Using Win32 functions in Visual FoxPro Image Gallery
Code examples:
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Obtaining names and positions for shortcuts located on the Windows Desktop
Disconnecting USB Mass Storage Device programmatically
Displaying icons in the system tray (VFP9)
Displaying dimmed window behind VFP top-level form
Generating random cryptographic keys
Reading and setting system access privileges for the current process
Adding a background image to VFP report (VFP9, ReportListener)
Browsing Windows Known Folders (Special Folders)
Enumerating devices installed on the local machine
Printing Image File, programmatically set print page orientation to landscape
Using Month Calendar Control (VFP9, Comctl32.dll)
Compressing and decompressing files with Windows API Runtime Library routines
How to find which fonts Windows uses for drawing captions, menus and message boxes
How to load a user profile
Starting a dialog box for connecting to network resources and passing input parameters
Customizing the frame of top-level form: removing the standard frame (VFP9, Vista)
GDI+ fun: roach-infested desktop
GDI+: Creating thumbnails to preview images in a directory
Moving shortcut to a specified position on the Windows Desktop
Windows Shell Icons displayed and exported to ICO files (Vista)
Writing entries to custom Event Log
Detecting changes in connections to removable drives (VFP9)
Finding out if the current user is the Guest account
How to perform Base64 encoding/decoding using Cryptography API Functions

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More code examples    Listed functions    Add comment     W32 Constants      Translate this page Printer friendly version of this code sample
#DEFINE CRYPT_STRING_BASE64 0x0001
#DEFINE CRYPT_STRING_NOCRLF 0x40000000
#DEFINE CRYPT_STRING_NOCR 0x80000000

DO declare
SET MEMOWIDTH TO 120

LOCAL cBuffer, cEncoded, cDecoded

TEXT TO cBuffer NOSHOW
Base cryptographic functions provide the most flexible means 
of developing cryptography applications. All communication 
with a cryptographic service provider (CSP) occurs through 
these functions.

A CSP is an independent module that performs all cryptographic 
operations. At least one CSP is required with each application 
that uses cryptographic functions. A single application can 
occasionally use more than one CSP.
ENDTEXT

cEncoded = ToBase64(m.cBuffer)
? cEncoded

cDecoded = FromBase64(cEncoded)
? cDecoded

* end of main

FUNCTION ToBase64(cSrc)
    LOCAL nFlags, nBufsize, cDst
    nFlags=CRYPT_STRING_BASE64

    nBufsize=0
    = CryptBinaryToString(@cSrc, LEN(cSrc),;
        m.nFlags, NULL, @nBufsize)

    cDst = REPLICATE(CHR(0), m.nBufsize)
    IF CryptBinaryToString(@cSrc, LEN(cSrc), m.nFlags,;
        @cDst, @nBufsize) = 0
        RETURN ""
    ENDIF
RETURN cDst

FUNCTION FromBase64(cSrc)
    LOCAL nFlags, nBufsize, cDst
    nFlags=CRYPT_STRING_BASE64

    nBufsize=0
    = CryptStringToBinary(@cSrc, LEN(m.cSrc),;
        nFlags, NULL, @nBufsize, 0,0)

    cDst = REPLICATE(CHR(0), m.nBufsize)
    IF CryptStringToBinary(@cSrc, LEN(m.cSrc),;
        nFlags, @cDst, @nBufsize, 0,0) = 0
        RETURN ""
    ENDIF
RETURN m.cDst

PROCEDURE declare
    DECLARE INTEGER CryptBinaryToString IN Crypt32;
        STRING @pbBinary, LONG cbBinary, LONG dwFlags,;
        STRING @pszString, LONG @pcchString

    DECLARE INTEGER CryptStringToBinary IN crypt32;
        STRING @pszString, LONG cchString, LONG dwFlags,;
        STRING @pbBinary, LONG @pcbBinary,;
        LONG pdwSkip, LONG pdwFlags

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1772 bytes  
Created: 2001-08-03 12:00:00  
Modified: 2015-10-28 09:29:17  
Visits in 7 days: 17  
Listed functions:
CryptBinaryToString
CryptStringToBinary
Printer friendly API declarations
My comment:
Starting VFP8, base64 conversion can be performed with STRCONV().

In my tests, API routines presented on this page encoded and decoded strings approximately 2 times faster than STRCONV() did -- on 100K cycles 3.7 seconds vs. 7.7 seconds.

* * *
This is an output from call to CryptBinaryToString with dwFlags set to CRYPT_STRING_HEXASCIIADDR (0x000b). Can make a good starting point for developing a simple binary viewer.


* * *
From Burkhard Stiller`s VFP Blog:
Another way to encode and store picture-data inside your classes -- relates to base64 encoding, and is an interesting sample of code by itself.
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