VB.NET Technology

Like the normal TextBox, the RichTextBox control is derived from TextBoxBase. Because of this, it shares a number of features with the TextBox, but is much more diverse. Where a TextBox is commonly used with the purpose of obtaining short text strings from the user, the RichTextBox is used to display and enter formatted text (for example bold, underline, and italic). It does so using a standard for formatted text called Rich Text Format or RTF.

RichTextBox Properties

Name	Availability	Description
CanRedo	Read/Write	This property is true if something has been undone, that can be reapplied,otherwise false.
CanUndo	Read/Write	This property is true if it is possible to perform an undo action on the RichTextBox, otherwise it is false.
RedoActionName	Read/Write	This property holds the name of an action that be used to redo something that has been undone in the RichTextBox.
DetectUrls	Read/Write	Set this property to true to make the control detect URLs and format them (underline as in a browser).
Rtf	Read/Write	This corresponds to the Text property, except that this holds the text in RTF.
SelectedRtf	Read/Write	Use this property to get or set the selected text in the control, in RTF. If you copy this text to another application, for example, MS Word, it will retain all formatting.
SelectedText	Read/Write	Like SelectedRtf you can use this property to get or set the selected text. Unlike the RTF version of the property however, all formatting is lost.
SelectionAlignment	Read/Write	This represents the alignment of the selected text. It can be Center, Left, or Right.
SelectionBullet	Read/Write	Use this property to find out if the selection is formatted with a bullet in front of it, or use it to insert or remove bullets.
BulletIndent	Read/Write	Use this property to specify the number of pixels a bullet should be indented.
SelectionColor	Read/Write	Allow you to change the color of the text in the selection.
SelectionFont	Read/Write	Allow you to change to font of the text in the selection.
SelectionLength	Read/Write	Using this property, you either set or retrieve the length of a selection.
SelectionType	Read/Write	This property holds information about the selection. It will tell you if one or more OLE objects are selected or if only text is selected.
ShowSelectionMargin	Read/Write	If you set this property to true, a margin will be shown at the left of the RichTextBox. This will make it easier for the user to select text.
UndoActionName	Read/Write	Gets the name of the action that will be used if the user chooses to undo something.
SelectionProtected	Read/Write	You can specify that certain parts of the text should not be changed by setting this property to true.

RichTextBox Events

Name	Description
LinkedClick	This event is sent when a user clicks on a link within the text.
Protected	This event is sent when a user attempts to modify text that has been marked as protected.
SelectionChanged	This event is sent when the selection changes. If for some reason you don't want the user to change the selection, you can prevent the change here.

Example of Rich TextBox

To implement rich textbox create new application and design form like below image, and change properties according to your choice.

In following image i am making selected text bold on clicking the bold Button. Coding for bold button is given below.

Code for Bold Button

Private Sub Button1_Click_1(ByVal sender As System.Object, 
ByVal e As System.EventArgs) Handles Button1.Click
        Dim oldFont As Font
        Dim newFont As Font
        ' Get the font that is being used in the selected text
        oldFont = Me.richTextBox1.SelectionFont
        ' If the font is using bold style now, we should remove the
        ' Formatting
        If oldFont.Bold Then
            newFont = New Font(oldFont, oldFont.Style And Not FontStyle.Bold)
        Else
            newFont = New Font(oldFont, oldFont.Style Or FontStyle.Bold)
        End If
        ' Insert the new font and return focus to the RichTextBox
        Me.richTextBox1.SelectionFont = newFont
        Me.richTextBox1.Focus()
    End Sub

In following image i am making selected text Italic on clicking the italic Button. Coding for italic button is given below.

Code for Italic Button

Private Sub Button2_Click_1(ByVal sender As System.Object, 
ByVal e As System.EventArgs) Handles Button2.Click
        Dim oldFont As Font
        Dim newFont As Font
        ' Get the font that is being used in the selected text
        oldFont = Me.richTextBox1.SelectionFont
        ' If the font is using Italic style now, we should remove it
        If oldFont.Italic Then
            newFont = New Font(oldFont, oldFont.Style And Not FontStyle.Italic)
        Else
            newFont = New Font(oldFont, oldFont.Style Or FontStyle.Italic)
        End If
        ' Insert the new font
        Me.richTextBox1.SelectionFont = newFont
        Me.richTextBox1.Focus()
    End Sub

In following image i am making selected text Underline on clicking the Underline Button. Coding for Underline Button is given below.

Coding for Underline Button

Private Sub Button2_Click_1(ByVal sender As System.Object, 
ByVal e As System.EventArgs) Handles Button2.Click
        Dim oldFont As Font
        Dim newFont As Font
        ' Get the font that is being used in the selected text
        oldFont = Me.richTextBox1.SelectionFont
        ' If the font is using Italic style now, we should remove it
        If oldFont.Italic Then
            newFont = New Font(oldFont, oldFont.Style And Not FontStyle.Italic)
        Else
            newFont = New Font(oldFont, oldFont.Style Or FontStyle.Italic)
        End If
        ' Insert the new font
        Me.richTextBox1.SelectionFont = newFont
        Me.richTextBox1.Focus()
    End Sub

In following image i am making selected text Center on clicking the Center Button. Coding for Center Button is given below.

Coding for Center Button

 Private Sub Button4_Click(ByVal sender As System.Object, 
	ByVal e As System.EventArgs) Handles Button4.Click
        If Me.richTextBox1.SelectionAlignment = HorizontalAlignment.Center Then
            Me.richTextBox1.SelectionAlignment = HorizontalAlignment.Left
        Else
            Me.richTextBox1.SelectionAlignment = HorizontalAlignment.Center
        End If
        Me.richTextBox1.Focus()
    End Sub

In following image i am making selected text size large and small by putting the value in size textbox. Coding for this is given below.

Coding for Size Change

for this you have to write following code on textbox validating event.

Private Sub txtSize_Validating(ByVal sender As System.Object, 
	ByVal e As System.ComponentModel.CancelEventArgs) Handles txtSize.Validating
        Dim txt As TextBox = DirectCast(sender, TextBox)
        ApplyTextSize(txt.Text)
        Me.richTextBox1.Focus()
    End Sub

And then you have to write keypress event on textbox event.

Private Sub txtSize_KeyPress(ByVal sender As System.Object, 
	ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles txtSize.KeyPress
        If (e.KeyChar < 48 OrElse e.KeyChar > 57) AndAlso e.KeyChar <> 8 
	AndAlso e.KeyChar <> 13 Then
            e.Handled = True
        ElseIf e.KeyChar = 8 Then
            MessageBox.Show("Please input valid size")
        ElseIf e.KeyChar = 13 Then
            ' Apply size if the user hits enter
            Dim txt As TextBox = DirectCast(sender, TextBox)
            If txt.Text.Length > 0 Then
                ApplyTextSize(txt.Text)
            End If
            e.Handled = True
            Me.richTextBox1.Focus()
        End If
    End Sub

and then make a method for applytextsize method

Private Sub ApplyTextSize(textSize As String)
	' Convert the text to a float because we'll be needing a float shortly
	Dim newSize As Single = Convert.ToSingle(textSize)
	Dim currentFontFamily As FontFamily
	Dim newFont As Font
	' Create a new font of the same family but with the new size
	currentFontFamily = Me.richTextBox1.SelectionFont.FontFamily
	newFont = New Font(currentFontFamily, newSize)
	' Set the font of the selected text to the new font
	Me.richTextBox1.SelectionFont = newFont
End Sub