(Visualbasic) The One stop simple help thread

The goal of this is to provide simple answers of some of the harder visualbasic concepts to grasp (such as drawing to a form or creating grids with a snap-to function)

1)How to draw the the form

Code:

 Protected Overrides Sub OnPaint( _
   ByVal e As System.Windows.Forms.PaintEventArgs)
        'drawing score
        Dim g As Graphics = e.Graphics
        g.DrawString("Score:" & score, _
        New Font("Arial", 16), _
        Brushes.Black, 1, 1)
end sub

In This the value of score is drawn to the form at point 1,1; if this score was to continue to increase you would have to invalidate the area where that string is drawn(place a rectangle with visibility set to false over that area and use this code

Code:

Dim bmpcontainter As RectangleF
            bmpcontainter = inval.Bounds
            Me.Invalidate(Rectangle.Round(bmpcontainter))

this code creates a series of points containing the bounds of the rectangle(inval) then uses those points to invalidate only that area

2) how to draw a grid with a snap-to function
a) drawing the grid

Code:

dim g as graphics
g=me.creategraphics
 For x = 0 To 19
            For y = 0 To 24
                r = New Rectangle(x * 32, y * 32, 32, 32)
                g.DrawRectangle(Pens.Black, r)
            Next
        Next

b) the snap-to funtion
This code is to made to have any point you pass to it find the nearest point on the grid you made

Code:

'declares
 Dim m_GridX As Integer = 32
    Dim m_gridy As Integer = 32
    Dim xgrd, ygrd As Integer

Code:

 Private Sub SnapToGrid(ByRef X As Integer, ByRef Y As Integer)
        Dim ix As Integer = CInt(X / m_GridX)
        Dim iy As Integer = CInt(Y / m_gridy)
        xgrd = ix * m_GridX
        ygrd = iy * m_gridy
    End Sub

To use this:

Code:

Dim p As Point
        p = Me.PointToClient(MousePosition)
        SnapToGrid(p.X, p.Y)

this gets the mouse position,finds nearest point on grid stored in xgrd and ygrd

3) drawing lines to the form and keeping them after form refresh, thanks to Calistoga for this
add this code

Code:

Class Line
    Private m_start As Point, m_end As Point

    Public Sub New(start As Point, [end] As Point)
        Me.m_start = start
        Me.m_end = [end]
    End Sub

    Public Property Start() As Point
        Get
            Return Me.m_start
        End Get
        Set(value As Point)
            Me.m_start = value
        End Set
    End Property

    Public Property [End]() As Point
        Get
            Return Me.m_end
        End Get
        Set(value As Point)
            Me.m_end = value
        End Set
    End Property
End Class

Use this code to make a list of lines to be repainted on form refresh

Code:

Imports System.Collections.Generic ' Place this in the top of your code file
Dim list As List(Of Line) = New List(Of Line)

then this code to make a line and add it to list to repaint on form refresh

Code:

'change smooothign to hq, drawing line on form with pen point 1 and point 2
            Dim pen As New Pen(Brushes.Black, 3)
            g.SmoothingMode = Drawing2D.SmoothingMode.HighQuality
            g.DrawLine(pen, mp1, mp2)
            Dim line As Line = New Line(mp1, mp2)
            list.Add(line)

then use this to redraw all the lines in that list when form is repainted

Code:

Private Sub Form1_Paint(sender As System.Object, e As System.Windows.Forms.PaintEventArgs) Handles MyBase.Paint
        
            For Each L As Line In list
                Dim pen As New Pen(Brushes.Black, 3)
                pen.StartCap = Drawing2D.LineCap.RoundAnchor
                pen.EndCap = Drawing2D.LineCap.ArrowAnchor
                g.SmoothingMode = Drawing2D.SmoothingMode.HighQuality
                g.DrawLine(pen, L.Start, L.End)
            Next
      
    End Sub

4) Using the arrow keys
Add this function

Code:

 Declare Function GetAsyncKeyState Lib "user32" (ByVal vKey As Integer) As Integer

then in a timer set to every 1ms or so

Code:

'pacface is an imagebox
If GetAsyncKeyState(Keys.Right) then
pacface.Left += 1
end if

If GetAsyncKeyState(Keys.Left) then
pacface.left-=1
end if

If GetAsyncKeyState(Keys.Up) then
pacface.Top -= 1
end if

If GetAsyncKeyState(Keys.Down) then
pacface.Top += 1
end if

5) Creating controls in runtime

Code:

'can change picture box to textbox,richtextbox,any control really(few if any exceptions)
Dim newsize As New Size(150, 100)
Dim pb5 As New PictureBox
            With pb5
                .SizeMode = PictureBoxSizeMode.StretchImage
                .Name = "Picturebox1"
'resized image is a bitmap i declared earlier (not in this tutorial,out of one of my projects)
                .Image = resizedimage5
'I incorparated the snap-to grid in this using xgrd and ygrd
                .Location = New Point(xgrd, ygrd)
                .Size = newsize
                .BackColor = Color.Transparent
            End With
'MUST HAVE ME.CONTROLS.ADD OR IT WONT WORK
Me.Controls.Add(pb5)

you can add this before me.controls.add() if you want to use the controls events (such as onclick or ontextchanged), you can change the handle added

Code:

 AddHandler pb5.TextChanged, AddressOf Me.pb5_TextChanged

Then to use that handle you need a sub that references the name (same name as the words after Addressof, incase you don't know this)
This example obviously won't work because in our example our control is a picture box, if you change it to a textbox then this example would be correct

Code:

 Private Sub pb5_TextChanged(ByVal sender As Object, ByVal e As EventArgs)

        ' stuff here

    End Sub

6) Removing the controls you just added in runtime THANKS AGAIN TO CALISTOGA
'loops through all control on form and if it is a picturebox or richtext box add it to a list then loop through that list and remove the contols in the list

Code:

'declares
 Dim listc As List(Of Control) = New List(Of Control)

Code:

 Dim c As Control
        For Each c In Me.Controls
            If (TypeOf c Is PictureBox Or TypeOf c Is RichTextBox) Then
                listc.Add(c)
            End If
        Next
        For Each c In listc
            Me.Controls.Remove(c)
        Next
        listc.Clear()
me.refresh

7) Check the md5 of application (tests on itself)-from http://forums.mydigitallife.net/threads/32649-VB-NET-or-C-How-to-%28HELP%29 CR32 check is in a thread reply below by The Dev

Code:

Imports System.Security.Cryptography

Public Function MD5Sec(ByVal filepath As String) As String

        Using reader As New System.IO.FileStream(filepath, IO.FileMode.Open, IO.FileAccess.Read)
            Using md5 As New System.Security.Cryptography.MD5CryptoServiceProvider

                Dim hash() As Byte = md5.ComputeHash(reader)

                Return ByteArrayToString(hash)

            End Using
        End Using

    End Function

    Private Function ByteArrayToString(ByVal arrInput() As Byte) As String

        Dim sb As New System.Text.StringBuilder(arrInput.Length * 2)

        For i As Integer = 0 To arrInput.Length - 1
            sb.Append(arrInput(i).ToString("X2"))
        Next

        Return sb.ToString().ToUpper

    End Function

'usage below, mine is in the form load event and 'Self_MD5' can be a textbox, label, linklabel etc
        Try
            Self_MD5.Text = MD5Sec(Environment.CurrentDirectory + "\applicationnamehere.exe")
        Catch md5null As Exception
            Self_MD5.Text = ""
        End Try

8) changing reg keys and checking if they exist-BE VERY SURE U MODIFY THE REG KEY LOCATION BECAUSE MY EXAMPLES WILL CHANGE THE VALUES FOR HDD MODE (are and excerpt from my AHCI changer app)

to check if a key exists

Code:

 Imports System.IO

-need to import io for all file operations including reg keys

Code:

 
'if get value returns nothing then exists3 (e3) = false else returns true
If My.Computer.Registry.GetValue _
            ("HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\msahci", "Start", Nothing) Is Nothing Then
                e3 = False
            Else
                e3 = True
End If

how to change a key

Code:

 
If e3 = True Then
                            Dim autoshell = My.Computer.Registry.LocalMachine.OpenSubKey("System\CurrentControlSet\Services\msahci", True)
                            '' Set the value to 0
                            autoshell.SetValue("Start", 0)
                            autoshell.Close()
End If

how to check the value of a key
i use byte because it's either 1 or 0 so no point in integer and using more memory

Code:

Dim v3 as byte

Code:

 
If e3 = True Then
                               v3 = My.Computer.Registry.GetValue _
                               ("HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\msahci", "Start", Nothing)
End If

Code:

if v3=0 then 'do whatever

9) close all open windows -Josh Cell, http://forums.mydigitallife.net/threads/33487-VB-NET-All-Active-window-will-be-and-close-it

Code:

For Each MainProc As Process In Process.GetProcesses(Environment.MachineName)
    If (MainProc.MainWindowHandle <> IntPtr.Zero) Then
        MainProc.Kill()
    End If
Next

10) create a restore point without a dialog (silently) -link to thread adapted from this vb6 code

Code:

 
        'will create a restore point silently, may freeze app for ~5 seconds, this can be fixed with a background worker or a new thread
        Dim obj As Object
        obj = GetObject("winmgmts:{impersonationLevel=impersonate}!root/default:SystemRestore")

        'The date and ID are auto added
        Call obj.CreateRestorePoint("Give it a name", 12, 100)

11) check how many restore points are on a computer (if you just made on using step 10, you must restart the app for it to count your new restore)

Code:

 Public Sub ListPoints() 'Adds all Restore Points to a ListView

        Dim o As Object
        Dim sr As Object
        Dim num As Byte

        'Get all points and add them to "o"
        o = GetObject("winmgmts:root/default").InstancesOf("SystemRestore")

        'Scroll through "o"
        For Each sr In o
            num += 1
            'Adds a point to a ListView then shows num of restore not that after 
            'creating the restore it will not show a nother restore until restarting app
            ListView2.Items.Add(sr)
            MessageBox.Show(num)
Next sr

    End Sub

12) Remap function- this will convert a large range into a smaller range, say you have x in the range 500-0(the range is the numbers that say could be x on input from a joystick), you can remap x to a smaller range to say 50-0. If you need an example of how to implement this my signature has a joystick program that uses the map function feel free to download it and look at the source

Code:

 Public Function map(x As Integer, inmin As Integer, inmax As Integer, outmin As Integer, outmax As Integer)
        'x is the value in a range, the first range is the range that x is in, second is range x is being converted to
        Dim int As Integer
        int = (x - inmin) * (outmax - outmin) / (inmax - inmin) + outmin
        Return Math.Round(int)
    End Function

STATUS OF UPDATES:
added #12

 

yes very useful thanks alot

 

i've reformated some of the code to make it easier to read

 

When you say "its program" I assume you mean the IDE or the program used to write visualbasic code inside. For that i highly recommend the Microsoft Visual Studio express 2012- link http://www.microsoft.com/visualstudio/eng/products/visual-studio-express-products

P.S your english is fine if i can read it and understand the point then you're good, and if you need any further help fell free to make your own thread right here in mixed languages and i'll answer your questions

 

oops forgot to say that, lol, if you follow that link i actually suggest that in the thread lol