1.什么是鼠標手勢:
   我的理解,按著鼠標某鍵(一般是右鍵)移動鼠標,然后放開某鍵,程序會識別你的移動軌跡,做出相應的響應.

2.實現原理:
首先說明一下,我在網上沒有找到相關的文檔,我的方法未必與其他人是一致的,實際效果感覺還可以.
鼠標移動的軌跡我們可以將其看成是許多小段直線組成的,然后這些直線的方向就是鼠標在這段軌跡中的方向了.
3.實現代碼:
還要說明一下,
a)要捕獲鼠標的移動事件,可以使用vb中的mousemove事件,但這個會受到一些限制(例如,在webbrowser控件上就沒有這個事件).于是這個例子中,我用win api,在程序中安裝個鼠標鉤子,這樣就能夠捕獲整個程序的鼠標事件了.
b)這個里只是個能捕獲鼠標向上,下,左,右的移動的例子.(呵呵,其實這四方向一般也足夠了:))

新建Standrad EXE,添加一個Module

form1的代碼如下

Option Explicit

Private Sub Form_Load()
Call InstallMouseHook
End Sub


Private Sub Form_QueryUnload(Cancel As Integer, UnloadMode As Integer)
Call UninstallMouseHook
End Sub


Module1的代碼如下

Option Explicit

Public Const HTCLIENT As Long = 1

Private hMouseHook As Long
Private Const KF_UP As Long = &H80000000

Public Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (hpvDest As Any, hpvSource As Any, ByVal cbCopy As Long)

Private Type POINTAPI
    X As Long
    Y As Long

End Type

Public Type MOUSEHOOKSTRUCT
    pt As POINTAPI
    hwnd As Long
    wHitTestCode As Long
    dwExtraInfo As Long

End Type

Public Declare Function CallNextHookEx Lib "user32" _
        (ByVal hHook As Long, _
        ByVal ncode As Long, _
        ByVal wParam As Long, _
        ByVal lParam As Long) As Long
Public 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
Public Declare Function UnhookWindowsHookEx Lib "user32" _
        (ByVal hHook As Long) As Long

Public Const WH_KEYBOARD As Long = 2
Public Const WH_MOUSE As Long = 7

Public Const HC_SYSMODALOFF = 5
Public Const HC_SYSMODALON = 4
Public Const HC_SKIP = 2
Public Const HC_GETNEXT = 1
Public Const HC_ACTION = 0
Public Const HC_NOREMOVE As Long = 3

Public Const WM_LBUTTONDBLCLK As Long = &H203
Public Const WM_LBUTTONDOWN As Long = &H201
Public Const WM_LBUTTONUP As Long = &H202
Public Const WM_MBUTTONDBLCLK As Long = &H209
Public Const WM_MBUTTONDOWN As Long = &H207
Public Const WM_MBUTTONUP As Long = &H208
Public Const WM_RBUTTONDBLCLK As Long = &H206
Public Const WM_RBUTTONDOWN As Long = &H204
Public Const WM_RBUTTONUP As Long = &H205
Public Const WM_MOUSEMOVE As Long = &H200
Public Const WM_MOUSEWHEEL As Long = &H20A


Public Declare Function PostMessage Lib "user32" Alias "PostMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
Public Const MK_RBUTTON As Long = &H2
Public Declare Function ScreenToClient Lib "user32" (ByVal hwnd As Long, lpPoint As POINTAPI) As Long


Public Declare Function GetAsyncKeyState Lib "user32" (ByVal vKey As Long) As Integer
Public Const VK_LBUTTON As Long = &H1
Public Const VK_RBUTTON As Long = &H2
Public Const VK_MBUTTON As Long = &H4

Dim mPt As POINTAPI
Const ptGap As Single = 5 * 5
Dim preDir As Long
Dim mouseEventDsp As String
Dim eventLength As Long

'######### mouse hook #############

Public Sub InstallMouseHook()
    hMouseHook = SetWindowsHookEx(WH_MOUSE, AddressOf MouseHookProc, _
            App.hInstance, App.ThreadID)
End Sub

Public Function MouseHookProc(ByVal iCode As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
Dim Cancel As Boolean
Cancel = False
On Error GoTo due
Dim i&
Dim nMouseInfo As MOUSEHOOKSTRUCT
Dim tHWindowFromPoint As Long
Dim tpt As POINTAPI

If iCode = HC_ACTION Then
    CopyMemory nMouseInfo, ByVal lParam, Len(nMouseInfo)
    tpt = nMouseInfo.pt
    ScreenToClient nMouseInfo.hwnd, tpt
    'Debug.Print tpt.X, tpt.Y
    If nMouseInfo.wHitTestCode = 1 Then
        Select Case wParam
            Case WM_RBUTTONDOWN
                mPt = nMouseInfo.pt
                preDir = -1
                mouseEventDsp = ""
                Cancel = True
            Case WM_RBUTTONUP
                Debug.Print mouseEventDsp
                Cancel = True
            Case WM_MOUSEMOVE
                If vkPress(VK_RBUTTON) Then
                    Call GetMouseEvent(nMouseInfo.pt)
                End If
        End Select
    End If
    
End If

If Cancel Then
    MouseHookProc = 1
Else
    MouseHookProc = CallNextHookEx(hMouseHook, iCode, wParam, lParam)
End If

Exit Function

due:
    
End Function

Public Sub UninstallMouseHook()
    If hMouseHook <> 0 Then
        Call UnhookWindowsHookEx(hMouseHook)
    End If
    hMouseHook = 0
End Sub

Public Function vkPress(vkcode As Long) As Boolean
If (GetAsyncKeyState(vkcode) And &H8000) <> 0 Then
    vkPress = True
Else
    vkPress = False
End If
End Function

Public Function GetMouseEvent(nPt As POINTAPI) As Long
Dim cx&, cy&
Dim rtn&
rtn = -1
cx = nPt.X - mPt.X: cy = -(nPt.Y - mPt.Y)
If cx * cx + cy * cy > ptGap Then
    If cx > 0 And Abs(cy) <= cx Then
        rtn = 0
    ElseIf cy > 0 And Abs(cx) <= cy Then
        rtn = 1
    ElseIf cx < 0 And Abs(cy) <= Abs(cx) Then
        rtn = 2
    ElseIf cy < 0 And Abs(cx) <= Abs(cy) Then
        rtn = 3
    End If
    mPt = nPt
    If preDir <> rtn Then
        mouseEventDsp = mouseEventDsp & DebugDir(rtn)
        preDir = rtn
    End If
End If
GetMouseEvent = rtn
End Function

Public Function DebugDir(nDir&) As String
Dim tStr$
Select Case nDir
    Case 0
        tStr = "右"
    Case 1
        tStr = "上"
    Case 2
        tStr = "左"
    Case 3
        tStr = "下"
    Case Else
        tStr = "無"
End Select
Debug.Print Timer, tStr
DebugDir = tStr
End Function

運行程序后,在程序窗口上,按著右鍵移動鼠標,Immediate Window就會顯示出鼠標移動的軌跡了.

這里面的常數 ptGap 就是"鼠標移動的軌跡我們可以將其看成是許多小段直線組成的"中的小段的長度的平方.里面用到的api函數的用法,可以參考msdn.這里我就懶說了.



lingll (lingll2001@21cn.com)
2004-7-23