           Handles BoldToolStripMenuItem.Click
        If Not rtbDoc.SelectionFont Is Nothing Then
            Dim currentFont As System.Drawing.Font = rtbDoc.SelectionFont
            Dim newFontStyle As System.Drawing.FontStyle
            If rtbDoc.SelectionFont.Bold = True Then
                newFontStyle = FontStyle.Regular
            Else
                newFontStyle = FontStyle.Bold
            End If

            rtbDoc.SelectionFont = New Font(currentFont.FontFamily, _
                                   currentFont.Size, newFontStyle)
        End If
    End Sub

The “Normal” font menu option returns the selected text to a normal, unadorned format:

    Private Sub NormalToolStripMenuItem_Click(ByVal sender As _
            System.Object, ByVal e As System.EventArgs) _
            Handles NormalToolStripMenuItem.Click
        If Not rtbDoc.SelectionFont Is Nothing Then
            Dim currentFont As System.Drawing.Font = rtbDoc.SelectionFont
            Dim newFontStyle As System.Drawing.FontStyle
            newFontStyle = FontStyle.Regular

            rtbDoc.SelectionFont = New Font(currentFont.FontFamily, _
                                   currentFont.Size, newFontStyle)
        End If
    End Sub

The menu option used to set the page color is used to expose a color dialog box to the user; if the user selects a color form the dialog, the back color of the rich text box control is set to that color. The code to support this function is as follows:

    Private Sub PageColorToolStripMenuItem_Click(ByVal sender _
            As System.Object, ByVal e As System.EventArgs) _
            Handles PageColorToolStripMenuItem.Click
        ColorDialog1.Color = rtbDoc.BackColor
        If ColorDialog1.ShowDialog = Windows.Forms.DialogResult.OK Then
            rtbDoc.BackColor = ColorDialog1.Color
        End If
    End Sub

Figure 11: Color dialog in use

The undo and redo functions are used to back up or restore changes made to the content of the control during an edit; the rich text box control supports the undo and redo function directly, so all you need to do in order to add undo and redo support is merely evoke the method directly from the control, make the call, test to determine whether or not the control can execute the undo or redo request, and, if it is supported, call the method:

    Private Sub mnuUndo_Click(ByVal sender As System.Object, _
            ByVal e As System.EventArgs) Handles mnuUndo.Click
        If rtbDoc.CanUndo Then rtbDoc.Undo()
    End Sub

    Private Sub mnuRedo_Click(ByVal sender As System.Object, _
            ByVal e As System.EventArgs) Handles mnuRedo.Click
        If rtbDoc.CanRedo Then rtbDoc.Redo()
    End Sub

The next three sections of code address setting the document’s horizontal alignment property to support left, centered, or right justification of the selected text. Each of these alignment control options is directly supported by the control:

    Private Sub LeftToolStripMenuItem_Click_1(ByVal sender _
            As System.Object, ByVal e As System.EventArgs) _
            Handles LeftToolStripMenuItem.Click
        rtbDoc.SelectionAlignment = HorizontalAlignment.Left
    End Sub

    Private Sub CenterToolStripMenuItem_Click_1(ByVal sender _
            As System.Object, ByVal e As System.EventArgs) _
            Handles CenterToolStripMenuItem.Click
        rtbDoc.SelectionAlignment = HorizontalAlignment.Center
    End Sub

    Private Sub RightToolStripMenuItem_Click_1(ByVal sender As _
            System.Object, ByVal e As System.EventArgs) _
            Handles RightToolStripMenuItem.Click
        rtbDoc.SelectionAlignment = HorizontalAlignment.Right
    End Sub

Figure 12: Alignment options

Adding and removing bullets is also directly supported by the control. The BulletIndent property sets the gap between the bullet and the text, and the SelectionBullet property merely instructs the control to add or remove the bullet from the selected text:

    Private Sub AddBulletsToolStripMenuItem_Click(ByVal sender _
            As System.Object, ByVal e As System.EventArgs) _
            Handles AddBulletsToolStripMenuItem.Click
        rtbDoc.BulletIndent = 10
        rtbDoc.SelectionBullet = True
    End Sub

    Private Sub RemoveBulletsToolStripMenuItem_Click(ByVal sender _
            As System.Object, ByVal e As System.EventArgs) _
            Handles RemoveBulletsToolStripMenuItem.Click
        rtbDoc.SelectionBullet = False
    End Sub

Figure 12: Bullet options

Setting the indentation level for the selected text is also directly supported by the control:

    Private Sub mnuIndent0_Click(ByVal sender As System.Object, _
            ByVal e As System.EventArgs) Handles mnuIndent0.Click
        rtbDoc.SelectionIndent = 0
    End Sub

Figure 13: Indentation options

The application contains a separate dialog box used to find a text string within the current document. If the user selects the Find menu option, the application will create and display a new instance of the search form (frmFind.vb):

    Private Sub FindToolStripMenuItem_Click(ByVal sender As System.Object, _
            ByVal e As System.EventArgs) Handles FindToolStripMenuItem.Click
        Dim f As New frmFind()
        f.Show()
    End Sub

Similarly, if the user selects the Find and Replace menu option, the application will create and display a new instance of the find and replace form (frmReplace.vb):

    Private Sub FindAndReplaceToolStripMenuItem_Click(ByVal sender _
            As System.Object, ByVal e As System.EventArgs) _
            Handles FindAndReplaceToolStripMenuItem.Click
        Dim f As New frmReplace()
        f.Show()
    End Sub

The print document is set to contain the contents of the current rich text box control. In order to support print preview, page setup, and printing, given the modifications made to the extended rich text box control, all that needs to be done is to pass the print document to each of the related standard dialog boxes:

    Private Sub PreviewToolStripMenuItem_Click(ByVal sender _
            As System.Object, ByVal e As System.EventArgs) _
            Handles PreviewToolStripMenuItem.Click
        PrintPreviewDialog1.Document = PrintDocument1
        PrintPreviewDialog1.ShowDialog()
    End Sub

    Private Sub PrintToolStripMenuItem_Click(ByVal sender As System.Object, _
            ByVal e As System.EventArgs) _
            Handles PrintToolStripMenuItem.Click
        PrintDialog1.Document = PrintDocument1
        If PrintDialog1.ShowDialog() = Windows.Forms.DialogResult.OK Then
            PrintDocument1.Print()
        End If
    End Sub

    Private Sub mnuPageSetup_Click(ByVal sender As System.Object, _
            ByVal e As System.EventArgs) Handles mnuPageSetup.Click
        PageSetupDialog1.Document = PrintDocument1
        PageSetupDialog1.ShowDialog()
    End Sub

The next subroutine is a little more interesting; it is used to embed an image file into the extended rich text box document. This subroutine uses an open file dialog box set to filter the extensions used for bitmaps, JPEGs, and GIF files. The user may navigate to the file that they want to embed into the document (placing it at the insertion point defined by the cursor).

    Private Sub InsertImageToolStripMenuItem_Click(ByVal sender _
            As System.Object, ByVal e As System.EventArgs) _
            Handles InsertImageToolStripMenuItem.Click

        OpenFileDialog1.Title = "RTE - Insert Image File"
        OpenFileDialog1.DefaultExt = "rtf"
        OpenFileDialog1.Filter = "Bitmap Files|*.bmp|JPEG Files|*.jpg|GIF 
        Files|*.gif"
        OpenFileDialog1.FilterIndex = 1
        OpenFileDialog1.ShowDialog()

        If OpenFileDialog1.FileName = "" Then Exit Sub

        Try
            Dim strImagePath As String = OpenFileDialog1.FileName
            Dim img As Image
            img = Image.FromFile(strImagePath)
            Clipboard.SetDataObject(img)
            Dim df As DataFormats.Format
            df = DataFormats.GetFormat(DataFormats.Bitmap)
            If Me.rtbDoc.CanPaste(df) Then
                Me.rtbDoc.Paste(df)
            End If
        Catch ex As Exception
            MessageBox.Show("Unable to insert image format selected.", "RTE – 
            Paste", MessageBoxButtons.OK, MessageBoxIcon.Error)
        End Try

    End Sub

Figure 15: Embedding an image file

Once the user selects a file through the open file dialog, the subroutine will create an image using the Image.FromFile method. This image is then placed into the clipboard, and subsequently pasted into the document.

The last section of the main form’s code is contained in the printing region. The calls used to print, due to the use of the extended rich text box control, are very simple:

    Private Sub PrintDocument1_BeginPrint(ByVal sender As Object, _
            ByVal e As System.Drawing.Printing.PrintEventArgs) _
            Handles PrintDocument1.BeginPrint
        ' Adapted from Microsoft's example for extended richtextbox control

        '

        checkPrint = 0
    End Sub

The BeginPrint subroutine is used to set the “checkPrint” variable back to zero at the start of each new print job.

The PrintPage subroutine evokes the extended rich text box control’s Print method to send the entire or selected section of the current document to the printer. The call also checks to see if more than a single page exists, and it will continue to print until all of the pages have been passed to the printer. The code used to print is as follows:

    Private Sub PrintDocument1_PrintPage(ByVal sender As Object, _
            ByVal e As System.Drawing.Printing.PrintPageEventArgs) _
            Handles PrintDocument1.PrintPage

        ' Adapted from Microsoft's example for extended richtextbox control

        '

        ' Print the content of the RichTextBox. Store the last character 

          printed.
        checkPrint = rtbDoc.Print(checkPrint, rtbDoc.TextLength, e)

        ' Look for more pages

        If checkPrint < rtbDoc.TextLength Then
            e.HasMorePages = True
        Else
            e.HasMorePages = False
        End If

    End Sub

Figure 16: Print preview

The print section wraps up the rest of the main form class.

Code: The Find and Replace Form

The find and replace form is supported with the frmReplace class. The find class is defined in frmFind, but since it contains two subroutines (Find and Find Next) which are also contained in the Find and Replace form, I will only discuss the code contained in the Find and Replace form.

The Find and Replace form supports four subroutines:

• Find
• Find Next
• Replace
• Replace All

The Find subroutine is pretty straightforward, it will search the entire document for the first occurrence of the search term defined by the user on the form. It will search in one of two ways: with or without matching the case of the search term. Depending upon whether or not the user has checked the Match Case check box on the form, the application will search for the text using either the binary or text compare method. With the binary method, the search term must match exactly (including case); with the text compare method, the strings just need to match. The “StartPosition” integer value is set to the value returned from the InStr call; InStr is passed the starting position of 1, the entire body of the text contained in the rich text box control (as the article to search), the search term entered by the user, and the search compare method. InStr will return the index position of the found text if the text is in fact found. If nothing is found, it will return a zero. If the starting position value is zero, the user will be notified that the search term was not found, else, the application will highlight the found text in the document, pan to its location, and set the focus back to the main form (which in turn makes the highlighting visible to the user).

    Private Sub btnFind_Click(ByVal sender As System.Object, _
            ByVal e As System.EventArgs) Handles btnFind.Click

        Dim StartPosition As Integer
        Dim SearchType As CompareMethod

        If chkMatchCase.Checked = True Then
            SearchType = CompareMethod.Binary
        Else
            SearchType = CompareMethod.Text
        End If

        StartPosition = InStr(1, frmMain.rtbDoc.Text, _
                         txtSearchTerm.Text, SearchType)

        If StartPosition = 0 Then
            MessageBox.Show("String: '" & txtSearchTerm.Text.ToString() & _
                            "' not found", "No Matches", _
                            MessageBoxButtons.OK, MessageBoxIcon.Asterisk)
            Exit Sub
        End If

        frmMain.rtbDoc.Select(StartPosition - 1, txtSearchTerm.Text.Length)
        frmMain.rtbDoc.ScrollToCaret()
        frmMain.Focus()

    End Sub

The Find Next function works in a manner consistent with the Find function; the only difference is that it sets the start position to the current position of the selection starting point within the document so that the Find Next function will not start at the beginning of the document each time it searches:

    Private Sub btnFindNext_Click(ByVal sender As System.Object, _
            ByVal e As System.EventArgs) Handles btnFindNext.Click

        Dim StartPosition As Integer = frmMain.rtbDoc.SelectionStart + 2
        Dim SearchType As CompareMethod

        If chkMatchCase.Checked = True Then
            SearchType = CompareMethod.Binary
        Else
            SearchType = CompareMethod.Text
        End If

        StartPosition = InStr(StartPosition, frmMain.rtbDoc.Text, _
                        txtSearchTerm.Text, SearchType)

        If StartPosition = 0 Then
            MessageBox.Show("String: '" & txtSearchTerm.Text.ToString() & _
                            "' not found", "No Matches", _
                            MessageBoxButtons.OK, MessageBoxIcon.Asterisk)
            Exit Sub
        End If

        frmMain.rtbDoc.Select(StartPosition - 1, txtSearchTerm.Text.Length)
        frmMain.rtbDoc.ScrollToCaret()
        frmMain.Focus()

    End Sub

The Replace subroutine is quite simple. It merely tests to see if any text is selected and, if it is, it is replaced with the replacement text entered into the form by the user; it then moves to the next occurrence of the search term if one exists:

    Private Sub btnReplace_Click(ByVal sender As System.Object, _
            ByVal e As System.EventArgs) Handles btnReplace.Click

        If frmMain.rtbDoc.SelectedText.Length <> 0 Then
            frmMain.rtbDoc.SelectedText = txtReplacementText.Text
        End If

        Dim StartPosition As Integer = frmMain.rtbDoc.SelectionStart + 2
        Dim SearchType As CompareMethod

        If chkMatchCase.Checked = True Then
            SearchType = CompareMethod.Binary
        Else
            SearchType = CompareMethod.Text
        End If

        StartPosition = InStr(StartPosition, frmMain.rtbDoc.Text,_
                        txtSearchTerm.Text, SearchType)

        If StartPosition = 0 Then
            MessageBox.Show("String: '" & txtSearchTerm.Text.ToString() & _
                            "' not found", "No Matches", _
                            MessageBoxButtons.OK, MessageBoxIcon.Asterisk)
            Exit Sub
        End If

        frmMain.rtbDoc.Select(StartPosition - 1, txtSearchTerm.Text.Length)
        frmMain.rtbDoc.ScrollToCaret()
        frmMain.Focus()

    End Sub

The Replace All function is a little different in that it uses the Replace method to replace every instance of the search term with the replacement term throughout the entire body of the text:

    Private Sub btnReplaceAll_Click(ByVal sender As System.Object, _
            ByVal e As System.EventArgs) Handles btnReplaceAll.Click

        Dim currentPosition As Integer = frmMain.rtbDoc.SelectionStart
        Dim currentSelect As Integer = frmMain.rtbDoc.SelectionLength

        frmMain.rtbDoc.Rtf = Replace(frmMain.rtbDoc.Rtf, _
                             Trim(txtSearchTerm.Text), _
                             Trim(txtReplacementText.Text))
        frmMain.rtbDoc.SelectionStart = currentPosition
        frmMain.rtbDoc.SelectionLength = currentSelect
        frmMain.Focus()

    End Sub

Again, the frmFind class is the same as the Replace class with the exception being that it does not support the Replace and Replace All methods.

Code: Rich Text Box Print Control

The code in the class library contained in the RichTextBoxPrintCtrl class was developed at Microsoft; for a complete description of the contents of the class, please refer to this link in your Visual Studio 2005 Help files.

Summary

This article and sample application have attempted to demonstrate some of the available techniques useful in creating and managing text and text files through the use of the RichTextBox control. The control itself was modified using an approach recommended by Microsoft to greatly facilitate the ease with which one may print the contents of a text or rich text file. Further, the application provides an approach to inserting an image into a RichTextBox as a means of creating a more useful application based upon the RichTextBox control.