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I'm trying to send and receive data using overlapped sockets and completion routines. Everything works fine, except that quite often the final WSARecv doesn't complete until after some kind of (VERY LONG) timeout. This is basically what my completion routine functions look like:
void CALLBACK OnReceiveComplete(...)
{
if(cbTransferred == 0)
{
printf("Done.\r\n");
}
else
{
printf("Received %d bytes.\r\n", cbTransferred);
WSARecv(..., &OnReceiveComplete);
}
}
void CALLBACK OnSendComplete(...)
{
printf("Sent %d bytes.\r\n", cbTransferred);
WSARecv(..., &OnReceiveComplete);
}
Obviously there is error checking and other things, but that is the gist of it.
Interestingly it doesn't happen on all attempts. I'm doing a simple HTTP GET, and it ALWAYS "hangs" on "www.google.com", but it NEVER does on "www.cnn.com". Does this have something to do with how the servers are setup, or is there something I can do about this? Right now I just forcefully close the socket if I don't get any response for a certain amount of time. I've seen lots of examples for IOCP and overlapped events, but NONE for overlapped completion routines. I haven't been able to figure out this problem for the longest time, so this is my last-ditch attempt to get an answer.
On a side note, if I use the WinInet functions asynchronously the problem goes away (but there are other issues with using WinInet so I want to avoid it). So obviously there must be some way to know when there is no more data to read. I just can't figure it out.
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I am new to c++. i understand programming i am a advanced vb programmer, but i am just havin problems learning and applying all these new keywords. i am a beginnering in c but i have had experience with the very basic fundamental things.
i am reading through a book and they want me to draw a single bitmap on a client window and have it jump around on the window and not go out of the window boundries. The only thing that happens right now is it just draws it over and over all over the screen without removing the previous instance of the bitmap. THIS IS MY CODE.
void Game_Run()<br />
{<br />
<br />
int x = 0, y = 0;<br />
RECT rect;<br />
GetClientRect(global_hwnd, &rect);<br />
<br />
if (rect.right > 0)<br />
{<br />
x = rand() % (rect.right - rect.left);<br />
y = rand() % (rect.bottom - rect.top);<br />
DrawBitmap(global_hdc, "c.bmp", x, y);<br />
}<br />
}
void DrawBitmap(HDC hdcDest, char *filename, int x, int y)<br />
{<br />
HBITMAP image;<br />
BITMAP bm;<br />
HDC hdcMem;<br />
<br />
image = LoadImage(0,"c.bmp",IMAGE_BITMAP,0,0,LR_LOADFROMFILE);<br />
<br />
GetObject(image, sizeof(BITMAP), &bm);<br />
<br />
hdcMem = CreateCompatibleDC(global_hdc);<br />
SelectObject(hdcMem, image);<br />
<br />
BitBlt(<br />
global_hdc,
x,y,
bm.bmWidth, bm.bmHeight,
hdcMem,
0,0,
SRCCOPY);
<br />
DeleteDC(hdcMem);<br />
DeleteObject((HBITMAP)image);<br />
ShowWindow(global_hwnd, SW_SHOW);<br />
}
all i need it to do is draw once and move around the screen with the rand() function. Any help would be great because this is not a essential task of the book but i like to know how to anything with the language i am learning. THANK YOU.
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to do this, you need to make a copy of the image underneath the bitmap before you draw it. something like this:
1. find out where you want to draw the bitmap
2. make a copy of the background where the bitmap will go to a new bitmap, before you draw there. (create a new bitmap, use BitBlt to copy)
3. when you need to move the bitmap, draw the background copy from step 2 at the place you copied it from. then go to step 1.
to do this smoothly, you'll need to use a double-buffering technique, where you place replace the background and draw the new bitmap in one BitBlt to the main screen. otherwise, you could get a flicker effect.
i think there are articles on CP that discuss how to do double buffering.
Cleek | Image Toolkits | Thumbnail maker
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ok i understand what i need to do but how do i go about making a copy of the background to a bitmap. If i was programming in vb this would take me like 2 seconds but i want to learn c because i have always known and can tell now that its a more powerful language. I appreciate any help thank you.
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making a copy of the background is just a BitBlt to an off-screen DC, using a CBitmap you've created specifically for that purpose.
but, this article[^] should help.
Cleek | Image Toolkits | Thumbnail maker
-- modified at 8:09 Wednesday 7th June, 2006
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which function gets color setting of PC?
such as 256 color, 16 bits etc.
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If you've got a screen device context, you can use GetDeviceCaps(BITSPIXEL)
Ryan "Punctuality is only a virtue for those who aren't smart enough to think of good excuses for being late" John Nichol "Point Of Impact"
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I'm having problems with my socket. Here is the scenario.
I have 2 network cards.
A. inet connection
B. Gigabit ethernet connected to network.
I'm trying to connect to an IP on card B. "1.2.3.4:18" for example.
My problem is that it is using network card A. and its not connecting properly because of this.
<br />
<br />
SOCKADDR_IN InternetAddr;<br />
InternetAddr.sin_family = AF_INET;<br />
InternetAddr.sin_addr.s_addr = htonl(inet_addr("1.2.3.4"));<br />
InternetAddr.sin_port = htons(18);<br />
<br />
Connection = socket (AF_INET, SOCK_DGRAM, IPPROTO_UDP);<br />
connect(Connection, (SOCKADDR *)&InternetAddr, sizeof(InternetAddr);<br />
<br />
I create the socket fine... and it sends fine... just on the wrong network card.
Please HELP!!
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signiture of the function is:
CreateDIBSection(HDC hdc,BITMAPINFO*pbf,..,void**ppBits..);
we must provide info for pbm to retrieve ppBits.
my question is:
how to get original BITMAPINFO and ppBits of the HDC?
are there other assistant functions to do that in general?
the HDC may not be memory DC, it may be PAINT DC whose HBITMAP size is 1x1.
the question is in general - not limited to memory DC.
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GetObject()
have to access several API for complete BITMAPINFO. look MSDN
Kuphryn
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I just told you in my post that GetObject() gets bitmap size of 1x1 for PAINT DC.
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includeh10 wrote: how to get original BITMAPINFO and ppBits of the HDC?
DC's do not have those things.
you need to allocate and fill-in the BITMAPINFO object yourself. and the ppvBits parameter is an output parameter, that receives a pointer to the start of a buffer. after you call CreateDIBSection, you copy your DIB's pixels into the buffer where that pointer points:
<br />
void *ppvBits = NULL;<br />
hbm = CreateDIBSection(hDC,(LPBITMAPINFO)lpbi, DIB_RGB_COLORS, &ppvBits, NULL, 0);<br />
<br />
if (ppvBits!=NULL)<br />
{<br />
memcpy((BYTE *)ppvBits, (BYTE *)lpDIBBits, numberOfPixelBytes);<br />
}<br />
Cleek | Image Toolkits | Thumbnail maker
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lpbi is [in].
my question is not about bits, but about how to get
numberOfPixelBytes and colors etc.
GetDIBits() can not help because HBITMAP size of PAINT DC is 1x1 pixels.
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mate,
do not type reply before thinking.
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excuse me?
<br />
BITMAP bm;<br />
GetObject(hBmp, sizeof(BITMAP), &bm);<br />
<br />
<br />
int bmType;<br />
int bmWidth;<br />
int bmHeight;<br />
int bmWidthBytes;<br />
BYTE bmPlanes;<br />
BYTE bmBitsPixel;<br />
LPVOID bmBits;<br />
} BITMAP;<br />
*/<br />
Cleek | Image Toolkits | Thumbnail maker
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I think any HBITMAP handle must contain color info and data bits, otherwise how can it be displayed?
my question is:
how to get color info and data bits for any HBITMAP - not limited to any condition, such as LR_CREATEDIBSECTION.
if can not get, why?
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int GetDIBits(
HDC hdc, // handle to DC
HBITMAP hbmp, // handle to bitmap
UINT uStartScan, // first scan line to set
UINT cScanLines, // number of scan lines to copy
LPVOID lpvBits, // array for bitmap bits
LPBITMAPINFO lpbi, // bitmap data buffer
UINT uUsage // RGB or palette index
);
HBITMAP contains enough info, but the function requres HDC.
why it is HDC ralated?
if HDC is different, (Printer DC or Paint DC), does it retrieve different info?
-- modified at 14:46 Tuesday 6th June, 2006
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just use HDC hDC = ::GetDC(NULL);
includeh10 wrote: if HDC is different, (Printer DC or Paint DC), does it retrieve different info?
not all DCs have the ability to do GetDIBits (see GetDeviceCaps). screen DCs generally do, but printer DCs sometimes can't handle all operations.
includeh10 wrote: HBITMAP contains enough info
but it needs to be formatted in a way that you can use . HBITMAPs are opaque objects - we don't know anything about what they look like on the other side of the HANDLE.
Cleek | Image Toolkits | Thumbnail maker
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mate,
another question:
we have a printer, GetDeviceCaps(RASTERCAPS) shows it supports RC_BITBLT, but BitBlt() function does not work anyway.
may the printer tell wrong info or my code is not correct?
print-preview is OK, so I think my code has no problem.
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includeh10 wrote: BitBlt() function does not work anyway
what happens ?
includeh10 wrote: may the printer tell wrong info or my code is not correct?
that depends on what you're trying to do. for example, printers often only support being on the receiving end of a BitBlt - you can't BitBlt from a printer DC to a different DC, but you can Blt to one. so, yes they support BitBlt, but only somewhat. and, some printers have limitations on how large they can print (see GetDeviceCaps DC_BITBLT64)
Cleek | Image Toolkits | Thumbnail maker
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do not type reply if you don't know.
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maybe you should go read up on general GDI techniques. when you've done that - when you understand how HBITMAPs, HDCs, GetDIBits, CreateDIBSection and the rest of GDI actually works - then you can come back here and tell me how much i don't know about it.
until then, good luck with the attitude.
Cleek | Image Toolkits | Thumbnail maker
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I am sure it's something simple that I'm over looking. I created a Dialog Bar and added some controls to it. I also created a class derived from CDialogBar. When I create my dialog bar in the main frame all the controls are functional except the buttons. The code I have is this:
class CLineBar : public CDialogBar<br />
{<br />
DECLARE_DYNAMIC(CLineBar)<br />
<br />
public:<br />
CLineBar();<br />
virtual ~CLineBar();<br />
<br />
<br />
protected:<br />
DECLARE_MESSAGE_MAP()<br />
};<br />
<br />
......<br />
CLineBar m_LineBar;<br />
<br />
.......<br />
<br />
m_LineBar.Create(this, IDD_LINE_DLG, WS_CHILD|WS_VISIBLE|CBRS_LEFT,0);<br />
<br />
<br />
Any suggestions? Thanks.
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