Using Win32 functions in Visual FoxPro Image Gallery
Code examples:
How to change display settings: screen resolution, screen refresh rate
Capturing keyboard activity of another application with the Raw Input API (VFP9)
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
Enumerating raw input devices attached to the system (keyboard, mouse, human interface device)
Enumerating data formats currently available on the clipboard
GDI+: copying to the Clipboard (a) image of active FoxPro window/form, (b) image file
Disabling mouse and keyboard input for the main VFP window (with the app still running)
Current keyboard type
Custom HttpRequest class (WinINet)
Storing content of the Clipboard to a bitmap file
Using Beep and Sleep functions to make the old tin buzz sing (WinNT only?)
Storing screen shot of a form to bitmap file
Attaching menu to a top-level form
Displaying icons in the system tray (VFP9)
Sending email messages with Simple MAPI
Using InternetSetFilePointer when resuming interrupted download from the Internet
Retrieving information about the specified icon
Drawing Windows predefined bitmaps using the LoadBitmap functions
Minimizing all running applications
How to activate Windows Calculator
Confining Windows calculator inside the VFP main window
How to print a bitmap file
Building a tree of subdirectories for a given path using FindFile functions
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

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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1750 bytes  
Created: 2001-08-03 12:00:00  
Modified: 2010-04-08 11:20:04  
Visits in 7 days: 37  
Listed functions:
CryptBinaryToString
CryptStringToBinary
Printer friendly API declarations
My comment:
In VFP8 base64 conversion is normally 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 programming 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 piece of code by itself.
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