notify when display is on or off

Question

Is there a way to get notified when the display is on or off? I can get notified when pen is down by waiting the event of "penisdown" on my diamond but can't find out any way to check the state of display.

Answer 1

Hi,

I think you are talking about suspend mode. Joel made very good sample on power state modes..

http://www.codeproject.com/KB/mobile/WiMoPower1.aspx


Regards,
Malleswar

Answer 2

Hi,

try this code

typedef enum tagPowerState {
   BacklightOff,
   On,
   Resuming,
   ScreenOff,
   Suspended,
   Unattended,
   UserIdle,

   Unknown
} PowerState;

// see http://msdn.microsoft.com/en-us/library/aa930499.aspx for details
PowerState cast(LPCTSTR szPowerState)
{
   if (!_tcsicmp(_T("BacklightOff"), szPowerState)) {
      return BacklightOff;
   } else if (!_tcsicmp(_T("On"), szPowerState)) {
      return On;
   } else if (!_tcsicmp(_T("Resuming"), szPowerState)) {
      return Resuming;
   } else if (!_tcsicmp(_T("ScreenOff"), szPowerState)) {
      return ScreenOff;
   } else if (!_tcsicmp(_T("Suspended"), szPowerState)) {
      return Suspended;
   } else if (!_tcsicmp(_T("Unattended"), szPowerState)) {
      return Unattended;
   } else if (!_tcsicmp(_T("UserIdle"), szPowerState)) {
      return UserIdle;
   } 

   return Unknown;
}

HANDLE         g_hMsgQ;
HANDLE         g_hPowerNotification;
HANDLE         g_hThreadPowerEvent;
PowerState     g_powerState;

 // start monitor power changes.
 MSGQUEUEOPTIONS msgOptions = {0};  
 msgOptions.dwSize = sizeof(MSGQUEUEOPTIONS);
 msgOptions.dwFlags = 0;
 msgOptions.dwMaxMessages = 20;
 msgOptions.cbMaxMessage = sizeof(POWER_BROADCAST) + MAX_PATH;
 msgOptions.bReadAccess = TRUE;

 g_hMsgQ = CreateMsgQueue(NULL, &msgOptions);
 if (g_hMsgQ) {
      g_hPowerNotification = RequestPowerNotifications(g_hMsgQ, PBT_TRANSITION);
      if (!g_hPowerNotification) {
         DEBUGMSG(1, (TEXT("RequestPowerNotifications error:0x%08x\r\n"), GetLastError()));
         return FALSE;
      }

      g_hThreadPowerEvent = CreateThread(NULL, 0, ThreadProcPowerEvent, NULL, 0, NULL);
      if (!g_hThreadPowerEvent) {
         DEBUGMSG(1, (TEXT("CreateThread error:0x%08x\r\n"), GetLastError()));
         return FALSE;
      }
   } else {
      DEBUGMSG(1, (TEXT("CreateMsgQueue error:0x%08x\r\n"), GetLastError()));
      return FALSE;
   }


// do something here...

// release resourcea
CloseMsgQueue(g_hMsgQ);
StopPowerNotifications(g_hPowerNotification);
CloseHandle(g_hThreadPowerEvent);



#include "tpcshell.h"
#pragma comment(lib, "Aygshell.lib")
DWORD WINAPI ThreadProcPowerEvent(LPVOID lpParam)
{
   POWER_BROADCAST pwrInfo[1024];
   DWORD dwRead;
   DWORD dwFlags;  
   DWORD dwWait;
   BOOL bRet;

   for (;;) {
      dwWait = WaitForSingleObject(g_hMsgQ, INFINITE);
      if (WAIT_OBJECT_0 == dwWait) {
         bRet = ReadMsgQueue(g_hMsgQ, &pwrInfo, sizeof(pwrInfo), &dwRead, INFINITE, &dwFlags);
         if (bRet) {
            DEBUGMSG(1, (TEXT("POWER_BROADCAST info:\r\n")));
            DEBUGMSG(1, (TEXT("Message: 0x%08x\r\n"), pwrInfo->Message));
            DEBUGMSG(1, (TEXT("Flags: 0x%08x\r\n"), pwrInfo->Flags));
            DEBUGMSG(1, (TEXT("SystemPowerState: %s\r\n"), pwrInfo->SystemPowerState));

            g_powerState = cast(pwrInfo->SystemPowerState);       

            if (g_powerState == BacklightOff || g_powerState == ScreenOff || g_powerState == UserIdle) {
               SetSystemPowerState(NULL, POWER_STATE_ON, 0);
            }
         } else {
            DEBUGMSG(1, (TEXT("ReadMsgQueue error: 0x%08x\r\n"), GetLastError()));
         }
      } else {
         // an error occurred or the message queue has been released.
         DEBUGMSG(1, (TEXT("ReadMsgQueue ret: 0x%08x\r\n"), dwWait));
         break;
      }
   }
  
   DEBUGMSG(1, (TEXT("ThreadProcPowerEvent thread exiting\r\n")));
   return 0;
}

Answer 3

Thanks ten0s, the code works well. By the way, the name of suspend event for my diamond is not the same as the MS doc, which spells just "suspend"