我需要2個不同的PInvokes來獲取和設置鼠標速度嗎？

Question

我想獲得當前的鼠標指針速度，並且我想設置它。

爲了得到它，我用

Public Declare Function SystemParametersInfo Lib "user32.dll" Alias "SystemParametersInfoA" (ByVal uAction As Int32, ByVal uParam As Int32, ByRef lpvParam As Int32, ByVal fuWinIni As Int32) As Int32 

    Dim Result As Int32 = 0 
    Dim iSuccess As Integer = SystemParametersInfo(SPI_GETMOUSESPEED, 0, Result, 0) 

要設置它，我用

Public Declare Function SystemParametersInfo Lib "user32.dll" Alias "SystemParametersInfoA" (ByVal uAction As Int32, ByVal uParam As Int32, ByVal lpvParam As Int32, ByVal fuWinIni As Int32) As Int32 

    Dim iVal As Integer = 10 
    Dim iSuccess As Integer = SystemParametersInfo(SPI_SETMOUSESPEED, 0, iVal, 0) 

請注意同一功能的不同聲明。

如果我將ByRef更改爲ByVal或反之亦然，其中一個功能不起作用。

我真的必須以不同的方式聲明相同的功能嗎？ 還是我犯了什麼錯誤？ 如果我這樣做，有人可以告訴我如何正確地做到這一點？

Answer 1

核心問題是，你不能在VB中聲明過載這種方式，因爲如錯誤消息所示，他們cannot overload each other because there differ only by parameters declared ByRef and ByVal（你沒有提到錯誤）。這在C＃中不會發生，因爲您會使用in和out這會更改簽名。

您有幾種選擇，一種是使用Alias：

' declaration for all ByVal args: 
Declare Function SetSysParam Lib "user32.dll" Alias "SystemParametersInfoA"... 

' one parm ByRef for getting the speed: 
Declare Function GetSysParam Lib "user32.dll" Alias "SystemParametersInfoA"... 

如果不是很明顯，你會調用它們爲SetSysParam和GetSysParam.

代碼分析/ FxCop的可能會抱怨關於你使用這些的方式，所以這裏是如何實現API調用，所以它沒有。從名爲NativeMethods的類開始：

<DllImport("user32.dll", SetLastError:=True)> 
Private Shared Function SystemParametersInfo(uiAction As SPI, 
     uiParam As UInteger, 
     pvParam As IntPtr, 
     fWinIni As SPIF) As <MarshalAs(UnmanagedType.Bool)> Boolean 
End Function 

' alias a ByRef version for GETting the speed, but this is not 
' needed since NET offers a cleaner way 
<DllImport("user32.dll", EntryPoint:="SystemParametersInfo", SetLastError:=True)> 
Private Shared Function SystemParametersInfoPVByRef(uiAction As SPI, 
     uiParam As UInteger, 
     ByRef pvParam As IntPtr, 
     fWinIni As SPIF) As <MarshalAs(UnmanagedType.Bool)> Boolean 
End Function 

' other stuff for the last param 
<Flags> 
Enum SPIF 
    None = &H0 
    SPIF_UPDATEINIFILE = &H1 
    SPIF_SENDCHANGE = &H2 
    SPIF_SENDWININICHANGE = &H2 
End Enum 

' there are lots and lots of Sys Params, so use an Enum to group them 
Enum SPI 
    SETMOUSESPEED = &H71 
    GETMOUSESPEED = &H70 
End Enum 

' exposed "wrapper" for setting the value to allow a more 
' meaningful name and hiding gory details of Msg values etc 
Friend Shared Function SetMouseSpeed(speed As Integer) As Boolean 
    ' somewhat optional error checking 
    If speed < 1 Then speed = 1 
    If speed > 20 Then speed = 20 

    Return SystemParametersInfo(SPI.SETMOUSESPEED, 0, New IntPtr(speed), SPIF.None) 
End Function 

Friend Shared Function GetMouseSpeed() As Integer 
    Dim speed As New IntPtr(0) 

    ' the caller will have to evaluate the return to see if this 
    ' succeeded 
    If SystemParametersInfoPVByRef(SPI.GETMOUSESPEED, 0, speed, SPIF.None) Then 
     Return speed.ToInt32 
    Else 
     Return -1   ' magic number that API call failed 
    End If 

End Function 

NET格式的一個優點是返回。幾乎所有的API調用都會返回0或1來表示成功或失敗。 MarshalAs... Boolean將其轉換爲Net布爾值。隨着時間的推移，您可以添加到類中，爲各種Win32 API調用收集正確的幻數，聲明，枚舉和結構。這是一個共享/靜態的過程，所以它被稱爲：

NativeMethods.SetMouseSpeed(myNewSpeed) 

的「包裝」，不僅隱藏在代碼中的API的凌亂的細節，它也還可以鍛鍊身體做什麼，如果API調用失敗。在獲得速度的情況下，如果/當呼叫失敗時，計算出返回值而不是當前速度，有些東西不可能被誤讀爲速度值（如可能爲-1）。正如代碼所指出的，有很好的清潔辦法讓鼠標速度.NET使得超載不必要的：

mySpeed = System.Windows.Forms.SystemInformation.MouseSpeed 

---

最後，我要指出，這不是一個好主意，單方面改變用戶在其系統上設置用戶的鼠標。他們選擇這個價值是有原因的。如果有足夠的理由這樣做，應用程序退出時應恢復原始值。

技術說明：我跑這通CA，以確保一切

Answer 2

的大小@Plutonix答案補充我將分享所有的SystemParametersInfo聲明，我需要在過去出於各種目的來寫的。

用法示例：

' Set Mouse Speed 
' (Minimum: 1, Maximum: 20) 
SystemParametersInfo(SPI.SPI_SETMOUSESPEED, False, 15UI, SPIF.None) 

注：我沒有固定的一些便攜式警告，罰全中API數據類型聲明的VS代碼分析工具。

''' <summary> 
''' (For setting a Boolean pvParam) 
''' Retrieves or sets the value of one of the system-wide parameters. 
''' This function can also update the user profile while setting a parameter. 
''' </summary> 
''' <param name="uiAction"> 
''' The system-wide parameter to be retrieved or set. 
''' </param> 
''' <param name="uiParam"> 
''' A parameter whose usage and format depends on the system parameter being queried or set. 
''' For more information about system-wide parameters, see the uiAction parameter. 
''' If not otherwise indicated, you must specify zero for this parameter. 
''' </param> 
''' <param name="pvParam"> 
''' A parameter whose usage and format depends on the system parameter being queried or set. 
''' For more information about system-wide parameters, see the uiAction parameter. 
''' If not otherwise indicated, you must specify NULL for this parameter. 
''' For information on the PVOID datatype, see Windows Data Types.</param> 
''' <param name="fWinIni"> 
''' If a system parameter is being set, specifies whether the user profile is to be updated, 
''' and if so, whether the WM_SETTINGCHANGE message is to be broadcast to all top-level windows to 
''' notify them of the change. 
''' This parameter can be zero if you do not want to update the user profile or broadcast the WM_SETTINGCHANGE message, 
''' or it can be one or more of the following values. 
''' </param> 
<DllImport("user32.dll", SetLastError:=True)> 
Friend Shared Function SystemParametersInfo(
       ByVal uiAction As SPI, 
       ByVal uiParam As UInteger, 
       ByVal pvParam As Boolean, 
       ByVal fWinIni As SPIF 
) As <MarshalAs(UnmanagedType.Bool)> Boolean 
End Function 

''' <summary> 
''' (For getting a Byref Boolean pvParam) 
''' Retrieves or sets the value of one of the system-wide parameters. 
''' This function can also update the user profile while setting a parameter. 
''' </summary> 
''' <param name="uiAction"> 
''' The system-wide parameter to be retrieved or set. 
''' </param> 
''' <param name="uiParam"> 
''' A parameter whose usage and format depends on the system parameter being queried or set. 
''' For more information about system-wide parameters, see the uiAction parameter. 
''' If not otherwise indicated, you must specify zero for this parameter. 
''' </param> 
''' <param name="pvParam"> 
''' A parameter whose usage and format depends on the system parameter being queried or set. 
''' For more information about system-wide parameters, see the uiAction parameter. 
''' If not otherwise indicated, you must specify NULL for this parameter. 
''' For information on the PVOID datatype, see Windows Data Types.</param> 
''' <param name="fWinIni"> 
''' If a system parameter is being set, specifies whether the user profile is to be updated, 
''' and if so, whether the WM_SETTINGCHANGE message is to be broadcast to all top-level windows to 
''' notify them of the change. 
''' This parameter can be zero if you do not want to update the user profile or broadcast the WM_SETTINGCHANGE message, 
''' or it can be one or more of the following values. 
''' </param> 
<DllImport("user32.dll", EntryPoint:="SystemParametersInfo", SetLastError:=True)> 
Friend Shared Function SystemParametersInfoByRefpv(
       ByVal uiAction As SPI, 
       ByVal uiParam As UInteger, 
       ByRef pvParam As Boolean, 
       ByVal fWinIni As SPIF 
) As <MarshalAs(UnmanagedType.Bool)> Boolean 
End Function 

''' <summary> 
''' (For setting a Boolean uiParam and Boolean pvParam parameter) 
''' Retrieves or sets the value of one of the system-wide parameters. 
''' This function can also update the user profile while setting a parameter. 
''' </summary> 
''' <param name="uiAction"> 
''' The system-wide parameter to be retrieved or set. 
''' </param> 
''' <param name="uiParam"> 
''' A parameter whose usage and format depends on the system parameter being queried or set. 
''' For more information about system-wide parameters, see the uiAction parameter. 
''' If not otherwise indicated, you must specify zero for this parameter. 
''' </param> 
''' <param name="pvParam"> 
''' A parameter whose usage and format depends on the system parameter being queried or set. 
''' For more information about system-wide parameters, see the uiAction parameter. 
''' If not otherwise indicated, you must specify NULL for this parameter. 
''' For information on the PVOID datatype, see Windows Data Types.</param> 
''' <param name="fWinIni"> 
''' If a system parameter is being set, specifies whether the user profile is to be updated, 
''' and if so, whether the WM_SETTINGCHANGE message is to be broadcast to all top-level windows to 
''' notify them of the change. 
''' This parameter can be zero if you do not want to update the user profile or broadcast the WM_SETTINGCHANGE message, 
''' or it can be one or more of the following values. 
''' </param> 
<DllImport("user32.dll", SetLastError:=True)> 
Friend Shared Function SystemParametersInfo(
       ByVal uiAction As SPI, 
       ByVal uiParam As Boolean, 
       ByVal pvParam As Boolean, 
       ByVal fWinIni As SPIF 
) As <MarshalAs(UnmanagedType.Bool)> Boolean 
End Function 

''' <summary> 
''' (For setting a IntPtr pvParam parameter) 
''' Retrieves or sets the value of one of the system-wide parameters. 
''' This function can also update the user profile while setting a parameter. 
''' </summary> 
''' <param name="uiAction"> 
''' The system-wide parameter to be retrieved or set. 
''' </param> 
''' <param name="uiParam"> 
''' A parameter whose usage and format depends on the system parameter being queried or set. 
''' For more information about system-wide parameters, see the uiAction parameter. 
''' If not otherwise indicated, you must specify zero for this parameter. 
''' </param> 
''' <param name="pvParam"> 
''' A parameter whose usage and format depends on the system parameter being queried or set. 
''' For more information about system-wide parameters, see the uiAction parameter. 
''' If not otherwise indicated, you must specify NULL for this parameter. 
''' For information on the PVOID datatype, see Windows Data Types.</param> 
''' <param name="fWinIni"> 
''' If a system parameter is being set, specifies whether the user profile is to be updated, 
''' and if so, whether the WM_SETTINGCHANGE message is to be broadcast to all top-level windows to 
''' notify them of the change. 
''' This parameter can be zero if you do not want to update the user profile or broadcast the WM_SETTINGCHANGE message, 
''' or it can be one or more of the following values. 
''' </param> 
<DllImport("user32.dll", SetLastError:=True)> 
Friend Shared Function SystemParametersInfo(
       ByVal uiAction As SPI, 
       ByVal uiParam As UInteger, 
       ByVal pvParam As IntPtr, 
       ByVal fWinIni As SPIF 
) As <MarshalAs(UnmanagedType.Bool)> Boolean 
End Function 

''' <summary> 
''' (For setting an UInteger uiParam and pvParam parameters) 
''' Retrieves or sets the value of one of the system-wide parameters. 
''' This function can also update the user profile while setting a parameter. 
''' </summary> 
''' <param name="uiAction"> 
''' The system-wide parameter to be retrieved or set. 
''' </param> 
''' <param name="uiParam"> 
''' A parameter whose usage and format depends on the system parameter being queried or set. 
''' For more information about system-wide parameters, see the uiAction parameter. 
''' If not otherwise indicated, you must specify zero for this parameter. 
''' </param> 
''' <param name="pvParam"> 
''' A parameter whose usage and format depends on the system parameter being queried or set. 
''' For more information about system-wide parameters, see the uiAction parameter. 
''' If not otherwise indicated, you must specify NULL for this parameter. 
''' For information on the PVOID datatype, see Windows Data Types.</param> 
''' <param name="fWinIni"> 
''' If a system parameter is being set, specifies whether the user profile is to be updated, 
''' and if so, whether the WM_SETTINGCHANGE message is to be broadcast to all top-level windows to 
''' notify them of the change. 
''' This parameter can be zero if you do not want to update the user profile or broadcast the WM_SETTINGCHANGE message, 
''' or it can be one or more of the following values. 
''' </param> 
<DllImport("user32.dll", SetLastError:=True)> 
Friend Shared Function SystemParametersInfo(
       ByVal uiAction As SPI, 
       ByVal uiParam As UInteger, 
       ByVal pvParam As UInteger, 
       ByVal fWinIni As SPIF 
) As <MarshalAs(UnmanagedType.Bool)> Boolean 
End Function 

''' <summary> 
''' (For setting an Boolean uiParam and UInteger pvParam) 
''' Retrieves or sets the value of one of the system-wide parameters. 
''' This function can also update the user profile while setting a parameter. 
''' </summary> 
''' <param name="uiAction"> 
''' The system-wide parameter to be retrieved or set. 
''' </param> 
''' <param name="uiParam"> 
''' A parameter whose usage and format depends on the system parameter being queried or set. 
''' For more information about system-wide parameters, see the uiAction parameter. 
''' If not otherwise indicated, you must specify zero for this parameter. 
''' </param> 
''' <param name="pvParam"> 
''' A parameter whose usage and format depends on the system parameter being queried or set. 
''' For more information about system-wide parameters, see the uiAction parameter. 
''' If not otherwise indicated, you must specify NULL for this parameter. 
''' For information on the PVOID datatype, see Windows Data Types.</param> 
''' <param name="fWinIni"> 
''' If a system parameter is being set, specifies whether the user profile is to be updated, 
''' and if so, whether the WM_SETTINGCHANGE message is to be broadcast to all top-level windows to 
''' notify them of the change. 
''' This parameter can be zero if you do not want to update the user profile or broadcast the WM_SETTINGCHANGE message, 
''' or it can be one or more of the following values. 
''' </param> 
<DllImport("user32.dll", SetLastError:=True)> 
Friend Shared Function SystemParametersInfo(
       ByVal uiAction As SPI, 
       ByVal uiParam As Boolean, 
       ByVal pvParam As UInteger, 
       ByVal fWinIni As SPIF 
) As <MarshalAs(UnmanagedType.Bool)> Boolean 
End Function 

''' <summary> 
''' (For setting a String pvParam parameter) 
''' Retrieves or sets the value of one of the system-wide parameters. 
''' This function can also update the user profile while setting a parameter. 
''' </summary> 
''' <param name="uiAction"> 
''' The system-wide parameter to be retrieved or set. 
''' </param> 
''' <param name="uiParam"> 
''' A parameter whose usage and format depends on the system parameter being queried or set. 
''' For more information about system-wide parameters, see the uiAction parameter. 
''' If not otherwise indicated, you must specify zero for this parameter. 
''' </param> 
''' <param name="pvParam"> 
''' A parameter whose usage and format depends on the system parameter being queried or set. 
''' For more information about system-wide parameters, see the uiAction parameter. 
''' If not otherwise indicated, you must specify NULL for this parameter. 
''' For information on the PVOID datatype, see Windows Data Types.</param> 
''' <param name="fWinIni"> 
''' If a system parameter is being set, specifies whether the user profile is to be updated, 
''' and if so, whether the WM_SETTINGCHANGE message is to be broadcast to all top-level windows to 
''' notify them of the change. 
''' This parameter can be zero if you do not want to update the user profile or broadcast the WM_SETTINGCHANGE message, 
''' or it can be one or more of the following values. 
''' </param> 
<DllImport("user32.dll", CharSet:=CharSet.Auto, SetLastError:=True, BestFitMapping:=False)> 
Friend Shared Function SystemParametersInfo(
       ByVal uiAction As UInteger, 
       ByVal uiParam As UInteger, 
       ByVal pvParam As String, 
       ByVal fWinIni As SPIF 
) As <MarshalAs(UnmanagedType.Bool)> Boolean 
End Function 

''' <summary> 
''' (For reading a String pvParam parameter) 
''' Retrieves or sets the value of one of the system-wide parameters. 
''' This function can also update the user profile while setting a parameter. 
''' </summary> 
''' <param name="uiAction"> 
''' The system-wide parameter to be retrieved or set. 
''' </param> 
''' <param name="uiParam"> 
''' A parameter whose usage and format depends on the system parameter being queried or set. 
''' For more information about system-wide parameters, see the uiAction parameter. 
''' If not otherwise indicated, you must specify zero for this parameter. 
''' </param> 
''' <param name="pvParam"> 
''' A parameter whose usage and format depends on the system parameter being queried or set. 
''' For more information about system-wide parameters, see the uiAction parameter. 
''' If not otherwise indicated, you must specify NULL for this parameter. 
''' For information on the PVOID datatype, see Windows Data Types.</param> 
''' <param name="fWinIni"> 
''' If a system parameter is being set, specifies whether the user profile is to be updated, 
''' and if so, whether the WM_SETTINGCHANGE message is to be broadcast to all top-level windows to 
''' notify them of the change. 
''' This parameter can be zero if you do not want to update the user profile or broadcast the WM_SETTINGCHANGE message, 
''' or it can be one or more of the following values. 
''' </param> 
<DllImport("user32.dll", CharSet:=CharSet.Auto, SetLastError:=True, BestFitMapping:=False)> 
Friend Shared Function SystemParametersInfo(
       ByVal uiAction As UInteger, 
       ByVal uiParam As UInteger, 
       ByVal pvParam As StringBuilder, 
       ByVal fWinIni As SPIF 
) As <MarshalAs(UnmanagedType.Bool)> Boolean 
End Function 

''' <summary> 
''' (For setting a AnimationInfo pvParam parameter) 
''' Retrieves or sets the value of one of the system-wide parameters. 
''' This function can also update the user profile while setting a parameter. 
''' </summary> 
''' <param name="uiAction"> 
''' The system-wide parameter to be retrieved or set. 
''' </param> 
''' <param name="uiParam"> 
''' A parameter whose usage and format depends on the system parameter being queried or set. 
''' For more information about system-wide parameters, see the uiAction parameter. 
''' If not otherwise indicated, you must specify zero for this parameter. 
''' </param> 
''' <param name="pvParam"> 
''' A parameter whose usage and format depends on the system parameter being queried or set. 
''' For more information about system-wide parameters, see the uiAction parameter. 
''' If not otherwise indicated, you must specify NULL for this parameter. 
''' For information on the PVOID datatype, see Windows Data Types.</param> 
''' <param name="fWinIni"> 
''' If a system parameter is being set, specifies whether the user profile is to be updated, 
''' and if so, whether the WM_SETTINGCHANGE message is to be broadcast to all top-level windows to 
''' notify them of the change. 
''' This parameter can be zero if you do not want to update the user profile or broadcast the WM_SETTINGCHANGE message, 
''' or it can be one or more of the following values. 
''' </param> 
<DllImport("user32.dll", SetLastError:=True)> _ 
Friend Shared Function SystemParametersInfo(
       ByVal uiAction As SPI, 
       ByVal uiParam As UInteger, 
       ByRef pvParam As AnimationInfo, 
       ByVal fWinIni As SPIF 
) As <MarshalAs(UnmanagedType.Bool)> Boolean 
End Function