我使用C语言中的BGI库编写了生成中点椭圆的代码。编译后，我尝试运行该代码。但是打开以接受输入的窗口立即关闭，甚至没有接受输入。我试图增加延迟时间，但是那也不起作用。从昨天开始就一直试图解决该问题，但未能解决问题。

我的代码：

#include<stdio.h>
#include<graphics.h>

void main()
{
    int x1,x2,y1,y2,Xwmin,Ywmin,Xwmax,Ywmax,dx,dy,count,tmin,tmax;
    float p[4],q[4];
    int gd=DETECT,gm;
    initgraph(&gd,&gm,NULL);
    printf("Enter the values of X1 and Y1:");
    scanf("%d %d",&x1,&y1);
    printf("Enter the values of X2 and Y2:");
    scanf("%d %d",&x2,&y2);
    printf("Enter the coordinates of the window:\n");
    printf("Value of Xwmin:");
    scanf("%d",&Xwmin);
    printf("Value of Xwmax:");
    scanf("%d",&Xwmax);
    printf("Value of Ywmin:");
    scanf("%d",&Ywmin);
    printf("Value of Ywmax:");
    scanf("%d",&Ywmax);
    rectangle(Xwmin,Ywmax);
    dx=x2-x1;
    dy=y2-y1;
    p[0]=-dx;
    p[1]=dx;
    p[2]=-dy;
    p[3]=dy;
    q[0]=x1-Xwmin;
    q[1]=Xwmax-x1;
    q[2]=y1-Ywmin;
    p[3]=Ywmax-y1;
    for(count = 0; count < 4; count++)
        {
            if(p[count] == 0)
            {
                  printf("\nLine is parallel\n");
                  if(q[count] >= 0)
                  {
                        if(count < 2)
                        {
                              if(y1 < Ywmin)
                              {
                                    y1 = Ywmin;
                              } 
                              if(y2 > Ywmax)
                              {
                                    y2 = Ywmax;
                              } 
                              line(x1,y2);
                        }
                        if(count > 1)
                        {
                              if(x1 < Xwmin)
                              {
                                    x1 = Xwmin;
                              }
                              if(x2 > Xwmax)
                              {
                                    x2 = Xwmax;
                              } 
                              line(x1,y2);
                        }
                  }
            }
        }

    int t_min=0;
    int t_max=1;
    for(count =0;count<4;count++)
    {
            float t = q[count] / p[count]; 
            if(p[count] < 0)
            {
                  if(tmin <= t)
                  {
                        tmin = t;
                  }
            }
            else
            {
                  if(tmax > t)
                  {
                        tmax = t;
                  }
            }
      }
      if(tmin < tmax)
      {
            int t_x0 = x1 + tmin * p[1];
            int t_x1 = x1 + tmax * p[1];
            int t_y0 = y1 + tmin * p[3];
            int t_y1 = y1 + tmax * p[3];
            line(t_x0,t_y0,t_x1,t_y1);
      }
delay(5000);
closegraph;
}

我得到的错误是：

./a.out
[xcb] Unknown sequence number while processing queue
[xcb] Most likely this is a multi-threaded client and XInitThreads has not been called
[xcb] Aborting,sorry about that.
a.out: ../../src/xcb_io.c:274: poll_for_event: Assertion `!xcb_xlib_threads_sequence_lost' failed.
Aborted (core dumped)
 [xcb] Unknown sequence number while processing queue
[xcb] Most likely this is a multi-threaded client and XInitThreads has not been called
[xcb] Aborting,sorry about that.
a.out: ../../src/xcb_io.c:274: poll_for_event: Assertion `!xcb_xlib_threads_sequence_lost' failed.

我正在Ubuntu 16.04中使用GCC编译器 预先谢谢你。