How to print windows form in .NET

First, we created a simple form with a few controls, that do nothing, so that the form would have something on it.  We added a Print Form command button and called it btnPrintForm.


Place the following code in the declaractions section of your form.  This code sets up a PrintDocument component and declares the prototype for the BitBlt API call.  The BitBlt function performs a bit-block transfer of the color data corresponding to a rectangle of pixels from the specified source device context into a destination device context. This API is used to capture the image of the form.

   ' create a printing component

    Private WithEvents pd As Printing.PrintDocument

    ' storage for form image

    Dim formImage As Bitmap

    ' create API prototype

    Private Declare Function BitBlt Lib "gdi32.dll" Alias _

       "BitBlt" (ByVal hdcDest As IntPtr, _

       ByVal nXDest As Integer, ByVal nYDest As _

       Integer, ByVal nWidth As Integer, _

       ByVal nHeight As Integer, ByVal _

       hdcSrc As IntPtr, ByVal nXSrc As Integer, _

       ByVal nYSrc As Integer, _

       ByVal dwRop As System.Int32) As Long

Next, place the following event handlers in the code window of the form.  The print command button is expected to have a Name of btnPrintForm.

' Callback from PrintDocument component to

    ' do the actual printing

Private Sub pd_PrintPage(ByVal sender As Object, _

       ByVal e As System.Drawing.Printing.PrintPageEventArgs) _

       Handles pd.PrintPage

        e.Graphics.DrawImage(formImage, 100, 100)

    End Sub

    Private Sub Form1_Load(ByVal sender As Object, _

      ByVal e As System.EventArgs) Handles MyBase.Load

        ' create an instance of the PrintDocument component

        pd = New Printing.PrintDocument

        Me.StartPosition = FormStartPosition.CenterScreen

    End Sub

Private Sub btnPrintForm_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnPrintForm.Click

        ' initiate the printdocument component

        GetFormImage()

        pd.Print()

    End Sub

In the Form_Load event, we have created an instance of the PrintDocument object.  In the btnPrintForm_Click event, we call a method, shown below, to capture the image of the form and create a Bitmap of it.  Then we call the Print method of the PrintDocument object to initiate the printing of the form.  That method will call the pd_PrintPage event handler to request the data to be printed.  In this case the data to be printed is a Bitmap, created by the GetFormImage method.

The following method, GetFormImage, captures the screen image of the form.

Private Sub GetFormImage()

        Dim g As Graphics = Me.CreateGraphics()

        Dim s As Size = Me.Size

        formImage = New Bitmap(s.Width, s.Height, g)

        Dim mg As Graphics = Graphics.FromImage(formImage)

        Dim dc1 As IntPtr = g.GetHdc

        Dim dc2 As IntPtr = mg.GetHdc

        ' added code to compute and capture the form

        ' title bar and borders

        Dim widthDiff As Integer = _

           (Me.Width - Me.ClientRectangle.Width)

        Dim heightDiff As Integer = _

           (Me.Height - Me.ClientRectangle.Height)

        Dim borderSize As Integer = widthDiff \ 2

        Dim heightTitleBar As Integer = heightDiff - borderSize

        BitBlt(dc2, 0, 0, _

           Me.ClientRectangle.Width + widthDiff, _

           Me.ClientRectangle.Height + heightDiff, dc1, _

           0 - borderSize, 0 - heightTitleBar, 13369376)

        g.ReleaseHdc(dc1)

        mg.ReleaseHdc(dc2)

    End Sub

When we completed our form, run the application, and clicked the Print Form button.  Regardless of what your form looks like, if you place a Print Button or a Menu Option on it, and call the Click event handler shown above, your form should print properly.