在YUV帧缓冲区中画线

李国帅 写于2010

Rgb的surface可以使用getdc得到，并把图形绘制在dc上，但是yuv不可以，需要使用直接写内存的方式。

​​http://www.fourcc.org/yuv.php​​

在维基 On wiki http://en.wikipedia.org/wiki/YUV，

while on fourcc.org http://www.fourcc.org/fccyvrgb.php。

yuv的前面是亮度数据一个点对应一个byte，后面的u变量4个点对应一个数据，v变量和u变量一样。

int src_off = 4 * sizeof(int);  //skip first 16 bytes,define by onself: size per line = 16BYTE
    int src_lineSize = *(int *)pOutData;
    int dst_off = 0;

    for (int i = 0; i < VideoHeight; i++)//亮度数据
    {
        memcpy(pBuffer + dst_off, pOutData + src_off, src_lineSize);
        dst_off += lPitch;
        src_off += src_lineSize;
    }

    YUV_drawLine(pBuffer, VideoWidth, VideoHeight, lPitch, 100, 100, 200, 200, 200);

    for (int i = 0; i < VideoHeight; i++)//v变量和u变量
    {
        memcpy(pBuffer + dst_off, pOutData + src_off, src_lineSize / 2);
        dst_off += lPitch / 2;
        src_off += src_lineSize / 2;
    }

void YUV_drawLine(unsigned char *dst_buf, int w, int h, int lpitch, int x0, int y0, int x1, int y1, unsigned char color)
{
    unsigned char *xoff;
    unsigned char *yoff;
    int rect_width = x1 - x0;
    int rect_height = y1 - y0;

    xoff = dst_buf + y0*lpitch + x0;
    memset(xoff, color, rect_width);

    xoff = dst_buf + y1*lpitch + x0;
    memset(xoff, color, rect_width);

    for (int i = 0; i < rect_height; i++)
    {
        yoff = dst_buf + (i + y0)*lpitch + x0;
        *yoff = color;

        yoff = dst_buf + (i + y0)*lpitch + x1;
        *yoff = color;
    }
}