Using Win32 functions in Visual FoxPro Image Gallery
Code examples:
Class library providing access to the System Registry
Drawing Windows predefined bitmaps using the LoadBitmap functions
Enumerating print jobs and retrieving information for default printer (JOB_INFO_1 structures)
GetFocus returns a HWND value
How to control Adobe Reader 9.0 (SDI mode) from VFP application
Quering Audio Mixer Device
Retrieving information about the specified icon
Running a regular FoxPro form while main VFP window is minimized
Scanning a hierarchy of child windows down from the Windows Desktop
Starting an external application in VFP using WinExec
Using File Mapping for enumerating files opened by Visual FoxPro
Using the MessageBox Win32 function
Winsock: reading email messages (POP3, port 110)
Creating a mailslot
CryptoAPI: Collection of Providers class
Generating random cryptographic keys
How to adjust monitor brightness (Vista, monitor with DDC support)
How to find which fonts Windows uses for drawing captions, menus and message boxes
Minimizing all running applications
Obtaining current Internet Explorer browser version and UserAgent
Obtaining list of tables stored in an ODBC Data Source
Printing text on the main VFP window
Retrieving the priority class for the current process
Semi-transparent Form
Displaying bitmap using the AlphaBlend function

User rating: 9/10 (1 votes)
Rate this code sample:
  • ~
More code examples    Listed functions    Add comment     W32 Constants      Translate this page Printer friendly version of this code sample
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
    
    
    

    User rating: 9/10 (1 votes)
    Rate this code sample:
    • ~
    3476 bytes  
    Created: 2002-03-23 10:43:13  
    Modified: 2009-01-17 11:17:30  
    Visits in 7 days: 58  
    Listed functions:
    AlphaBlend
    CreateCompatibleDC
    DeleteDC
    DeleteObject
    GetActiveWindow
    GetLastError
    GetObject
    GetWindowDC
    LoadImage
    ReleaseDC
    SelectObject
    Printer friendly API declarations
    Word Index links for this example:
    Translate this page:
      Spanish    Portuguese    German    French    Italian  
    FreeTranslation.com offers instant, free translations of text or web pages.
    User Contributed Notes:
    There are no notes on this subject.


    Copyright 2001-2015 News2News, Inc. Before reproducing or distributing any data from this site please ask for an approval from its owner. Unless otherwise specified, this page is for your personal and non-commercial use. The information on this page is presented AS IS, meaning that you may use it at your own risk. Microsoft Visual FoxPro and Windows are trade marks of Microsoft Corp. All other trademarks are the property of their respective owners. 

    Privacy policy
    Credits: PHP (4.4.9), an HTML-embedded scripting language, MySQL (5.5.43), the Open Source standard SQL database, AceHTML Freeware Version 4, freeware HTML Editor of choice.   Hosted by Korax Online Inc.
    Last Topics Visited (54.91.38.221)
    2.55 min.Function: 'WNetGetProviderName'
    Function group: 'Windows Networking'
    Google
    Advertise here!