Copying a portion of a Picture

I'm trying to find a way to copy the contents of a portion (given by x, y, height and width) of a picture control to the clipboard. VB's standard function for this will only copy part of a picture.

Does anyone know if this is possible? If so, can you point me in the right direction.

Re: Copying a portion of a Picture

Search the MSDN library for the "CreateCompatibleBitmap" API function. Here is an example of what you can do whith it.

Example
Start a new project. Form1 is created by default.

Place six CommandButtons on the form along the left side.

Place one picture box on the form to the right of the buttons.

Put the following code in Form1:

'--------------------------------------------------------------------
' Capture the entire screen.

private Sub Command1_Click()
set Picture1.Picture = CaptureScreen()
End Sub

' Capture the entire form including title and border.
private Sub Command2_Click()
set Picture1.Picture = CaptureForm(me)
End Sub

' Capture the client area of the form.
private Sub Command3_Click()
set Picture1.Picture = CaptureClient(me)
End Sub

' Capture the active window after two seconds.
private Sub Command4_Click()
MsgBox "Two seconds after you close this dialog " & _
"the active window will be captured."

' Wait for two seconds.
Dim EndTime as date
EndTime = DateAdd("s", 2, Now)
Do Until Now > EndTime
DoEvents
Loop

set Picture1.Picture = CaptureActiveWindow()

' set focus back to form.
me.SetFocus
End Sub

' print the current contents of the picture box.
private Sub Command5_Click()
PrintPictureToFitPage Printer, Picture1.Picture
Printer.EndDoc
End Sub

' Clear out the picture box.
private Sub Command6_Click()
set Picture1.Picture = nothing
End Sub

' Initialize the form and controls.
private Sub Form_Load()
me.Caption = "Capture and print Example"
Command1.Caption = "&Screen"
Command2.Caption = "&Form"
Command3.Caption = "&Client"
Command4.Caption = "&Active"
Command5.Caption = "&print"
Command6.Caption = "C&lear"
Picture1.AutoSize = true
End Sub
'--------------------------------------------------------------------

Add a new standard module to the project (module1 by default).

Put the following code in the new module:

'--------------------------------------------------------------------
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
'
' Visual Basic 4.0 16/32 Capture Routines
'
' This module contains several routines for capturing windows into a
' picture. All the routines work on both 16 and 32 bit Windows
' platforms.
' The routines also have palette support.
'
' CreateBitmapPicture - Creates a picture object from a bitmap and
' palette.
' CaptureWindow - Captures any window given a window handle.
' CaptureActiveWindow - Captures the active window on the desktop.
' CaptureForm - Captures the entire form.
' CaptureClient - Captures the client area of a form.
' CaptureScreen - Captures the entire screen.
' PrintPictureToFitPage - prints any picture as big as possible on
' the page.
'
' NOTES
' - No error trapping is included in these routines.
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
'
option Explicit
option Base 0

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

#If Win32 then

private Const RASTERCAPS as Long = 38
private Const RC_PALETTE as Long = &H100
private Const SIZEPALETTE as Long = 104

private Type RECT
Left as Long
Top as Long
Right as Long
Bottom as Long
End Type

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 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 SelectObject Lib "GDI32" ( _
byval hDC as Long, byval hObject as Long) as Long
private Declare Function BitBlt Lib "GDI32" ( _
byval hDCDest as Long, byval XDest as Long, _
byval YDest as Long, byval nWidth as Long, _
byval nHeight as Long, byval hDCSrc 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 GetForegroundWindow Lib "USER32" () _
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 GetWindowDC Lib "USER32" ( _
byval hWnd as Long) as Long
private Declare Function GetDC Lib "USER32" ( _
byval hWnd as Long) as Long
private Declare Function GetWindowRect Lib "USER32" ( _
byval hWnd as Long, lpRect as RECT) as Long
private Declare Function ReleaseDC Lib "USER32" ( _
byval hWnd as Long, byval hDC as Long) as Long
private Declare Function GetDesktopWindow Lib "USER32" () as Long

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

#ElseIf Win16 then

private Const RASTERCAPS as Integer = 38
private Const RC_PALETTE as Integer = &H100
private Const SIZEPALETTE as Integer = 104

private Type RECT
Left as Integer
Top as Integer
Right as Integer
Bottom as Integer
End Type

private Declare Function CreateCompatibleDC Lib "GDI" ( _
byval hDC as Integer) as Integer
private Declare Function CreateCompatibleBitmap Lib "GDI" ( _
byval hDC as Integer, byval nWidth as Integer, _
byval nHeight as Integer) as Integer
private Declare Function GetDeviceCaps Lib "GDI" ( _
byval hDC as Integer, byval iCapabilitiy as Integer) as Integer
private Declare Function GetSystemPaletteEntries Lib "GDI" ( _
byval hDC as Integer, byval wStartIndex as Integer, _
byval wNumEntries as Integer, _
lpPaletteEntries as PALETTEENTRY) as Integer
private Declare Function CreatePalette Lib "GDI" ( _
lpLogPalette as LOGPALETTE) as Integer
private Declare Function SelectObject Lib "GDI" ( _
byval hDC as Integer, byval hObject as Integer) as Integer
private Declare Function BitBlt Lib "GDI" ( _
byval hDCDest as Integer, byval XDest as Integer, _
byval YDest as Integer, byval nWidth as Integer, _
byval nHeight as Integer, byval hDCSrc as Integer, _
byval XSrc as Integer, byval YSrc as Integer, _
byval dwRop as Long) as Integer
private Declare Function DeleteDC Lib "GDI" ( _
byval hDC as Integer) as Integer
private Declare Function GetForegroundWindow Lib "USER" _
Alias "GetActiveWindow" () as Integer
private Declare Function SelectPalette Lib "USER" ( _
byval hDC as Integer, byval hPalette as Integer, byval _
bForceBackground as Integer) as Integer
private Declare Function RealizePalette Lib "USER" ( _
byval hDC as Integer) as Integer
private Declare Function GetWindowDC Lib "USER" ( _
byval hWnd as Integer) as Integer
private Declare Function GetDC Lib "USER" ( _
byval hWnd as Integer) as Integer
private Declare Function GetWindowRect Lib "USER" ( _
byval hWnd as Integer, lpRect as RECT) as Integer
private Declare Function ReleaseDC Lib "USER" ( _
byval hWnd as Integer, byval hDC as Integer) as Integer
private Declare Function GetDesktopWindow Lib "USER" () as Integer

private Type PicBmp
Size as Integer
Type as Integer
hBmp as Integer
hPal as Integer
Reserved as Integer
End Type

private Declare Function OleCreatePictureIndirect _
Lib "oc25.dll" ( PictDesc as PicBmp, RefIID as GUID, _
byval fPictureOwnsHandle as Integer, IPic as IPicture) _
as Integer

#End If

'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
'
' CreateBitmapPicture
' - Creates a bitmap type Picture object from a bitmap and
' palette.
'
' hBmp
' - Handle to a bitmap.
'
' hPal
' - Handle to a Palette.
' - Can be null if the bitmap doesn't use a palette.
'
' Returns
' - Returns a Picture object containing the bitmap.
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
'
#If Win32 then
public Function CreateBitmapPicture(byval hBmp as Long, _
byval hPal as Long) as Picture

Dim r as Long
#ElseIf Win16 then
public Function CreateBitmapPicture(byval hBmp as Integer, _
byval hPal as Integer) as Picture

Dim r as Integer
#End If
Dim Pic as PicBmp
' IPicture requires a reference to "Standard OLE Types."
Dim IPic as IPicture
Dim IID_IDispatch as GUID

' Fill in with IDispatch Interface ID.
With IID_IDispatch
.Data1 = &H20400
.Data4(0) = &HC0
.Data4(7) = &H46
End With

' Fill Pic with necessary parts.
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 Picture object.
r = OleCreatePictureIndirect(Pic, IID_IDispatch, 1, IPic)

' Return the new Picture object.
set CreateBitmapPicture = IPic
End Function

'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
'
' CaptureWindow
' - Captures any portion of a window.
'
' hWndSrc
' - Handle to the window to be captured.
'
' Client
' - If true CaptureWindow captures from the client area of the
' window.
' - If false CaptureWindow captures from the entire window.
'
' LeftSrc, TopSrc, WidthSrc, HeightSrc
' - Specify the portion of the window to capture.
' - Dimensions need to be specified in pixels.
'
' Returns
' - Returns a Picture object containing a bitmap of the specified
' portion of the window that was captured.
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
''''''
'
#If Win32 then
public Function CaptureWindow(byval hWndSrc as Long, _
byval Client as Boolean, byval LeftSrc as Long, _
byval TopSrc as Long, byval WidthSrc as Long, _
byval HeightSrc as Long) as Picture

Dim hDCMemory as Long
Dim hBmp as Long
Dim hBmpPrev as Long
Dim r as Long
Dim hDCSrc as Long
Dim hPal as Long
Dim hPalPrev as Long
Dim RasterCapsScrn as Long
Dim HasPaletteScrn as Long
Dim PaletteSizeScrn as Long
#ElseIf Win16 then
public Function CaptureWindow(byval hWndSrc as Integer, _
byval Client as Boolean, byval LeftSrc as Integer, _
byval TopSrc as Integer, byval WidthSrc as Long, _
byval HeightSrc as Long) as Picture

Dim hDCMemory as Integer
Dim hBmp as Integer
Dim hBmpPrev as Integer
Dim r as Integer
Dim hDCSrc as Integer
Dim hPal as Integer
Dim hPalPrev as Integer
Dim RasterCapsScrn as Integer
Dim HasPaletteScrn as Integer
Dim PaletteSizeScrn as Integer
#End If
Dim LogPal as LOGPALETTE

' Depending on the value of Client get the proper device context.
If Client then
hDCSrc = GetDC(hWndSrc) ' get device context for client area.
else
hDCSrc = GetWindowDC(hWndSrc) ' get device context for entire
' window.
End If

' Create a memory device context for the copy process.
hDCMemory = CreateCompatibleDC(hDCSrc)
' Create a bitmap and place it in the memory DC.
hBmp = CreateCompatibleBitmap(hDCSrc, WidthSrc, HeightSrc)
hBmpPrev = SelectObject(hDCMemory, hBmp)

' get screen properties.
RasterCapsScrn = GetDeviceCaps(hDCSrc, RASTERCAPS) ' Raster
' capabilities.
HasPaletteScrn = RasterCapsScrn And RC_PALETTE ' Palette
' support.
PaletteSizeScrn = GetDeviceCaps(hDCSrc, SIZEPALETTE) ' Size of
' palette.

' If the screen has a palette make a copy and realize it.
If HasPaletteScrn And (PaletteSizeScrn = 256) then
' Create a copy of the system palette.
LogPal.palVersion = &H300
LogPal.palNumEntries = 256
r = GetSystemPaletteEntries(hDCSrc, 0, 256, _
LogPal.palPalEntry(0))
hPal = CreatePalette(LogPal)
' Select the new palette into the memory DC and realize it.
hPalPrev = SelectPalette(hDCMemory, hPal, 0)
r = RealizePalette(hDCMemory)
End If

' Copy the on-screen image into the memory DC.
r = BitBlt(hDCMemory, 0, 0, WidthSrc, HeightSrc, hDCSrc, _
LeftSrc, TopSrc, vbSrcCopy)

' Remove the new copy of the on-screen image.
hBmp = SelectObject(hDCMemory, hBmpPrev)

' If the screen has a palette get back the palette that was
' selected in previously.
If HasPaletteScrn And (PaletteSizeScrn = 256) then
hPal = SelectPalette(hDCMemory, hPalPrev, 0)
End If

' Release the device context resources back to the system.
r = DeleteDC(hDCMemory)
r = ReleaseDC(hWndSrc, hDCSrc)

' Call CreateBitmapPicture to create a picture object from the
' bitmap and palette handles. then return the resulting picture
' object.
set CaptureWindow = CreateBitmapPicture(hBmp, hPal)
End Function

'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
'
' CaptureScreen
' - Captures the entire screen.
'
' Returns
' - Returns a Picture object containing a bitmap of the screen.
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
'
public Function CaptureScreen() as Picture
#If Win32 then
Dim hWndScreen as Long
#ElseIf Win16 then
Dim hWndScreen as Integer
#End If

' get a handle to the desktop window.
hWndScreen = GetDesktopWindow()

' Call CaptureWindow to capture the entire desktop give the handle
' and return the resulting Picture object.

set CaptureScreen = CaptureWindow(hWndScreen, false, 0, 0, _
Screen.Width \ Screen.TwipsPerPixelX, _
Screen.Height \ Screen.TwipsPerPixelY)
End Function

'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
'
' CaptureForm
' - Captures an entire form including title bar and border.
'
' frmSrc
' - The Form object to capture.
'
' Returns
' - Returns a Picture object containing a bitmap of the entire
' form.
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
'
public Function CaptureForm(frmSrc as Form) as Picture
' Call CaptureWindow to capture the entire form given its window
' handle and then return the resulting Picture object.
set CaptureForm = CaptureWindow(frmSrc.hWnd, false, 0, 0, _
frmSrc.ScaleX(frmSrc.Width, vbTwips, vbPixels), _
frmSrc.ScaleY(frmSrc.Height, vbTwips, vbPixels))
End Function

'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
'
' CaptureClient
' - Captures the client area of a form.
'
' frmSrc
' - The Form object to capture.
'
' Returns
' - Returns a Picture object containing a bitmap of the form's
' client area.
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
'
public Function CaptureClient(frmSrc as Form) as Picture
' Call CaptureWindow to capture the client area of the form given
' its window handle and return the resulting Picture object.
set CaptureClient = CaptureWindow(frmSrc.hWnd, true, 0, 0, _
frmSrc.ScaleX(frmSrc.ScaleWidth, frmSrc.ScaleMode, vbPixels), _
frmSrc.ScaleY(frmSrc.ScaleHeight, frmSrc.ScaleMode, vbPixels))
End Function

'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
'
' CaptureActiveWindow
' - Captures the currently active window on the screen.
'
' Returns
' - Returns a Picture object containing a bitmap of the active
' window.
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
'
public Function CaptureActiveWindow() as Picture
#If Win32 then
Dim hWndActive as Long
Dim r as Long
#ElseIf Win16 then
Dim hWndActive as Integer
Dim r as Integer
#End If
Dim RectActive as RECT

' get a handle to the active/foreground window.
hWndActive = GetForegroundWindow()

' get the dimensions of the window.
r = GetWindowRect(hWndActive, RectActive)

' Call CaptureWindow to capture the active window given its
' handle and return the Resulting Picture object.
set CaptureActiveWindow = CaptureWindow(hWndActive, false, 0, 0, _
RectActive.Right - RectActive.Left, _
RectActive.Bottom - RectActive.Top)
End Function

'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
'
' PrintPictureToFitPage
' - Prints a Picture object as big as possible.
'
' Prn
' - Destination Printer object.
'
' Pic
' - Source Picture object.
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
'
public Sub PrintPictureToFitPage(Prn as Printer, Pic as Picture)
Const vbHiMetric as Integer = 8
Dim PicRatio as Double
Dim PrnWidth as Double
Dim PrnHeight as Double
Dim PrnRatio as Double
Dim PrnPicWidth as Double
Dim PrnPicHeight as Double

' Determine if picture should be printed in landscape or portrait
' and set the orientation.
If Pic.Height >= Pic.Width then
Prn.Orientation = vbPRORPortrait ' Taller than wide.
else
Prn.Orientation = vbPRORLandscape ' Wider than tall.
End If

' Calculate device independent Width-to-Height ratio for picture.
PicRatio = Pic.Width / Pic.Height

' Calculate the dimentions of the printable area in HiMetric.
PrnWidth = Prn.ScaleX(Prn.ScaleWidth, Prn.ScaleMode, vbHiMetric)
PrnHeight = Prn.ScaleY(Prn.ScaleHeight, Prn.ScaleMode, vbHiMetric)
' Calculate device independent Width to Height ratio for printer.
PrnRatio = PrnWidth / PrnHeight

' Scale the output to the printable area.
If PicRatio >= PrnRatio then
' Scale picture to fit full width of printable area.
PrnPicWidth = Prn.ScaleX(PrnWidth, vbHiMetric, Prn.ScaleMode)
PrnPicHeight = Prn.ScaleY(PrnWidth / PicRatio, vbHiMetric, _
Prn.ScaleMode)
else
' Scale picture to fit full height of printable area.
PrnPicHeight = Prn.ScaleY(PrnHeight, vbHiMetric, Prn.ScaleMode)
PrnPicWidth = Prn.ScaleX(PrnHeight * PicRatio, vbHiMetric, _
Prn.ScaleMode)
End If

' print the picture using the PaintPicture method.
Prn.PaintPicture Pic, 0, 0, PrnPicWidth, PrnPicHeight
End Sub
'--------------------------------------------------------------------

Save the project.

Before running this project verify in Project References that a Reference to OLE Automation exists (StdOle2.tlb).

Run the project and test. You should be able to capture the form, the form's client area, the screen, and the active window. You will also be able to print any of these.

Re: Copying a portion of a Picture

Picture2.PaintPicture Picture1.Image, x, y, Width, Height
Clipboard.SetData Picture2.Image

Re: Copying a portion of a Picture

Shree, just great!!!

Iouri Boutchkine
[email protected]

Re: Copying a portion of a Picture

Thanks for the suggestion. Unfortunately, this and BitBlt suffer from a common problem. When I call SetData, only the background of Picture2 gets copied to the clipboard. In other words, just a gray box with the dimensions of Picture2. I seem to have no programmatic access to the contents of Picture2.

Re: Copying a portion of a Picture

Check the autoredraw property of Picture2. It may be false. Set it to true.