Using Win32 functions in Visual FoxPro Image Gallery
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Enumerating data formats currently available on the clipboard
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Winsock: retrieving directory listing from an FTP server using passive data connection (FTP, port 21)
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How to download a file from the FTP server using FtpGetFile
Enumerating raw input devices attached to the system (keyboard, mouse, human interface device)
How to play AVI file on the _screen
Using Font and Text functions
Enumerating network resources
Using EnumPrinters function to enumerate locally installed printers
Vertical Label control
Creating irregularly shaped FoxPro form using transparency color key
Changing system colors
Custom HttpRequest class (WinHTTP)
Subclassing CommandButton control to create BackColor property
Using Video Capture: displaying on FoxPro form frames and previewing video obtained from a digital camera
Converting Unicode data from the Clipboard to a character string using a given code page
Using the DrawText function
Using Common Controls: the Header Control
GDI+: copying to the Clipboard (a) image of active FoxPro window/form, (b) image file

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Before you begin:
The code is based on custom GDI+ class. Download the class module first and save it in gdiplus.prg file.

Related code samples:
  • GDI+: Storing content of the Clipboard to a bitmap file
  • Copying picture of the active form to the Clipboard using Bitmap API functions
  • Copying picture of the active form to the Clipboard using Enhanced Metafile API functions
  • Storing content of the Clipboard to a bitmap file
  • Storing screen shot of a form to a bitmap file

  •  
    SET PROCEDURE TO gdiplus ADDITIVE
    DO decl
     
    * an instance of gdiplusinit should be created before
    * and released after using any of gdi+ objects
    PRIVATE gdiplus
    gdiplus = CREATEOBJECT("gdiplusinit")
     
    = FormToClip(GetFocus())
    *= FileToClip("c:\windows\forest.bmp")
    * end of main
     
    PROCEDURE FormToClip(hwindow)
    #DEFINE SRCCOPY  0x00CC0020
        LOCAL hdc, bmp, nWidth, nHeight
        hdc = GetWindowDC(hwindow)
        STORE 0 TO nWidth, nHeight
        = GetWinRect(hwindow, @nWidth, @nHeight)
     
        bmp = CREATEOBJECT("gdibitmap", m.nWidth, m.nHeight)
        WITH bmp
            .graphics.GetDC
            = BitBlt(.graphics.hdc, 0,0, .imgwidth, .imgheight,;
                m.hdc, 0,0, SRCCOPY)
            .graphics.ReleaseDC
        ENDWITH
        = ReleaseDC(m.hwindow, m.hdc)
     
        IF NOT img2clip(bmp)
            ? "Error code:", bmp.errorcode
        ENDIF
     
    PROCEDURE FileToClip(cFilename)
        LOCAL img, nResult
        img = CREATEOBJECT("gdiimage", cFilename)
     
        IF NOT img2clip(img)
            ? "Error code:", img.errorcode
        ENDIF
     
    FUNCTION img2clip(img)
    * sends gdi+ image or bitmap object to the Clipboard
    #DEFINE CF_BITMAP  2
        IF img.GetHBITMAP() <> 0
            = OpenClipboard(0)
            = EmptyClipboard()
            = SetClipboardData(CF_BITMAP, img.hbitmap)
            = CloseClipboard()
            = LockClipboardData()
        ENDIF
    RETURN (img.errorcode=0)
     
    PROCEDURE LockClipboardData
    * the shortest way of locking clipboard data I have found;
    * otherwise it does not survive beyond the lifetime of its parent gdi+ object
        = OpenClipboard(0)
        LOCAL nIndex, hData
        nIndex = 0
        DO WHILE .T.
            nIndex = EnumClipboardFormats(nIndex)
            IF nIndex = 0
                EXIT
            ELSE
                hData = GetClipboardData(nIndex)
            ENDIF
        ENDDO
        = CloseClipboard()
     
    PROCEDURE GetWinRect(hwindow, nWidth, nHeight)
    #DEFINE maxDword  0xffffffff
        LOCAL lpRect, nLeft, nTop, nRight, nBottom
        lpRect = REPLI (Chr(0), 16)
        = GetWindowRect (hwindow, @lpRect)
        nRight  = buf2dword(SUBSTR(lpRect, 9,4))
        nBottom = buf2dword(SUBSTR(lpRect, 13,4))
     
        nLeft = buf2dword(SUBSTR(lpRect, 1,4))
        IF nLeft > nRight
            nLeft = nLeft - maxDword
        ENDIF
        nTop = buf2dword(SUBSTR(lpRect, 5,4))
        IF nTop > nBottom
            nTop = nTop - maxDword
        ENDIF
        nWidth = nRight - nLeft
        nHeight = nBottom - nTop
    RETURN
     
    PROCEDURE decl
        DECLARE INTEGER CloseClipboard IN user32 
        DECLARE INTEGER EmptyClipboard  IN user32 
        DECLARE INTEGER OpenClipboard IN user32 INTEGER hwnd 
        DECLARE INTEGER GetClipboardData IN user32 INTEGER uFormat
        DECLARE INTEGER EnumClipboardFormats IN user32 INTEGER wFormat
     
        DECLARE INTEGER SetClipboardData IN user32;
            INTEGER wFormat, INTEGER hMem
     
        DECLARE INTEGER GetFocus IN user32
        DECLARE INTEGER GetWindowDC IN user32 INTEGER hwindow
        DECLARE INTEGER ReleaseDC IN user32 INTEGER hwindow, INTEGER hdc
        DECLARE INTEGER GetWindowRect IN user32 INTEGER hwnd, STRING @lpRect 
     
        DECLARE INTEGER BitBlt IN gdi32;
            INTEGER hDestDC, INTEGER x, INTEGER y,;
            INTEGER nWidth, INTEGER nHeight, INTEGER hSrcDC,;
            INTEGER xSrc, INTEGER ySrc, INTEGER dwRop
     
     
     

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    2960 bytes  
    Created: 2004-07-16 11:19:39  
    Modified: 2004-12-05 15:04:21  
    Visits in 7 days: 148  
    Listed functions:
    BitBlt
    CloseClipboard
    EmptyClipboard
    EnumClipboardFormats
    GetClipboardData
    GetFocus
    GetWindowDC
    GetWindowRect
    OpenClipboard
    ReleaseDC
    SetClipboardData
    Printer friendly API declarations
    My comment:
    Call the FormToClip function from a method or event of a FoxPro form when that form is active, i.e. posesses the keyboard focus.

    For the FileToClip make sure the source file name is valid. The source file can be in any of graphics formats supported by the GDI+: BMP, GIF, JPG, TIF, EMF...

    The LockClipboardData function is kind of a lazy way to avoid complexities of locking data on the Clipboard. The SetClipboardData in the code above creates three sets of data on the Clipboard:

  • Bitmap handle (2)
  • BITMAPINFO structure (8)
  • BITMAPV5HEADER structure (17)

    The last two, if not locked properly, are getting wiped out as soon as gdi+ img object is out of scope or released.

    Even if this works on WinXP and Win2K computers, this behaviour of the GetClipboardData looks rather undocumented. As soon as I come with another solution (short enough) I will post it here.

    * * *
    August 2, 2004: Alexander Golovlev in his GDI+ class uses solution that looks better.

    To disconnect image handle from the GDI+ object he applies the CopyImage API function that creates a duplicate of the bitmap handle and then passes this new handle to the SetClipboardData function. That simple :)

    * * *
    An article How To Copy the Screen or Active Window to the Clipboard from Visual Basic published on Microsoft Help and Support page describes a different approach -- the picture of the whole screen is sent to the clipboard by virtually pressing (through the keybd_event call) PrtScr key.

    #kwd: sln_gdiplus.
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