bmcv_image_draw_lines
======================

可以实现在一张图像上画一条或多条线段，从而可以实现画多边形的功能，并支持指定线的颜色和线的宽度。


**处理器型号支持：**

该接口支持BM1684/BM1684X。


**接口形式：**

    .. code-block:: c

        typedef struct {
            int x;
            int y;
        } bmcv_point_t;

        typedef struct {
            unsigned char r;
            unsigned char g;
            unsigned char b;
        } bmcv_color_t;

        bm_status_t bmcv_image_draw_lines(
                bm_handle_t handle,
                bm_image img,
                const bmcv_point_t* start,
                const bmcv_point_t* end,
                int line_num,
                bmcv_color_t color,
                int thickness);


**参数说明：**

* bm_handle_t handle

  输入参数。 bm_handle 句柄。

* bm_image img

  输入/输出参数。需处理图像的 bm_image，bm_image 需要外部调用 bmcv_image_create 创建。image 内存可以使用 bm_image_alloc_dev_mem 或者 bm_image_copy_host_to_device 来开辟新的内存，或者使用 bmcv_image_attach 来 attach 已有的内存。

* const bmcv_point_t* start

  输入参数。线段起始点的坐标指针，指向的数据长度由 line_num 参数决定。图像左上角为原点，向右延伸为x方向，向下延伸为y方向。

* const bmcv_point_t* end

  输入参数。线段结束点的坐标指针，指向的数据长度由 line_num 参数决定。图像左上角为原点，向右延伸为x方向，向下延伸为y方向。

* int line_num

  输入参数。需要画线的数量。

* bmcv_color_t color

  输入参数。画线的颜色，分别为RGB三个通道的值。

* int thickness

  输入参数。画线的宽度，对于YUV格式的图像建议设置为偶数。


**返回值说明：**

* BM_SUCCESS: 成功

* 其他:失败


**格式支持：**

该接口目前支持以下 image_format:

+-----+------------------------+
| num | image_format           |
+=====+========================+
| 1   | FORMAT_GRAY            |
+-----+------------------------+
| 2   | FORMAT_YUV420P         |
+-----+------------------------+
| 3   | FORMAT_YUV422P         |
+-----+------------------------+
| 4   | FORMAT_YUV444P         |
+-----+------------------------+
| 5   | FORMAT_NV12            |
+-----+------------------------+
| 6   | FORMAT_NV21            |
+-----+------------------------+
| 7   | FORMAT_NV16            |
+-----+------------------------+
| 8   | FORMAT_NV61            |
+-----+------------------------+

目前支持以下 data_type:

+-----+--------------------------------+
| num | data_type                      |
+=====+================================+
| 1   | DATA_TYPE_EXT_1N_BYTE          |
+-----+--------------------------------+


**代码示例：**

    .. code-block:: c


        int channel   = 1;
        int width     = 1920;
        int height    = 1080;
        int dev_id    = 0;
        int thickness = 4
        bmcv_point_t start = {0, 0};
        bmcv_point_t end = {100, 100};
        bmcv_color_t color = {255, 0, 0};
        bm_handle_t handle;
        bm_status_t dev_ret = bm_dev_request(&handle, dev_id);
        std::shared_ptr<unsigned char> data_ptr(
                new unsigned char[channel * width * height],
                std::default_delete<unsigned char[]>());
        for (int i = 0; i < channel * width * height; i++) {
            data_ptr.get()[i] = rand() % 255;
        }
        // calculate res
        bm_image img;
        bm_image_create(handle,
                        height,
                        width,
                        FORMAT_GRAY,
                        DATA_TYPE_EXT_1N_BYTE,
                        &img);
        bm_image_alloc_dev_mem(img);
        bm_image_copy_host_to_device(img, (void **)&(data_ptr.get()));
        if (BM_SUCCESS != bmcv_image_draw_lines(handle, img, &start, &end, 1, color, thickness)) {
            std::cout << "bmcv draw lines error !!!" << std::endl;
            bm_image_destroy(img);
            bm_dev_free(handle);
            return;
        }
        bm_image_copy_device_to_host(img, (void **)&(data_ptr.get()));
        bm_image_destroy(img);
        bm_dev_free(handle);