通過select較高效的捕獲和處理鼠標鍵盤事件

select監聽這些文件描述符的狀態，若有一個發生變化則返回，否則阻塞。

#include <stdio.h>
#include <stdlib.h>
#include <linux/input.h>
#include <fcntl.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>

int main(int argc,char **argv)
{
    int fd, retval;
    char buf[6];
    fd_set readfds;
    struct timeval tv;

    // 打開鼠標設備
    fd = open( "/dev/input/mice", O_RDONLY );
    // 判斷是否打開成功
    if(fd<0) {
        printf("Failed to open \"/dev/input/mice\".\n");
        exit(1);
    } else {
        printf("open \"/dev/input/mice\" successfuly.\n");
    }

    int fd_kb;
    struct input_event event_kb;
    fd_kb = open("/dev/input/event1", O_RDONLY); //鍵盤輸入
    if(fd_kb <= 0)
    {
            printf("open device error\n");
            return 0;
    }

    int fd_mouse;
    struct input_event event_mouse;
    fd_mouse = open("/dev/input/event4", O_RDONLY); //鼠標輸入
    if(fd_mouse <= 0)
    {
            printf("open device error\n");
            return 0;
    }


    while(1) {
        // 設置最長等待時間
        tv.tv_sec = 5;
        tv.tv_usec = 0;

        FD_ZERO( &readfds );
        FD_SET( fd, &readfds );
        FD_SET( fd_kb, &readfds );
        FD_SET( fd_mouse, &readfds );

        int max=fd>fd_kb?(fd>fd_mouse?fd:fd_mouse):(fd_kb>fd_mouse?fd_kb:fd_mouse);

        retval = select( max+1, &readfds, NULL, NULL, &tv );//有文件描述符的狀態發生變化（變爲可讀）或者超時和錯誤就返回，否則就阻塞
        if(retval==0) {
            printf( "Time out!\n" );
        }else if(retval<0){
            printf( "error!\n" );
        }else{                      //判斷是哪個文件描述符的狀態發生了變化，進行處理即可

            //鼠標位置
            if(FD_ISSET(fd,&readfds))
            {
                // 讀取鼠標設備中的數據
                if(read(fd, buf, 6) <= 0) {
                    continue;
                }
                // 打印出從鼠標設備中讀取到的數據
                printf("Button type = %d, X = %d, Y = %d, Z = %d\n", (buf[0] & 0x07), buf[1], buf[2],   buf[3]);
            }

            //鍵盤點擊
            if(FD_ISSET(fd_kb,&readfds))
            {
                if(read(fd_kb, &event_kb, sizeof(event_kb)) == sizeof(event_kb))
                {
                    if (event_kb.type == EV_KEY)
                    {
                        //if (event_kb.value == 0 || event_kb.value == 1)//1表示按下，0表示釋放，會檢測到兩次
                        if (event_kb.value == 1)//鍵按下
                        {
                                //printf("key %d %s\n", event_kb.code, (event_kb.value) ? "Pressed" : "Released");
                                if(event_kb.code == KEY_ESC)
                                        break;
                                if(event_kb.code == KEY_Q)
                                    printf("q\n");
                                if(event_kb.code == KEY_W)
                                    printf("w\n");
                                if(event_kb.code == KEY_E)
                                    printf("e\n");
                                if(event_kb.code == KEY_R)
                                    printf("r\n");
                        }

                    }

                }
            }

            //鼠標點擊
            if(FD_ISSET(fd_mouse,&readfds))
            {
                if(read(fd_mouse, &event_mouse, sizeof(event_mouse)) == sizeof(event_mouse))
                {
                    if(event_mouse.type = EV_REL)
                    {
                        if(event_mouse.code == REL_WHEEL)
                            printf("REL_WHEEL %d\n", event_mouse.value);//-1表示下滑，1表示上滑
                    }

                    if(event_mouse.code == BTN_LEFT && event_mouse.value==1)//左鍵按下，1表示按下，0表示釋放。不然會檢測到兩次
                        printf("left down: %d\n", event_mouse.code);

                    if(event_mouse.code == BTN_RIGHT && event_mouse.value==1)
                        printf("right down: %d\n", event_mouse.code);

                    if(event_mouse.code == BTN_MIDDLE && event_mouse.value==1)
                        printf("middle down: %d\n", event_mouse.code);

                }
            }

        }

    }
    close(fd);
    close(fd_kb);
    close(fd_mouse);
    return 0;
}