有问到关于API的内容的。 API函数也是比较多的。这里分享几个常用的API函数。
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
！请注意你WINDOWS的版本
*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)
强制关闭计算机：用API函数ExitWindowsEx可以实现强制关机，即便是您的应用程序尚未保存文件。
Private Declare Function ExitWindowsEx Lib "user32" (ByVal uFlags As Long, ByVal dwReserved As Long) As Long
Const EWX_SHUTDOWN = 1
Const EWX_LOGOFF = 0
Const EWX_REBOOT = 2
Const EWX_FORCE = 4
Private Sub Command1_Click()
Dim a
a = ExitWindowsEx(EWX_LOGOFF or EWX_FORCE or EWX_SHUTDOWN, 0)
End Sub
如果将
a = ExitWindowsEx(EWX_LOGOFF or EWX_FORCE or EWX_SHUTDOWN, 0)
改换为
a = ExitWindowsEx(EWX_LOGOFF or EWX_REBOOT, 0)
即可实现强制重启计算机！
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 ：
Call DisableCtrlAltDelete(False)
16、如何移动没有标题栏的窗口
我们一般是用鼠标按住窗口的标题栏，然后移动窗口，当窗口没有标题栏时，我们可以用下面的方法来移动窗口：
*API函数声明：
Declare Function ReleaseCapture Lib "user32" () As Long 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 HTCAPTION = 2
Public Const WM_NCLBUTTONDOWN = &HA1
在 Form_MouseDown 事件中：
Private Sub Form_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
ReleaseCapture SendMessage hwnd, WM_NCLBUTTONDOWN, HTCAPTION,0&
End Sub
17、VB中如何使用延时函数
*API函数声明：
Declare Sub Sleep Lib "kernel32" (ByVal dwMilliseconds As Long)
调用：
注释：延时1秒
Call Sleep(1000)
18、调用修改屏幕保护口令的窗口
Private Declare Function PwdChangePassword Lib "mpr" Alias "PwdChangePasswordA" (ByVal lpcRegkeyname As String, ByVal hwnd As Long, ByVal uiReserved1 As Long, ByVal uiReserved2 As Long) As Long
调用：
Call PwdChangePassword("SCRSAVE", Me.hwnd, 0, 0)
19、使Windows开始屏幕保护
*API函数声明
Private Declare Function SendMessage Lib "user32"
Alias "SendMessageA" (ByVal hWnd As Long, ByVal wMsg
As Long, ByVal wParam As Long, ByVal lParam As Long)
As Long
Const WM_SYSCOMMAND = &H112&
Const SC_SCREENSAVE = &HF140&
注释：调用
Dim result As Long
result = SendMessage(Form1.hWnd, WM_SYSCOMMAND, SC_SCREENSAVE, 0&)
20、如何改变Windows桌面背景
*API函数声明
Const SPI_SETDESKWALLPAPER = 20
Const SPIF_UPDATEINIFILE = &H1
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
注释：调用
Call SystemParametersInfo(SPI_SETDESKWALLPAPER, 0, "C:windowsClouds.bmp", SPIF_UPDATEINIFILE)
21、怎样确定系统是否安装了声卡
*API函数声明：
Declare Function waveOutGetNumDevs Lib "winmm.dll" Alias "waveOutGetNumDevs" () As Long
代码如下：
Dim I As Integer
I = waveOutGetNumDevs()
If I > 0 Then MsgBox "你的系统可以播放声音。", vbInformation, "声卡检测"
Else
MsgBox "你的系统不能播放声音。", vbInformation, "声卡检测"
End If
22、如何找到CD-ROM驱动器的盘号
下面的函数将检查你计算机所有的驱动器看是否是 CD-ROM，如果是就返回驱动器号，如果没有就返回空字符
Public Function GetCDROMDrive() As String
Dim lType As Long,I As Integer,tmpDrive as String,found as Boolean
On Error GoTo errL
For I = 0 To 25
tmpDrive = Chr(65 + I) & ":"
lType = GetDriveType(tmpDrive) 注释：Win32 API 函数
If (lType = DRIVE_CDROM) Then 注释：Win32 API 常数
found = True
Exit For
End If
Next
If Not found Then tmpDrive = ""
BI_GetCDROMDrive = tmpDrive
exit Function
errL: msgbox error$
End Function
23、如何将文件放入回收站
**API函数声明
Public Type SHFILEOPSTRUCT
hwnd As Long
wFunc As Long
pFrom As String
pTo As String
fFlags As Integer
fAnyOperationsAborted As Long
hNameMappings As Long
lpszProgressTitle As Long
End Type
Public Declare Function SHFileOperation Lib _ "shell32.dll" Alias "SHFileOperationA" (lpFileOp As SHFILEOPSTRUCT) As Long
Public Const FO_DELETE = &H3
Public Const FOF_ALLOWUNDO = &H40
注释：调用
Dim Shop As SHFILEOPSTRUCT, strFile as string
With Shop
.wFunc = FO_DELETE
.pFrom = strFile + Chr(0)
.fFlags = FOF_ALLOWUNDO
End With
24、VB中如何使用未安装的字体
Declare Function AddFontResource Lib "gdi32" Alias "AddFontResourceA" (ByVal lpFileName As String) As Long
Declare Function RemoveFontResource Lib "gdi32" Alias "RemoveFontResourceA" (ByVal lpFileName As String) As Long
增加字体：
Dim lResult As Long
lResult = AddFontResource("c:myAppmyFont.ttf")
删除字体：
Dim lResult As Long
lResult = RemoveFontResource("c:myAppmyFont.ttf")
25、如何得知键盘number lock等开关键的状态
Declare Function GetKeyState Lib "User32" (ByVal lngVirtKey As Long) As Integer
GetKeyState(vbKeyNumLock)
GetKeyState(vbKeyCapital)
如果要用程序更改 NUMLOCK 状态，可以通过条调用 API SetKeyboardState(Windows 95, 98, or Me)或者调用keybd_event (Windows NT or Windows 2000)来实现。
下面的这篇文章详细地讲述了如何在VB中实现这个功能，您可以适当修改其中的代码来实现自动控制打开Num灯。
177674 HOWTO: Toggle the NUM LOCK, CAPS LOCK, and SCROLL LOCK Keys
26、如何让应用程序在任务栏上不显示
Public Const SW_HIDE = 0
Public Const GW_OWNER = 4
Declare Function GetWindow Lib "user32" Alias "GetWindow" (ByVal hwnd As _
Long, ByVal wCmd As Long) As Long
Declare Function ShowWindow Lib "user32" Alias "ShowWindow" (ByVal hwnd _
As Long, ByVal nCmdShow As Long) As Long
将下面的代码添加到窗体的Load事件中：
Dim rc As Long
Dim OwnerhWnd As Long
'让窗体不可见
Me.Visible = False
'从任务管理器列表中移除
OwnerhWnd = GetWindow(Me.hWnd, GW_OWNER)
rc = ShowWindow(OwnerhWnd, SW_HIDE)
请看本文中所用到的两个API函数GetWindow和ShowWindow的用法。
