How to Invert Image in PictureBox (VB.Net)

In many developing programs allow us to develop program to edit image or customize as you want. This tutorial will show you how to develop a small application to invert image in PictureBox. I use two PictureBoxes which one is stored the base image and another one for getting result the image which is inverted.

No	Control Type	Name	Text	Event
1	Form1	FormInvertImage	Inverting Image
2	PictureBox1	PictureBoxBase
3	PictureBox2	PictureBoxInvert
4	Button1	ButtonInvert	Invert	Click

   

• As you see in the application screenshot, when you click on button "Invert" , you will get the image result in PictureBoxInvert. 

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How to make Font Auto Size in Textbox (VB.Net)

This tutorial will show you how to set font size of Textbox to autosize means that when you type more words in Textbox, It will set the font size to fit the Textbox which contains these text.

No	Control Type	Name	Text	Event
1	Form1	FormAutoSize	AutoSize Font
2	Textbox1	TextBoxAuto		Text_Changed

Code

Public Class FormAutoSizeFont

    Dim h As String

    Dim w As String

    Private Sub FormAutoSizeFont_Paint(sender As Object, e As PaintEventArgs) Handles Me.Paint

        Dim orgFont As New Font(TextBoxAutosize.Font.Name, TextBoxAutosize.Font.Size, TextBoxAutosize.Font.Style)

        Dim textSize As New SizeF

        textSize = e.Graphics.MeasureString(TextBoxAutosize.Text, orgFont)

        h = textSize.Height

        w = textSize.Width

    End Sub

    Private Sub TextBoxAutosize_TextChanged(sender As Object, e As EventArgs) Handles TextBoxAutosize.TextChanged

        TextBoxAutosize.Font = New Font(TextBoxAutosize.Font.Name, 12, TextBoxAutosize.Font.Style)

        TextBoxAutosize.BorderStyle = BorderStyle.Fixed3D

        Do Until w > TextBoxAutosize.Size.Width - 5 Or TextBoxAutosize.Text = Nothing Or h > 182

            TextBoxAutosize.Font = New Font(TextBoxAutosize.Font.Name, TextBoxAutosize.Font.Size + 2, TextBoxAutosize.Font.Style)

        Loop

        TextBoxAutosize.BorderStyle = BorderStyle.None

        TextBoxAutosize.TextAlign = HorizontalAlignment.Center

        TextBoxAutosize.WordWrap = True

    End Sub

End Class

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How to set input number only in textbox (VB.Net)

When the most program developers create one control on a form which to operate number such as Quantity of Item, Number of item.., always set that control use only number to help user avoid using wrong input. In this application, I add one TextBox(Name: TextBoxOnlyNumber;  Text: Only Number) and use this textbox with KeyPress_Event(When we type text in textbox, the code will execute) then message box will show("Please enter numbers only"), if we input not number.

 

Code

Public Class OnlyNumber

    Private Sub TextBoxOnlyNumber_Click(sender As Object, e As EventArgs) Handles TextBoxOnlyNumber.Click

        TextBoxOnlyNumber.Text = ""

    End Sub

    Private Sub TextBoxOnlyNumber_MouseLeave(sender As Object, e As EventArgs) Handles TextBoxOnlyNumber.MouseLeave

        TextBoxOnlyNumber.Text = "Only Number!"

    End Sub

    Private Sub TextBoxOnlyNumber_KeyPress(sender As Object, e As KeyPressEventArgs) Handles TextBoxOnlyNumber.KeyPress

        If Asc(e.KeyChar) <> 13 AndAlso Asc(e.KeyChar) <> 8 AndAlso Not IsNumeric(e.KeyChar) Then

            MessageBox.Show("Please enter numbers only")

            e.Handled = True

        End If

    End Sub

End Class

  

this code, there are 3 block,our main code is only one block(TextBoxOnlyNumber_KeyPress), but I added another 2 blocks are:

1. TextBoxOnlyNumber_Click : For clear textbox when we click on textbox.
2. TextBoxOnlyNumber_MouseLeave : for showing text("Only Number") when the mouse leave from textbox.

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How to find a word after specific one word (VB.Net)

Sometime programmers need a method to find the word after one specific word in one specific develop program such as VB.Net, C#, Java.... To reply this, I wrote the sample one application using VB.Net to find word after one specific word which input in textbox as below:

Application Design

 

No	Control Type	Name	Text
1	Form1	FormWordAfterWord	Get Word After Word
2	Textbox1	TextboxWord
3	Textbox2	TextboxFind
4	Button1	ButtonFind	Find

• As you see sample above, we input text in TextBoxWord "Visual Basic is my favourite" and we want to find one word which located after word "my" in TextBoxFind and the message box show that "The word after word : my is favourite" which is right to our goal.

 Code

Imports System.Text.RegularExpressions

Public Class FormWordAfterWord

    Private Sub ButtonFind_Click(sender As Object, e As EventArgs) Handles ButtonFind.Click

        Dim text As String = TextBoxWord.Text

        Dim word As String = "\b" & TextBoxFind.Text & "\b\s+(\w+)"

        For Each a As Match In Regex.Matches(text, word, RegexOptions.IgnoreCase)

            MessageBox.Show("The word after word: " & TextBoxFind.Text & "  is  " & a.Groups(1).Value)

        Next

    End Sub

End Class

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How to Validate Email Address in Textbox (VB.Net)

The small application below show you how to validate email address in textbox using VB.Net. To test process, I have designed as below:

No	Control Type	Name	Text
1	Form1	ValidateEmail	Validate Email
2	Textbox1	TextBoxEmail
3	Label1	LabelStatus
4	Button1	ButtonValidate	Validate Email

This process, I used ButtonValidate_Click to check email address in TextBoxEmail. I use to condition which is True/False condition as you see in code below and the result will show in LabelStatus. This code work propertly!!!

Code

Imports System.Text.RegularExpressions

Public Class ValidateEmail

    Private Sub ButtonValidate_Click(sender As Object, e As EventArgs) Handles ButtonValidate.Click

        Dim pattern As String = "^[a-z][a-z|0-9|]*([_][a-z|0-9]+)*([.][a-z|0-9]+([_][a-z|0-9]+)*)?@[a-z][a-z|0-9|]*\.([a-z][a-z|0-9]*(\.[a-z][a-z|0-9]*)?)$"

        Dim match As System.Text.RegularExpressions.Match = Regex.Match(TextBoxEmail.Text.Trim(), pattern, RegexOptions.IgnoreCase)

        If (match.Success) Then

            LabelStatus.Text = "The email address :  " & TextBoxEmail.Text & "  is corrected"

        Else

            LabelStatus.Text = "The email address :  " & TextBoxEmail.Text & "  is incorrected !!!"

            TextBoxEmail.Clear()

        End If

    End Sub

End Class

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