API在VB中应用之技巧集锦

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 ：
     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")