Using Win32 functions in Visual FoxPro Image Gallery
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Code examples:
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Enumerating print processors and supporting data types installed on the specified server
Enumerating printer drivers installed
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Enumerating the subkeys of a user-specific key
Finding parameters for the region specified
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Locking the workstation
Monitoring changes occurring within a directory
Obtaining I/O counts for the current process
Obtaining physical parameters for a drive: sectors, clusters, cylinders...
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Printing Image File, programmatically set print page orientation to landscape
Reading and setting system access privileges for the current process
Reading current hardware profile
Reading entries from Event logs
Reading security permissions for NTFS files and folders
Reading the structure of VFP main menu
Removing FTP directory
Retrieveing information about the active window (even if it is not owned by the calling process)
Retrieving a handle to DLL and address of an exported function in it
Retrieving graphic capabilities of default printer
Retrieving local computer and user names
Retrieving the name of the default printer for the current user on the local computer (Win NT/XP)
Retrieving the System Time adjustment
Scanning a hierarchy of child windows down from the Windows Desktop
Setting the date and time that a file was created
Setting the last-error code for the FoxPro
Setting the volume label
Setting the Window Region for a form
Simple printer queue monitor: deletes, pauses, resumes print jobs for local printer
Start an executable from VFP application by using the CreateProcess
Starting external program from VFP and waiting for its termination
Storing registration key in the resources of an executable file
Testing serial ports
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Using Change Notification Objects to monitor changes to the printer or print server
Using EnumPrinters function to enumerate locally installed printers
Using File Mapping for enumerating files opened by Visual FoxPro
Using FtpCommand
Using LoadLibrary
Using named pipes for interprocess communication
Using shared memory to exchange data between two FoxPro applications
Using the CreateFile
Using the NetMessageBufferSend to send messages on the network
Using the Semaphore object
Using the Semaphore object to allow only one instance of VFP application running
Validating the heap of the calling process
Wininet last error description
Winsock: retrieving information from a host database for a given host name
Writing entries to custom Event Log
Displaying bitmap using the AlphaBlend function

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Before you begin:
The AlphaBlend function displays bitmaps that have transparent or semitransparent pixels.

See also:
  • Bitmap Class for Visual FoxPro application
  • Semi-transparent Form
  • Form Magnifier
  • GDI+: Color Transparency
  •  
    #DEFINE LR_LOADFROMFILE 16
    #DEFINE AC_SRC_OVER 0
    #DEFINE AC_SRC_ALPHA 1
    #DEFINE AC_SRC_NO_ALPHA 2
    #DEFINE IMAGE_BITMAP 0
    #DEFINE SRCCOPY 0xCC0020
    #DEFINE BITMAP_STRU_SIZE 24
     
    DO declare
     
    LOCAL lcBitmap
    *lcBitmap = "C:\WinNT\system32\setup.bmp"
    lcBitmap = "C:\Windows\Forest.bmp"
    = LoadAndShowBitmap(lcBitmap, LR_LOADFROMFILE, 20,100)
    * end of main
     
    PROCEDURE LoadAndShowBitmap(lcBitmap, lnLoadOptions, lnX,lnY)
        LOCAL hBitmap
        hBitmap = LoadImage(0, lcBitmap, IMAGE_BITMAP,;
            0,0, lnLoadOptions)
     
        IF hBitmap <> 0
            = ShowBitmap(hBitmap, lnX,lnY)
            = DeleteObject(hBitmap)
        ELSE
            = MESSAGEBOX(lcBitmap + Chr(13) + Chr(13) +;
                "Check if this is a valid bitmap file.",;
                32, " Unable to load an image from file")
        ENDIF
     
    PROCEDURE ShowBitmap(hBitmap, lnX, lnY)
    *|typedef struct _BLENDFUNCTION {
    *|  BYTE     BlendOp;
    *|  BYTE     BlendFlags;
    *|  BYTE     SourceConstantAlpha;
    *|  BYTE     AlphaFormat;
    *|}BLENDFUNCTION, *PBLENDFUNCTION, *LPBLENDFUNCTION;
     
        LOCAL hWindow, hDC, hMemDC, lnWidth, lnHeight
        STORE 0 TO lnWidth, lnHeight
        = GetBitmapSize(hBitmap, @lnWidth, @lnHeight)
     
        hWindow = GetActiveWindow()
        hDC = GetWindowDC(hWindow)
     
        hMemDC = CreateCompatibleDC(hDC)
        = SelectObject(hMemDC, hBitmap)
     
        LOCAL lnAlphaBlend, lnResult,;
            lnBlendOp, lnBlendFlags, lnSrcConstAlpha, lnAlphaFormat
     
        lnBlendOp = AC_SRC_OVER  && always
        lnBlendFlags = 0         && always
        lnSrcConstAlpha = 48     && intensity, up to 255
        lnAlphaFormat = 0        && try AC_SRC_ALPHA on non-white background
     
        * assembling the BLENDFUNCTION structure 
        lnAlphaBlend = lnBlendOp +;
            BitLShift(lnBlendFlags, 8) +;
            BitLShift(lnSrcConstAlpha, 16) +;
            BitLShift(lnAlphaFormat, 24)
     
        lnResult = AlphaBlend(hDC, lnX,lnY, lnWidth,lnHeight,;
            hMemDC, 0,0, lnWidth,lnHeight,;
            lnAlphaBlend)
     
        IF lnResult = 0
        *  6 = The handle is invalid
        * 87 = The parameter is incorrect
            ? "Error:", GetLastError()
        ENDIF
     
        = DeleteDC(hMemDC)
        = ReleaseDC(hWindow, hDc)
    RETURN .T.
     
    FUNCTION GetBitmapSize(hBitmap, lnWidth, lnHeight)
        LOCAL lcBuffer
        lcBuffer = Repli(Chr(0), BITMAP_STRU_SIZE)
     
        IF GetObjectA(hBitmap, BITMAP_STRU_SIZE, @lcBuffer) <> 0
            lnWidth  = buf2dword(SUBSTR(lcBuffer, 5,4))
            lnHeight = buf2dword(SUBSTR(lcBuffer, 9,4))
           ENDIF
     
    FUNCTION buf2dword(lcBuffer)
    RETURN Asc(SUBSTR(lcBuffer, 1,1)) + ;
        BitLShift(Asc(SUBSTR(lcBuffer, 2,1)),  8) +;
        BitLShift(Asc(SUBSTR(lcBuffer, 3,1)), 16) +;
        BitLShift(Asc(SUBSTR(lcBuffer, 4,1)), 24)
     
    PROCEDURE declare
        DECLARE INTEGER CreateCompatibleDC IN gdi32 INTEGER hdc
        DECLARE INTEGER DeleteDC IN gdi32 INTEGER hdc
        DECLARE INTEGER GetActiveWindow IN user32
        DECLARE INTEGER GetWindowDC IN user32 INTEGER hWindow
        DECLARE INTEGER ReleaseDC IN user32 INTEGER hWindow, INTEGER dc
        DECLARE INTEGER DeleteObject IN gdi32 INTEGER hObject
        DECLARE INTEGER SelectObject IN gdi32 INTEGER hdc, INTEGER hObject
     
        DECLARE INTEGER LoadImage IN user32;
            INTEGER hinst, STRING lpszName, INTEGER uType,;
            INTEGER cxDesired, INTEGER cyDesired, INTEGER fuLoad
     
        DECLARE INTEGER GetObject IN gdi32 AS GetObjectA;
            INTEGER hgdiobj, INTEGER cbBuffer, STRING @lpvObject
     
        DECLARE INTEGER AlphaBlend IN Msimg32;
            INTEGER hDestDC, INTEGER x, INTEGER y,;
            INTEGER nWidth, INTEGER nHeight, INTEGER hSrcDC,;
            INTEGER xSrc, INTEGER ySrc, INTEGER nWidthSrc,;
            INTEGER nHeightSrc, INTEGER blendFunction
     
        DECLARE INTEGER GetLastError IN kernel32
     
     
     

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    3476 bytes  
    Created: 2002-03-23 10:43:13  
    Modified: 2009-01-17 11:17:30  
    Visits in 7 days: 191  
    Listed functions:
    AlphaBlend
    CreateCompatibleDC
    DeleteDC
    DeleteObject
    GetActiveWindow
    GetLastError
    GetObject
    GetWindowDC
    LoadImage
    ReleaseDC
    SelectObject
    Printer friendly API declarations
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