Passing a string to a function inside a WinXP DLL

[Ray Crumrine]

I am trying to write a "wrapper" for the WinXP function
"rundll32.exe shimgvw.dll,ImageView_Fullscreen %1"
I have it in a batch file and it works fine but I have been unable to figure out how to pass the filename inside of the PB code. I have;

DECLARE FUNCTION ImageView_Fullscreen LIB "C:\WINDOWS\system32\shimgvw.dll" ALIAS "ImageView_Fullscreen" (command_str AS STRING) AS LONG

FUNCTION PBMAIN () AS LONG
LOCAL n AS LONG
LOCAL command_str AS STRING

command_str = COMMAND$

n = ImageView_Fullscreen(command_str)
END FUNCTION

At one point I was able to bring up the WinXP image viewer but could not get the file name. I can't find any documentation on how to call this function. I don't think I have the declaration correct and I'm guessing I need to "dummy up" the file name from the command line in a particular way.

[Kev Peel]

No, it's wrong. It's important to note that no native API calls use "As String" as a parameter* (if they do exist, I've never come across one in 12 years of Windows programming).

*VB calls do not count, as they use translation from STRING to ASCII internally.

This is the correct DECLARE you need to call the function:

Declare Function ImageView_Fullscreen Alias "ImageView_Fullscreen" Lib "shimgvw.dll" (ByRef pFileName As Asciiz) As Long

You also do not need to include the path, since the DLL is already in the Windows (system) folder.

[Edwin Knoppert]

DECLARE FUNCTION ImageView_Fullscreen LIB "shimgvw.dll" ALIAS "ImageView_Fullscreen" (BYVAL command_str AS STRING) AS LONG

[Ray Crumrine]

using the "ByRef pFileName As Asciiz" from the first post I got a crash. using the BYVAL declaration from the 2nd post doesn't seem to do anything at all. The only way I have been able to make it work is by using the SHELL command but that doesn't seem like a very clean way to do it. Any suggestions?

DECLARE FUNCTION ImageView_Fullscreen LIB "shimgvw.dll" ALIAS "ImageView_Fullscreen" (BYVAL file_name AS STRING) AS LONG

FUNCTION PBMAIN () AS LONG
LOCAL AStr, file_name AS STRING
LOCAL rval AS LONG

'AStr = "rundll32.exe shimgvw.dll,ImageView_Fullscreen "

file_name = COMMAND$

'This works
'shell AStr + file_name

'This doesn't
rval = ImageView_Fullscreen(file_name)
END FUNCTION

[Edwin Knoppert]

And this?

Local n As Long
Local command_str As String
command_str = "C:\.............\image1.png"
n = Shell( "rundll32.exe shimgvw.dll,ImageView_Fullscreen " & command_str, %SW_SHOWMAXIMIZED )

[Ray Crumrine]

I suspect that would work as well but I was trying to avoid using the SHELL function / statement. I found some mentions of DDE. Maybe I am missing something.

[Edwin Knoppert]

1) I used the ..A call (the alias) and the window came up but without a file.
That's odd..

2) it seems that the library also has a com interface.

This *should* work but doesn't:

    Local o As Dispatch
    Local v As Variant
    Local v1 As Variant

    Set o = New Dispatch In "Preview.Preview"    
    
    v = "C:\.....BEEMW.jpg"
    v1 = 0
    
    Object Call o.ShowFile( v, v1 )
    
    'MsgBox  Str$( IsObject( o ) )

[Michael Mattias]

You mean you want to call your function from your own program?

Functions which work with RUNDLL32 must have the following prototype which you could have found in your WinAPI reference:

The Run DLL utility (Rundll32.exe) included in Windows enables you to call functions exported from a 32-bit DLL. These functions must have the following syntax:

void CALLBACK EntryPoint(
  HWND hwnd,        // handle to owner window
  HINSTANCE hinst,  // instance handle for the DLL
  LPTSTR lpCmdLine, // string the DLL will parse
  int nCmdShow      // show state
);

So you need a DECLARE for the way the function must be defined...

DECLARE FUNCTION ImageView_Fullscreen ALIAS "ImageView_FullScreen"  LIB "shimgvw.dll" ALIAS "ImageView_Fullscreen"  _
   (BYVAL hWnd AS LONG, _
    BYVAL hinst AS LONG,_
    sz  AS ASCIIZ, _
    BYVAL iCmdShow AS LONG) AS LONG

Then you just set it up and call it...

FUNCTION PBMAIN() AS LONG

  LOCAL sz AS ASCIIZ * %MAX_PATH, iret as long
  LOCAL hWnd AS LONG, hInst AS LONG, icmdShow AS LONG

   hWnd        = GetDesktopWindow()
   hINst        = GetModuleHandle ("shimgvw.dll") * 
   iCmdShow  = %SW_SHOW
   sz             = "C:\folder\...\amd,sadsmand\nmdnamsnd.png"

   iRet = ImageView_Fullscreen (hWnd, hINst, sz, iCmdShow) 

END FUNCTION

The doc is not real clear if you need an instance handle for the DLL file or for the owning program. If above does not work try making hinst = GetModuleHandle(BYVAL %NULL) and try again.

MCM

[Ray Crumrine]

Got it to work with

DECLARE FUNCTION ImageView_Fullscreen LIB "shimgvw.dll" ALIAS "ImageView_Fullscreen" (BYVAL DWORD) AS LONG

FUNCTION PBMAIN () AS LONG
LOCAL file_name AS STRING
LOCAL rval AS LONG

file_name = UCODE$(COMMAND$) + $NUL
rval = ImageView_Fullscreen(STRPTR(file_name))
END FUNCTION

Apparently requires a two byte string format

[José Roca]

1)
2) it seems that the library also has a com interface.

This *should* work but doesn't:

    Local o As Dispatch
    Local v As Variant
    Local v1 As Variant

    Set o = New Dispatch In "Preview.Preview"    
    
    v = "C:\.....BEEMW.jpg"
    v1 = 0
    
    Object Call o.ShowFile( v, v1 )
    
    'MsgBox  Str$( IsObject( o ) )

It is a visual ActiveX control, so you have to provide a host.

The following example demonstrates how to embed the Preview control (remember to change the path and name of the picture to load).

#COMPILE EXE
#DIM ALL
#DEBUG ERROR ON
#INCLUDE "WIN32API.INC"

%IDC_PREVIEW = 1001

' ========================================================================================
' ATL functions
' ========================================================================================
DECLARE FUNCTION AtlAxWinInit LIB "ATL.DLL" ALIAS "AtlAxWinInit" () AS LONG
DECLARE FUNCTION AtlAxGetControl LIB "ATL.DLL" ALIAS "AtlAxGetControl" (BYVAL hWnd AS DWORD, BYREF pp AS DWORD) AS DWORD

' ========================================================================================
' The IUnknown::AddRef method increments the reference count for an interface on an object. It
' should be called for every new copy of a pointer to an interface on a given object.
' ========================================================================================
FUNCTION IUnknown_AddRef (BYVAL pthis AS DWORD PTR) AS DWORD
    LOCAL DWRESULT AS LONG
    IF ISFALSE pthis THEN EXIT FUNCTION
    CALL DWORD @@pthis[1] USING IUnknown_AddRef(pthis) TO DWRESULT
    FUNCTION = DWRESULT
END FUNCTION

' ========================================================================================
' Puts the address of an object in a variant and marks it as containing a dispatch variable
' ========================================================================================
SUB AtlMakeDispatch (BYVAL lpObj AS DWORD, BYREF vObj AS VARIANT) EXPORT
   LOCAL lpvObj AS VARIANTAPI PTR                 ' Pointer to a VARIANTAPI structure
   LET vObj = EMPTY                               ' Make sure is empty to avoid memory leaks
   lpvObj = VARPTR(vObj)                          ' Get the VARIANT address
   @lpvObj.vt = %VT_DISPATCH                      ' Mark it as containing a dispatch variable
   @lpvObj.vd.pdispVal = lpObj                    ' Set the dispatch pointer address
   IUnknown_AddRef lpObj                          ' Increment the reference counter
END SUB

' ========================================================================================
' Main
' ========================================================================================
FUNCTION WINMAIN (BYVAL hInstance AS DWORD, BYVAL hPrevInstance AS DWORD, BYVAL lpszCmdLine AS ASCIIZ PTR, BYVAL nCmdShow AS LONG) AS LONG

   LOCAL hWndMain AS dword
   LOCAL hCtl AS DWORD
   LOCAL hFont AS DWORD
   LOCAL wcex AS WndClassEx
   LOCAL szClassName AS ASCIIZ * 80
   LOCAL rc AS RECT
   LOCAL szCaption AS asciiz * 255
   LOCAL nLeft AS LONG
   LOCAL nTop AS LONG
   LOCAL nWidth AS LONG
   LOCAL nHeight AS LONG

   AtlAxWinInit   ' Initialize ATL

   hFont = GetStockObject(%ANSI_VAR_FONT)

   ' Register the window class
   szClassName        = "MyClassName"
   wcex.cbSize        = SIZEOF(wcex)
   wcex.style         = %CS_HREDRAW OR %CS_VREDRAW
   wcex.lpfnWndProc   = CODEPTR(WndProc)
   wcex.cbClsExtra    = 0
   wcex.cbWndExtra    = 0
   wcex.hInstance     = hInstance
   wcex.hCursor       = LoadCursor (%NULL, BYVAL %IDC_ARROW)
   wcex.hbrBackground = %COLOR_3DFACE + 1
   wcex.lpszMenuName  = %NULL
   wcex.lpszClassName = VARPTR(szClassName)
   wcex.hIcon         = LoadIcon (%NULL, BYVAL %IDI_APPLICATION) ' Sample, if resource icon: LoadIcon(hInst, "APPICON")
   wcex.hIconSm       = LoadIcon (%NULL, BYVAL %IDI_APPLICATION) ' Remember to set small icon too..
   RegisterClassEx wcex

   ' Window caption
   szCaption = "Preview Demo"

   ' Retrieve the size of the working area
   SystemParametersInfo %SPI_GETWORKAREA, 0, BYVAL VARPTR(rc), 0

   ' Calculate the position and size of the window
   nWidth  = (((rc.nRight - rc.nLeft)) + 2) * 0.95   ' 95% of the client screen width
   nHeight = (((rc.nBottom - rc.nTop)) + 2) * 0.95   ' 95% of the client screen height
   nLeft   = ((rc.nRight - rc.nLeft) \ 2) - nWidth \ 2
   nTop    = ((rc.nBottom - rc.nTop) \ 2) - (nHeight \ 2)

   ' Create a window using the registered class
   hWndMain = CreateWindowEx(%WS_EX_CONTROLPARENT, _           ' extended style
                             szClassName, _                    ' window class name
                             szCaption, _                      ' window caption
                             %WS_OVERLAPPEDWINDOW OR _
                             %WS_CLIPCHILDREN, _               ' window style
                             nLeft, _                          ' initial x position
                             nTop, _                           ' initial y position
                             nWidth, _                         ' initial x size
                             nHeight, _                        ' initial y size
                             %NULL, _                          ' parent window handle
                             0, _                              ' window menu handle
                             hInstance, _                      ' program instance handle
                             BYVAL %NULL)                      ' creation parameters

   ' Create the Preview control
   hCtl = CreateWindowEx(%NULL, _                                             ' extended styles
                         "AtlAxWin", _                                        ' class name
                         "Preview.Preview.1", _                               ' caption
                         %WS_CHILD OR %WS_VISIBLE OR %WS_CLIPSIBLINGS OR _    ' window styles
                         %WS_TABSTOP, _
                         0, 0, _                                              ' left, top
                         0, 0, _                                              ' width, height
                         hWndMain, %IDC_PREVIEW, _                            ' handle of parent, control ID
                         hInstance, BYVAL %NULL)                              ' handle of instance, creation parameters

   ' Get the interface pointer of the Preview control
   LOCAL pUnk AS DWORD
   AtlAxGetControl(hCtl, pUnk)

   ' Make a dispatch variant from it to be able to use PB automation
   LOCAL vVar AS VARIANT
   LOCAL oPreview AS DISPATCH
   AtlMakeDispatch(pUnk, vVar)
   SET oPreview = vVar
   vVar = EMPTY

   ' Load the file
   LOCAL vName AS VARIANT
   LOCAL vSelectCount AS VARIANT
   ' --> Change me!
   vName = "C:\Documents and Settings\Pepe\Mis documentos\Mis imágenes\Capture.jpg"
   vSelectCount = 0 AS LONG
   OBJECT CALL oPreview.ShowFile(vName, vSelectCount)

   ' Show the window
   ShowWindow hWndMain, nCmdShow
   UpdateWindow hWndMain

   ' Message handler loop
   LOCAL Msg AS tagMsg
   WHILE GetMessage(Msg, %NULL, 0, 0)
      IF ISFALSE IsDialogMessage(hWndMain, Msg) THEN
         TranslateMessage Msg
         DispatchMessage Msg
      END IF
   WEND

   FUNCTION = msg.wParam

END FUNCTION
' ****************************************************************************************

' ****************************************************************************************
' Main Window procedure
' ****************************************************************************************
FUNCTION WndProc (BYVAL hWnd AS DWORD, BYVAL wMsg AS DWORD, BYVAL wParam AS DWORD, BYVAL lParam AS LONG) AS LONG

   LOCAL rc AS RECT

   SELECT CASE wMsg

      CASE %WM_COMMAND
         SELECT CASE LOWRD(wParam)

            CASE %IDCANCEL
               IF HIWRD(wParam) = %BN_CLICKED THEN
                  SendMessage hWnd, %WM_CLOSE, wParam, lParam
                  FUNCTION = 0
                  EXIT FUNCTION
               END IF

         END SELECT

      CASE %WM_SYSCOMMAND
         ' Capture this message and send a WM_CLOSE message
         IF (wParam AND &HFFF0) = %SC_CLOSE THEN
            SendMessage hWnd, %WM_CLOSE, wParam, lParam
            EXIT FUNCTION
         END IF

      CASE %WM_DESTROY
         PostQuitMessage 0
         EXIT FUNCTION

      CASE %WM_SIZE
         IF wParam <> %SIZE_MINIMIZED THEN
            GetClientRect hWnd, rc
            MoveWindow GetDlgItem(hWnd, %IDC_PREVIEW), rc.nLeft, rc.nTop, rc.nRight - rc.nLeft, rc.nBottom - rc.nTop, %TRUE
         END IF

   END SELECT

   FUNCTION = DefWindowProc(hWnd, wMsg, wParam, lParam)

END FUNCTION

[Edwin Knoppert]

1) I tried the unicode as well but on the ..W function.
The $nul should not be needed but maybe this is the clue?

2) And yes, i almost tried it with ATL but i thought it was a stand alone app, ha!

[Michael Mattias]

>Got it to work with

I don't know how that worked if that function was designed for use with RunDll32.Exe, since the procedure header does not match the doc for "rundll" functions.

Oh, wait a minute ... it looks you never got it work correctly using rundll32.exe.

The part about needing a Unicode filename is because that's the way the function author wrote it.