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BitBlt question

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Started by wind_addict November 22, 2007 05:11 PM

4 comments, last by scorpion007 16 years, 4 months ago

wind_addict

122

Author

November 22, 2007 05:11 PM

Have a simple question, can I only use BitBlt() within the WM_PAINT message? As it only seems to draw a black window if I try and use it outside of that. I have tried doing this in a seperate function: BitBlt from a loaded bmp in a memory DC to my primary memory dc. then under WMPAINT I blit from that primary memory dc to the screen but only get a black window. If I instead do the same thing in the WMPAINT block, it works fine.

ExcessNeo

619

November 22, 2007 05:21 PM

Could you post your code for when you place it out of WM_PAINT?

wind_addict

122

Author

November 22, 2007 05:38 PM

  while(true)  {    if(PeekMessage(&msg,NULL,0,0, PM_REMOVE))    {      if(msg.message == WM_QUIT)        break;      TranslateMessage(&msg);      DispatchMessage(&msg);    }         BitBlt(hdcmem, 0, 0, 200, 200, bmp[HBMT54].GethDC(), 0, 0, SRCCOPY);

If I put the same line of code in a WM_PAINT it works. hdcmem is initialised prior to entering the message loop.

scorpion007

118

November 22, 2007 05:50 PM

Did you check the return value to see if there was an error?

wind_addict

122

Author

November 22, 2007 06:03 PM

You guys basically answered my question in that you CAN use BitBlt outside of WM_PAINT.

I figured it out now. I was releasing the screen DC too soon.

thanks!

[Edited by - wind_addict on November 22, 2007 6:03:41 PM]

scorpion007

118

November 22, 2007 06:19 PM

Did you call GetLastError for extended error information? Then use the Error Lookup utility from the PSDK to map it to a text description.

BitBlt question

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