;H20000
Const STANDARD_RIGHTS_READ = (READ_CONTROL)
Const KEY_QUERY_VALUE = &H1
Const KEY_ENUMERATE_SUB_KEYS = &H8
Const KEY_NOTIFY = &H10
Const SYNCHRONIZE = &H100000
Const KEY_READ = ((STANDARD_RIGHTS_READ Or _
KEY_QUERY_VALUE Or KEY_ENUMERATE_SUB_KEYS Or _
KEY_NOTIFY) And (Not SYNCHRONIZE))
Dim key5 As String, ValueName as String, strBuff as String, ResultStr as String
Dim leng1 As Long, resul As Long, hkey As Long
Dim tp As Long, i As Long
key5 = " SOFTWARE\Microsoft\Windows\CurrentVerson "
resul = RegOpenKeyEx(HKEY_CLASSES_ROOT, key5, 0, KEY_READ, hkey)
''''hkey便是subkey (key5)的KeyHandle，先取得它才能存取Subkey内的ValueName
ValueName= "ProDuctId "
tp = REG_SZ
strBuff = String(255, 0)
leng1 = Len(strBuff) + 1
resul = RegQueryString(hkey, ValueName, 0, tp, strBuff, leng1)
''''注意，第三个参数传0，leng1传回copy 到strBuff的字元个数(anci)
leng1 = InStr(1, strBuff, Chr(0), vbBinaryCompare) ''''重新算个数(UniCode)
ResultStr = Left(StrBuff,leng1-1) ''''这便是ProductId的值
*****************************************************************************
在这里有另外一件事要特别说明，范例三程式中有一行leng1=Len(strBuffer)+1，
这行可省不得，很奇怪吧，为什麽明明是一个传回值，却一定要设定给它一个strBuff
的大小呢？这是因为许多WIN API 不会聪明到找strBuff的Null Char在哪里，所以需要
程式传进去，而後它再依这个栏位传回填入strBuff 的数目。
五、Array参数的传递
我们知道Win API 的阵列传递是传阵列的起始位址，所以了，在VB中唯一要注意的
是起始位置的写法。以另一个取得Window目录所在路径的API为
例：
-----------------------------------------------------------------------------
UINT GetWindowsDirectory(
LPTSTR lpBuffer, // address of buffer for Windows directory
UINT uSize // size of directory buffer
); // 若成功，则传回目录的字元数
VB的宣告(API检视员)
Declare Function GetWindowsDirectory Lib "kernel32" Alias _
"GetWindowsDirectoryA" (ByVal lpBuffer As String, ByVal nSize As Long) _
As Long
我们将之更改为
Declare Function GetWindowsDirectory Lib "kernel32" Alias _
"GetWindowsDirectoryA" ( lpBuffer As Byte, ByVal nSize As Long) As Long
-----------------------------------------------------------------------------
范例四
*****************************************************************************
Dim n as Long
Dim Buff() as Byte
Dim StrA as String
Buff = space(256)
n=GetWindowsDirectory(Buff(0), 256)
Buff = Leftb(Buff, n)
StrA = StrConv(Buff, vbUniCode) ''''StrA便是Windows所在目录
*****************************************************************************
在范例四中，GetWindowsDirectory()传入的第一个参数Buff(0)便是这阵列的起始
Byte ，因VB 宣告成lpBuffer As Byte，故传过去的是ByRef Buff(0)的位址，当然了
，你也可以呼叫成n=GetWindowsDirectory(Buff(1), 256)，只是传回值是填在Buff(1)
to Buff(n)，而Buff(0)则仍为起始的Space Character(32)，因为该API传回值是字
元个数，再加上存於Buff中的是Byte Array故，使用Leftb()去除多出的byte，再用
StrConv将Byte Array转成Unicode的字串。比照范例二的作法，我们也可以将Byte
Array 改成以String的方式来做，二者可做一比较，谁比较好或比较顺畅，那见人见智
，不过可以肯定的是，如果传的值是Binary的值，那麽使用Byte Array来做才对，因用
String来传的话，会经过转换成UniCode的步骤，这中间会发生什麽事，没人知道。
六、CallBack Function的作法
VB的使用者通常对於这个名词有著多多少少的疑惑，或称之为"哭爸"Function，而
VB5使用手册使用Window Procedure来说明，除非对Window 系统有一些了解，否则可能
令人更不知所云；我使用另一个例子来说明，那便是KeyBoard Hook。什麽是KeyBoard
Hook 呢，简言之便是按键盘时，便会自动执行某一段Function的功能，就好比Dos时代
的拦截中断向量一般。让我们先看一下设定Hook的宣告吧。
-----------------------------------------------------------------------------
HHOOK SetWindowsHookEx(
int idHook, // type of hook to install
HOOKPROC hkprc, // address of hook procedure
HINSTANCE hMod, // handle of application instance
DWORD dwThreadID // identity of thread to install hook for
);
Declare Function SetWindowsHookEx Lib "user32" Alias SetWindowsHookExA" _
(ByVal idHook As Long, _
ByVal lpfn As Long, _
ByVal hmod As Long, _
ByVal dwThreadId As Long) As Long
-----------------------------------------------------------------------------
Hook有很多种，如KeyBoard Hook, Mouse Hook, JournalRecord Hook等，所以第
一个参数指明了要哪一种Hook，第二个参数便是Hook Procedure所在，也就是方才所说
"自动执行某一段Function的功能"中的那一个Function，这个Function的名称可以随意
给定，但有一定的参数传递规则，例如：
hnexthookproc = SetWindowsHookEx(WH_KEYBOARD, _
AddressOf MyKBHFunc, App.Hinstance, 0)
如此设定则每当按任一个键时，程式自动会去执行 MyKBHFunc。这个Hook Function
是由我们所定义，但是它是由Window自动去呼叫，而不是由我们的程式呼叫，这类的
Function就叫CallBack Function。
以上面的例子来说，这个CallBack Function定义如下：
-----------------------------------------------------------------------------
Public Function MyKBHFunc(ByVal iCode As Long, _
ByVal wParam As Long, ByVal lParam As Long) As Long
MyKBHFunc = 0
If iCode < 0 Then
MyKBHFunc = CallNextHookEx(hnexthookproc, iCode, wParam, lParam)
Exit Function
End If
''''侦测 有没有按到PrintScreen键
If wParam = vbKeySnapshot Then
MyKBHFunc = 1
Debug.Print "haha"
End If
End Function
-----------------------------------------------------------------------------
这个KeyBoard Hook Function的目的主要是想拦截有没有按到Print Screen这个键
，这个键不会在Form的KeyDown, KeyPress, KeyUp Event中作用，所以只好透过KeyBoa
rd Hook去拦截。而CallBack Function放的位置有规定，一个是要与呼叫SetWindowsHo
okEx() 的地方在同样的一个Project，另外，它只能存在於.BAS档，不能放在其他地方
。KeyBoard Hook的程式於范五。
范例五
*****************************************************************************
''''以下程式於Hook.bas
Declare Function SetWindowsHookEx Lib "user32" Alias _
"SetWindowsHookExA" (ByVal idHook As Long, ByVal lpfn As Long, _
ByVal hmod As Long, ByVal dwThreadId As Long) As Long
Declare Function UnhookWindowsHookEx Lib "user32" _
(ByVal hHook As Long) As Long
Declare Function CallNextHookEx Lib "user32" (ByVal hHook As Long, _
ByVal ncode As Long, ByVal wParam As Long, lParam As Any) As Long
Public hnexthookproc As Long
Public Const HC_ACTION = 0
Public Const WH_KEYBOARD = 2
Public Sub UnHookKBD()
If hnexthookproc 0 Then
UnhookWindowsHookEx hnexthookproc
hnexthookproc = 0
End If
End Sub
Public Function EnableKBDHook()
If hnexthookproc 0 Then
Exit Function
End If
hnexthookproc = SetWindowsHookEx(WH_KEYBOARD, AddressOf _
MyKBHFunc, App.Hinstance, 0)
If hnexthookproc 0 Then
EnableKBDHook = hnexthookproc
End If
End Function
Public Function MyKBHFunc(ByVal iCode As Long, _
ByVal wParam As Long, ByVal lParam As Long) As Long
''''这三个参数是固定的，不能动，而MyKBHFunc这个名称只要和
''''SetWindowsHookex()中 AddressOf後的名称一样便可，不一定叫什麽
MyKBHFunc = 0
If iCode < 0 Then
MyKBHFunc = CallNextHookEx(hnexthookproc, iCode, wParam, lParam)
Exit Function
End If
If wParam = vbKeySnapshot Then ''''侦测 有没有按到PrintScreen键
MyKBHFunc = 1
Debug.Print "haha"
End If
End Function
''''以下程式於Form
Private Sub Form_Load()
Call EnableKBDHook
End Sub
Private Sub Form_Unload(Cancel As Integer)
Call UnHookKBD
End Sub
*****************************************************************************
七、自订型态的传递
因这只要用ByRef的方式来做就没有什麽大的问题，故不做说明。
八、综合应用
我们再以一个实例来说明Win API在VB5中呼叫的技巧。有一个函式叫CopyMemory
的宣告如下：
-----------------------------------------------------------------------------
Declare Sub CopyMemory Lib "KERNEL32" Alias "RtlMoveMemory" ( _
lpvDest As Any, lpvSource As Any, ByVal cbCopy as Long)
-----------------------------------------------------------------------------
这个函式可以将 lpvDest的momory copy 到lpvSource上去，cbCopy则代表要copy
多少个byte。有了这个函式，我们可以知道一个Double值存在Memory中的各个byte到底
是多少。
-----------------------------------------------------------------------------
Dim dbl as Double
Dim bte(0 to 7) as Byte
Dbl = 168.256
CopyMemory dbl, byt(0), 8
-----------------------------------------------------------------------------
如此检视bte阵列便可以知道这Double值的各个byte是多少。再以另一个
JournalRecord Hook为例来说明：
范例六
*****************************************************************************
'''' 以下在Hook.bas
Const WM_MOUSELAST = &H209
Const WM_MOUSEFIRST = &H200
Public Const WM_KEYLAST = &H108
Public Const WM_KEYFIRST = &H100
Public Const WH_JOURNALRECORD = 0
Type EVENTMSG
message As Long
paramL As Long
paramH As Long
time As Long
hwnd As Long
End Type
Declare Function SetWindowsHookEx Lib "user32" Alias _
"SetWindowsHookExA" (ByVal idHook As Long, ByVal lpfn As Long, _
ByVal hmod As Long, ByVal dwThreadId As Long) As Long
Declare Function UnhookWindowsHookEx Lib "user32" _
(ByVal hHook As Long) As Long
Declare Function CallNextHookEx Lib "user32" (ByVal hHook As Long, _
ByVal nCode As Long, ByVal wParam As Long, lParam As Any) As Long
Declare Sub CopyMemory Lib "KERNEL32" Alias "RtlMoveMemory" _
(lpvDest As Any, ByVal lpvSource As Long, ByVal cbCopy As Long)
Public hNxtHook As Long '''' handle of Hook Procedure
Public msg As EVENTMSG
Sub EnableHook()
hNxtHook = SetWindowsHookEx(0, AddressOf HookProc, App.hInstance, 0)
End Sub
Sub FreeHook()
Dim ret As Long
ret = UnhookWindowsHookEx(hNxtHook)
End Sub
Function HookProc(ByVal code As Long, ByVal wParam As Long, _
ByVal lParam As Long) As Long
CopyMemory msg, lParam, Lenb(msg)
If (msg.message >= WM_KEYFIRST _
And msg.message <= WM_KEYLAST) Then
Debug.Print msg.message, msg.paramH
End If
HookProc = CallNextHookEx(hNxtHook, code, wParam, lParam)
End Function
''''以下程式於Form1
Private Sub Form_Load()
Call EnableHook
End Sub
Private Sub Form_Unload(Cancel As Integer)
Call FreeHook
End Sub
*****************************************************************************
详细的流程不多做说明，我们只把重点放在HookProc这个Hook Procedure，如果我
们查JournalRecord Hook的Hook Procedure可得定义如下：
-----------------------------------------------------------------------------
LRESULT CALLBACK JournalRecordProc(
int code, // hook code
WPARAM wParam, // undefined
LPARAM lParam // 为一个EVENTMSG Structure的address值
);
这个JournalRecordProc 对应到我们的HookProc便是
Function HookProc(ByVal code As Long, ByVal wParam As Long, _
ByVal lParam As Long) As Long
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