2

代码有点长,但这只是因为我评论了所有内容,所以很容易阅读。基本上这是我正在处理的一个简单的基于文本的选择菜单。你需要在 Linux 上并且有一个 C++11 编译器才能正确运行它。这是代码(功能齐全的示例,可以编译):

#include <string>
#include <vector>
#include <iostream>
#include <unistd.h>
#include <sys/ioctl.h>
#include "raw_terminal.h" // for setting the terminal to raw mode
using namespace std;

/* Simple escape sequences to control the cursor and colors on the screen */
#define CLI_HIDE_CUR            "\033[?25l"
#define CLI_SHOW_CUR            "\033[?25h"
#define CLI_SAVE_CUR_POS        "\033[s"
#define CLI_REST_CUR_POS        "\033[u"
#define CLI_CLR_LAST_LINE       "\033[A\033[2K"
#define CLI_MV_CUR_UP           "\033[A"
#define CLI_MV_CUR_DN           "\033[B"
#define CLI_DEFAULT_COLOR       "\033[0m"
#define CLI_FGROUND_BLACK       "\033[0;30m"
#define CLI_FGROUND_RED         "\033[0;31m"
#define CLI_FGROUND_GREEN       "\033[0;32m"
#define CLI_FGROUND_BROWN       "\033[0;33m"
#define CLI_FGROUND_BLUE        "\033[0;34m"
#define CLI_FGROUND_MAGENTA     "\033[0;35m"
#define CLI_FGROUND_CYAN        "\033[0;36m"
#define CLI_FGROUND_LIGHTGREY   "\033[0;37m"
#define CLI_BOLD                "\033[0;1m"
#define CLI_BGROUND_BLACK       "\033[7;30m"
#define CLI_BGROUND_RED         "\033[7;31m"
#define CLI_BGROUND_GREEN       "\033[7;32m"
#define CLI_BGROUND_BROWN       "\033[7;33m"
#define CLI_BGROUND_BLUE        "\033[7;34m"
#define CLI_BGROUND_MAGENTA     "\033[7;35m"
#define CLI_BGROUND_CYAN        "\033[7;36m"
#define CLI_BGROUND_LIGHTGREY   "\033[7;37m"


/* Centers a string in a 'width' character wide terminal
 by appending spaces before and after the string */
auto centerText(string& text, int width) -> void;

/* Creates a selection menu on the screen */
auto selectionMenu(std::vector<std::string> items) -> int;

int main() {
    std::vector<string> items;
    items.push_back("Menu item one");
    items.push_back("Menu item two");
    items.push_back("Menu item three");

    int selection = selectionMenu(items);
    if (selection == -1) return 0;
    cout << "You selected: " << items[selection] << endl;

    cin.get();

    return 0;
}

auto centerText(string& text, int width) -> void {
    size_t len = text.length();
    if (width <= len+1) return;
    for (int i=0; i<(width - len)/2; i++) text.insert(text.begin(), ' ');
    for (int i=0; i<(width - len)/2+len%2; i++) text.push_back(' ');
    return;
}

auto selectionMenu(std::vector<std::string> items) -> int {
    /* This stuff is required to get the width of the terminal
     in order to center the text on the screen with centerText() */
    struct winsize w;
    ioctl(0, TIOCGWINSZ, &w);

    /* Hide the cursor, initialize some variables */
    cout << CLI_HIDE_CUR << CLI_DEFAULT_COLOR << endl;
    int selection = 0, prevSelection, key;

    /* Center the menu items on the screen */
    for (const auto& s : items) centerText(s, w.ws_col);

    /* Print out the menu items */
    for (const auto& s : items) cout << s << endl;

    /* Highlight the first item */
    for (int i=0; i<items.size(); i++) cout << CLI_MV_CUR_UP;
    cout << CLI_BGROUND_BROWN << items[selection] << endl;

    /* Configure stuff so that we're able to retrieve raw keystrokes from stdin */
    raw_terminal::setRawTerminal();

    /* If the enter key is down, wait until it's released.
     This prevents the user from accidentally selecting
     an item after hitting enter in a previous menu. */
    while (getchar() == '\n') { usleep(1000); }

    /* Main loop */
    while (1) {
        key = getchar();

        /* We're only interested in escape sequences (starting with '\033') */
        if (key == '\033') {

            /* If nothing comes after the escape character, then esc was pressed, so we quit. */
            if (getchar() == -1) {
                selection = -1;
                goto MENU_END;
            }

            /* Get the next character in the received sequence */
            key = getchar();

            /* up arrow */
            if (key == 65) {
                prevSelection = selection;
                selection--;
            }

            /* down arrow */
            else if (key == 66) {
                prevSelection = selection;
                selection++;
            }

            /* If (first item - 1) or (last item + 1) is selected, loop around */
            if (selection < 0) selection = items.size()+selection;
            if (selection > items.size()-1) selection -= items.size();

            /* Draw the previously selected line with the default colors */
            cout << CLI_MV_CUR_UP << CLI_DEFAULT_COLOR << items[prevSelection] << endl;
            cout << CLI_MV_CUR_UP;

            /* Move the cursor to the new selection */
            if (selection < prevSelection) for (int i=0; i<(prevSelection-selection); i++) cout << CLI_MV_CUR_UP;
            if (selection > prevSelection) for (int i=0; i<(selection-prevSelection); i++) cout << CLI_MV_CUR_DN;

            /* Draw the newly selected line with the highlighting color */
            cout << CLI_BGROUND_BROWN << items[selection] << endl;

        }

        /* If the retrieved key is not an escape sequence, check whether it's the enter key.
         If so, break the main loop and return the selected item's number. */
        else if (key == '\n') break;
    }

MENU_END:
    cout << CLI_DEFAULT_COLOR;

    /* Position the cursor below the menu to continue */
    for (int i=0; i<items.size()-selection; i++) cout << CLI_MV_CUR_DN;

    /* Unhide the cursor, and set the terminal back to normal mode */
    cout << CLI_SHOW_CUR << endl;
    raw_terminal::restoreTerminal();

    /* Return selected item's number */
    return selection;
}

这是 raw_terminal.h :

#ifndef _RAW_TERMINAL_H_
#define _RAW_TERMINAL_H_

#include <cstring>
#include <iostream>
#include <termios.h>

class raw_terminal {
public:
    static void setRawTerminal() {
        /* set the terminal to raw mode */
        if (isRaw) return;
        tcgetattr(fileno(stdin), &orig_term_attr);
        memcpy(&new_term_attr, &orig_term_attr, sizeof(struct termios));
        new_term_attr.c_lflag &= ~(ECHO|ICANON);
        new_term_attr.c_cc[VTIME] = 0;
        new_term_attr.c_cc[VMIN] = 0;
        tcsetattr(fileno(stdin), TCSANOW, &new_term_attr);
        isRaw = true;
    }
    static void restoreTerminal() {
        tcsetattr(fileno(stdin), TCSANOW, &orig_term_attr);
        isRaw = false;
    }
private:
    static struct termios orig_term_attr;
    static struct termios new_term_attr;
    static bool isRaw;
};

struct termios raw_terminal::orig_term_attr;
struct termios raw_terminal::new_term_attr;
bool raw_terminal::isRaw = false;

#endif

如果您只使用向上/向下箭头,它就可以正常工作。但是,如果您按左或右(不应该做任何事情),它会完全弄乱屏幕,复制菜单项和东西。我猜问题不在代码中,因为它完全忽略了左右键。我猜是终端在按下它们时会做一些事情。那么我怎样才能防止这种情况发生呢?

任何帮助,将不胜感激。谢谢!

4

1 回答 1

1

哇,这让我有点震惊。我通过在程序中包含左右箭头解决了这个问题,如下所示:

if (key == 65 || key == 68) // ...
if (key == 66 || key == 67) // ...

这样左右键可以正常改变选择。我原本想忽略这些键,只使用向上/向下,但这仍然比让屏幕发疯要好。

于 2014-08-29T16:19:24.610 回答