使用ncurses开发linux界面程序示例

       因为项目需要，本人接到一个任务：开发一个linux控制台程序，C/S架构，客户端连接服务端后，用户在界面输入命令，发给服务端，并显示服务端的响应内容。这个任务的难点在客户端，类似xshell、securecrt的远程操作功能。在网上查找资料得知，这类程序一般使用ncurses库开发，ncurses库接口比较繁琐，不像MFC之类的Windows开发工具，提供简单易用的界面控件。

       本文不介绍nucuses库和接口的具体用法，网上的资料也比较琐碎，如果感兴趣可以参考：https://download.youkuaiyun.com/download/willy16/20199446

       这里将项目的界面部分代码贴出来，留作纪念，如果能帮助同行当然最好，这类程序有点偏门不好找。   

        这个程序把窗口分成两部分：底下部分提供用户输入，可以自动换行，支持上下左右键、BackSpace键、Tab键等；上半部分显示用户输入的内容（扩展一下就可以显示服务端发来的消息，还可以设置字体颜色），大概效果如下图：

      下面是具体代码，可以直接编译，比如代码保存为test.c，编译命令：gcc test.c -o test -lncurses。

//控制台客户端
#include <signal.h>
#include <ncurses.h>
#include <sys/ioctl.h>

#define CMD_FLAG            "<cmd> "
#define FLAG_LEN            6
#define MAX_Y               (LINES - 1)
#define KEY_CTRL_C          0x03
#define KEY_BackSpace       0x08
#define KEY_TAB             0x09
#define KEY_Enter           0x0A
#define RECORD_SUM          100
#define CMD_MAX             1024

typedef struct console_win {
    int resp_line;
    WINDOW *resp_win;
    int cmd_y;
    int cmd_x;
    int cmd_len;
    int cmd_line;
    char cmd[CMD_MAX+FLAG_LEN];
} console_win_t;

console_win_t s_win;

static int resp_win_lines()
{
    return LINES - s_win.cmd_line;
}

static int cursor_len()
{
    return s_win.cmd_x + (s_win.cmd_line-1-(MAX_Y-s_win.cmd_y))*COLS;
}

static char *cmd_str()
{
    return &s_win.cmd[FLAG_LEN];
}

void show_resp_win(const char *data, const char *flag)
{
    if (flag == NULL) {
        int lines = strlen(data) / COLS + 1;
        if (s_win.resp_line >= (resp_win_lines()-1)) { 
            mvwprintw(s_win.resp_win, resp_win_lines()-1, 0, "%s", data);
            wrefresh(s_win.resp_win);
            wscrl(s_win.resp_win, 1);
            wrefresh(s_win.resp_win);
        } else {
            mvwprintw(s_win.resp_win, s_win.resp_line, 0, "%s", data);
            wrefresh(s_win.resp_win);
            s_win.resp_line += lines;
        }
    } else {
        int lines = (strlen(data) + strlen(flag)) / COLS + 1;
        if (s_win.resp_line >= (resp_win_lines()-1)) {
            mvwprintw(s_win.resp_win, resp_win_lines()-1, 0, "%s%s", flag, data);
            wrefresh(s_win.resp_win);
            wscrl(s_win.resp_win, 1);
            wrefresh(s_win.resp_win);
        } else {
            mvwprintw(s_win.resp_win, s_win.resp_line, 0, "%s%s", flag, data);
            wrefresh(s_win.resp_win);
            s_win.resp_line += lines;
        }
    }

    wrefresh(s_win.resp_win);
    move(s_win.cmd_y, s_win.cmd_x);
    refresh();
}

static void resize_resp_win()
{
    wresize(s_win.resp_win, resp_win_lines(), COLS);
    wsetscrreg(s_win.resp_win, 0, resp_win_lines());
    wrefresh(s_win.resp_win);
}

//显示用户正在输入的命令
static void show_cmd()
{
    if (s_win.cmd_line == 1) {
        mvprintw(s_win.cmd_y, 0, "%s", s_win.cmd);
        refresh();
    } else {
        char tmp[CMD_MAX] = {0};
        memcpy(tmp, s_win.cmd, COLS);
        mvprintw(LINES - s_win.cmd_line, 0, "%s", tmp);
        refresh();

        char i = 1;
        for (; i < s_win.cmd_line; i++) {
            move(LINES-s_win.cmd_line+i, 0);
            clrtoeol();
            refresh();
            mvprintw(LINES-s_win.cmd_line+i, 0, "%s", &s_win.cmd[COLS*i]);
            refresh();
        }
    }

    move(s_win.cmd_y, s_win.cmd_x);
    refresh();
}

//处理终端大小变化
static void sig_winch(int signo)
{
    int old_cols = COLS;
    int old_lines = LINES;

    //get the screen size
    struct winsize w;
    ioctl(0, TIOCGWINSZ, &w);
    COLS = w.ws_col;
    LINES = w.ws_row;

    s_win.cmd_y = MAX_Y;
    s_win.cmd_line = s_win.cmd_len / COLS + 1;
    s_win.cmd_x = s_win.cmd_len % COLS;

    resize_resp_win();
    refresh();
    show_cmd();
}

static int init_win()
{
    signal(SIGWINCH, sig_winch);

    initscr();
    raw();
    //noecho();
    keypad(stdscr, TRUE);
    refresh();

    memset(&s_win, 0, sizeof(s_win));

    s_win.resp_win = newwin(resp_win_lines(), COLS, 0, 0);
    if(s_win.resp_win == NULL) {
        return -1;
    }

    leaveok(s_win.resp_win, TRUE);
    scrollok(s_win.resp_win, TRUE);
    wsetscrreg(s_win.resp_win, 0, resp_win_lines());

    return 0;
}

static void destroy_win()
{
    if (s_win.resp_win != NULL) {
        move(MAX_Y, 0);
        clrtoeol();
        refresh();
    }

    char tmp[128];
    sprintf(tmp, "kill -9 %d", getpid());
    system(tmp);
}

static void stop()
{
    destroy_win();
}

static void on_key_left()
{
    if (s_win.cmd_x > 0) {
        if ((MAX_Y - s_win.cmd_y) < (s_win.cmd_line - 1)) {
            move(s_win.cmd_y, --s_win.cmd_x);
        } else if (s_win.cmd_x > FLAG_LEN) {
            move(s_win.cmd_y, --s_win.cmd_x);
        }
    } else {
        s_win.cmd_x = COLS - 1;
        move(--s_win.cmd_y, s_win.cmd_x);
    }
}

static void on_key_right()
{
    if (s_win.cmd_y < MAX_Y) {
        if (s_win.cmd_x < (COLS - 1)) {
            move(s_win.cmd_y, ++s_win.cmd_x);
        } else {
            s_win.cmd_x = 0;
            move(++s_win.cmd_y, s_win.cmd_x);
        }
    } else if (s_win.cmd_x < (strlen(s_win.cmd) % COLS)) {
        move(s_win.cmd_y, ++s_win.cmd_x);
    }
}

static void on_key_tab(const char *cmd)
{
    //get command from the server
}

static void on_key_normal(int ch)
{
    int tail_len = 0;
    if (s_win.cmd_y == MAX_Y &&
        s_win.cmd_x >= (s_win.cmd_len - COLS*(s_win.cmd_line-1))) {
        //append character
        s_win.cmd[s_win.cmd_len] = ch;
    } else {
        //insert character
        char *pos = &s_win.cmd[s_win.cmd_x + (s_win.cmd_line-1-(MAX_Y-s_win.cmd_y))*COLS];
        tail_len = strlen(pos);
        memcpy(pos + 1, pos, tail_len);
        *pos = ch;
    }

    s_win.cmd_len++;
    s_win.cmd_x++;

    if (s_win.cmd_x >= COLS) {
        s_win.cmd_x = 0;

        if (s_win.cmd_y < MAX_Y) {
            s_win.cmd_y++;
        } else if (tail_len == 0) {
            s_win.cmd_line++;
        }
    }

    if (tail_len > 0 && s_win.cmd_len >= s_win.cmd_line*COLS) {
        s_win.cmd_line++;
        s_win.cmd_y--;
    }

    resize_resp_win();
    show_cmd();
}

static void on_key_backspace()
{
    if ((MAX_Y-s_win.cmd_y) == (s_win.cmd_line-1) && s_win.cmd_x <= FLAG_LEN) {
        move(s_win.cmd_y, s_win.cmd_x);
        return;
    }

    char *pos = &s_win.cmd[s_win.cmd_x + (s_win.cmd_line-1-(MAX_Y-s_win.cmd_y))*COLS];
    memcpy(pos - 1, pos, strlen(pos));
    mvdelch(s_win.cmd_y, --s_win.cmd_x);
    s_win.cmd[--s_win.cmd_len] = 0;

    if (s_win.cmd_x == 0) {
        s_win.cmd_x = COLS;
        s_win.cmd_y--;
    }

    resize_resp_win();
    show_cmd();
}

static void on_key_delete()
{
    if (s_win.cmd_len == cursor_len()) {
        return;
    }

    mvdelch(s_win.cmd_y, s_win.cmd_x);
    char *pos = &s_win.cmd[cursor_len()];
    memcpy(pos, pos + 1, strlen(pos + 1));
    s_win.cmd[--s_win.cmd_len] = 0;

    resize_resp_win();
    show_cmd();
}

//接收用户输入字符
static int proc_user_cmd()
{
    while(1) {
        int cmd_count = 0;
        s_win.cmd_line = 1;
        s_win.cmd_y = MAX_Y;
        s_win.cmd_x = FLAG_LEN;
        s_win.cmd_len = FLAG_LEN;
        memset(s_win.cmd, 0, sizeof(s_win.cmd));
        strcpy(s_win.cmd, CMD_FLAG);

        move(s_win.cmd_y, 0);
        clrtoeol();
        refresh();
        mvprintw(s_win.cmd_y, 0, "%s", s_win.cmd);
        refresh();

        int ch;
        while((ch=getch()) != KEY_Enter) {
            switch (ch) {
            case KEY_CTRL_C:
                return 0;
            case KEY_UP:
                if (cmd_count < RECORD_SUM) {
                    //show_cmd_record(++cmd_count);
                }       
                break;
            case KEY_DOWN:
                if (cmd_count > 0) {
                    //show_cmd_record(--cmd_count);
                } else {
                    mvprintw(MAX_Y, 0, CMD_FLAG);
                    clrtoeol();
                }
                break;
            case KEY_LEFT:
                on_key_left();
                break;
            case KEY_RIGHT:
                on_key_right();
                break;
            case KEY_TAB:
                on_key_tab(cmd_str());
                move(MAX_Y, s_win.cmd_x);
                break;
            case KEY_BackSpace:
                on_key_backspace();
                break;
            case KEY_DC:
                on_key_delete();
                break;
            default:
                if (s_win.cmd_len < CMD_MAX) {
                    on_key_normal(ch);
                }
                break;
            }

            refresh();
        }

        show_resp_win(s_win.cmd, NULL);
        if (s_win.cmd_len > FLAG_LEN) {
            if (strcasecmp(cmd_str(), "exit") != 0) {
                //parse_cmd(cmd_str());
            } else {
                return 0;
            }
        }

        s_win.cmd_line = 1;
        resize_resp_win();
        usleep(1000);
    }
    return 0;  
}

int main(int argc, char *argv[])
{
    if (init_win() != 0) {
        printf("init_win fail!\n");
        destroy_win();
        return -1;
    }

    proc_user_cmd();
    stop();

    return 0;
}