GDI problems.
Author
Hello,
I am currently using GDI to write a simple pacman clone (for a school project). I have run into a slight problem, that I can't seem to figure out.
For some reason, my double buffering code is causing my program to slow down, and eventually freeze. It sounds like I am not deleting/releasing objects, and device handles, but as far as I can see I am doing it right.
Here is the troublesome code:
HDC hdc = GetDC(_hwnd);
HDC buffer = CreateCompatibleDC(hdc);
HBITMAP memBM = CreateCompatibleBitmap(hdc, _winWidth, _winHeight);
SelectObject(buffer, memBM);
DeleteObject(memBM);
ReleaseDC(_hwnd, hdc);
DeleteDC(buffer);
Thanks a lot for your help. Let me know if you need anymore information.
Edit: Forgot to mention I'm using c++.
Are you making these calls once during initialization/shutdown, or every time you draw? Hopefully not the second one.
You're not deselecting memBM from the buffer. The code should look like this:
Not sure if that'll fix your issues, though.
HDC hdc = GetDC(_hwnd);HDC buffer = CreateCompatibleDC(hdc);HBITMAP memBM = CreateCompatibleBitmap(hdc, _winWidth, _winHeight);HBITMAP bitmapOld = (HBITMAP)SelectObject(buffer, memBM);SelectObject(buffer, bitmapOld);DeleteObject(memBM);ReleaseDC(_hwnd, hdc);DeleteDC(buffer);Not sure if that'll fix your issues, though.
Author
Thanks for the replies so far.
I have fixed the deselecting problem. Still hasn't helped though.
I've fooled around a bit, and have gotten just a plain window working (no blitting to it).
As soon as I add:
BitBlt(hdc, 0, 0, 640, 480, buffer, 0, 0, SRCCOPY);
It slows down so much it almost locks up my whole system.
I have fixed the deselecting problem. Still hasn't helped though.
I've fooled around a bit, and have gotten just a plain window working (no blitting to it).
As soon as I add:
BitBlt(hdc, 0, 0, 640, 480, buffer, 0, 0, SRCCOPY);
It slows down so much it almost locks up my whole system.
Author
I've figured it out.
Just had to put a small Sleep in my main loop.
Thanks a lot everyone.
Just had to put a small Sleep in my main loop.
Thanks a lot everyone.
Quote:Original post by diablo2_vJust had to put a small Sleep in my main loop.
Umm, from what you described, I don't think just adding a sleep statement into the main loop is going to fix your problem. All that will do is just delay the eventual lock-up you mentioned. I think you still have a problem in the code somewhere... (perhaps with a different piece of code than what was posted earlier?)
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