Pass struct to WinAPI

[JimmyK]

Some winapi functions ' parameters is struct. How can i invoke that kind of function in visual Fox?

Tnanks

Jimmy
[sig][/sig]

 

[dgrewe]

Example 1
I am calling Win32Api kernel32.dll function [red]WinExec[/red] in the return line

lparameters pcExeName, pcParameters, [red]pnWindowStat[/red]
* first parameter required, other - optional
if Parameters() < 2.5 .or. type(&quot;pnWindowStat&quot != &quot;N&quot; .or. empty(pnWindowStat)
pnWindowStat = 1 && see Win32Api function ShowWindow for values of pnWindowStat
endif
local lcRunString
[red]m.lcRunString[/red] = '&quot;'+ allt(m.pcExeName) + '&quot;' + iif(parameters() > 1 , + &quot; &quot; + m.pcParameters , &quot;&quot
[red]declare integer WinExec in kernel32 string lpCmdLine, integer uCmdShow[/red]
return [red]WinExec(m.lcRunString, m.pnWindowStat)[/red] > 31
endproc

Example 2
Here I'm call Win32Api advapi32.dll function [red]RegOpenKey[/red]
*procedure IsFileInReg
lparameters pcExeName
* returns fill path of EXE file taking it from Windows registry, or empty string
if empty(m.pcExeName) .or. type(&quot;m.pcExeName&quot != &quot;C&quot; .or. parameter() < 0.5
return ' '
endif
m.pcExeName = justfname(m.pcExeName)
...more code

local lnErrorRes, phkResult, lpSubKey, lpValue, lpcbValue
#define [red]HKEY_LOCAL_MACHINE[/red] -2147483646 && bitset(0,31)+2
[red]phkResult[/red] = 0
[red]lpSubKey[/red] = 'SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths'
[red]lpValue[/red] = .null.
[red]declare long RegOpenKey in advapi32 long hKey, string lpSubKey, long @phkResult[/red]
lnErrorRes =[red] RegOpenKey(HKEY_LOCAL_MACHINE, lpSubKey, @phkResult)[/red]
if lnErrorRes # 0 or phkResult = 0 && Cannot open registry key - unknown error
= messagebox('Cannot open Windows registry.')
return ''
endif
... more code

Does This Help You ? [sig]<p>David W. Grewe<br><a href=mailtoave@internationalbid.net>Dave@internationalbid.net</a><br>[/sig]

 

[jonscott8]

Hi Jimmy,
IMO, you've just stumbled on one of VFP's few weaknesses. A struct, AISI, is nothing more than sequentially allocated memory space.
Handling structs from VFP requires creating a &quot;buffer&quot; to return the values, passing that buffer to the function by reference, and parsing the values out of that buffer. Here's an example of the GetSystemTime function:

DECLARE GetSystemTime IN WIN32API STRING @lcBuffer

*!* typedef struct _SYSTEMTIME {
*!* WORD wYear; && 2 bytes
*!* WORD wMonth; && 2 bytes
*!* WORD wDayOfWeek; && 2 bytes
*!* WORD wDay; && 2 bytes
*!* WORD wHour; && 2 bytes
*!* WORD wMinute; && 2 bytes
*!* WORD wSecond; && 2 bytes
*!* WORD wMilliseconds; && 2 bytes
*!* } SYSTEMTIME, *PSYSTEMTIME;

lcBuffer=SPACE(16) && total struct length is 16 bytes

GetSystemTime(@lcBuffer)

lcYear=Str2Word(SUBSTR(lcBuffer,1,2))
lcMonth=Str2Word(SUBSTR(lcBuffer,3,2))
lcDOW=Str2Word(SUBSTR(lcBuffer,5,2))
lcDay=Str2Word(SUBSTR(lcBuffer,7,2))
lcHour=Str2Word(SUBSTR(lcBuffer,9,2))
lcMinute=Str2Word(SUBSTR(lcBuffer,11,2))
lcSecond=Str2Word(SUBSTR(lcBuffer,13,2))
lcMilli=Str2Word(SUBSTR(lcBuffer,15,2))

*********************
FUNCTION Str2Word
*********************

PARAMETERS m.wordstr

PRIVATE i, m.retval

m.retval = 0
FOR i = 0 TO 8 STEP 8
m.retval = m.retval + (ASC(m.wordstr) * (2^i))
m.wordstr = RIGHT(m.wordstr, LEN(m.wordstr) - 1)
NEXT
RETURN m.retval

Str2Word is used to convert the returned value to WORD data type. [sig]<p>Jon Hawkins<br><a href=mailto: jonscott8@yahoo.com> jonscott8@yahoo.com</a><br><a href= > </a><br>Carpe Diem! - Seize the Day![/sig]

 

[JimmyK]

Thanks for all respones,
Jon's example is exactly what i wanted

[sig][/sig]