Using Win32 functions in Visual FoxPro Image Gallery
Code examples:
Converting Unicode data from the Clipboard to a character string using a given code page
Copying picture of the active form to the Clipboard using Enhanced Metafile API functions
GDI+: printing vertical text on VFP reports via generated images (VFP9)
GDI+: Storing content of the Clipboard to a bitmap file
How to assemble an array of strings and pass it to external function
How to display the Properties dialog box for a file (ShellExecuteEx)
How to generate GUID values
Monitoring changes occurring within a directory
Obtaining heap handles and enumerating memory blocks for the current VFP session (WinNT only)
Using NetWkstaTransportEnum to obtain MAC Address of remote server
Exporting DLL icon resources as .ICO files
How to draw custom Window Caption on FoxPro form
How to initiate System shutdown
How to ping a remote site using ICMP API calls
How to view icons stored in executable files (Icon Viewer)
Reading security permissions for NTFS files and folders
Storing screen shot of a form to enhanced metafile (*.emf)
Using FlashWindowEx to flash the taskbar button of the VFP application
Using FrameRgn for displaying system colors
Winsock: connecting to a news server (NNTP, port 119)
Copying files as a transacted operation (Vista)
Obtaining physical parameters for a drive: sectors, clusters, cylinders...
Printing text on the main VFP window
Reading and setting the priority class values for the current process and thread
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
    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)
            = MESSAGEBOX(lcBitmap + Chr(13) + Chr(13) +;
                "Check if this is a valid bitmap file.",;
                32, " Unable to load an image from file")
    PROCEDURE ShowBitmap(hBitmap, lnX, lnY)
    *|typedef struct _BLENDFUNCTION {
    *|  BYTE     BlendOp;
    *|  BYTE     BlendFlags;
    *|  BYTE     SourceConstantAlpha;
    *|  BYTE     AlphaFormat;
        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,;
        IF lnResult = 0
        *  6 = The handle is invalid
        * 87 = The parameter is incorrect
            ? "Error:", GetLastError()
        = 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))
    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  
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