.net截屏代码

Imports System.Runtime.InteropServices
Imports System.Drawing
Imports System.Drawing.Imaging
Namespace ScreenShotDemo
    ''' <summary>
    ''' Provides functions to capture the entire screen, or a particular window, and save it to a file.
    ''' </summary>
    Public Class ScreenCapture
        ''' <summary>
        ''' Creates an Image object containing a screen shot of the entire desktop
        ''' </summary>
        ''' <returns></returns>
        Public Function CaptureScreen() As Image
            Return CaptureWindow(User32.GetDesktopWindow())
        End Function
        ''' <summary>
        ''' Creates an Image object containing a screen shot of a specific window
        ''' </summary>
        ''' <param name="handle">The handle to the window. (In windows forms, this is obtained by the Handle property)</param>
        ''' <returns></returns>
        Public Function CaptureWindow(handle As IntPtr) As Image
            ' get te hDC of the target window
            Dim hdcSrc As IntPtr = User32.GetWindowDC(handle)
            ' get the size
            Dim windowRect As New User32.RECT()
            User32.GetWindowRect(handle, windowRect)
            Dim width As Integer = windowRect.right - windowRect.left
            Dim height As Integer = windowRect.bottom - windowRect.top
            ' create a device context we can copy to
            Dim hdcDest As IntPtr = GDI32.CreateCompatibleDC(hdcSrc)
            ' create a bitmap we can copy it to,
            ' using GetDeviceCaps to get the width/height
            Dim hBitmap As IntPtr = GDI32.CreateCompatibleBitmap(hdcSrc, width, height)
            ' select the bitmap object
            Dim hOld As IntPtr = GDI32.SelectObject(hdcDest, hBitmap)
            ' bitblt over
            GDI32.BitBlt(hdcDest, 0, 0, width, height, hdcSrc, _
             0, 0, GDI32.SRCCOPY)
            ' restore selection
            GDI32.SelectObject(hdcDest, hOld)
            ' clean up
            GDI32.DeleteDC(hdcDest)
            User32.ReleaseDC(handle, hdcSrc)
            ' get a .NET image object for it
            Dim img As Image = Image.FromHbitmap(hBitmap)
            ' free up the Bitmap object
            GDI32.DeleteObject(hBitmap)
            Return img
        End Function
        ''' <summary>
        ''' Captures a screen shot of a specific window, and saves it to a file
        ''' </summary>
        ''' <param name="handle"></param>
        ''' <param name="filename"></param>
        ''' <param name="format"></param>
        Public Sub CaptureWindowToFile(handle As IntPtr, filename As String, format As ImageFormat)
            Dim img As Image = CaptureWindow(handle)
            img.Save(filename, format)
        End Sub
        ''' <summary>
        ''' Captures a screen shot of the entire desktop, and saves it to a file
        ''' </summary>
        ''' <param name="filename"></param>
        ''' <param name="format"></param>
        Public Sub CaptureScreenToFile(filename As String, format As ImageFormat)
            Dim img As Image = CaptureScreen()
            img.Save(filename, format)
        End Sub


        ''' <summary>
        ''' Helper class containing Gdi32 API functions
        ''' </summary>
        Private Class GDI32


            Public Const SRCCOPY As Integer = &HCC0020
            ' BitBlt dwRop parameter
            <DllImport("gdi32.dll")> _
            Public Shared Function BitBlt(hObject As IntPtr, nXDest As Integer, nYDest As Integer, nWidth As Integer, nHeight As Integer, hObjectSource As IntPtr, _
    nXSrc As Integer, nYSrc As Integer, dwRop As Integer) As Boolean
            End Function
            <DllImport("gdi32.dll")> _
            Public Shared Function CreateCompatibleBitmap(hDC As IntPtr, nWidth As Integer, nHeight As Integer) As IntPtr
            End Function
            <DllImport("gdi32.dll")> _
            Public Shared Function CreateCompatibleDC(hDC As IntPtr) As IntPtr
            End Function
            <DllImport("gdi32.dll")> _
            Public Shared Function DeleteDC(hDC As IntPtr) As Boolean
            End Function
            <DllImport("gdi32.dll")> _
            Public Shared Function DeleteObject(hObject As IntPtr) As Boolean
            End Function
            <DllImport("gdi32.dll")> _
            Public Shared Function SelectObject(hDC As IntPtr, hObject As IntPtr) As IntPtr
            End Function
        End Class


        ''' <summary>
        ''' Helper class containing User32 API functions
        ''' </summary>
        Private Class User32
            <StructLayout(LayoutKind.Sequential)> _
            Public Structure RECT
                Public left As Integer
                Public top As Integer
                Public right As Integer
                Public bottom As Integer
            End Structure
            <DllImport("user32.dll")> _
            Public Shared Function GetDesktopWindow() As IntPtr
            End Function
            <DllImport("user32.dll")> _
            Public Shared Function GetWindowDC(hWnd As IntPtr) As IntPtr
            End Function
            <DllImport("user32.dll")> _
            Public Shared Function ReleaseDC(hWnd As IntPtr, hDC As IntPtr) As IntPtr
            End Function
            <DllImport("user32.dll")> _
            Public Shared Function GetWindowRect(hWnd As IntPtr, ByRef rect As RECT) As IntPtr
            End Function
        End Class
    End Class
End Namespace