C / C++ / MFC

12-Aug-02 14:26

Hi,
I was in need to do a listview with 100x100x32 bitmaps/thumbs and I did so. But then a problem appeared, as the 9x windows don't seem to be able to handle the 330 neccessary items (13 megs in image list... ImageList_Add fails for one of the items, seemingly due to lack of resources). So I followed a fellows idea and did it over LVS_OWNERDATA. He told me making a 1-item image list and changing the image actually when the text is asked for. But here comes my problem:

1) I specify the ownerdata flag when creating
2) I specify the number of items in the listview control
3) The listview starts immediately asking me for texts... and I provide them... so far all right
4) It also asks for images. I provide them (the index = 0 and an appropriate image in the imagelist)

Problems
1) With that many items (330 and more), the application starts saying low on resources again. But mostly when I start moving thru the list itself. So it's a fault in my imagelist construction routines. Could someone send me his/her? Or is it because the incorrect appoarch?
2) I DO NOT add any items, I just specify the count and the control starts immediately asking me... Where's the fault?

It's kind of urgent and I would REALLY apperciate any ideas, hints, thoughts, suggestions, better appoarches. Thanks

Christian Graus12-Aug-02 15:01

Christian Graus

12-Aug-02 15:01

If you're running out of resources you are creating DCs or HBITMAPs and not cleaning them up. Do you deselect everything you select into a DC before deleting it ?

Christian

We're just observing the seasonal migration from VB to VC. Most of these birds will be killed by predators or will die of hunger. Only the best will survive - Tomasz Sowinski 29-07-2002 ( on the number of newbie posters in the VC forum )

Cats, and most other animals apart from mad cows can write fully functional vb code. - Simon Walton - 6-Aug-2002

CaesarCZ12-Aug-02 15:16

12-Aug-02 15:16

HBITMAP hBitmap;
HGDIOBJ hOld;
HDC hDC,hTempDC;
RECT rect = {0, 0, 100, 100};
int width,height,x_offset,y_offset;

hDC = ::GetDC(Window->GetHWND());
hTempDC = CreateCompatibleDC(hDC);

hBitmap = CreateCompatibleBitmap(hDC, 100, 100);

hOld = SelectObject(hTempDC, hBitmap);
FillRect(hTempDC, &rect, (HBRUSH)GetStockObject(GRAY_BRUSH));
SelectObject(hTempDC, hOld);

m_Thumb->CreateFromHBITMAP(hBitmap); //this is a 3rd party lib and I assume it's correct

DeleteDC(hTempDC);
DeleteObject(hBitmap);
ReleaseDC(Window->GetHWND(), hDC);
}

the second one (there are two funcs working with this stuff is exactly the same, just that it returns the HBITMAP to another function which Adds it to image list and then DeleteObjects it

Thanks

Christian Graus12-Aug-02 15:42

Christian Graus

12-Aug-02 15:42

All looks fine to me, except I'm not sure why hOld is not a HBITMAP ? That may be the problem, but I don't see why.

Christian

We're just observing the seasonal migration from VB to VC. Most of these birds will be killed by predators or will die of hunger. Only the best will survive - Tomasz Sowinski 29-07-2002 ( on the number of newbie posters in the VC forum )

Cats, and most other animals apart from mad cows can write fully functional vb code. - Simon Walton - 6-Aug-2002

CaesarCZ13-Aug-02 1:05

13-Aug-02 1:05

Can someone help my with the item addition issue then? Maybe I could find something there

Joel Lucsy13-Aug-02 5:39

Joel Lucsy

13-Aug-02 5:39

You almost/kinda have it. I'm not sure what exactly m_Thumb->CreateFromHBITMAP( hBitmap ); does.
The theory is once you have a HBITMAP from your thumbnail you either use the CImageList Replace method if you're using MFC, or ImageList_Replace using straight win32. It looks like your 3rd party lib will give you a HBITMAP when you need it. Just use that to replace the 0th image in the imagelist.
If you need further help, let me know. What I do is slightly different. I store the raw image data using a FAST data (un)compression library and decompress it on-the-fly. Image lists tend to consume large amounts of memory when used exclusively. Once I figured out this method my app consumes about 1/10th the memory it used to.

Joel Lucsy (jjlucsy@ameritech.net)

CaesarCZ13-Aug-02 10:13

OnSysCommand - cant find it in ClassWizard

13-Aug-02 10:13

Well, it seems like I'm unable to make the listview handle my handles properly or what... I still cannot figure it out. Could you contact me via e-mail? I need to discuss some related issues. My ICQ is 100419594 - thanks much for your help

ns12-Aug-02 14:13

12-Aug-02 14:13

I was told that I could debug with the OnSysCommmand handler. I cant find in the Clas wizard where it is to add it. Will it be a handler in the mainframe? Or the view? Anyways I dont see a SySCOMMAND message or anything likethatin theCW for mainframe class or view class...
Thanks,
ns

(I want to debug a crash that happens when I click the right cross system menu)

Found it, but which class should have the handler?

567890123412-Aug-02 19:25

5678901234

12-Aug-02 19:25

Add Windows Message Handler dialog has combo box "Filter for messages available to class". Select "window" in this combo, and you will see all messages, including WM_SYSCOMMAND.

ns13-Aug-02 2:53

13-Aug-02 2:53

I want to debug the crash when I close with the right hand x (WM_SYSCOMMAND). Which class should I put the handler in? The mainframe? Or the view? Or the doc?

Thank you
ns Confused | :confused:

Re: Found it, but which class should have the handler?

567890123413-Aug-02 3:02

5678901234

13-Aug-02 3:02

CMainFrame

ns13-Aug-02 3:30

13-Aug-02 3:30

Now that I've found the WM_SYSCOMMAND message, how exactly do I debug the crash? The handler is going to be empty, so what shall I put a breakpoint on?

void CMainFrame::OnSysCommand(UINT nID, LPARAM lParam) 
{
	// TODO: Add your message handler code here and/or call default
	
	CMDIFrameWnd::OnSysCommand(nID, lParam);
}

How does having an almost empty handler help you figure out why you are crashing when exiting wit the system right cross?

I must be missing something obvious!! Help!
Thanks,
ns Unsure | :~

Bijesh13-Aug-02 6:28

Bijesh

13-Aug-02 6:28

ns wrote:
How does having an almost empty handler help you figure out why you are crashing when exiting wit the system right cross?

It may not help. If your application crashes on exit, you probably have a big memory leak or something. Run the exe from the debugger and look at your ouput window in MsDev after you exit the application. See if it is reporting any memory leaks and so on..

Bijesh

------------------------------------------

ns13-Aug-02 7:51

13-Aug-02 7:51

Since this crash was happening after several times of rerunning a particular function, I looked at it, found a new char being created, and never deleted. It was a pretty big char array. SO I did a delete and set the pointer = NULL. Are these two steps the right thing to do? In my main app, I have lots of 'new' variables but they are all small and in 90% of the places I dont delete them . But since this turns out to be a cumulative problem, I am going to weed them out and delete them, and NULL them. Is the NULL a good practice or unnecessary?
Thanks,
ns