VB.net中实现打印窗体

Imports System

Imports System.Drawing.Printing

Public Class Form1

    <System.Runtime.InteropServices.DllImport("gdi32.dll")> _

   Public Shared Function 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 Integer) As Boolean

    End Function

    <System.Runtime.InteropServices.DllImport("User32.dll")> _

    Public Shared Function GetWindowDC(ByVal hwd As IntPtr) As IntPtr

    End Function

    <System.Runtime.InteropServices.DllImport("User32.dll")> _

    Public Shared Function ReleaseDC(ByVal hwd As IntPtr, ByVal dc As IntPtr) As Integer

    End Function

    <System.Runtime.InteropServices.DllImport("user32.dll")> _

    Public Shared Function GetWindowRect(ByVal hWnd As IntPtr, ByRef lpRect As RECT) As Boolean

    End Function

    <Serializable(), System.Runtime.InteropServices.StructLayout(System.Runtime.InteropServices.LayoutKind.Sequential)> _

    Public Structure RECT

        Public Left As Integer

        Public Top As Integer

        Public Right As Integer

        Public Bottom As Integer

    End Structure

    Private memoryImage As Bitmap

    Private Sub CaptureScreen()

        Dim mygraphics As Graphics = Me.CreateGraphics()

        Dim r As RECT

        GetWindowRect(Me.Handle, r)

        Dim s As Rectangle = Rectangle.FromLTRB(r.Left, r.Top, r.Right, r.Bottom)

        memoryImage = New Bitmap(s.Width, s.Height, mygraphics)

        Dim memoryGraphics As Graphics = Graphics.FromImage(memoryImage)

        Dim dc1 As IntPtr = GetWindowDC(Me.Handle)

        Dim dc2 As IntPtr = memoryGraphics.GetHdc()

        BitBlt(dc2, 0, 0, s.Width, s.Height, dc1, 0, 0, 13369376)

        ReleaseDC(Me.Handle, dc1)

        memoryGraphics.ReleaseHdc(dc2)

    End Sub

    Private Sub Document_PrintPage(ByVal sender As System.Object, ByVal e As System.Drawing.Printing.PrintPageEventArgs)

        e.Graphics.DrawImage(memoryImage, 0, 0)

    End Sub

    Private Sub Button1_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        CaptureScreen()

        PrintDialog1.ShowDialog()

        Dim pd As PrintDocument = New PrintDocument

        pd.PrinterSettings = PrintDialog1.PrinterSettings

        AddHandler pd.PrintPage, AddressOf Document_PrintPage

        pd.Print()

    End Sub