调用SetDIBits修改位图内容 from http://blog.csdn.net/iamshuke/article/details/5749933

通过调用SetDIBits直接修改位图数据。下面的示例在黑色背景上画了一个十字。

void CTest5Dlg::OnOK()
{
    // TODO: Add extra validation here
    CClientDC dc(this);
    CDC memDC;
    memDC.CreateCompatibleDC(&dc);

    CBitmap bmp;
    bmp.CreateCompatibleBitmap(&dc, 300, 200);
    memDC.SelectObject(&bmp);

    BITMAPINFO bmpInfo;
    bmpInfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
    bmpInfo.bmiHeader.biWidth = 300;
    bmpInfo.bmiHeader.biHeight = -200;
    bmpInfo.bmiHeader.biPlanes = 1;
    bmpInfo.bmiHeader.biBitCount = 24;
    bmpInfo.bmiHeader.biCompression = BI_RGB;
    bmpInfo.bmiHeader.biSizeImage = 0;
    bmpInfo.bmiHeader.biXPelsPerMeter = 3000;
    bmpInfo.bmiHeader.biYPelsPerMeter = 3000;
    bmpInfo.bmiHeader.biClrUsed = 0;
    bmpInfo.bmiHeader.biClrImportant = 0;

    long nLnBytes = (bmpInfo.bmiHeader.biWidth*3+3)/4*4;
    BYTE *pData = new BYTE[nLnBytes*abs(bmpInfo.bmiHeader.biHeight)];

    //清成黑色
    memset(pData,0,nLnBytes*abs(bmpInfo.bmiHeader.biHeight));

    //画一个十字
    for(int i=10; i<90; i++)
    {
        //横线, 黄色
        pData[50*nLnBytes+i*3+1] = 255; //g
        pData[50*nLnBytes+i*3+2] = 255; //r

        //竖线, 蓝色
        pData[i*nLnBytes+50*3] = 255; //b
    }

    SetDIBits(dc.m_hDC, bmp, 0, abs(bmpInfo.bmiHeader.biHeight), pData, &bmpInfo, DIB_RGB_COLORS);

    delete []pData;

    dc.BitBlt(0, 0, bmpInfo.bmiHeader.biWidth, abs(bmpInfo.bmiHeader.biHeight), &memDC, 0, 0, SRCCOPY);
}

 效果图：