capture screen/desktop?

[anita2002]

Hi all,
Can anyone knows the API whith which we can capture the screen/desktop and store it as image file?
Help me,
Anita

[gilly]

Yes, i have attached a program which does just that.

[anita2002]

Originally posted by gilly
Yes, i have attached a program which does just that.

Thanks Gilly,
But this program is not running. It is asking me for a dll file. Besides there is no source code, its an exe file.
Can anyone have an idea about capturing the desktop/screen with API? And can anyone give me the source code for it?
Help,
Anita

[mendhak]

From vb-faq

The following code uses a standard VB form
(FDesktop) containing a PictureBox (Picture1) and a module
(MDesktop). Create a new form, name it FDesktop and add a
PictureBox control to the form. (Please be aware that some
line wrapping is bound to occur)

'-----------------------------------------------------------
------------
' This sample project shows the use of a few GDI functions 
to capture an
' image of the desktop and any currently open windows.
'-----------------------------------------------------------
------------

Option Explicit

' the sleep API is used to give the screen time to refresh 
before capture
Private Declare Sub Sleep Lib "kernel32" _
    ( _
      ByVal dwMilliseconds As Long _
    )

Private Sub Form_Load()
  
  ' printer mode is changed to landscape to allow printing
  ' of the form
  Printer.Orientation = vbPRORLandscape
  
  ' set various properties of the picture box control
  With Picture1
    .AutoRedraw = True
    .BorderStyle = 0 'none
    .ScaleMode = vbPixels
  End With
  
End Sub

Private Sub Form_Resize()
  
  ' when the form is resized the picture box must also be 
resized to
  ' fill the form
  Picture1.Move 0, 0, Me.ScaleWidth, Me.ScaleHeight
  
End Sub

Private Sub Picture1_Click()

  ' this hides the form so the desktop can be captured - 
the DoEvents
  ' and Sleep API allow the form to be hidden and any 
windows which were
  ' hidden by the form to be refreshed before the desktop 
is captured
  Me.Visible = False
  DoEvents
  Sleep (1)
  CopyDesktop Picture1
  Me.Visible = True
  
End Sub

Private Sub Picture1_MouseDown(Button As Integer, Shift As 
Integer, X As Single, Y As Single)
  
  ' a right click will cause the form (picture of desktop) 
to be printed
  If Button And 2 Then Me.PrintForm
  
End Sub

[code location="MDesktop"]
Option Explicit

' the declarations...
Private Declare Function GetDC Lib "user32" _
( _
ByVal hWnd As Long _
) _
As Long

Private Declare Function GetDesktopWindow Lib "user32" ()
As Long

Private Declare Function ReleaseDC Lib "user32" _
( _
ByVal hWnd As Long, _
ByVal hDC As Long _
) _
As Long

Private Declare Function StretchBlt Lib "gdi32" _
( _
ByVal hDC 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 nSrcWidth As Long, _
ByVal nSrcHeight As Long, _
ByVal dwRop As Long _
) _
As Long

' constant for use with the StrechBlt API
Private Const SRCCOPY = &HCC0020

Public Sub CopyDesktop(pb As PictureBox)
Dim hWndDesktop As Long
Dim hDCDesktop As Long
Dim lRet As Long
Dim rWidth As Single, rHeight As Single

' get the screen dimensions
rWidth = pb.ScaleX(Screen.Width, vbTwips, vbPixels)
rHeight = pb.ScaleY(Screen.Height, vbTwips, vbPixels)

' get the desktop's handle
hWndDesktop = GetDesktopWindow

' get the desktop's DC
hDCDesktop = GetDC(hWndDesktop)

' blit the desktop image to the picture box - StrechBlt
is used to
' dynamically fit the desktop image to the picture box.
lRet = StretchBlt(pb.hDC, 0, 0, pb.ScaleWidth,
pb.ScaleHeight, _
hDCDesktop, 0, 0, rWidth, rHeight,
SRCCOPY)

' release the desktop's DC
Call ReleaseDC(hWndDesktop, hDCDesktop)

' refresh the picture box to cause it to redraw
pb.Refresh

' save the picture to a bmp file (change to a file of
' your choice)
SavePicture pb.Image, "c:\dt.bmp"

End Sub
[/code]

[anita2002]

Thanks Mendhak,
U'r code is working fine. But just the problem is it is saving the image of desktop in .BMP format. And its taking more than 1 MB space for a single image.
So is there any way to reduce the size of image?
Anyone please help,
Anita

[skald2k]

Convert it to a JPG? Using the Windows API, because XP can do so.

[mendhak]

Originally posted by anita2002
Thanks Mendhak,
U'r code is working fine. But just the problem is it is saving the image of desktop in .BMP format.

Ahem... may I refer you to your first post?

...can capture the screen/desktop and store it as image file?

Anyways, I suppose a JPG would be smaller, so try ths:

Private Sub mnuconvertBMPtoJPG_Click()
   Dim tmpimage As imgdes    ' Image descriptors
   Dim tmp2image As imgdes
   Dim rcode As Long
   Dim quality As Long
   Dim vbitcount As Long
   Dim bdat As BITMAPINFOHEADER ' Reserve space for BMP struct
   Dim bmp_fname As String
   Dim jpg_fname As String
 
   bmp_fname = "test.bmp"
   jpg_fname = "test.jpg"
 
   quality = 75
   ' Get info on the file we're to load
   rcode = bmpinfo(bmp_fname, bdat)
   If (rcode <> NO_ERROR) Then
      MsgBox "Cannot find file", 0, "Error encountered!"
      Exit Sub
   End If
    
   vbitcount = bdat.biBitCount
   If (vbitcount >= 16) Then  ' 16-, 24-, or 32-bit image is loaded into 24-bit buffer
      vbitcount = 24
   End If
   
   ' Allocate space for an image
   rcode = allocimage(tmpimage, bdat.biWidth, bdat.biHeight, vbitcount)
   If (rcode <> NO_ERROR) Then
     MsgBox "Not enough memory", 0, "Error encountered!"
     Exit Sub
   End If
   
   ' Load image
   rcode = loadbmp(bmp_fname, tmpimage)
   If (rcode <> NO_ERROR) Then
      freeimage tmpimage ' Free image on error
      MsgBox "Cannot load file", 0, "Error encountered!"
      Exit Sub
   End If
 
   If (vbitcount = 1) Then ' If we loaded a 1-bit image, convert to 8-bit grayscale
       ' because jpeg only supports 8-bit grayscale or 24-bit color images
     rcode = allocimage(tmp2image, bdat.biWidth, bdat.biHeight, 8)
     If (rcode = NO_ERROR) Then
         rcode = convert1bitto8bit(tmpimage, tmp2image)
         freeimage tmpimage  ' Replace 1-bit image with grayscale image
         copyimgdes tmp2image, tmpimage
     End If
   End If
 
   ' Save image
   rcode = savejpg(jpg_fname, tmpimage, quality)
   freeimage tmpimage
 
End Sub
 
........... Add these defines and declarations to your Global module ...........
' Image descriptor
Type imgdes
   ibuff As Long
   stx As Long
   sty As Long
   endx As Long
   endy As Long
   buffwidth As Long
   palette As Long
   colors As Long
   imgtype As Long
   bmh As Long
   hBitmap As Long
End Type
 
Type BITMAPINFOHEADER
    biSize As Long
    biWidth As Long
    biHeight As Long
    biPlanes As Integer
    biBitCount As Integer
    biCompression As Long
    biSizeImage As Long
    biXPelsPerMeter As Long
    biYPelsPerMeter As Long
    biClrUsed As Long
    biClrImportant As Long
End Type
 
Declare Function bmpinfo Lib "VIC32.DLL" (ByVal Fname As String, bdat As BITMAPINFOHEADER) As Long
Declare Function allocimage Lib "VIC32.DLL" (image As imgdes, ByVal wid As Long, ByVal leng As Long, ByVal BPPixel As Long) As Long
Declare Function loadbmp Lib "VIC32.DLL" (ByVal Fname As String, desimg As imgdes) As Long
Declare Sub freeimage Lib "VIC32.DLL" (image As imgdes)
Declare Function convert1bitto8bit Lib "VIC32.DLL" (srcimg As imgdes, desimg As imgdes) As Long
Declare Sub copyimgdes Lib "VIC32.DLL" (srcimg As imgdes, desimg As imgdes)
Declare Function savejpg Lib "VIC32.DLL" (ByVal Fname As String, srcimg As imgdes, ByVal quality As Long) As Long

[anita2002]

Ahem... may I refer you to your first post?

Anyways, I suppose a JPG would be smaller, so try ths:

B][/QUOTE]

Thanks Mendhak,
By the way, what do u want to refer? ( my first post???) what do u want?
Anita

[mendhak]

...and store it as image file?

and then later,

But just the problem is it is saving the image of desktop in .BMP format

But never mind that. My ESP hasn't come in handy today.