WM_DEVICECHANGE Problem [SOLVED]

goldenrose9

LRESULT CALLBACK devDlgProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{

switch(msg)
{
	case WM\_DEVICECHANGE:
		PDEV\_BROADCAST\_VOLUME pVol = (PDEV\_BROADCAST\_VOLUME)lParam;
		switch(wParam)
		{
		case DBT\_DEVICEARRIVAL:
			MessageBox(NULL,\_T("FOUND"), \_T(""),MB\_OK);
			break;
		case DBT\_DEVICEREMOVECOMPLETE:
			MessageBox(NULL,\_T("REMOVED"), \_T(""),MB\_OK);
			break;
		}
	break;
}
return FALSE;

}

While Inserting memory card reader DBT_DEVICEARRIVAL notifies about Four Removable Drives (O,P,Q,R Drives), But while removing memory card reader DBT_DEVICEREMOVECOMPLETE notifies about only ONE Removable Drive (O Drive). Why DBT_DEVICEREMOVECOMPLETE does not notifies about other Three removable drives ( P,Q,R Drives). Help :confused:

Some Day I Will Prove MySelf :: GOLD

modified on Monday, March 7, 2011 5:43 AM

Ozer Karaagac · modified on Monday, March 7, 2011 5:43 AM

All bit mask fields of removed units in pVol->dbcv_unitmask may come in one turn. You had also better check (pVol->dbcv_devicetype == DBT_DEVTYP_VOLUME) like below.

...
case WM_DEVICECHANGE:
{
PDEV_BROADCAST_VOLUME pVol = (PDEV_BROADCAST_VOLUME)lParam;
switch(wParam)
{
case DBT_DEVICEARRIVAL:
{
if(pVol->dbcv_devicetype == DBT_DEVTYP_VOLUME)
{
pVol->dbcv_unitmask; // test this mask for one or more volume letters (bit flags)
MessageBox(NULL,_T("FOUND"), _T(""),MB_OK);
}
}
break;
case DBT_DEVICEREMOVECOMPLETE:
{
if(pVol->dbcv_devicetype == DBT_DEVTYP_VOLUME)
{
pVol->dbcv_unitmask; // test this mask for one or more volume letters
// may be consisting of more than one bit flag (ORed together)

      MessageBox(NULL,\_T("REMOVED"), \_T(""),MB\_OK);
    }
  }
  break;

}
break;
...

goldenrose9

this code is not notifying neither DEVICE_ARRIVAL nor DEVICE REMOVAL.

Some Day I Will Prove MySelf :: GOLD

Ozer Karaagac

Does your device generate something other than DBT_DEVTYP_VOLUME as dbcv_devicetype member of the structure? Because this is the only difference from your code snippet above. You can inspect it by setting a break point on that line if you would like to.

goldenrose9

Ozer Karaagac wrote:

Does your device generate something other than DBT_DEVTYP_VOLUME as dbcv_devicetype member of the structure

dbcv_devicetype = 2 When i insert the memory card reader DBT_DEVICEARRIVAL detect four drives (O,P,Q,R) but when memory card is removed DBT_DEVICEREMOVECOMPLTE detect only one drive removed from system (O drive), why other three drives is not notified. (P,Q,R Drives)

Some Day I Will Prove MySelf :: GOLD

Ozer Karaagac

DBT_DEVTYP_VOLUME as defined 2 already. Could you also inspect dbcv_unitmask in case DBT_DEVICEREMOVECOMPLETE, it should be occurred only once (according to you)?

goldenrose9

Ozer Karaagac wrote:

dbcv_unitmask in case DBT_DEVICEREMOVECOMPLETE

is 245760. and this is occurred only once.

Some Day I Will Prove MySelf :: GOLD

Ozer Karaagac

Well, 245760 = 0x3c000 in hex = 111100000000000000 in binary. 111100000000000000 RQPONMLKJIHGFEDCBA Which means that you got notifications for all 4 volumes. You should test its bit flags.

DWORD dwTestMask = 1;
char archVols[32];
int nCount = 0;

for(int i = 0; i < 26; i++)
{
if(pVol->dbcv_unitmask & dwTestMask)
archVols[nCount++] = 'A' + i;

dwTestMask <<= 1;

}

You will receive array of volume letters in archVols. This notifications may or may not be occurred one per volume.

goldenrose9

thanx, it worked:thumbsup:

Some Day I Will Prove MySelf :: GOLD