WaveMix Update:
Question:
Is there in existence a version of the WAVEMIX DLL that is capable of merging two (or
more) 16 bit stereo sound samples.
Answer:
Regarding the WAVEMIX issue, it is what it is. As far as I know there is only one version
of WAVEMIX and it works as advertised. For better sound mixing capabilities look to the
future: DirectSound, part of the Game SDK.
Chapter 7.9 problem:
The fix to chapter 7.9 is in the EXECICON.CLS class file, in the PaintIcons routine. The
code should be changed in text-code in the book and in the class file. Two lines need to
be changed as marked below:
Private Sub PaintIcons(i As Integer, Optional c As Variant)
'
' Limit the number of icons to paint to a single icon if the
' calling routine didn't set a limit. Otherwise limit it to
' the number requested or the number that will fit in the
' container, whichever is less.
'
Dim IconLimit As Integer
If IsMissing(c) Then
IconLimit = i
Else
If c > m_Container.ScaleWidth \ 32 Then
IconLimit = i + m_Container.ScaleWidth \ 32
Else
IconLimit = c
End If
End If
'
' And finally, paint one or more icons into the container!
' For each icon to be painted, extract the icon handle. Then
' draw it into the container starting at the left (0) edge of
' the container and always aligning at the top (0) edge.
'
' * Replace these two lines
Dim IconIndex As Integer
Dim hIcon As Integer
' * With these two lines
Dim IconIndex As Long
Dim hIcon As Long
For IconIndex = i To IconLimit
DrawIcon m_Container.hDC, (IconIndex - i) * 32, 0, hIcon
DestroyIcon hIcon
Next IconIndex
End Sub
Chapter 1 problems:
How To 1-5, P.20, Step 5
Change: "Add the following code to the General Section of
Form1."
To: "Add the following code to the General Section of cGen."
How To 1-5, P.21, Step 10
Change: "Use the Insert Class Module menu item to insert a new module called
Module 1."
To: "Use the Insert Module menu item to insert a new module called
Module1."
Note: Remove space between "Module" and "1".
How To 1-6, P.34, Step 4
Change:
Randomize
Option1_Click (0)
Picture1.ScaleMode = 3 ' Switch to Pixel mode
To:
Private Sub Form_Load()
Randomize
Option1_Click (0)
Picture1.ScaleMode = 3 ' Switch to Pixel mode
How To 1-6, P.38
Change: "Sprite(n). MoveTo X,Y"
To: "Sprite(n).MoveTo X, Y"
The following function can be used to copy data-structures passed in lParam:
Private Declare Sub CopyMemory Lib "Kernel32" _
Alias "RtlMoveMemory" (dst As Any, src As Any, _
ByVal SIZE As Long)
The action variable is still used.
The result variable is still used as it was before, to set the value returned from the
control to windows as the result of sending the message.
MsgHook.vbx Causing GPF
Problem:
Using msghook.vbx to hook messages to a control of an application other than the one
containing the hook could cause a general protection fault.
To clarify, assume HOOK is the program that I use to initialize the msghook.Test is the
program that I am observing. When I set the msghook.HwndHook property and move the mouse
over the object that I have hooked, a GPF error occurs as soon as that object has focus.
Solution:
MsgHook cannot be used to hook windows belonging to applications other than the one owning
the MsgHook control.
Auto3D Property:
Question:
There doesn't seem to be a "Auto 3D" form property.
Answer:
This is true. Late in the beta the Auto 3D property was replaced with Appearance which can
have the values 0 - Flat or 1 - 3D.
Class Instancing Properties:
Question:
Also, in the class modules there is an instancing property which has three(3)
possibilities and no Creatable property as indicated in the text.
Author's response:
There are lots of class modules and I have no idea which ones he's talking about. Here's
what the help file says:
The Instancing property has these settings:
| Setting |
Description |
| 0 - Not Creatable
(Default) |
You can create instances of the class
inside the project only. |
| 1 - Creatable SingleUse |
You can create instances of the class
both inside and outside the project. Each request for an instance of the class by an OLE
client outside the project causes a separate copy of the OLE server to be started. |
| 2 - Creatable MultiUse |
You can create instances of the class
both inside and outside the project. Requests for an instance of the class by an OLE
client outside the project will be supplied by an already running copy of the OLE server,
if any. If there are no copies of the OLE server running, a copy is started to supply the
class. |
Remarks
When a class is creatable, you can use any of the following techniques to create instances
of the class from other applications: Use the CreateObject function, as in:
Set MyInstance = CreateObject("MyProject.MyClass")
Use the Dim statement within the
same project (or outside the project if the Public property is also set to True), as in:
Dim MyInstance As New MyClass
|
If the Public property is False, the setting of the Instancing property is ignored. You
can always create instances of the class within the project that defines the class. If the
Public property is True, the class is visible and therefore can be controlled by other
applications once an instance of the class exists.
Runtime DLLs:
We struggled long and hard to avoid the runtime dll problem, to no avail. At the time I
built the final versions MS had built controls for the release version of VB4 using a
version of VC/MFC4.0 which was not, and never will be, available outside of MS ... so we
couldn't use the dlls that shipped with VB4.
And, we couldn't build controls using the release version of MFC 4.0 since it wasn't
released yet.
So, we did what major control vendors did: we used MFC3.0 and its runtime libs. If we
were to rebuild now then users would have to ship new MFC4 dlls, the size would probably
be somewhat greater because of this.
There is no getting around this problem, that's they way VB4 is. Crescent and
Microhelp, for instance, have the same problem we do and require the programmer to ship
the exact same large dlls we require.
Problem with How To 7.1 on NT 3.51:
Question:
I have run the example 7.1 on Windows 95 without any problems, but when I run the
same project on Win NT 3.51 ( service pack 3 loaded ) , a job does not appear in the print
manager. The program does not error. The machine I tested on is a dual boot machine.
Solution:
Yep, Microsoft changed things on us! This HT did work as written in NT 3.5, but it seems
that in NT 3.51 and in Win95 the behavior of Both this HT (2.1), and the one about
floating toolbars (2.4) use SetWindowWord to make one form the parent of another. In both,
all references to "SetWindowWord" need to be modified to
"SetWindowLong" (and references to "GWW_HWNDPARENT" need to be changed
to "GWL_HWNDPARENT". A new declaration and constant are also required:
Declare Function SetWindowLong Lib "user32" Alias _
"SetWindowLongA" (ByVal hwnd As Long, ByVal nIndex
As Long, ByVal dwNewLong As Long) As Long
Const GWL_HWNDPARENT = (-8)
If either of these was preceeded by Public or Private, those designations need to
remain the same.
How To 7.1 - Missing ByVal:
Problem:
I have run the example 7.1 on Windows 95 without any problems, but when I run the same
project on Win NT 3.51 (service pack 3 loaded) , a job does not appear in the print
manager.
Solution:
Turns out there's a simple fix. Add a ByVal to the OpenPrinter call in the
SpoolFileNow routine (in Spool.Bas). It should look like this:
Call OpenPrinter(PrnName, hPrinter, ByVal vbNullString)
How To 7.2 - Missing ByVal:
Problem:
I discovered a minor error in the INI file program 7-2 caused by how the Win32 API calls
for WritePrivateProfileString are declaired. The BYVAL was omitted in the data string.
This omission makes it impossible to set values in INI files using the Win32 API.
Solution:
This isn't an error, per se. The ByVal can also be used in the call line, if it's omited
from the declaration. James wrote this HT, and looking at the code, I see the reader is
correct. As written, it won't work. The reader's suggested change would indeed be the
correct one.
How To 7.3 is 32-bit Only:
The reality is, GetWindowThreadProcessId doesn't exist in Win16. However, I did cover
this topic in my Sept '95 VBPJ Programming Techniques column. Here's the
heart of the solution:
Function GetHWndByInst (hInstFind%) As Integer
Dim hWndTmp%
'
' Find first window and loop through all subsequent
' windows in master window list.
'
hWndTmp = FindWindow(0&, 0&)
Do Until hWndTmp = 0
'
' Make sure this window has no parent.
'
If GetParent(hWndTmp) = 0 Then
'
' Compare passed hInst against this window's hInst.
' If a match, then return hWnd for current window.
'
If hInstFind% = GetWindowWord(hWndTmp, GWW_HINSTANCE) Then
GetHWndByInst = hWndTmp
Exit Do
End If
End If
'
' Get next window in master window list and continue.
'
hWndTmp = GetWindow(hWndTmp, GW_HWNDNEXT)
Loop
End Function
DLL Synch Question:
On the CD that comes with our book Visual Basic 4 How-To, we included some controls
created by one of the authors. As I understand it, at the very last minute we discovered
that there were some library DLL synchronization problems between the version of VC++ used
to build VB4 and the version we used to build the controls, so we told people that they
had to be sure that the OC30.DLL used to build the controls is placed in their
WINDOWS/SYSTEM folder. If the OC30.DLL file is missing, the controls won't register, and
the projects that run them won't run properly.
We've been receiving some complaints from people about having to put the OC30.DLL into
their WINDOWS/SYSTEM folder. My question is, do they still need to do this or has the
VC++/VB4 synchronization problem been fixed?
Here is your answer.
It has nothing to do with VB/VC. It depends on which version of VC the controls were
built with. If controls were built with VC 2.x, then they will need OC30.DLL. If the
controls were built with VC 4.0, then they will need MFC40.DLL. VB4 ships with MFC40, but
they should ship their own version, since the one that ships with VB4 is not the final
version that shipped with VC 4.0.
VB 4 returns an error code of 20000:
Problem:
I'm trying to run the first lesson that involves the use of Crystal Reports for
printing records from a database.
However, the 16-bit version of AUTHORS.VBP that came on the CD with the book generates
an error when I try to run the application. It accepts the two dates okay and calls the
open report dialog box okay, but after I choose the Authors.rpt and press the OK button,
Visual Basic 4 returns an error.
When I typed "error 20000" in the debug window, VB 4 deciphered it as an
application-defined or object-defined error.
The program actually stops on the line of code that says:
CrystalReport1.Action = 1
Solution:
This problem is a function of Crystal's relative inflexibility with a database's location,
and particularly how hard they make it to change a database location. The file uses
c:\vb\biblio.mdb. If this isn't the directory where the file is located, it'll have to be
changed in the ..rpt file. This should clear up the problem. On pages 781-2, the hProcess
and hProcessCur variables should be declared as Long, not Integer.
Operator Error:
Problem:
My problem is with an error message that I'm getting in section 1.3 on some code
found on page 12 (a number generator). I'm getting error message 340 (Control Array does
not exist).
Here is the problem code:
Private Sub GenerateNums()
Debug.Print
For i = 0 to m_Limit
Debug.Print i;
Next i
End Sub
When I checked on Microsoft's For Developers Only Site I found a reference to the error
code and some code that appears similiar to the code found in your book. The reply to that
question was that it was somethng that designed into VB4 or was something intentional and
therefore was not correctible.
Solution:
An author suggests that you copy the code off of the CD-ROM as this generates no errors
for him. He also states that the error message you are getting isn't a valid one, thus the
suggestion to use the code from the CD. It is possible that the code from the CD and the
book don't agree, and this may also be why you are encountering problems.
NT4 Support:
Problem:
When I installed NT4.0 on my machine, some examples didn't work.
Some of these examples were 2.2 Include rollup tools in my application 2.4 Make a
floating Toolbar with a mini-title bar and 3.6 Create a more powerful Combobox
I found out that the API-Functions SetWindowWord (in 2.2 and 2.4) and SendMessage with
some Parameters(Constants like CB_Showdropdown or CB_Limittext etc.) don't work as
expected under NT 4.0.
These problems were in NT4.0 Beta1 and Beta2 too.
Solution:
On page xx in the front matter of the book, you will notice that this book was optimized
for VB 4 running on either the Windows 95 or Windows NT 3.51 operating systems. I don't
believe, given these parameters, that NT 4.0 was even a test machine during this process.
