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vb screendump

Posted on 2003-11-12
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Last Modified: 2007-12-19
anyone knows how to make a screendump with vb with the option to save it to a file ?

thx M
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Question by:MKrauss
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6 Comments
 
LVL 53

Expert Comment

by:Dhaest
ID: 9731585
Multiple possibilities:
1)
Private Declare Sub keybd_event Lib "user32" (ByVal bVk As Byte, ByVal bScan As Byte, ByVal dwFlags As Long, ByVal dwExtraInfo As Long)

Private Sub Command1_Click()
    keybd_event vkkeysnapshot, 1, 0&, 0&
    DoEvents
    SavePicture Clipboard.GetData(vbCFBitmap), "c:\my.bmp"

End Sub

2)
Const RC_PALETTE As Long = &H100
Const SIZEPALETTE As Long = 104
Const RASTERCAPS As Long = 38
Private Type PALETTEENTRY
    peRed As Byte
    peGreen As Byte
    peBlue As Byte
    peFlags As Byte
End Type
Private Type LOGPALETTE
    palVersion As Integer
    palNumEntries As Integer
    palPalEntry(255) As PALETTEENTRY ' Enough for 256 colors
End Type
Private Type GUID
    Data1 As Long
    Data2 As Integer
    Data3 As Integer
    Data4(7) As Byte
End Type
Private Type PicBmp
    Size As Long
    Type As Long
    hBmp As Long
    hPal As Long
    Reserved As Long
End Type
Private Declare Function OleCreatePictureIndirect Lib "olepro32.dll" (PicDesc As PicBmp, RefIID As GUID, ByVal fPictureOwnsHandle As Long, IPic As IPicture) As Long
Private Declare Function CreateCompatibleDC Lib "gdi32" (ByVal hdc As Long) As Long
Private Declare Function CreateCompatibleBitmap Lib "gdi32" (ByVal hdc As Long, ByVal nWidth As Long, ByVal nHeight As Long) As Long
Private Declare Function SelectObject Lib "gdi32" (ByVal hdc As Long, ByVal hObject As Long) As Long
Private Declare Function GetDeviceCaps Lib "gdi32" (ByVal hdc As Long, ByVal iCapabilitiy As Long) As Long
Private Declare Function GetSystemPaletteEntries Lib "gdi32" (ByVal hdc As Long, ByVal wStartIndex As Long, ByVal wNumEntries As Long, lpPaletteEntries As PALETTEENTRY) As Long
Private Declare Function CreatePalette Lib "gdi32" (lpLogPalette As LOGPALETTE) As Long
Private Declare Function SelectPalette Lib "gdi32" (ByVal hdc As Long, ByVal hPalette As Long, ByVal bForceBackground As Long) As Long
Private Declare Function RealizePalette Lib "gdi32" (ByVal hdc As Long) As Long
Private Declare Function BitBlt Lib "gdi32" (ByVal hDestDC As Long, ByVal x As Long, ByVal y As Long, ByVal nWidth As Long, ByVal nHeight As Long, ByVal hSrcDC As Long, ByVal xSrc As Long, ByVal ySrc As Long, ByVal dwRop As Long) As Long
Private Declare Function DeleteDC Lib "gdi32" (ByVal hdc As Long) As Long
Private Declare Function GetDC Lib "user32" (ByVal hwnd As Long) As Long
Private Declare Function GetForegroundWindow Lib "user32" () As Long
Function CreateBitmapPicture(ByVal hBmp As Long, ByVal hPal As Long) As Picture
    Dim R As Long, Pic As PicBmp, IPic As IPicture, IID_IDispatch As GUID

    'Fill GUID info
    With IID_IDispatch
        .Data1 = &H20400
        .Data4(0) = &HC0
        .Data4(7) = &H46
    End With

    'Fill picture info
    With Pic
        .Size = Len(Pic) ' Length of structure
        .Type = vbPicTypeBitmap ' Type of Picture (bitmap)
        .hBmp = hBmp ' Handle to bitmap
        .hPal = hPal ' Handle to palette (may be null)
    End With

    'Create the picture
    R = OleCreatePictureIndirect(Pic, IID_IDispatch, 1, IPic)

    'Return the new picture
    Set CreateBitmapPicture = IPic
End Function
Function hDCToPicture(ByVal hDCSrc As Long, ByVal LeftSrc As Long, ByVal TopSrc As Long, ByVal WidthSrc As Long, ByVal HeightSrc As Long) As Picture
    Dim hDCMemory As Long, hBmp As Long, hBmpPrev As Long, R As Long
    Dim hPal As Long, hPalPrev As Long, RasterCapsScrn As Long, HasPaletteScrn As Long
    Dim PaletteSizeScrn As Long, LogPal As LOGPALETTE

    'Create a compatible device context
    hDCMemory = CreateCompatibleDC(hDCSrc)
    'Create a compatible bitmap
    hBmp = CreateCompatibleBitmap(hDCSrc, WidthSrc, HeightSrc)
    'Select the compatible bitmap into our compatible device context
    hBmpPrev = SelectObject(hDCMemory, hBmp)

    'Raster capabilities?
    RasterCapsScrn = GetDeviceCaps(hDCSrc, RASTERCAPS) ' Raster
    'Does our picture use a palette?
    HasPaletteScrn = RasterCapsScrn And RC_PALETTE ' Palette
    'What's the size of that palette?
    PaletteSizeScrn = GetDeviceCaps(hDCSrc, SIZEPALETTE) ' Size of

    If HasPaletteScrn And (PaletteSizeScrn = 256) Then
        'Set the palette version
        LogPal.palVersion = &H300
        'Number of palette entries
        LogPal.palNumEntries = 256
        'Retrieve the system palette entries
        R = GetSystemPaletteEntries(hDCSrc, 0, 256, LogPal.palPalEntry(0))
        'Create the palette
        hPal = CreatePalette(LogPal)
        'Select the palette
        hPalPrev = SelectPalette(hDCMemory, hPal, 0)
        'Realize the palette
        R = RealizePalette(hDCMemory)
    End If

    'Copy the source image to our compatible device context
    R = BitBlt(hDCMemory, 0, 0, WidthSrc, HeightSrc, hDCSrc, LeftSrc, TopSrc, vbSrcCopy)

    'Restore the old bitmap
    hBmp = SelectObject(hDCMemory, hBmpPrev)

    If HasPaletteScrn And (PaletteSizeScrn = 256) Then
        'Select the palette
        hPal = SelectPalette(hDCMemory, hPalPrev, 0)
    End If

    'Delete our memory DC
    R = DeleteDC(hDCMemory)

    Set hDCToPicture = CreateBitmapPicture(hBmp, hPal)
End Function

Just use:

Set picMyPicture.Picture = hDCToPicture(GetDC(myhWnd), 0, 0, Screen.Width / Screen.TwipsPerPixelX, Screen.Height / Screen.TwipsPerPixelY)

Where myhWnd is the hWnd of the window you want to capture. You can then use SavePicture(picMyPicture.Picture) to save it to a file.

3)
Use the keybd_event API function to simulate Alt-PrintScreen to copy the form's image to the clipboard. Use the Clipboard object's GetData method to get the picture and use SavePicture to save the picture into a bitmap file.

Private Sub Command1_Click()
#Const WINDOWS_VERSION = "Windows2000"

Dim alt_key As Long

    ' Capture an image of the form in the clipboard.
    ' Press Alt.
    alt_key = MapVirtualKey(VK_MENU, 0)
    keybd_event VK_MENU, alt_key, 0, 0
    DoEvents

    ' Press Print Scrn.
    #If WINDOWS_VERSION = "Windows2000" Then
        keybd_event VK_SNAPSHOT, 0, 0, 0
    #Else
        keybd_event VK_SNAPSHOT, 1, 0, 0
    #End If
    DoEvents

    ' Release Alt.
    keybd_event VK_MENU, alt_key, KEYEVENTF_KEYUP, 0
    DoEvents

    ' Paste the image into the bitmap file.
    SavePicture Clipboard.GetData(vbCFBitmap), Text1.Text
End Sub

(source: http://www.vb-helper.com/howto_alt_prnt_to_file.html)

0
 
LVL 1

Author Comment

by:MKrauss
ID: 9732324
I tried option 1, it seems that
SavePicture Clipboard.GetData(vbCFBitmap), "c:\my.bmp"
works only if there are datas in the clipboard, of none then
i get a invalid property value, i already tried to declare the keybd_event
as private on the main form and alternative as global in a module.
Any idea ?
thx M

0
 
LVL 16

Expert Comment

by:Richie_Simonetti
ID: 9732467
0
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LVL 26

Accepted Solution

by:
EDDYKT earned 375 total points
ID: 9733350
should be vbkeysnapshot not vkkeysnapshot
0
 
LVL 26

Expert Comment

by:EDDYKT
ID: 9733481
?

Should assign pt to  Dhaest
0
 
LVL 1

Author Comment

by:MKrauss
ID: 9733495
sorry, i was unsure to who i should accept, dhaest didnt respond ....
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