Question

我在Qt嵌入式应用程序（Cannot use keyboard within Qt app without sudo）中遇到了关于键盘输入读取的大问题。这个问题已经持续很长一段时间我不认为它会以正常的方式最终得到解决。由于我的Qt应用程序没有看到键盘事件（/dev/input/event1），我想我被迫观看设备文件mysalfe并等待事件发生并手动解释。

在原始c ++应用程序中，我会选择这样的东西：

/** BB-BONE-GPIO Test code to test the GPIO-KEYS interface.
* Written by Derek Molloy (www.derekmolloy.ie) for the book
* Exploring BeagleBone.
*
* This code is based on work in the document:
*    www.kernel.org/doc/Documentation/input/input.txt
*
* Written by Derek Molloy for the book "Exploring BeagleBone: Tools and 
* Techniques for Building with Embedded Linux" by John Wiley & Sons, 2014
* ISBN 9781118935125. Please see the file README.md in the repository root 
* directory for copyright and GNU GPLv3 license information.            */


#include<iostream>
#include<fcntl.h>
#include<stdio.h>
#include<stdlib.h>
#include<linux/input.h>
using namespace std;

#define KEY_PRESS 1
#define KEY_RELEASE 0

int main(){
   int fd, count=0;
   struct input_event event[64];
   if(getuid()!=0){
      cout << "You must run this program as root. Exiting." << endl;
      return -1;
   }
   cout << "Starting BB-BONE-GPIO Test (press 10 times to end):" << endl;
   if ((fd = open("/dev/input/event1", O_RDONLY)) < 0){
      perror("Failed to open event1 input device. Exiting.");
      return -1;
   }
   while(count < 20){  // Press and Release are one loop each
      int numbytes = (int)read(fd, event, sizeof(event));
      if (numbytes < (int)sizeof(struct input_event)){
         perror("The input read was invalid. Exiting.");
         return -1;
      }
      for (int i=0; i < numbytes/sizeof(struct input_event); i++){
         int type = event[i].type;
         int val  = event[i].value;
         int code = event[i].code;
         if (type == EV_KEY) {
            if (val == KEY_PRESS){
               cout << "Press  : Code "<< code <<" Value "<< val<< endl;
            }
            if (val == KEY_RELEASE){
               cout << "Release: Code "<< code <<" Value "<< val<< endl;
            }
         }
      }
      count++;
   }
   close(fd);
   return 0;
}

我想知道Qt库是否有任何更高级别的机制允许我这样做？我正在寻找一些，但我只找到QKeyPress课。或者我需要以裸C方式做到这一点？我会帮助你！

编辑：在创建main对象之前，我刚刚在我的Qt应用的MainWindow中实现了上述代码。代码有效，这意味着应用程序具有读取输入所需的所有权限。为什么Qt不解释呢？

Answer 1

您需要使用QKeyEvent类来获取键盘事件。你可以按下面的方式捕捉键盘事件

void yourClass :: keyPressEvent(QKeyEvent *event)
{
    if (event->key() == Qt::Key_P)
        qDebug() << "Key P is Pressed";
}

如果您根本没有获得键盘事件，请检查this link

Qt嵌入式linux事件监视器

1 个答案: