window – 如何在xcb中使用shm pixmap？

这是我的测试代码：

#include <stdlib.h>
#include <stdio.h>

#include <sys/ipc.h>
#include <sys/shm.h>

#include <xcb/xcb.h>
#include <xcb/shm.h>
#include <xcb/xcb_image.h>


#define WID 512
#define HEI 512



int main(){
    xcb_connection_t*       connection;
    xcb_window_t            window;
    xcb_screen_t*           screen;
    xcb_gcontext_t          gcontext;
    xcb_generic_event_t*    event;

    uint32_t value_mask;
    uint32_t value_list[2];

    //connect to the X server and get screen

    connection = xcb_connect(NULL,NULL);
    screen = xcb_setup_roots_iterator(xcb_get_setup(connection)).data;

    //create a window

    value_mask = XCB_CW_BACK_PIXEL | XCB_CW_EVENT_MASK;
    value_list[0] = screen->black_pixel;
    value_list[1] = XCB_EVENT_MASK_EXPOSURE;

    window = xcb_generate_id(connection);

    xcb_create_window(
        connection,screen->root_depth,window,screen->root,WID,HEI,XCB_WINDOW_CLASS_INPUT_OUTPUT,screen->root_visual,value_mask,value_list  
    );

    //create a graphic context

    value_mask = XCB_GC_FOREGROUND | XCB_GC_GRAPHICS_EXPOSURES;
    value_list[0] = screen->black_pixel;
    value_list[1] = 0;

    gcontext = xcb_generate_id(connection);
    xcb_create_gc(connection,gcontext,value_list);

    //map the window onto the screen

    xcb_map_window(connection,window);
    xcb_flush(connection);


    //Shm test
    xcb_shm_query_version_reply_t*  reply;
    xcb_shm_segment_info_t          info;

    reply = xcb_shm_query_version_reply(
        connection,xcb_shm_query_version(connection),NULL
    );

    if(!reply || !reply->shared_pixmaps){
        printf("Shm error...n");
        exit(0);
    }

    info.shmid   = shmget(IPC_PRIVATE,WID*HEI*4,IPC_CREAT | 0777);
    info.shmaddr = shmat(info.shmid,0);

    info.shmseg = xcb_generate_id(connection);
    xcb_shm_attach(connection,info.shmseg,info.shmid,0);
    shmctl(info.shmid,IPC_RMID,0);

    uint32_t* data = info.shmaddr;

    xcb_pixmap_t pix = xcb_generate_id(connection);
    xcb_shm_create_pixmap(
        connection,pix,0
    );

    int i = 0;
    while(1){
        usleep(10000);

        data[i] = 0xFFFFFF;
        i++;

        xcb_copy_area(
            connection,HEI
        );

        xcb_flush(connection);
    }

    xcb_shm_detach(connection,info.shmseg);
    shmdt(info.shmaddr);

    xcb_free_pixmap(connection,pix);

    xcb_destroy_window(connection,window);
    xcb_disconnect(connection);

    return 0;
}