PB/DLL 2.0 Debugging

[Spencer Shearer]

I am creating a 16 bit DLL using PB/DLL 2.0. This DLL will be
called from VB 3.0 16 bit. I am receiving an error message when
trying to compile the DLL for testing. I can compile the DLL for
use with VB 3.0 and access the DLL and display the File Open Dialog.
There is a bug that preventing diplay of files. I took most of this
code from someones previous form post about a 32 bit File Open. I
need to be able to debug this code to resolve the issue.

Thanks for any help or suggestions.
Spencer

The following is the code:

PowerBasic Code

%DEBUG = 1 'set to 0 for no debugging

$IF %DEBUG
$DEBUG PBD ON
$COMPILE DLL
$INCLUDE "\pbdll60\winapi\WINAPI.INC"
$INCLUDE "\PBDLL60\WINAPI\COMMDLG.INC"
$INCLUDE "\PBDLL60\WINAPI\CTL3D.INC"
DECLARE FUNCTION OpenFilesDialog(BYVAL hWnd AS LONG, _ ' parent window
Caption AS ASCIIZ, _ ' caption
Filespec AS ASCIIZ, _ ' filename (input/output)
InitialDir AS ASCIIZ, _ ' start directory
Filter AS ASCIIZ, _ ' filename filter
DefExtension AS ASCIIZ, _ ' default extension
Flags AS LONG) AS LONG ' flags

SUB PBDebug () EXPORT
OPTION EXPLICIT
Dim returnvalue as long
Dim sCaption as String
DIM sFileName AS String
DIM sPath AS String
Dim sFilter as String
Dim sDefExt as String
DIM lStyle AS LONG
sCaption = "File Open Dialog Test"
sFileName = "*.*"
sPath = CURDIR$
sFilter = "All Files (*.*)|*.*|Text files (*.TXT, *.BAT)|*.TXT;*.BAT|"
sDefExt = "*.txt"
lStyle = %OFN_ALLOWMULTISELECT Or %OFN_FILEMUSTEXIST
returnvalue = OpenFilesDialog(0, sCaption, sFileName, sPath, sFilter, sDefExt, lStyle)
END SUB
$ELSE
$COMPILE DLL
$INCLUDE "\pbdll60\winapi\WINAPI.INC"
$INCLUDE "\PBDLL60\WINAPI\COMMDLG.INC"
$INCLUDE "\PBDLL60\WINAPI\CTL3D.INC"
DECLARE FUNCTION OpenFilesDialog(BYVAL hWnd AS LONG, _ ' parent window
Caption AS ASCIIZ, _ ' caption
Filespec AS ASCIIZ, _ ' filename (input/output)
InitialDir AS ASCIIZ, _ ' start directory
Filter AS ASCIIZ, _ ' filename filter
DefExtension AS ASCIIZ, _ ' default extension
Flags AS LONG) AS LONG ' flags

$ENDIF

'----------------------------------------------------------
'- OpenFilesDialog
'----------------------------------------------------------

Function OpenFilesDialog( BYVAL hWnd AS LONG, _ ' parent window
Caption AS ASCIIZ, _ ' caption
Filespec AS ASCIIZ, _ ' filename (input/output)
InitialDir AS ASCIIZ, _ ' start directory
Filter AS ASCIIZ, _ ' filename filter
DefExtension AS ASCIIZ, _ ' default extension
Flags AS LONG) EXPORT AS LONG ' flags

LOCAL sFile AS STRING
LOCAL Ofn AS OPENFILENAME
LOCAL zFileTitle AS ASCIIZ * 256
LOCAL zFilter AS ASCIIZ * 256
LOCAL zInitialDir AS ASCIIZ * 256
LOCAL zTitle AS ASCIIZ * 256
LOCAL zDefExt AS ASCIIZ * 10

REPLACE "|" WITH CHR$(0) IN Filter

IF LEN(InitialDir) = 0 THEN
InitialDir = CURDIR$
END IF

zFilter = Filter + CHR$(0)
zInitialDir = InitialDir + CHR$(0)

sFile = STRING$(4096,0) 'PLENTY OF ROOM FOR MULTIPLE FILES
MID$(sFile,1) = FileSpec

zDefExt = DefExtension + CHR$(0)
zTitle = Caption + CHR$(0)

ofn.lStructSize = SIZEOF(ofn)
ofn.hWndOwner = hWnd
ofn.lpstrFilter = VARPTR(zFilter)
ofn.nFilterIndex = 1
ofn.lpstrFile = STRPTR(sFile)
ofn.nMaxFile = LEN(sFile)
ofn.lpstrFileTitle = VARPTR(zFileTitle)
ofn.nMaxFileTitle = SIZEOF(zFileTitle)
ofn.lpstrInitialDir = VARPTR(zInitialDir)
IF LEN(zTitle) THEN
ofn.lpstrTitle = VARPTR(zTitle)
END IF
ofn.Flags = Flags
ofn.lpstrDefExt = VARPTR(zDefExt)

FUNCTION = GetOpenFilename(ofn)

Filespec = RTRIM$(sFile,CHR$(0))
Flags = ofn.Flags

END FUNCTION


Visual Basic 3.0 Code
Declare Function OpenFilesDialog Lib "jds.DLL" Alias "OpenFilesDialog" (ByVal hWnd As
Long, ByVal Caption As String, ByVal Filespec As String, ByVal InitialDir As String, ByVal
Filter As String, ByVal DefExtension As String, Flags As Long) As Long
'File Open/Save Dialog Flags
Global Const OFN_READONLY = &H1&
Global Const OFN_OVERWRITEPROMPT = &H2&
Global Const OFN_HIDEREADONLY = &H4&
Global Const OFN_NOCHANGEDIR = &H8&
Global Const OFN_SHOWHELP = &H10&
Global Const OFN_NOVALIDATE = &H100&
Global Const OFN_ALLOWMULTISELECT = &H200&
Global Const OFN_EXTENSIONDIFFERENT = &H400&
Global Const OFN_PATHMUSTEXIST = &H800&
Global Const OFN_FILEMUSTEXIST = &H1000&
Global Const OFN_CREATEPROMPT = &H2000&
Global Const OFN_SHAREAWARE = &H4000&
Global Const OFN_NOREADONLYRETURN = &H8000&
Dim sCaption As String
Dim sFileName As String
Dim sPath As String
Dim sFilter As String
Dim sDefExt As String
Dim lStyle As Long

sCaption = "File Open Test..."
sFileName = Space$(4096)
sFileName = "*.*"
sPath = CurDir$
sFilter = "All Files (*.*)|*.*|Text files (*.TXT, *.BAT)|*.TXT;*.BAT|"
sDefExt = "*.txt"
lStyle = OFN_ALLOWMULTISELECT Or OFN_FILEMUSTEXIST

If OpenFilesDialog(Me.hWnd, sCaption, sFileName, sPath, sFilter, sDefExt, lStyle) Then
'Need to format sFileName
MsgBox "Directory = " & sFileName
Else
MsgBox "No file(s) selected.", MB_OK, "Error"
End If

[Lance Edmonds]

You can't pass a dynamic string BYREF to a function expecting an BYREF ASCIIZ - the solution is to pass the strings BYCOPY instead.

Alternatively, you could override the type-checking by passing address of the string's data BYVAL.

Confused?

Examine this simple psuedocode example:
[code]
DECLARE Afunction(MyData AS ASCIIZ) AS LONG
...
DIM A$
X& = Afunction(a$) ' wont work as string types incompatible - you can't pass a string handle to a function that expects the actual data address
X& = Afunction(BYCOPY a$) ' works fine as the actual data contents of the string is copied to a new location and the address of this data is passed to the function.
X& = Afunction(a$ + "") ' expressions are always translated to BYCOPY as there is no "address" for an expression, only the result
X& = Afunction( (a$) ) ' works fine - the parenthesis force the paremeter to be evaluated as an expression (as above)
X& = Afunction(BYVAL STRPTR(a$)) ' Works fine - we are passing the address of the strings' data to the function - overriding the type checking by using an explicit BYVAL override.

------------------
Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

[Spencer Shearer]

Thanks Lance,

Using the above code and taking your suggestion I replaced the
following line:

returnvalue = OpenFilesDialog(0, sCaption, sFileName, sPath, sFilter, sDefExt, lStyle)

with:

returnvalue = OpenFilesDialog(0, (sCaption), (sFileName), (sPath), (sFilter), (sDefExt), lStyle)

and I am now able to debug the routine. My code is causing a GPF
in PBDW right after I select a file and click on Ok. I wonder if
it is because I am passing to OpenFilesDialog()ASCIIZ (I am using
ASCIIZ because this DLL will be called from VB when complete)
strings in the OFN UDT. I think that this might also be the reason
why the Filter and the Default Extension seem to be ignored by
this call.

Thanks for any insight into this problem.
Spencer



------------------

[Spencer Shearer]

The GPF problem and the filter being ignored problem is because I
am passing ASCIIZ to the function. I am doing this because this dll
is to be called by Visual Basic 3.0. For testing I changed the
ASCIIZ data type in the prototype and the call to a string data type.
Once I did this I was able to run the PB/DLL 2.0 debugger without
a GPF. In addition the file open dialog box understood the filters
and displayed the appropriate files.

Now the challange is to figure out how to make this work with VB. I think
that I will pass ASCIIZ to the function and then copy the strings
to a string value.

Any better ideas would be appreciated.
Thanks...
Spencer

------------------