我需要2个不同的PInvokes来获取和设置鼠标速度吗？

Question

我想获得当前的鼠标指针速度，并且我想设置它。

为了得到它，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) 

要设置它，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) 

请注意同一功能的不同声明。

如果我将ByRef更改为ByVal或反之亦然，其中一个功能不起作用。

我真的必须以不同的方式声明相同的功能吗？ 还是我犯了什么错误？ 如果我这样做，有人可以告诉我如何正确地做到这一点？

Answer 1

核心问题是，你不能在VB中声明过载这种方式，因为如错误消息所示，他们cannot overload each other because there differ only by parameters declared ByRef and ByVal（你没有提到错误）。这在C＃中不会发生，因为您会使用in和out这会更改签名。

您有几种选择，一种是使用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"... 

如果不是很明显，你会调用它们为SetSysParam和GetSysParam.

代码分析/ FxCop的可能会抱怨关于你使用这些的方式，所以这里是如何实现API调用，所以它没有。从名为NativeMethods的类开始：

<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格式的一个优点是返回。几乎所有的API调用都会返回0或1来表示成功或失败。 MarshalAs... Boolean将其转换为Net布尔值。随着时间的推移，您可以添加到类中，为各种Win32 API调用收集正确的幻数，声明，枚举和结构。这是一个共享/静态的过程，所以它被称为：

NativeMethods.SetMouseSpeed(myNewSpeed) 

的“包装”，不仅隐藏在代码中的API的凌乱的细节，它也还可以锻炼身体做什么，如果API调用失败。在获得速度的情况下，如果/当呼叫失败时，计算出返回值而不是当前速度，有些东西不可能被误读为速度值（如可能为-1）。正如代码所指出的，有很好的清洁办法让鼠标速度.NET使得超载不必要的：

mySpeed = System.Windows.Forms.SystemInformation.MouseSpeed 

---

最后，我要指出，这不是一个好主意，单方面改变用户在其系统上设置用户的鼠标。他们选择这个价值是有原因的。如果有足够的理由这样做，应用程序退出时应恢复原始值。

技术说明：我跑这通CA，以确保一切

Answer 2

的大小@Plutonix答案补充我将分享所有的SystemParametersInfo声明，我需要在过去出于各种目的来写的。

用法示例：

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

注：我没有固定的一些便携式警告，罚全中API数据类型声明的VS代码分析工具。

''' <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