Help with CDC.

This is a discussion on Help with CDC. within the Windows Programming forums, part of the Platform Specific Boards category; I have just signed up for this new board so lets see if can get any replies for this. I ...

  1. #1
    Registered User headexplodes's Avatar
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    Smile Help with CDC.

    I have just signed up for this new board so lets see if can get any replies for this.

    I have the following code in Microsoft Visual C++ 6.0

    CBitmap bmpBlue;
    bmpBlue.LoadBitmap(IDB_BLUE);

    CDC bmpDC;
    bmpDC.CreateCompatibleDC(dc);
    bmpDC.SelectObject(&bmpBlue);

    CDC memDC;
    memDC.CreateCompatibleDC(dc);
    memDC.BitBlt(0,0,400,400,&bmpDC,0,0,SRCCOPY);

    BitBlt(dc->m_hDC, 0, 0, 400, 400, memDC.m_hDC, 0, 0, SRCCOPY);

    and it outputs nothing. I belive this is because the memDC does not have a size. If i just paint the tmpDC like this:

    BitBlt(dc->m_hDC, 0, 0, 400, 400, bmpDC.m_hDC, 0, 0, SRCCOPY);

    it works fine. Do you know i can fix my problem?

    Thanx,
    HeadExplodes .
    /* MSN and E-Mail - head_explodeshotmail.com */
    If Bill Gates got a dollar for every time windows crahsed... oh... he does.
    I always use MSVC++6.0

  2. #2
    zen
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    You have to select your bitmap into your memDC to 'paint' onto.

  3. #3
    Registered User headexplodes's Avatar
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    So i HAVE to have a window or bitmap accociated with the CDC for it to work?
    /* MSN and E-Mail - head_explodeshotmail.com */
    If Bill Gates got a dollar for every time windows crahsed... oh... he does.
    I always use MSVC++6.0

  4. #4
    zen
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    Yes, you need to create the memDC from an existing DC and then select a bitmap into the memDC.

    Then when you use GDI functions using the memDC you are drawing on the bitmap you've selected into it.

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