winapi - 如何在 VB6 中定义 POWERBROADCAST_SETTING？

Question

我想检测监视器状态。

为此，我注册了 WM_POWERBROADCAST消息。

此消息的lParam 包含PBT_POWERSETTINGCHANGE .

typedef struct {
  GUID  PowerSetting;
  DWORD DataLength;
  UCHAR Data[1];
} POWERBROADCAST_SETTING, *PPOWERBROADCAST_SETTING;

GUID 在 VB6 中是这样定义的:

Private Type GUID
    Data1 As Long
    Data2 As Integer
    Data3 As Integer
    Data4(0 To 7) As Byte
End Type

怎么样

  DWORD DataLength;
  UCHAR Data[1];

要翻译成 VB6？

Answer 1

POWERBROADCAST_SETTING 结构的 UCHAR Data[1] 成员表示一个字节数组，它取决于 PowerSetting 和 DataLength 成员。根据docs , Data 成员可以是 GUID 或 DWORD。所以在VB6中最简单的方法是为固定成员声明一个结构，然后根据PowerSetting成员在第二步中获取剩余数据。

Public Type Guid
    Data1 As Long
    Data2 As Integer
    Data3 As Integer
    Data4(0 To 7) As Byte
End Type

Private Type PowerBroadcastSetting
    PowerSetting As Guid
    DataLength As Long
End Type

窗口过程应该是这样的:

Public Function WindowProc(ByVal hWnd As Long, ByVal iMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
    Dim g As Guid
    Dim L As Long
    Dim pbs As PowerBroadcastSetting
    
    Select Case iMsg
        Case WM_POWERBROADCAST
            Select Case wParam
                Case PBT_APMPOWERSTATUSCHANGE
                    DebugPrint "PBT_APMPOWERSTATUSCHANGE"
                Case PBT_APMRESUMEAUTOMATIC
                    DebugPrint "PBT_APMRESUMEAUTOMATIC"
                Case PBT_APMRESUMESUSPEND
                    DebugPrint "PBT_APMRESUMESUSPEND"
                Case PBT_APMSUSPEND
                    DebugPrint "PBT_APMSUSPEND"
                Case PBT_POWERSETTINGCHANGE
                    CopyMemory pbs, ByVal lParam, Len(pbs)
                    DebugPrint "PBT_POWERSETTINGCHANGE " & GuidToString(pbs.PowerSetting)
                    Select Case GuidToString(pbs.PowerSetting)
                        Case GUID_POWERSCHEME_PERSONALITY
                            CopyMemory g, ByVal lParam + Len(pbs), 16
                            DebugPrint "New power scheme: " & GuidToString(g)
                        Case GUID_SESSION_DISPLAY_STATUS
                            CopyMemory L, ByVal lParam + Len(pbs), 4
                            DebugPrint "Display status: " & L
                        Case GUID_MONITOR_POWER_ON
                            CopyMemory L, ByVal lParam + Len(pbs), 4
                            DebugPrint "Primary Monitor state: " & L
                        Case GUID_CONSOLE_DISPLAY_STATE
                            CopyMemory L, ByVal lParam + Len(pbs), 4
                            DebugPrint "Console Display state: " & L
                    End Select
            End Select
            'An application should return TRUE if it processes this message.
            WindowProc = 1
            Exit Function
    End Select
    'Pass message to original window proc
    WindowProc = CallWindowProc(ProcOld, hWnd, iMsg, wParam, lParam)
End Function

使用了以下 API 声明:

Public Const GWL_WNDPROC As Long = (-4)
Private Const WM_POWERBROADCAST As Long = 536

Public Type Guid
    Data1 As Long
    Data2 As Integer
    Data3 As Integer
    Data4(0 To 7) As Byte
End Type

Private Type PowerBroadcastSetting
    PowerSetting As Guid
    DataLength As Long
End Type


'Power status has changed.
Private Const PBT_APMPOWERSTATUSCHANGE = 10

'Operation is resuming automatically from a low-power state. This message is sent every time the system resumes.
Private Const PBT_APMRESUMEAUTOMATIC As Long = 18

'Operation is resuming from a low-power state. This message is sent after PBT_APMRESUMEAUTOMATIC if the resume is triggered by user input, such as pressing a key.
Private Const PBT_APMRESUMESUSPEND As Long = 7

'System is suspending operation.
Private Const PBT_APMSUSPEND As Long = 4

'A power setting change event has been received.
Private Const PBT_POWERSETTINGCHANGE As Long = 32787

'Power Setting GUIDs

'The active power scheme personality has changed. All power schemes map to one of these personalities.
'The Data member is a GUID that indicates the new active power scheme personality.
Public Const GUID_POWERSCHEME_PERSONALITY As String = "{245D8541-3943-4422-B025-13A784F679B7}"

'The display associated with the application's session has been powered on or off.
'The Data member is a DWORD with one of the following values.
'0x0 - The display is off.
'0x1 - The display is on.
'0x2 - The display is dimmed.
Public Const GUID_SESSION_DISPLAY_STATUS As String = "{2B84C20E-AD23-4DDF-93DB-05FFBD7EFCA5}"

Public Const GUID_MONITOR_POWER_ON As String = "{02731015-4510-4526-99E6-E5A17EBD1AEA}"
' Windows 8 +
Public Const GUID_CONSOLE_DISPLAY_STATE As String = "{6FE69556-704A-47A0-8F24-C28D936FDA47}"

'Notifications are sent using WM_POWERBROADCAST messages with a wParam parameter of PBT_POWERSETTINGCHANGE.
Public Const DEVICE_NOTIFY_WINDOW_HANDLE As Long = 0
Private Declare Sub CopyMemory Lib "kernel32.dll" Alias "RtlMoveMemory" (lpDest As Any, lpSource As Any, ByVal cbCopy As Long)
Public Declare Function RegisterPowerSettingNotification Lib "user32.dll" (ByVal hRecipient As Long, PowerSettingGuid As Guid, ByVal Flags As Long) As Long
Public Declare Function UnregisterPowerSettingNotification Lib "user32.dll" (ByVal Handle As Long) As Long
Private Declare Function StringFromGUID2 Lib "ole32.dll" (rguid As Guid, ByVal lpsz As Long, ByVal cchMax As Long) As Long
Private Declare Function CLSIDFromString Lib "ole32.dll" (ByVal lpsz As Long, pclsid As Guid) As Long
Public Declare Function SetWindowLong Lib "user32" Alias "SetWindowLongA" (ByVal hWnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long
Public Declare Function CallWindowProc Lib "user32" Alias "CallWindowProcA" (ByVal lpPrevWndFunc As Long, ByVal hWnd As Long, ByVal Msg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
Private Declare Sub OutputDebugString Lib "kernel32" Alias "OutputDebugStringA" (ByVal lpOutputString As String)

辅助函数:

Public Function GuidToString(g As Guid) As String
    Dim L As Long
    Dim b(0 To 77) As Byte
    
    'we have space for 38 unicode chars (guid incl. brackets) + terminating zero (78 bytes)
    L = StringFromGUID2(g, VarPtr(b(0)), 39)
    'strip terminating 0, convert to string
    GuidToString = Left(b, L - 1)
End Function

Public Function GuidFromString(ByVal gs As String) As Guid
    CLSIDFromString StrPtr(gs), GuidFromString
End Function

Public Sub DebugPrint(ByVal s As String)
    OutputDebugString s & vbCrLf
End Sub

VB6 中的测试表单:

Option Explicit

Private isSubclassed As Boolean
Private hScheme As Long
Private hDisplay As Long
Private hMonitor As Long
Private hConsole As Long

Private Sub cmdRegister_Click()
    Unregister
    Register
End Sub

Private Sub cmdUnregister_Click()
    Unregister
End Sub

Private Sub Register()
    ProcOld = SetWindowLong(hWnd, GWL_WNDPROC, AddressOf WindowProc)
    isSubclassed = True
    MsgBox "Subclassed"
    'Register Power Events
    hScheme = RegisterPowerSettingNotification(hWnd, GuidFromString(GUID_POWERSCHEME_PERSONALITY), DEVICE_NOTIFY_WINDOW_HANDLE)
    hDisplay = RegisterPowerSettingNotification(hWnd, GuidFromString(GUID_SESSION_DISPLAY_STATUS), DEVICE_NOTIFY_WINDOW_HANDLE)
    hConsole = RegisterPowerSettingNotification(hWnd, GuidFromString(GUID_CONSOLE_DISPLAY_STATE), DEVICE_NOTIFY_WINDOW_HANDLE)
    MsgBox "Registered " & hScheme & " " & hDisplay & " " & hMonitor & " " & hConsole
End Sub

Private Sub Unregister()
    'Unregister Power Events
    If hScheme Then
        UnregisterPowerSettingNotification hScheme
        hScheme = 0
    End If
    
    If hDisplay Then
        UnregisterPowerSettingNotification hDisplay
        hDisplay = 0
    End If
    
    If hMonitor Then
        UnregisterPowerSettingNotification hMonitor
        hMonitor = 0
    End If
    If hConsole Then
        UnregisterPowerSettingNotification hConsole
        hConsole = 0
    End If
    'Unsubclass
    If isSubclassed Then
        SetWindowLong hWnd, GWL_WNDPROC, ProcOld
        isSubclassed = False
        MsgBox "Unsubclassed"
    End If
End Sub

Private Sub Form_Unload(Cancel As Integer)
    Unregister
End Sub

编辑:添加了 GUID_CONSOLE_DISPLAY_STATE。这是 DebugView 捕获的输出在 Windows 10 上:

显示在不活动后由 Windows 的电源管理置于待机状态:

[7752] PBT_POWERSETTINGCHANGE {6FE69556-704A-47A0-8F24-C28D936FDA47}
[7752] Console Display state: 2
[7752] PBT_POWERSETTINGCHANGE {2B84C20E-AD23-4DDF-93DB-05FFBD7EFCA5}
[7752] Display status: 2

15 秒后:

[7752] PBT_POWERSETTINGCHANGE {6FE69556-704A-47A0-8F24-C28D936FDA47}
[7752] Console Display state: 0
[7752] PBT_POWERSETTINGCHANGE {02731015-4510-4526-99E6-E5A17EBD1AEA}
[7752] Primary Monitor state: 0
[7752] PBT_POWERSETTINGCHANGE {2B84C20E-AD23-4DDF-93DB-05FFBD7EFCA5}
[7752] Display status: 0

唤醒:

[7752] PBT_POWERSETTINGCHANGE {6FE69556-704A-47A0-8F24-C28D936FDA47}
[7752] Console Display state: 1
[7752] PBT_POWERSETTINGCHANGE {02731015-4510-4526-99E6-E5A17EBD1AEA}
[7752] Primary Monitor state: 1
[7752] PBT_POWERSETTINGCHANGE {2B84C20E-AD23-4DDF-93DB-05FFBD7EFCA5}
[7752] Display status: 1

如果您手动关闭显示器，将不会有任何通知，至少在我的硬件上是这样。不确定，如果在其他系统上会引发事件。