Question

尝试实现虚拟键盘。程序在5秒循环中发送击键事件。它在PC（Ubuntu Linux）上工作。问题是Beaglebone Black / Raspberry Pi3上没有显示任何内容。

Plaftorm Beaglebone Black，Debian Jessie：

debian@beaglebone:~$ uname -a
Linux beaglebone 4.9.9-ti-r22 #1 SMP PREEMPT Mon Feb 13 18:39:00 UTC 2017 armv7l GNU/Linux

代码：

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#include <string.h>
#include <linux/uinput.h>

/* emit function is identical to of the first example */

void emit(int fd, int type, int code, int val)
{
   struct input_event ie;

   ie.type = type;
   ie.code = code;
   ie.value = val;
   /* timestamp values below are ignored */
   ie.time.tv_sec = 0;
   ie.time.tv_usec = 0;

   int res = write(fd, &ie, sizeof(ie));
   printf("emit write bytes=%d fd=%d code=%d val=%d\n",res, fd, code, val);
}

int main(void)
{
   struct uinput_user_dev uud;
   int version, rc, fd;

   fd = open("/dev/uinput", O_WRONLY | O_NONBLOCK);
   printf("fd=%d\n",fd);

   rc = ioctl(fd, UI_GET_VERSION, &version);
   printf("rd=%d\n",rc); 

   if (rc == 0 && version >= 5) 
   {
    printf("Error! version=%d\n",version);
      //return 0;
   }

   /*
    * The ioctls below will enable the device that is about to be
    * created, to pass key events, in this case the space key.
    */
   int i1 = ioctl(fd, UI_SET_EVBIT, EV_KEY);
   int i2 = ioctl(fd, UI_SET_EVBIT, EV_SYN);
   int i3 = ioctl(fd, UI_SET_KEYBIT, KEY_D);
   int i4 = ioctl(fd, UI_SET_KEYBIT, KEY_U);
   int i5 = ioctl(fd, UI_SET_KEYBIT, KEY_P);
   int i6 = ioctl(fd, UI_SET_KEYBIT, KEY_A);

//  printf("ioctl = %d, %d, %d ,%d , %d, %d\n", i1,i2,i3,i4,i5,i6);

   memset(&uud, 0, sizeof(uud));
   snprintf(uud.name, UINPUT_MAX_NAME_SIZE, "uinput-keyboard");
   uud.id.bustype = BUS_HOST;
   uud.id.vendor  = 0x1;
   uud.id.product = 0x2;
   uud.id.version = 1;

   write(fd, &uud, sizeof(uud));
   sleep(2);

   int i = ioctl(fd, UI_DEV_CREATE);
   printf("dev create =%d\n", i);

   sleep(2);

   /* Key press, report the event, send key release, and report again */
for(;;)
{
   emit(fd, EV_KEY, KEY_D, 1);
   emit(fd, EV_SYN, SYN_REPORT, 1);
   sleep(1);
   emit(fd, EV_KEY, KEY_D, 0);
   emit(fd, EV_SYN, SYN_REPORT, 0);

   emit(fd, EV_KEY, KEY_U, 1);
   emit(fd, EV_SYN, SYN_REPORT, 0);
   emit(fd, EV_KEY, KEY_U, 0);
   emit(fd, EV_SYN, SYN_REPORT, 0);

   emit(fd, EV_KEY, KEY_P, 1);
   emit(fd, EV_SYN, SYN_REPORT, 0);
   emit(fd, EV_KEY, KEY_P, 0);
   emit(fd, EV_SYN, SYN_REPORT, 0);

   emit(fd, EV_KEY, KEY_A, 1);
   emit(fd, EV_SYN, SYN_REPORT, 0);
   emit(fd, EV_KEY, KEY_A, 0);
   emit(fd, EV_SYN, SYN_REPORT, 0);

   sleep(5);
}
   ioctl(fd, UI_DEV_DESTROY);

   close(fd);
   return 0;
}

lsinput - ev位是否正确？：

/dev/input/event1
   bustype : BUS_HOST
   vendor  : 0x1
   product : 0x2
   version : 1
   name    : "uinput-keyboard"
   bits ev : (null) (null)

Evtest - 向内核发送事件（OK）：

root@beaglebone:/home/debian/KeyEvent# evtest
No device specified, trying to scan all of /dev/input/event*
Available devices:
/dev/input/event0:  tps65217_pwr_but
/dev/input/event1:  uinput-keyboard
Select the device event number [0-1]: 1
Input driver version is 1.0.1
Input device ID: bus 0x19 vendor 0x1 product 0x2 version 0x1
Input device name: "uinput-keyboard"
Supported events:
  Event type 0 (EV_SYN)
  Event type 1 (EV_KEY)
    Event code 22 (KEY_U)
    Event code 25 (KEY_P)
    Event code 30 (KEY_A)
    Event code 32 (KEY_D)
Properties:
Testing ... (interrupt to exit)
Event: time 1499869756.493690, type 1 (EV_KEY), code 32 (KEY_D), value 1
Event: time 1499869756.493690, -------------- SYN_REPORT ------------
Event: time 1499869757.494181, type 1 (EV_KEY), code 32 (KEY_D), value 0
Event: time 1499869757.494181, -------------- SYN_REPORT ------------
Event: time 1499869757.494304, type 1 (EV_KEY), code 22 (KEY_U), value 1
Event: time 1499869757.494304, -------------- SYN_REPORT ------------
Event: time 1499869757.494370, type 1 (EV_KEY), code 22 (KEY_U), value 0
Event: time 1499869757.494370, -------------- SYN_REPORT ------------
Event: time 1499869757.494434, type 1 (EV_KEY), code 25 (KEY_P), value 1
Event: time 1499869757.494434, -------------- SYN_REPORT ------------
Event: time 1499869757.494495, type 1 (EV_KEY), code 25 (KEY_P), value 0
Event: time 1499869757.494495, -------------- SYN_REPORT ------------
Event: time 1499869757.494558, type 1 (EV_KEY), code 30 (KEY_A), value 1
Event: time 1499869757.494558, -------------- SYN_REPORT ------------
Event: time 1499869757.499785, type 1 (EV_KEY), code 30 (KEY_A), value 0
Event: time 1499869757.499785, -------------- SYN_REPORT ------------
Event: time 1499869762.502378, type 1 (EV_KEY), code 32 (KEY_D), value 1
Event: time 1499869762.502378, -------------- SYN_REPORT ------------
Event: time 1499869763.225387, type 1 (EV_KEY), code 32 (KEY_D), value 0
Event: time 1499869763.225402, -------------- SYN_REPORT ------------
expected 16 bytes, got -1

Answer 1

我解决了这个问题。屏幕没有连接到BeagleBone / Raspberry，系统无法将字符发送到屏幕。

虚拟键盘（Linux / libevdev） - 发送事件

1 个答案: