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API在VB中应用之技巧集锦
API函数在VB中得到了充分的运用，同时也让无数VB爱好者沉溺于其中。以下是笔者几年来收集整理的几十个API函数在VB中应用的实例，现在写出来与大伙分享，希望能对大伙有所帮助。
1、如何让窗体总在最前面？
*API函数声明
Declare Function SetWindowPos Lib "user32" ( ByVal hwnd As Long, ByVal hWndInsertAfter As Long, ByVal x As Long, ByVal y As Long, ByVal cx As Long, ByVal cy As Long, ByVal wFlags As Long) As Long
注释：常量声明
Private Const SWP_NOSIZE = &H1
Private Const SWP_NOMOVE = &H2
Private Const HWND_TOPMOST = -1
Private Const HWND_NOTOPMOST = -2
注释： 在某个form里写：
SetWindowPos me.hWnd,WND_TOPMOST,0,0,0,0, SWP_NOMOVE 注释：或下面
SetWindowPos me.hWnd,WND_TOPMOST,0,0,0,0, SWP_NOSIZE
2、使用API函数sendmessage，获得光标所在行和列。
Sub getcaretpos(byval TextHwnd&,LineNo&,ColNo&)
注释：TextHwnd为TextBox的hWnd属性值， LineNo为所在行数，ColNo为列数
dim i&,j&,k& 注释：获取起始位置到光标所在位置字节数 i=SendMessage(TextHwnd,&HB0&,0,0) j=i/2^16 注释：确定所在行 LineNo=SendMessage(TextHwnd,&HC9&,j,0)+1
注释：确定所在列
k=SendMessage(TextHwnd,&HBB&,-1,0)
ColNo=j-k+1
End sub
3、如何以某种颜色填充某区域？
*API函数声明
Private Declare Sub FloodFill Lib "gdi32" _ (ByVal hDC As Long, ByVal X As Long, ByVal Y As _ Long, ByVal crColor As Long
注释：设(fillx,filly)为此区域内任一点
注释：Color为某种颜色
FloodFill Picture1.hDC, fillx, filly,Color
4、如何关闭计算机？
*API函数声明
Declare Function ExitWindows Lib "User" (ByVal dwReturnCode As Long, ByVal wReserved As Integer) As Integer
注释：执行
Dim DUMMY
DUMMY=ExitWindows(0，0)
5、如何获取Windows目录和System目录？
注释：复制以下代码到一模块中
Public Declare Function GetWindowsDirectory Lib "kernel32" Alias "GetWindowsDirectoryA" (ByVal lpBuffer As String, ByVal nSize As Long) As Long
Public Declare Function GetSystemDirectory Lib "kernel32" Alias "GetSystemDirectoryA" (ByVal lpBuffer As String, ByVal nSize As Long) As Long
注释：在程序中调用
Dim WindowsDirectory As String, SystemDirectory As String, x As Long
WindowsDirectory = Space(255)
SystemDirectory = Space(255)
x = GetWindowsDirectory(WindowsDirectory, 255)
x = GetSystemDirectory(SystemDirectory, 255)
MsgBox "Windows的安装目录是:" + WindowsDirectory+",系统目录是:" + SystemDirectory
6、如何建立简单的超级连接？
*API函数声明
Private Declare Function ShellExecute Lib "shell32.dll" Alias "ShellExecute A" (ByVal hWnd As Long, ByVal lpOperation As String, ByVal lpFile As String, ByVal lpParameters As String, ByVal lpDirectory As String, ByVal nShowCmd A s Long) As Long
注释：打开某个网址
ShellExecute 0, "open", "http://tyvb.126.com", vbNullString, vbNullString, 3
注释：给某个信箱发电子邮件
ShellExecute hwnd, "open", "mailto:sst95@21cn.com", vbNullString, vbNullString, 0
7、如何得知TextBox中文字所有的行数？
*API函数声明
Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
Public Const EM_GETLINECOUNT = &HBA
注释：在程序中调用
LineCnt = SendMessage(ctl.hwnd, EM_GETLINECOUNT, 0, 0)
注释：LineCnt即为此TextBox的行数。
8、如何设置ListBox的水平卷动轴的宽度？
*API函数声明
Const LB_SETHORIZONTALEXTENT = &H194
Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" _ (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, _ lParam As Any) As Long
注释：调用
Call SendMessage(List1.hwnd, LB_SETHORIZONTALEXTENT, 400, ByVal 0&)
注释：注意400是以象素为单位，你可以根据情况自行设定。
9、如何交换鼠标按键？
*API函数声明
Declare Function SwapMouseButton& Lib "user32" _ (ByVal bSwap as long)
要交换鼠标按键，将bSwap参数设置为True。要恢复正常设置，将bSwap设置为False。 然后调用函数就可以交换和恢复鼠标按键了。
10、如何让窗体的标题条闪烁以引起用户注意？
在窗体中放一个Timer控件Timer1,设置其Inteval=200
*API函数声明
Private Declare Function FlashWindow Lib "user32" (ByVal hwnd As Long, ByVal bInvert As Long) As Long
注释：在窗体中写下如下代码:
Private Sub Timer1_Timer()
FlashWindow Me.hwnd, True
End Sub
11、怎样找到鼠标指针的XY坐标？
*API函数声明
Type POINTAPI
x As Long
y As Long
End Type
Declare Function GetCursorPos Lib "user32" (lpPoint As POINTAPI) As Long
调用：
GetCursorPos z
print z.x
print z.y
12、怎样获得和改变双击鼠标的时间间隔？
获得鼠标双击间隔时间：
Public Declare Function GetDoubleClickTime Lib "user32" Alias _ "GetDoubleClickTime" () As Long
获得鼠标双击间隔时间：
Declare Function SetDoubleClickTime Lib "user32" Alias "SetDoubleClickTime" (ByVal wCount As Long) As Long
注释：注意：这种改变将影响到整个操作系统
以上两个函数都可精确到毫秒级。
13、在程序中如何打开和关闭光驱门？
*API函数声明如下:
Private Declare Function mciSendString Lib "winmm.dll" Alias "mciSendStringA" (ByVal lpstrCommand As String, ByVal lpstrReturnString As String, ByVal uReturnLength As Long, ByVal hwndCallback As Long) As Long
注释：调用时的代码如下
Dim Ret As Long
Dim RetStr As String
注释：打开光驱门
Ret = mciSendString("set CDAudio door open", RetStr, 0, 0)
注释：关闭光驱门
Ret = mciSendString("set CDAudio door closed", RetStr, 0, 0)
14、如何获得Windows启动方式?
在Form1中加入一个CommandButton、一个Label并加入如下代码:
Private Declare Function GetSystemMetrics Lib "user32" (ByVal nIndex As Long) As Long
Const SM_CLEANBOOT = 67
Private Sub Command1_Click()
Select Case GetSystemMetrics(SM_CLEANBOOT)
Case 1
Label1 = "安全模式."
Case 2
Label1 = "支持网络的安全模式."
Case Else
Label1 = "Windows运行在普通模式."
End Select
End Sub
15、怎样使Ctrl-Alt-Delete无效？
*API函数声明
Private Declare Function SystemParametersInfo Lib "user32" Alias "SystemParametersInfoA" (ByVal uAction As Long, ByVal uParam As Long, ByVal lpvParam As Any, ByVal fuWinIni As Long) As Long
编写如下函数：
Sub DisableCtrlAltDelete(bDisabled As Boolean)
Dim X As Long
X = SystemParametersInfo(97, bDisabled, CStr(1), 0)
End Sub
使Ctrl-Alt-Delete无效 ：
Call DisableCtrlAltDelete(True)
恢复Ctrl-Alt-Delete ：
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