<span style="font-size:18px;">void GetStringSize(HDC hDC, const char* str, int* w, int* h)
{
    SIZE size;
    GetTextExtentPoint32A(hDC, str, strlen(str), &size);
    if(w != 0) *w = size.cx;
    if(h != 0) *h = size.cy;
}

void paDrawString(Mat& dst, const char* str, Point org, Scalar color, int fontSize, bool italic, bool underline)
{
    CV_Assert(dst.data != 0 && (dst.channels() == 1 || dst.channels() == 3));

    int x, y, r, b;
    if(org.x > dst.cols || org.y > dst.rows) return;
    x = org.x < 0 ? -org.x : 0;
    y = org.y < 0 ? -org.y : 0;

    LOGFONTA lf;
    lf.lfHeight         = - fontSize ;
    lf.lfWidth          = 0 ;
    lf.lfEscapement     = 0 ;
    lf.lfOrientation    = 0 ;
    lf.lfWeight         = 5;
    lf.lfItalic         = italic ;    //斜体
    lf.lfUnderline      = underline ;    //下划线
    lf.lfStrikeOut       = 0 ;
    lf.lfCharSet        = DEFAULT_CHARSET ;
    lf.lfOutPrecision    = 0 ;
    lf.lfClipPrecision    = 0 ;
    lf.lfQuality         = PROOF_QUALITY ;
    lf.lfPitchAndFamily  = 0 ;
    strcpy (lf.lfFaceName, "华文行楷" );

    HFONT hf = CreateFontIndirectA(&lf);
    HDC hDC = CreateCompatibleDC(0);
    HFONT hOldFont = (HFONT)SelectObject(hDC, hf);

    int strBaseW = 0, strBaseH = 0;
    int singleRow = 0;
    char buf[1 << 12];
    strcpy(buf, str);

    //处理多行
    {
        int nnh = 0;
        int cw, ch;
        const char* ln = strtok(buf, "\n");
        while(ln != 0)
        {
            GetStringSize(hDC, ln, &cw, &ch);
            strBaseW = max(strBaseW, cw);
            strBaseH = max(strBaseH, ch);

            ln = strtok(0, "\n");
            nnh++;
        }
        singleRow = strBaseH;
        strBaseH *= nnh;
    }

    if(org.x + strBaseW < 0 || org.y + strBaseH < 0)
    {
        SelectObject(hDC, hOldFont);
        DeleteObject(hf);
        DeleteObject(hDC);
        return;
    }

    r = org.x + strBaseW > dst.cols? dst.cols - org.x - 1 : strBaseW - 1;    
    b = org.y + strBaseH > dst.rows ? dst.rows - org.y - 1 : strBaseH - 1;
    org.x = org.x < 0 ? 0 : org.x;
    org.y = org.y < 0 ? 0 : org.y;

    BITMAPINFO bmp = {0};
    BITMAPINFOHEADER& bih = bmp.bmiHeader;
    int strDrawLineStep = strBaseW * 3 % 4 == 0 ? strBaseW * 3 : (strBaseW * 3 + 4 - ((strBaseW * 3) % 4));

    bih.biSize=sizeof(BITMAPINFOHEADER);
    bih.biWidth=strBaseW;
    bih.biHeight=strBaseH;
    bih.biPlanes=1;
    bih.biBitCount=24;
    bih.biCompression=BI_RGB;
    bih.biSizeImage=strBaseH * strDrawLineStep;
    bih.biClrUsed=0;
    bih.biClrImportant=0;

    void* pDibData = http://www.mamicode.com/0;
    HBITMAP hBmp = CreateDIBSection(hDC, &bmp, DIB_RGB_COLORS, &pDibData, 0, 0);

    CV_Assert(pDibData != 0);
    HBITMAP hOldBmp = (HBITMAP)SelectObject(hDC, hBmp);

    //color.val[2], color.val[1], color.val[0]
    SetTextColor(hDC, RGB(255, 255, 255));
    SetBkColor(hDC, 0);
    //SetStretchBltMode(hDC, COLORONCOLOR);

    strcpy(buf, str);
    const char* ln = strtok(buf, "\n");
    int outTextY = 0;
    while(ln != 0)
    {
        TextOutA(hDC, 0, outTextY, ln, strlen(ln));
        outTextY += singleRow;
        ln = strtok(0, "\n");
    }
    uchar* dstData = http://www.mamicode.com/(uchar*)dst.data;
    int dstStep = dst.step/sizeof(dstData[0]);
    unsigned char* pImg = (unsigned char*)dst.data + org.x * dst.channels() + org.y * dstStep;
    unsigned char* pStr = (unsigned char*)pDibData + x * 3;
    for(int tty = y; tty <= b; ++tty)
    {
        unsigned char* subImg = pImg + (tty - y) * dstStep;
        unsigned char* subStr = pStr + (strBaseH - tty - 1) * strDrawLineStep;
        for (int ttx = x; ttx <= r; ++ttx)
        {
            for (int n = 0; n < dst.channels(); ++n){
                double vtxt = subStr[n] / 255.0;
                int cvv =  vtxt * color.val[n] + (1 - vtxt) * subImg[n];
                subImg[n] = cvv > 255 ? 255 : (cvv < 0 ? 0 : cvv);
            }

            subStr += 3;
            subImg += dst.channels();
        }
    }

    SelectObject(hDC, hOldBmp);
    SelectObject(hDC, hOldFont);
    DeleteObject(hf);
    DeleteObject(hBmp);
    DeleteDC(hDC);
}

void main()
{
    Mat img = imread("cat.jpg");
    if(!img.data)
    {
        cout<<"load image error"<<endl;
        return;
    }
    paDrawString(img, "测试汉字哈...\n换行了哟\n真的可以啊！！！~",Point(10, 10), Scalar(255,0,0), 50, true, true);
    imshow("img", img);
    waitKey();
}