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Slugsnack
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 Posted: Thu Jun 10, 2010 8:52 am Post subject: Refreshing A Process List |
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So for two of my recent projects, I have found that having a process list is useful. Having a refreshing process list is even more useful it seems : D
This is my current code for refreshing:
| Code: | case WM_TIMER: {
int nFound, nLastMatch;
TCHAR szPID[8] = {0};
TCHAR szExeFile[MAX_PATH] = {0};
PROCESSENTRY32 pe32 = {0};
LVFINDINFO lvfi = {0};
LVITEM lvi = {0};
HWND hwndProcessList = GetDlgItem( hwndDlg, IDC_PROCESSLIST );
HANDLE hSnapshot = CreateToolhelp32Snapshot( TH32CS_SNAPPROCESS, NULL );
int nProcesses = ListView_GetItemCount( hwndProcessList );
LPBYTE arrProcessFlags = ( LPBYTE )malloc( nProcesses + NEWPROCESSTOLERANCE );
RtlZeroMemory( arrProcessFlags, nProcesses + NEWPROCESSTOLERANCE );
lvfi.flags = LVFI_PARAM;
lvi.mask = LVIF_TEXT | LVIF_PARAM;
lvi.iSubItem = 0;
lvi.pszText = ( LPTSTR )&pe32.szExeFile;
pe32.dwSize = sizeof pe32;
Process32First( hSnapshot, &pe32 );
do {
lvfi.lParam = pe32.th32ProcessID;
nFound = ListView_FindItem( hwndProcessList, -1, &lvfi );
if( nFound != -1 ) {
nLastMatch = nFound;
arrProcessFlags[nFound] = 1;
}
else {
MoveMemory( &arrProcessFlags[nLastMatch+2], &arrProcessFlags[nLastMatch+1], nProcesses + NEWPROCESSTOLERANCE - nLastMatch - 2 );
nLastMatch++;
arrProcessFlags[nLastMatch] = 1;
lvi.lParam = pe32.th32ProcessID;
lvi.iItem = nLastMatch;
_ultot_s( pe32.th32ProcessID, szPID, _countof( szPID ), 10 );
ListView_InsertItem( hwndProcessList, &lvi );
ListView_SetItemText( hwndProcessList, nLastMatch, 0, ( LPTSTR )&pe32.szExeFile );
ListView_SetItemText( hwndProcessList, nLastMatch, 1, szPID );
}
}
while( Process32Next( hSnapshot, &pe32 ) );
CloseHandle( hSnapshot );
nProcesses = ListView_GetItemCount( hwndProcessList );
for( int i = nProcesses - 1; i >= 0; i-- )
if( arrProcessFlags[i] == 0 )
ListView_DeleteItem( hwndProcessList, i );
free( arrProcessFlags );
break;
} |
The most obvious way to do refreshing is to simply clear the entire listview and rewrite it however this causes flickering as well as loss of focus of the current item I believe.
What the current method does is to count the number of processes. It then creates a table with that many elements + NEWPROCESSTOLERANCE which is currently defined as 10. What happens then is that we use the old listview and compare it to a new enumeration of processes. The table is initialised to all 0s and then we set each index to 1 depending on whether it's found in the new enumeration. If a process is found which does not have a match, it is inserted into the listview in the relevant place. And the table shifted up one. This means we have enough space for 10 extra processes ( that was what the tolerance was for ). Since this code is all in a timer I doubt 10 new processes are gonna be created in 0.5 second. Oh we also have the problem here if a process dies and another is created with the same PID. I don't check for that but I don't feel it's necessary. The situation is extremely unlikely considering it all has to happen in a 500ms time frame.
Anyway at the end, we find the new number of processes ( in case it's changed ) according to our new listview, and iterate through the table backwards checking for 0s. If we find a 0 we delete that index. The reason we go backwards is so the index doesn't get all screwed up in the case a delete does happen.
Well this method works fine for the time being. It's just a sloppy method IMO. I'm always looking for an 'elegant' method to everything I suppose and was wondering if you guys had any ideas.
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Stylo
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hcavolsdsadgadsg
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Slugsnack
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| Posted: Thu Jun 10, 2010 9:04 pm Post subject: |
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I'm more into looking at an efficient method than caring about the flickering. The flickering is just a byproduct of using the most inefficient method.
Flickering can be avoided even with that method though. I had thought of that before. That is to create a virtual listview with the new enumeration. Compare that to the current listview. If there are differences then draw those differences. As you can imagine though that would be even more inefficient than the current method.
@Stylo : Thanks that is ugly ugly code though :/ And an even uglier method IMO
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hcavolsdsadgadsg
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| Posted: Fri Jun 11, 2010 12:00 am Post subject: |
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i think you're severely overthinking this whole efficiency thing.
is this a purely C project?
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Slugsnack
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| Posted: Fri Jun 11, 2010 3:40 am Post subject: |
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| Yeah. Actually it's not even the efficiency I care about. It's like I said.. uhhh you know this method just seems inelegant.. It just sort of bugs me..
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