Private Declare Sub CopyMemory or Vb6.CopyMemory

[fabel358]

In my application, I'm using "modCOMDLG32.bas" Module, created By : Kevin Wilson taken from "http://www.TheVBZone.com". This module uses CopyMemory several times. Now, if I use

Private Declare Sub CopyMemory Lib "kernel32.dll" Alias "RtlMoveMemory" (ByRef lpvDest As Any, ByRef lpvSource As Any, ByVal cbCopy As Long)

everything is OK.
If I use "Vb6.CopyMemory" from Vb6.tlb, taken from VbSpeed, although it looks absolutely identical (Destination As Any, Source As Any, Length As Long), it doesn't work. In all other cases where I use "Vb6.CopyMemory", I don't have this problem.
Maybe there are incompatibilities between "Vb6.tlb" and "comdlg32.dll"?
Of course I used

Private Declare Sub CopyMemory Lib "kernel32.dll" Alias "RtlMoveMemory" (ByRef lpvDest As Any, ByRef lpvSource As Any, ByVal cbCopy As Long)

in the module header, but I would like to understand the reason for this inconsistency...
Has anyone experienced a problem and can explain to me why?

[couttsj]

What are the 2 question marks for? I use:
Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (Destination As Any, Source As Any, ByVal Length As Long)

The DLL file is the default, as is the ByRef.

J.A. Coutts

[Zvoni]

although it looks absolutely identical (Destination As Any, Source As Any, Length As Long)

It doesn't.........

[fafalone]

I couldn't find a Vb6.tlb on VBSpeed but the two typelibs they have with it, there is no difference... post some code demonstrating the issue... include this tlb and ideally its source.

[wqweto]

Object Viewer does *not* show ByRef/ByVal modifiers of parameters of methods of interfaces in a typelib for no apparent reason.

It's not possible to check if both variants are equivalent unless you decompile the typelib with OleView.

cheers,
</wqw>

[fabel358]

https://drive.google.com/file/d/10c9...usp=drive_link
https://drive.google.com/file/d/1vJh...ew?usp=sharing
Here are the two files in question...
I don't have VB6.tlb source code; it isn't mine.
here a discussion: https://www.vbforums.com/showthread....ed-source-code

[fafalone]

There's no difference.

Dim x As Long
Dim y As Long
Dim z As Long
x = 5
modCOMDLG32.CopyMemory y, x, 4
VB6.Kernel.CopyMemory z, x, 4
Debug.Print x, y, z

prints 5 5 5

[wqweto]

Btw, there is nothing suspicious in CopyMemory declaration in VB6.tlb i.e. it matches Destination As Any, Source As Any, ByVal Length As Long params in the API declare.

        [entry("RtlMoveMemory"), helpstring("Copies Length Bytes from Source to Destination")]
        void _stdcall CopyMemory(
                        [in] void* Destination, 
                        [in] void* Source, 
                        [in] long Length);

It must be something in your project that makes the difference.

cheers,
</wqw>

[Zvoni]

It must be something in your project that makes the difference.

cheers,
</wqw>

First guess: Passing Strings (Pointer to Pointer)

[fabel358]

For fafalone: Vb6's copymemory works great and I know; this because I use it in all my applications (Vb6.tlb also has the advantage of the GetMemx and PutMemx functions).
As any of you may have noticed, it is apparently identical in input to the

Public Declare Sub CopyMemory Lib "kernel32.dll" Alias "RtlMoveMemory" (ByRef lpvDest As Any, ByRef lpvSource As Any, ByVal cbCopy As Long)

declaration;
However, if you try to use the ShowPrinter function, you will find that everything seems to work except printing. From my experience, the problem is in the following line:

' Get the DevInfo structure
pDevMode = GlobalLock(PrintInfo.hDevMode)
CopyMemory DevInfo, ByVal pDevMode, Len(DevInfo)

If CopyMemory is the one in the Header declaration, printing works; if it is Vb6.Copymemory, nothing works.

[wqweto]

Seems like you are bitten by ANSI<->Unicode transcoding.

Using Len (instead of LenB) is wrong on many levels too but this is a vast topic I don't have the patience to explain here and now (w/ fixed length strings vs byte arrays in UDT).

Also, DEVMODE struct is a beast to handle esp. when spit by buggy printer drivers.

cheers,
</wqw>

[fafalone]

Does VB6 automatically turn it off for typelib APIs with As Any? I know it supports Unicode strings, as input at least, if declared as such.

[fabel358]

Seems like you are bitten by ANSI<->Unicode transcoding.

Using Len (instead of LenB) is wrong on many levels too but this is a vast topic I don't have the patience to explain here and now (w/ fixed length strings vs byte arrays in UDT).

Even with LenB instead of len, nothing works with Vb6.CopyMemory, rather, the application crashes.

Anyway, with the declaration in the Header, everything works fine and this is the solution I adopted. However I was interested to understand why this huge difference between CopyMemory inside a tlb and as a declaration in the module header, since they are apparently identical.

[Zvoni]

Even with LenB instead of len, nothing works with Vb6.CopyMemory.

Anyway, with the declaration in the Header, everything works fine and this is the solution I adopted. However I was interested to understand why this huge difference between CopyMemory inside a tlb and as a declaration in the module header, since they are apparently identical.

Now you are contradicting yourself

If I use "Vb6.CopyMemory" from Vb6.tlb, taken from VbSpeed, although it looks absolutely identical (Destination As Any, Source As Any, Length As Long), it doesn't work.
In all other cases where I use "Vb6.CopyMemory", I don't have this problem.

is the CopyMemory from the tlb now working or not?

Or is the tlb not working just for this Printer-Mess?

[fabel358]

Now you are contradicting yourself


is the CopyMemory from the tlb now working or not?

Or is the tlb not working just for this Printer-Mess?

Apparently, I was not clear enough.
Vb6.CopyMemory does NOT work only when I replace CopyMemory (with declaration in Header) inside the module "modCOMDLG32.bas". Everywhere I've used it, it works fine. Read the first post (#1)... Clear now?

[Zvoni]

Apparently I was not clear enough.
Vb6.CopyMemory does NOT work only when I replace CopyMemory (with declaration in Header) inside the module "modCOMDLG32.bas". Everywhere I've used it it works fine. Read the first post (#1)... Clear now?

No
From first Post

In all other cases where I use "Vb6.CopyMemory", I don't have this problem.

Meaning: You DO USE vb6.CopyMemory (from the TLB) and it works for all OTHER cases
At least i read it like that

[fabel358]

No
From first Post

[/B][/COLOR]

Meaning: You DO USE vb6.CopyMemory (from the TLB) and it works for all OTHER cases
At least i read it like that

Exactly. So? What was unclear?
The problem is only for modCOMDLG32.bas which works with CopyMemory declared in Header and doesn't work with Vb6.CopyMemory.

[VanGoghGaming]

You haven't posted the actual code where you used these CopyMemory functions. If you used them to manipulate strings then the proper usage is to supply "StrPtr(string)" instead of the actual string variable. Then both declarations of CopyMemory will work identically.

[fabel358]

You haven't posted the actual code where you used these CopyMemory functions. If you used them to manipulate strings then the proper usage is to supply "StrPtr(string)" instead of the actual string variable. Then both declarations of CopyMemory will work identically.

Not so: I provided the bas module, I provided Vb6.tlb. Just replace, for example in ShowPrinter, CopyMemory with Vb6.CopyMemory and it turns out that with CopyMemory declared in Header, the printer prints, replacing with Vb6.Copymemory the printer does not print. Apparently Vb6.CopyMemory and CopyMemory about data entry and yet one works, the other does not.
What I asked was whether anyone had the same problem that I encountered or not. Maybe no one has ever used a tlb with CopyMemory in an application?

In a Form:

Option Explicit


Private Sub Form_Load()
   Dim Max              As Integer
   Dim Min              As Integer
   Dim Fasc             As Boolean
   Dim Orient           As Integer
   Dim SelPaper         As Integer
   Dim FlagSeg          As Long
   Dim Printer1         As String
   Dim StFromPage       As Integer
   Dim StToPage         As Integer
   Dim StCopies         As Integer

   On Error Resume Next

   StFromPage = 1
   StToPage = 1
   StCopies = 1
   Max = 1
   Min = 1
   StFromPage = Min

   StToPage = Max
   Fasc = True
   Orient = 1
   SelPaper = 1
   FlagSeg = FlagSeg Or PD_HIDEPRINTTOFILE Or PD_NOSELECTION Or _
       PD_USEDEVMODECOPIES Or PD_RETURNDC Or PD_CURRENTPAGE

   If CD_ShowPrinter(hWnd, FlagSeg, Printer1, StFromPage, StToPage, Min, Max, _
       StCopies, , Orient, SelPaper, , , , Fasc) Then
      Err.Clear
   Else
      Err.Raise CDLCANCEL
   End If
End Sub

[VanGoghGaming]

Yeah I've seen it and it was as expected, you are copying stuff into UDTs which contain String members. In this case there is indeed a difference between CopyMemory declared in a TLB vs CopyMemory declared in code.

[fabel358]

Yeah I've seen it and it was as expected, you are copying stuff into UDTs which contain String members. In this case there is indeed a difference between CopyMemory declared in a TLB vs CopyMemory declared in code.

Huh? According to this interpretation, copying "UDTs" with "header's CopyMemory" copies not only the pointers to the strings, but also the strings? instead in ".tlb" the pointer to the strings is copied but not the strings?
I had obviously realized that there were differences between Header's CopyMemory and in a ".tlb". I'm curious to understand "why"...

[VanGoghGaming]

The solution is very simple, do NOT use String members in UDTs!

Replace variable-length strings with "Long" and fixed-length strings with byte arrays. Then you won't encounter these types of problems anymore!

[wqweto]

The solution is very simple, do NOT use String members in UDTs!

Replace variable-length strings with "Long" and fixed-length strings with byte arrays. Then you won't encounter these types of problems anymore!

And can use LenB everywhere to get correct sizes on UDTs (incl. correct padding) i.e. matching SDK structs.

cheers,
</wqw>

[fabel358]

The solution is very simple, do NOT use String members in UDTs!

Replace variable-length strings with "Long" and fixed-length strings with byte arrays. Then you won't encounter these types of problems anymore!

For example

Public Type LOGFONT
    lfHeight             As Long            ' Specifies the height, in logical units, of the font’s character cell or character
    lfWidth              As Long            ' Specifies the average width, in logical units, of characters in the font
    lfEscapement         As Long            ' Specifies the angle, in tenths of degrees, between the escapement vector and the x-axis of the device. The escapement vector is parallel to the base line of a row of text
    lfOrientation        As Long            ' Specifies the angle, in tenths of degrees, between each character’s base line and the x-axis of the device
    lfWeight             As Long            ' Specifies the weight of the font in the range 0 through 1000 (See Constants)
    lfItalic             As Byte            ' Specifies an italic font if set to TRUE (1)
    lfUnderline          As Byte            ' Specifies an underlined font if set to TRUE (1)
    lfStrikeOut          As Byte            ' Specifies a strikeout font if set to TRUE (1)
    lfCharSet            As Byte            ' Specifies the character set (See Constants)
    lfOutPrecision       As Byte            ' Specifies the output precision. The output precision defines how closely the output must match the requested font’s height, width, character orientation, escapement, pitch, and font type (See Constants)
    lfClipPrecision      As Byte            ' Specifies the clipping precision. The clipping precision defines how to clip characters that are partially outside the clipping region
    lfQuality            As Byte            ' Specifies the output quality. The output quality defines how carefully the graphics device interface (GDI) must attempt to match the logical-font attributes to those of an actual physical font (See Constants)
    lfPitchAndFamily     As Byte            ' Specifies the pitch and family of the font. The two low-order bits specify the pitch of the font (See Constants) - Bits 4 through 7 of the member specify the font family (See Constants)
    lfFaceName           As String * 31     ' A null-terminated string that specifies the typeface name of the font. The length of this string must not exceed 32 characters, including the null terminator. The EnumFontFamilies function can be used to enumerate the typeface names of all currently available fonts. If lfFaceName is an empty string, GDI uses the first font that matches the other specified attributes.
End Type

Somenthing like this?

Public Type LOGFONT
    lfHeight             As Long            ' Specifies the height, in logical units, of the font’s character cell or character
    lfWidth              As Long            ' Specifies the average width, in logical units, of characters in the font
    lfEscapement         As Long            ' Specifies the angle, in tenths of degrees, between the escapement vector and the x-axis of the device. The escapement vector is parallel to the base line of a row of text
    lfOrientation        As Long            ' Specifies the angle, in tenths of degrees, between each character’s base line and the x-axis of the device
    lfWeight             As Long            ' Specifies the weight of the font in the range 0 through 1000 (See Constants)
    lfItalic             As Byte            ' Specifies an italic font if set to TRUE (1)
    lfUnderline          As Byte            ' Specifies an underlined font if set to TRUE (1)
    lfStrikeOut          As Byte            ' Specifies a strikeout font if set to TRUE (1)
    lfCharSet            As Byte            ' Specifies the character set (See Constants)
    lfOutPrecision       As Byte            ' Specifies the output precision. The output precision defines how closely the output must match the requested font’s height, width, character orientation, escapement, pitch, and font type (See Constants)
    lfClipPrecision      As Byte            ' Specifies the clipping precision. The clipping precision defines how to clip characters that are partially outside the clipping region
    lfQuality            As Byte            ' Specifies the output quality. The output quality defines how carefully the graphics device interface (GDI) must attempt to match the logical-font attributes to those of an actual physical font (See Constants)
    lfPitchAndFamily     As Byte            ' Specifies the pitch and family of the font. The two low-order bits specify the pitch of the font (See Constants) - Bits 4 through 7 of the member specify the font family (See Constants)
    lfFaceName(31)       As Byte            ' A null-terminated string that specifies the typeface name of the font. The length of this string must not exceed 32 characters, including the null terminator. The EnumFontFamilies function can be used to enumerate the typeface names of all currently available fonts. If lfFaceName is an empty string, GDI uses the first font that matches the other specified attributes.
End Type

[VanGoghGaming]

lfFaceName(31)       As Integer
' or
lfFaceName(63)       As Byte

A character in a string counts as two bytes.

[wqweto]

> Somenthing like this?

Depends if you are implementing LOGFONTA struct or LOGFONTW struct. There is no LOGFONT actually, the way there is no spoon.

cheers,
</wqw>

[fabel358]

lfFaceName(31)       As Integer
' or
lfFaceName(63)       As Byte

A character in a string counts as two bytes.

Yep. My mistake.