通过发布合适的话题可以在rviz的视图中显示合适的话题。可以在example_rviz_marker中查看例子example_rviz_marker.cpp。

#include <ros/ros.h> 
#include <visualization_msgs/Marker.h> // need this for publishing markers
#include <geometry_msgs/Point.h> //data type used for markers
#include <string.h>
#include <stdio.h>  
#include <example_rviz_marker/SimpleFloatSrvMsg.h> //自定义的消息类型
using namespace std;

//set these two values by service callback, make available to "main"
double g_z_height = 0.0;
bool g_trigger = true;

//a service to prompt a new display computation.
// E.g., to construct a plane at height z=1.0, trigger with: 
// rosservice call rviz_marker_svc 1.0

bool displaySvcCB(example_rviz_marker::SimpleFloatSrvMsgRequest& request,
    example_rviz_marker::SimpleFloatSrvMsgResponse& response) {
    g_z_height = request.request_float32;
    ROS_INFO("example_rviz_marker: received request for height %f", g_z_height);
    g_trigger = true; // inform "main" a new computation is desired
    response.resp=true;
    return true;
}

void init_marker_vals(visualization_msgs::Marker &marker) {
    marker.header.frame_id = "/world"; // reference frame for marker coords
    marker.header.stamp = ros::Time();
    marker.ns = "my_namespace";
    marker.id = 0;
    // use SPHERE if you only want a single marker
    // use SPHERE_LIST for a group of markers
    marker.type = visualization_msgs::Marker::SPHERE_LIST; //SPHERE;
    marker.action = visualization_msgs::Marker::ADD;
    // if just using a single marker, specify the coordinates here, like this:

    //marker.pose.position.x = 0.4;  
    //marker.pose.position.y = -0.4;
    //marker.pose.position.z = 0;
    //ROS_INFO("x,y,z = %f %f, %f",marker.pose.position.x,marker.pose.position.y,                       
    //        marker.pose.position.z);    
    // otherwise, for a list of markers, put their coordinates in the "points" array, as below

    //whether a single marker or list of markers, need to specify marker properties
    // these will all be the same for SPHERE_LIST
    marker.pose.orientation.x = 0.0;
    marker.pose.orientation.y = 0.0;
    marker.pose.orientation.z = 0.0;
    marker.pose.orientation.w = 1.0;
    marker.scale.x = 0.02;
    marker.scale.y = 0.02;
    marker.scale.z = 0.02;
    marker.color.a = 1.0;
    marker.color.r = 1.0;
    marker.color.g = 0.0;
    marker.color.b = 0.0;     
}

int main(int argc, char **argv) {
    ros::init(argc, argv, "example_rviz_marker");
    ros::NodeHandle nh;
    ros::Publisher vis_pub = nh.advertise<visualization_msgs::Marker>("example_marker_topic", 0);
    visualization_msgs::Marker marker; // 实例化一个标记对象
    geometry_msgs::Point point; // 点云用来表示标记点的位置

    //set up a service to compute marker locations on request设置一个服务计算所请求的标记点的位置
    ros::ServiceServer service = nh.advertiseService("rviz_marker_svc", displaySvcCB);

    init_marker_vals(marker);//调用预定义函数，初始化标记点

    double z_des;

    // build a wall of markers; set range and resolution建立标记墙，设置范围和分辨率
    double x_min = -1.0;
    double x_max = 1.0;
    double y_min = -1.0;
    double y_max = 1.0;
    double dx_des = 0.1;
    double dy_des = 0.1;

    while (ros::ok()) {
        if (g_trigger) {  // did service get request for a new computation?
            g_trigger = false; //reset the trigger from service
            z_des = g_z_height; //use z-value from service callback
            ROS_INFO("constructing plane of markers at height %f",z_des);
            marker.header.stamp = ros::Time();
            marker.points.clear(); // clear out this vector

            for (double x_des = x_min; x_des < x_max; x_des += dx_des) {
                for (double y_des = y_min; y_des < y_max; y_des += dy_des) {
                        point.x = x_des;
                        point.y = y_des;
                        point.z = z_des;
                        marker.points.push_back(point);
                }
            }
        }
     ros::Duration(0.1).sleep();
    //ROS_INFO("publishing...");
    vis_pub.publish(marker);
    ros::spinOnce();       
    }
    return 0;
}

节点的源代码定义了一个服务rviz_marker_svc。服务使用自定义的消息SimpleFloatSrvMsg，期望客户端提供一个单浮点数。服务可以通过以下命令手动调用：

rosservice call rviz_marker_svc 1.0

当服务被调用的时候，example_rviz_maker节点将在高度为1.0的位置计算一系列的平面点。
运行这个例子，首先启动roscore，然后输入

rosrun example_rviz_marker example_rv_marker 

启动rviz

rosrun rviz rviz

选择world为固定坐标系，添加Marker组件，选择Marker Topic为/example_marker_topic，可以观察到平面标记点信息

调用服务

rosservice call rviz_marker_svc 1.0

标记点向上平移了一个单位

三维显示示例

先上triad_display.cpp代码

// triad_display.cpp
// Wyatt Newman, 8/16
// node to assist display of triads (axes) in rviz
// this node subscribes to topic "triad_display_pose", from which it receives geometry_msgs/PoseStamped poses
// it uses this info to populate and publish axes, using whatever frame_id is in the pose header
// To see the result, add a "Marker" display in rviz and subscribe to the marker topic "/triad_display"
// Can test this display node with the test node: "triad_display_test_node", which generates moving poses
// corresponding to a marker origin spiraling up in z

#include <ros/ros.h>
#include <visualization_msgs/Marker.h>
//#include <visualization_msgs/InteractiveMarkerFeedback.h>
#include <geometry_msgs/Point.h>
#include <geometry_msgs/PointStamped.h>
#include <geometry_msgs/PoseStamped.h>
#include <math.h>
#include <Eigen/Eigen>  
#include <Eigen/Core>
#include <Eigen/Geometry>
#include <Eigen/Dense>
#include <tf_conversions/tf_eigen.h>

//some globals...
geometry_msgs::Point vertex1;
geometry_msgs::PoseStamped g_stamped_pose;
Eigen::Affine3d g_affine_marker_pose;

// create arrow markers; do this 3 times to create a triad (frame)
visualization_msgs::Marker arrow_marker_x; //this one for the x axis
visualization_msgs::Marker arrow_marker_y; //this one for the y axis
visualization_msgs::Marker arrow_marker_z; //this one for the y axis

//udpdate_arrows() set the frame and 

void update_arrows() {
    geometry_msgs::Point origin, arrow_x_tip, arrow_y_tip, arrow_z_tip;
    Eigen::Matrix3d R;
    Eigen::Quaterniond quat;
    quat.x() = g_stamped_pose.pose.orientation.x;
    quat.y() = g_stamped_pose.pose.orientation.y;
    quat.z() = g_stamped_pose.pose.orientation.z;
    quat.w() = g_stamped_pose.pose.orientation.w;
    R = quat.toRotationMatrix();
    Eigen::Vector3d x_vec, y_vec, z_vec;
    double veclen = 0.2; //make the arrows this long
    x_vec = R.col(0) * veclen;
    y_vec = R.col(1) * veclen;
    z_vec = R.col(2) * veclen;

    //update the arrow markers w/ new pose:
    origin = g_stamped_pose.pose.position;
    arrow_x_tip = origin;
    arrow_x_tip.x += x_vec(0);
    arrow_x_tip.y += x_vec(1);
    arrow_x_tip.z += x_vec(2);
    arrow_marker_x.points.clear();
    arrow_marker_x.points.push_back(origin);
    arrow_marker_x.points.push_back(arrow_x_tip);
    arrow_marker_x.header = g_stamped_pose.header;

    arrow_y_tip = origin;
    arrow_y_tip.x += y_vec(0);
    arrow_y_tip.y += y_vec(1);
    arrow_y_tip.z += y_vec(2);

    arrow_marker_y.points.clear();
    arrow_marker_y.points.push_back(origin);
    arrow_marker_y.points.push_back(arrow_y_tip);
    arrow_marker_y.header = g_stamped_pose.header;

    arrow_z_tip = origin;
    arrow_z_tip.x += z_vec(0);
    arrow_z_tip.y += z_vec(1);
    arrow_z_tip.z += z_vec(2);

    arrow_marker_z.points.clear();
    arrow_marker_z.points.push_back(origin);
    arrow_marker_z.points.push_back(arrow_z_tip);
    arrow_marker_z.header = g_stamped_pose.header;
}

//init persistent params of markers, then variable coords    

void init_markers() {
    //initialize stamped pose for at a legal (if boring) pose
    g_stamped_pose.header.stamp = ros::Time::now();
    g_stamped_pose.header.frame_id = "world";
    g_stamped_pose.pose.position.x = 0;
    g_stamped_pose.pose.position.y = 0;
    g_stamped_pose.pose.position.z = 0;
    g_stamped_pose.pose.orientation.x = 0;
    g_stamped_pose.pose.orientation.y = 0;
    g_stamped_pose.pose.orientation.z = 0;
    g_stamped_pose.pose.orientation.w = 1;

    //the following parameters only need to get set once
    arrow_marker_x.type = visualization_msgs::Marker::ARROW;
    arrow_marker_x.action = visualization_msgs::Marker::ADD; //create or modify marker
    arrow_marker_x.ns = "triad_namespace";
    arrow_marker_x.lifetime = ros::Duration(); //never delete
    // make the arrow thin
    arrow_marker_x.scale.x = 0.01;
    arrow_marker_x.scale.y = 0.01;
    arrow_marker_x.scale.z = 0.01;
    arrow_marker_x.color.r = 1.0; // red, for the x axis
    arrow_marker_x.color.g = 0.0;
    arrow_marker_x.color.b = 0.0;
    arrow_marker_x.color.a = 1.0;
    arrow_marker_x.id = 0;
    arrow_marker_x.header = g_stamped_pose.header;

    //y and z arrow params are the same, except for colors
    arrow_marker_y = arrow_marker_x;
    arrow_marker_y.color.r = 0.0;
    arrow_marker_y.color.g = 1.0; //green for y axis
    arrow_marker_y.color.b = 0.0;
    arrow_marker_y.color.a = 1.0;
    arrow_marker_y.id = 1;

    arrow_marker_z = arrow_marker_x;
    arrow_marker_z.id = 2;
    arrow_marker_z.color.r = 0.0;
    arrow_marker_z.color.g = 0.0;
    arrow_marker_z.color.b = 1.0; //blue for z axis
    arrow_marker_z.color.a = 1.0;
    //set the poses of the arrows based on g_stamped_pose
    update_arrows();
}

void poseCB(const geometry_msgs::PoseStamped &pose_msg) {
    ROS_DEBUG("got pose message");
    //ROS_INFO("got pose message");
    g_stamped_pose.header = pose_msg.header;
    g_stamped_pose.pose = pose_msg.pose;

}

int main(int argc, char** argv) {
    ros::init(argc, argv, "triad_display"); // this will be the node name;
    ros::NodeHandle nh;

    // subscribe to stamped-pose publications
    ros::Subscriber pose_sub = nh.subscribe("triad_display_pose", 1, poseCB);
    ros::Publisher vis_pub = nh.advertise<visualization_msgs::Marker>("triad_display", 1);
    init_markers();

    ros::Rate timer(20); //timer to run at 20 Hz

    while (ros::ok()) {
        update_arrows();
        vis_pub.publish(arrow_marker_x); //publish the marker
        ros::Duration(0.01).sleep();
        vis_pub.publish(arrow_marker_y); //publish the marker
        ros::Duration(0.01).sleep();
        vis_pub.publish(arrow_marker_z); //publish the marker
        ros::spinOnce(); //let callbacks perform an update
        timer.sleep();
    }
}

依次运行以下命令：

roscore

rosrun example_rviz_marker triad _display

rosrun rviz rviz

rosrun example_rviz_marker triad_display_test_node

可以看到一个直角坐标标记螺旋上升。

rviz中的交互式标记（interactive marker）

交互式标记的例子可以在example_interactive_marker包中找到。以下是示例代码

// IM_6DOF_example.cpp
// Wyatt Newman, based on ROS tutorial 4.2 on Interactive Markers
#include <ros/ros.h>
#include <iostream>
#include <interactive_markers/interactive_marker_server.h>
#include <geometry_msgs/Point.h>
#include <example_interactive_marker/ImNodeSvcMsg.h>

const int IM_GET_CURRENT_MARKER_POSE = 0;
const int IM_SET_NEW_MARKER_POSE = 1;

geometry_msgs::Point g_current_point;
geometry_msgs::Quaternion g_current_quaternion;
ros::Time g_marker_time;

interactive_markers::InteractiveMarkerServer *g_IM_server; //("rt_hand_marker");
visualization_msgs::InteractiveMarkerFeedback *g_IM_feedback;

//service:  return pose of marker from above globals;
// depending on mode, move IM programmatically, 

bool IM6DofSvcCB(example_interactive_marker::ImNodeSvcMsgRequest& request, example_interactive_marker::ImNodeSvcMsgResponse& response) {
    //if busy, refuse new requests;

    // for a simple status query, handle it now;
    if (request.cmd_mode == IM_GET_CURRENT_MARKER_POSE) {
        ROS_INFO("IM6DofSvcCB: rcvd request for query--GET_CURRENT_MARKER_POSE");
        response.poseStamped_IM_current.header.stamp = g_marker_time;
        response.poseStamped_IM_current.header.frame_id = "world";
        response.poseStamped_IM_current.pose.position = g_current_point;//返回位置
        response.poseStamped_IM_current.pose.orientation = g_current_quaternion;//返回方向
        return true;
    }

    //command to move the marker to specified pose:
    if (request.cmd_mode == IM_SET_NEW_MARKER_POSE) {
        geometry_msgs::PoseStamped poseStamped_IM_desired;
        ROS_INFO("IM6DofSvcCB: rcvd request for action--SET_NEW_MARKER_POSE");
        g_current_point = request.poseStamped_IM_desired.pose.position;//设置位置
        g_current_quaternion = request.poseStamped_IM_desired.pose.orientation;//设置当前方向
        g_marker_time = ros::Time::now();
        poseStamped_IM_desired = request.poseStamped_IM_desired;
        poseStamped_IM_desired.header.stamp = g_marker_time;
        response.poseStamped_IM_current = poseStamped_IM_desired;
        //g_IM_feedback->pose = poseStamped_IM_desired.pose;

        response.poseStamped_IM_current.header.stamp = g_marker_time;
        response.poseStamped_IM_current.header.frame_id = "torso";
        response.poseStamped_IM_current.pose.position = g_current_point;
        response.poseStamped_IM_current.pose.orientation = g_current_quaternion;
        g_IM_server->setPose("des_hand_pose", poseStamped_IM_desired.pose); //g_IM_feedback->marker_name,poseStamped_IM_desired.pose);
        g_IM_server->applyChanges();
        return true;
    }
    ROS_WARN("IM6DofSvcCB: case not recognized");
    return false;
}

void processFeedback(
        const visualization_msgs::InteractiveMarkerFeedbackConstPtr &feedback) {
    ROS_INFO_STREAM(feedback->marker_name << " is now at "
            << feedback->pose.position.x << ", " << feedback->pose.position.y
            << ", " << feedback->pose.position.z);
    g_current_quaternion = feedback->pose.orientation;
    g_current_point = feedback->pose.position;
    g_marker_time = ros::Time::now();
}

void init_arrow_marker_x(visualization_msgs::Marker &arrow_marker_x) {
    geometry_msgs::Point temp_point;

    arrow_marker_x.type = visualization_msgs::Marker::ARROW; //ROS example was a CUBE; changed to ARROW
    // specify/push-in the origin point for the arrow 
    temp_point.x = temp_point.y = temp_point.z = 0;
    arrow_marker_x.points.push_back(temp_point);
    // Specify and push in the end point for the arrow 
    temp_point = g_current_point;
    temp_point.x = 0.2; // arrow is this long in x direction
    temp_point.y = 0.0;
    temp_point.z = 0.0;
    arrow_marker_x.points.push_back(temp_point);

    // make the arrow very thin
    arrow_marker_x.scale.x = 0.01;
    arrow_marker_x.scale.y = 0.01;
    arrow_marker_x.scale.z = 0.01;

    arrow_marker_x.color.r = 1.0; // red, for the x axis
    arrow_marker_x.color.g = 0.0;
    arrow_marker_x.color.b = 0.0;
    arrow_marker_x.color.a = 1.0;
}

void init_arrow_marker_y(visualization_msgs::Marker &arrow_marker_y) {
    geometry_msgs::Point temp_point;
    arrow_marker_y.type = visualization_msgs::Marker::ARROW;
    // Push in the origin point for the arrow 
    temp_point.x = temp_point.y = temp_point.z = 0;
    arrow_marker_y.points.push_back(temp_point);
    // Push in the end point for the arrow 
    temp_point.x = 0.0;
    temp_point.y = 0.2; // points in the y direction
    temp_point.z = 0.0;
    arrow_marker_y.points.push_back(temp_point);

    arrow_marker_y.scale.x = 0.01;
    arrow_marker_y.scale.y = 0.01;
    arrow_marker_y.scale.z = 0.01;

    arrow_marker_y.color.r = 0.0;
    arrow_marker_y.color.g = 1.0; // color it green, for y axis
    arrow_marker_y.color.b = 0.0;
    arrow_marker_y.color.a = 1.0;
}

void init_arrow_marker_z(visualization_msgs::Marker &arrow_marker_z) {
    geometry_msgs::Point temp_point;

    arrow_marker_z.type = visualization_msgs::Marker::ARROW; //CUBE;
    // Push in the origin point for the arrow 
    temp_point.x = temp_point.y = temp_point.z = 0;
    arrow_marker_z.points.push_back(temp_point);
    // Push in the end point for the arrow 
    temp_point.x = 0.0;
    temp_point.y = 0.0;
    temp_point.z = 0.2;
    arrow_marker_z.points.push_back(temp_point);

    arrow_marker_z.scale.x = 0.01;
    arrow_marker_z.scale.y = 0.01;
    arrow_marker_z.scale.z = 0.01;

    arrow_marker_z.color.r = 0.0;
    arrow_marker_z.color.g = 0.0;
    arrow_marker_z.color.b = 1.0;
    arrow_marker_z.color.a = 1.0;
}

void init_translate_control_x(visualization_msgs::InteractiveMarkerControl &translate_control_x) {
    translate_control_x.name = "move_x";
    translate_control_x.interaction_mode =
            visualization_msgs::InteractiveMarkerControl::MOVE_AXIS;
}

void init_translate_control_y(visualization_msgs::InteractiveMarkerControl &translate_control_y) {
    translate_control_y.name = "move_y";
    translate_control_y.interaction_mode =
            visualization_msgs::InteractiveMarkerControl::MOVE_AXIS;
    translate_control_y.orientation.x = 0; //point this in the y direction
    translate_control_y.orientation.y = 0;
    translate_control_y.orientation.z = 1;
    translate_control_y.orientation.w = 1;
}

void init_translate_control_z(visualization_msgs::InteractiveMarkerControl &translate_control_z) {
    translate_control_z.name = "move_z";
    translate_control_z.interaction_mode =
            visualization_msgs::InteractiveMarkerControl::MOVE_AXIS;
    translate_control_z.orientation.x = 0; //point this in the y direction
    translate_control_z.orientation.y = 1;
    translate_control_z.orientation.z = 0;
    translate_control_z.orientation.w = 1;
}

void init_rotx_control(visualization_msgs::InteractiveMarkerControl &rotx_control) {
    rotx_control.always_visible = true;
    rotx_control.interaction_mode = visualization_msgs::InteractiveMarkerControl::ROTATE_AXIS;
    rotx_control.orientation.x = 1;
    rotx_control.orientation.y = 0;
    rotx_control.orientation.z = 0;
    rotx_control.orientation.w = 1;
    rotx_control.name = "rot_x";
}

void init_roty_control(visualization_msgs::InteractiveMarkerControl &roty_control) {
    roty_control.always_visible = true;
    roty_control.interaction_mode = visualization_msgs::InteractiveMarkerControl::ROTATE_AXIS;
    roty_control.orientation.x = 0;
    roty_control.orientation.y = 0;
    roty_control.orientation.z = 1;
    roty_control.orientation.w = 1;
    roty_control.name = "rot_y";
}

void init_rotz_control(visualization_msgs::InteractiveMarkerControl &rotz_control) {
    rotz_control.always_visible = true;
    rotz_control.interaction_mode = visualization_msgs::InteractiveMarkerControl::ROTATE_AXIS;
    rotz_control.orientation.x = 0;
    rotz_control.orientation.y = 1;
    rotz_control.orientation.z = 0;
    rotz_control.orientation.w = 1;
    rotz_control.name = "rot_z";
}

void init_IM_control(visualization_msgs::InteractiveMarkerControl &IM_control,
        visualization_msgs::Marker &arrow_marker_x,
        visualization_msgs::Marker &arrow_marker_y, visualization_msgs::Marker &arrow_marker_z) {
    init_arrow_marker_x(arrow_marker_x); //set up arrow params for x
    init_arrow_marker_y(arrow_marker_y); //set up arrow params for y
    init_arrow_marker_z(arrow_marker_z); //set up arrow params for z    
    IM_control.always_visible = true;

    IM_control.markers.push_back(arrow_marker_x);
    IM_control.markers.push_back(arrow_marker_y);
    IM_control.markers.push_back(arrow_marker_z);
}

void init_int_marker(visualization_msgs::InteractiveMarker &int_marker) {
    int_marker.header.frame_id = "world"; //base_link"; ///world"; // the reference frame for pose coordinates
    int_marker.name = "des_hand_pose"; //name the marker
    int_marker.description = "Interactive Marker";

    /** Scale Down: this makes all of the arrows/disks for the user controls smaller than the default size */
    int_marker.scale = 0.2;

    /** specify/push-in the origin for this marker */
    //let's pre-position the marker, else it will show up at the frame origin by default
    int_marker.pose.position.x = g_current_point.x;
    int_marker.pose.position.y = g_current_point.y;
    int_marker.pose.position.z = g_current_point.z;
}

int main(int argc, char** argv) {
    ros::init(argc, argv, "simple_marker"); // this will be the node name;
    ros::NodeHandle nh; //standard ros node handle 
    // create an interactive marker server on the topic namespace simple_marker
    interactive_markers::InteractiveMarkerServer server("rt_hand_marker");
    g_IM_server = &server;
    ros::ServiceServer IM_6dof_interface_service = nh.advertiseService("IM6DofSvc", &IM6DofSvcCB);
    // look for resulting pose messages on the topic: /rt_hand_marker/feedback,
    // which publishes a message of type visualization_msgs/InteractiveMarkerFeedback, which
    // includes a full "pose" of the marker.
    // Coordinates of the pose are with respect to the named frame
    g_current_point.x = 0.5; //init these global values
    g_current_point.y = -0.5; //will be used in subsequent init fncs
    g_current_point.z = 0.2;

    // create an interactive marker for our server
    visualization_msgs::InteractiveMarker int_marker;
    init_int_marker(int_marker);

    // arrow markers; 3 to create a triad (frame)
    visualization_msgs::Marker arrow_marker_x, arrow_marker_y, arrow_marker_z;
    // create a control that contains the markers
    visualization_msgs::InteractiveMarkerControl IM_control;
    //initialize values for this control
    init_IM_control(IM_control, arrow_marker_x, arrow_marker_y, arrow_marker_z);
    // add the control to the interactive marker
    int_marker.controls.push_back(IM_control);

    // create a control that will move the marker
    // this control does not contain any markers,
    // which will cause RViz to insert two arrows
    visualization_msgs::InteractiveMarkerControl translate_control_x,
            translate_control_y, translate_control_z;
    init_translate_control_x(translate_control_x);
    init_translate_control_y(translate_control_y);
    init_translate_control_z(translate_control_z);

    // add x,y,and z-rotation controls
    visualization_msgs::InteractiveMarkerControl rotx_control, roty_control,
            rotz_control;
    init_rotx_control(rotx_control);
    init_roty_control(roty_control);
    init_rotz_control(rotz_control);

    // add the controls to the interactive marker
    int_marker.controls.push_back(translate_control_x);
    int_marker.controls.push_back(translate_control_y);
    int_marker.controls.push_back(translate_control_z);
    int_marker.controls.push_back(rotx_control);
    int_marker.controls.push_back(rotz_control);
    int_marker.controls.push_back(roty_control);

    // add the interactive marker to our collection &
    // tell the server to call processFeedback() when feedback arrives for it
    //server.insert(int_marker, &processFeedback);
    g_IM_server->insert(int_marker, &processFeedback);
    // 'commit' changes and send to all clients
    //server.applyChanges();
    g_IM_server->applyChanges();

    // start the ROS main loop
    ROS_INFO("going into spin...");
    ros::spin();
}

在前期的基础上运行

rosrun example_interactive_marker exale_interactive_marker_node 

然后在rviz界面添加Interactive Marker组件，

可以看到

鼠标移动标记会显示出原点位置。