C / C++ / MFC

17-Jul-07 14:13

Hello,

Well, I have created a custom MFC control that derives from CWnd. I have done some work to add double buffering, but now i have a problem. My application sucks up 100% of the CPU.

I have it narrowed down to one line.

void CGameArea::OnPaint()<br />
{<br />
   //CWnd::OnPaint();   //PROBLEM HERE<br />
   mPlayer->Draw();<br />
<br />
	 //BitBlt the memory HDC to the screen HDC<br />
   CRect r;<br />
   GetClientRect(&r);<br />
<br />
	 CDC *dc = GetDC();<br />
	 dc->BitBlt(r.left,r.top,r.right-r.left,r.bottom-r.top,&mBackgroundDC,0,0,SRCCOPY);<br />
	 ReleaseDC(dc);<br />
}

I am currently not calling the base CWnd OnPaint function because I am doing all the painting myself. Somehow, this is causing the problem.

If I uncomment the base class OnPaint call, my CPU usage goes back to normal, but I get a lot of flicker.

Any idea why NOT calling the CWnd OnPaint would cause 100% CPU usage??

Thanks ahead of time for any help.

-Kevin

-- modified at 8:53 Wednesday 18th July, 2007

Mark Salsbery17-Jul-07 14:24

Mark Salsbery

17-Jul-07 14:24

If you don't validate the invalid region of the window then you will continue to receive WM_PAINT
messages until you do so Smile | :)

Not good!

This should do it:

::ValidateRect(*this, NULL);

or use a CPaintDC instead of a CDC

//CDC *dc = GetDC();
CPaintDC dc(this);
...

Mark

Mark Salsbery
Microsoft MVP - Visual C++

"Great job team! Head back to base for debriefing and cocktails."

kalden17-Jul-07 14:34

17-Jul-07 14:34

Holy crap, you're the man. You know, I almost tried switching to CPaintDC, but kept telling myself it wouldn't matter.

It all works now. Thanks.

Naveen17-Jul-07 14:32

Naveen

17-Jul-07 14:32

kalden wrote:
mPlayer->Draw();

In addition to what Mark said, I also doubt how you took the DC in the mPlayer->Draw() function;( I am not sure what exactly that draw function does). I suggest you to pass the CPaintDC object to that function and do all the drawing in that DC.

nave

[OpenedFileFinder]

kalden17-Jul-07 14:40

17-Jul-07 14:40

I am passing a memory DC to a game DLL at initialization. That DLL has the mPlayer->Draw() code and uses GDI+ to draw to the memory DC. The memory DC is then copied to the control DC using Bitblt.

I know there are potential problems with this if the window resizes, but I am not worrying about that at the moment.

Naveen17-Jul-07 14:45

Naveen

17-Jul-07 14:45

So you stil have problem even after changing the CPaintDC? (Comment out the statement ReleaseDC(dc); also )

nave

[OpenedFileFinder]

kalden17-Jul-07 14:47

17-Jul-07 14:47

No, it resolved the issue. See my response to Mark's post.

Thanks for your input!

How to Implement a Virtual Grid [modified]

Naveen17-Jul-07 14:49

Naveen

17-Jul-07 14:49

ho I didn't noticed.

nave

[OpenedFileFinder]

Stuck At Zero17-Jul-07 9:37

17-Jul-07 9:37

I am a novice programmer and have been trying to implement a virtual grid control for a tool I am building. The source files I am dealing with are very large binary files and I was told that I need to turn on the virtual mode of the CGridCtrl due to the size of the source files. I was also told that I probably need to use what is called a callback function or OnNotify.

I do have a non-virtual grid control up and running and I am already parsing and displaying data via a worker thread up to a finite number of columns and rows. The moment I turn on virtual mode, the box where my grid should be immediately pops up shows absolutely no cells. It's as if the source file was never even parsed.

I do understand that a virtual grid does not have actual cells defined or something to this effect. This is what I am observing now. I am completely clueless as to how things are done differently when it comes to actually adding data to a virtual cell.

If I must use OnNotify or a callback function, I have been struggling on trying to find useful information on either of these. I do not know exactly what they do or how to use them.

If this helps, I am using VS.NET 2003. Any help would be greatly appreciated.

led mike17-Jul-07 10:44

17-Jul-07 10:44

Stuck At Zero wrote:
If I must use OnNotify or a callback function, I have been struggling on trying to find useful information on either of these. I do not know exactly what they do or how to use them.

Usually they hide that information in the documentation[^]

CWnd::OnNotify

The framework calls this member function to inform the parent window of a control that an event has occurred in the control or that the control requires some kind of information.

more[^]

Those little blue underlined parts are called "links". You place your mouse cursor over them and click the "left button"... unless you have a left-handed mouse then you click the "right button".

Stuck At Zero17-Jul-07 11:14

17-Jul-07 11:14

Thanks Led. I have an OnNotify function in my code, but I don't know what to do with it. Part of that problem is my confusion over what I need to inside of it as well as feed it. My root problem is the virtual grid. I can turn it on, but after that, I do not know how to add data.

Once I can get that going, I guess I can tackle the OnNotify to try and get the cells to actually display in Virtual mode. For now, I don't even know what to feed an OnNotify at least from glossing over what you referred me to, nor do I know what to do inside of an OnNotify function to get the desired effect.

I also noted that some of the info you pointed me too is VB. I forgot to mention I'm using Visual C++. Sorry for that oversight on my part.

Thanks for the tip on how a hyperlink works. Laugh | :laugh:

led mike17-Jul-07 11:23

17-Jul-07 11:23

Stuck At Zero wrote:
For now, I don't even know what to feed an OnNotify

That is specific to each control/message combination. You have to refer to the documentation for the specific control to discover that. In your case it is the CGridControl yes? I haven't worked with it for a few years but you should find lot's of information here on CodeProject about it. Did you look through the CodeProject Articles?

Stuck At Zero17-Jul-07 11:40

17-Jul-07 11:40

I have tried looking at the GridControl v2.26 (if I recall correctly), but it's very general information. It's great if I've had experience on CGridControl. It assumes I know what to do on the Callback function.

The other problem I have ran into is that it seems CGridCtrl has been ditched in favor of CListCtrl or something like that in other searches I have done via Google / MSDN.

If there is a CGridCtrl tutorial that would be appropriate for my situation, I'm more than happy to check it out. I have not been successful in finding what I need in the articles. I'm hoping that someone in the forums knows of a great site that I cannot find via simply googling. If I can find a "Stumble Upon" nudge in the direction of an good site, it would be appreciated.

Stuck At Zero18-Jul-07 4:12

18-Jul-07 4:12

I went back and queried for CGridCtrl and the closest thing I get that would be of any help is Chris Maunder's MFC Grid Control 2.26. Because I'm such a newb, I do not totally understand all of the details. I do google those, but nothing that cements everything together... I've got a warm fuzzy.

So what I did just now is simply copied and pasted Chris' GridCallback and OnNotify functions one at a time and rebuilt my solution. There is no change. While my worker thread is parsing through the source file, I have it periodically GetCallback after it has been registered (which was after I made the grid into a virtual grid).

The other concept I am struggling with is the idea of adding data to a cell that does not exist. With a regular grid control, it was really straightforward. Here, I do not know what I am not doing right.

Is there an actual article on CodeProject that goes into more detail into how to implement a Virtual Grid? Maybe Chris has spelled it out, but if it's "obvious", it's not clicking due to my lack of knowledge of all things MFC.

led mike18-Jul-07 6:29

18-Jul-07 6:29

Chris Maunders MFC Grid Control is the only CGridCtrl I am aware of. If that is NOT what you are using I don't know where you can find information. If it is Chris's control then the Virtual mode operation is spelled out in the Articl[^]e for the control here on CodeProject.

Stuck At Zero wrote:
Because I'm such a newb, I do not totally understand all of the details.

Any documentation for a control or an API or samples are not going to be trying to help you understand fundamental concepts. They are going to assume you already understand those fundamental concepts because you shouldn't even be trying to do "whatever" unless you already have programming fundamentals required to do it. D'Oh! | :doh:

Which leads to the obvious question, if you are a novice as you state, a newb, why are working on a project that is above your knowledge level?

Stuck At Zero18-Jul-07 6:48

18-Jul-07 6:48

I am struggling to see where virtual mode implementation is spelled out. The link you sent me is the same I've been looking at. I see descriptions of what each function does and I see code examples of OnNotify and CallBack. There's no explanation I see that explains exactly how data is added to a virtual cell other than saying OnNotify and CallBack are needed for this operation.

What I have at the moment is a working non-virtual grid. I need to make it virtual for the reasons Chris explained as to why one is needed. I can populate this non-virtual grid with data. But when I flip the switch for Virtual, poof! Nothing.

As for why I'm trying to implement a virtual grid, it's because I was told that this would be needed in order to accomplish listing lots of data on a grid control. No one around me has tried this feature so I'm left on my own to figure it out.

If I am a novice as I state? You sound like you don't believe me. Laugh | :laugh:

I get the idea of what Chris is trying to convey, but I don't understand the implementation.

led mike18-Jul-07 7:14

18-Jul-07 7:14

Stuck At Zero wrote:
There's no explanation I see that explains exactly how data is added to a virtual cell

Are you blind? From the article sample code in the "Virtual Mode" section:

pDispInfo->item.strText.Format(_T("Message %d,%d")

Stuck At Zero wrote:

No one around me has tried this feature

No one in your shop knows how callbacks or OnNotify work or knows how to read and understand the sample code in the article? Is this a school project?

Stuck At Zero18-Jul-07 7:36