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在 Ubuntu 中使用 graphics.h 时出现问题

tag-icon • tag-icon graphics c++
在 Ubuntu 中使用 graphics.h 时出现问题 
# include<stdio.h>
# include<graphics.h>
# include<math.h>
using namespace std;
int main(void)
{
    int gd=DETECT,gm;
    int r,x,y,p,xc=320,yc=240;

    initgraph(&gd,&gm,NULL);
    cleardevice();


    printf("Enter the radius ");
    scanf("%d",&r);


    x=0;
    y=r;
    putpixel(xc+x,yc-y,1);

    p=3-(2*r);

    for(x=0;x<=y;x++)
    {
        if (p<0)
        {
             y=y;
            p=(p+(4*x)+6);
        }
        else
        {
            y=y-1;

            p=p+((4*(x-y)+10));
        }

    putpixel(xc+x,yc-y,1);
    putpixel(xc-x,yc-y,2);
    putpixel(xc+x,yc+y,3);
    putpixel(xc-x,yc+y,4);
    putpixel(xc+y,yc-x,5);
    putpixel(xc-y,yc-x,6);
    putpixel(xc+y,yc+x,7);
    putpixel(xc-y,yc+x,8);

    }
    getch();
    closegraph();
}
  • 已安装graphics.h
  • 使用编译gcc filename.cpp -0 filename -lgraph
  • 然后使用./filename
  • 该窗口出现了10秒，然后出现以下错误：
[xcb] 处理队列时出现未知序列号
[xcb] 这很可能是一个多线程客户端，并且尚未调用 XInitThreads
[xcb] 中止，对此深感抱歉。
心脏：../../src/xcb_io.c:273：poll_for_event：断言“！xcb_xlib_threads_sequence_lost”失败。
已中止

有什么解决办法吗？

答案1

有一个错误已提交至 Launchpad与上述问题非常相似。

一信息包含来自源的引文，详细说明了何时发生此错误情况：

错误消息“处理队列时出现未知序列号”出现在一大段文本中，该文本前面有一条很大的警告，涉及客户端代码中的线程安全：

/* Thread-safety rules:
 *
 * At most one thread can be reading from XCB's event queue at a time.
 * If you are not the current event-reading thread and you need to find
 * out if an event is available, you must wait.
 *
 * The same rule applies for reading replies.
 *
 * A single thread cannot be both the the event-reading and the
 * reply-reading thread at the same time.
 *
 * We always look at both the current event and the first pending reply
 * to decide which to process next.
 *
 * We always process all responses in sequence-number order, which may
 * mean waiting for another thread (either the event_waiter or the
 * reply_waiter) to handle an earlier response before we can process or
 * return a later one. If so, we wait on the corresponding condition
 * variable for that thread to process the response and wake us up.
 */

这似乎表明该客户端应用程序在与 xcb 调用相关的线程处理中可能存在一些错误逻辑？

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