QWidget keyPressEvent override [英] QWidget keyPressEvent override

问题描述

我试图半个永恒现在覆盖QWidgets的keyPressEvent函数在QT，但它只是不会工作。我不得不说我是新的CPP，但我知道ObjC和标准C。

我的问题看起来像这样：

  class QSGameBoard：public QWidget {
 Q_OBJECT 
 
 public：
 QSGameBoard（QWidget * p，int w，int h ，QGraphicsScene * s）; 
 
信号：
 void keyCaught（QKeyEvent * e）; 
 
 protected：
 virtual void keyPressEvent（QKeyEvent * event）; 
}; 
 

QSGameBoard是我的QWidget子类，我需要重写keyPressEvent，并对每个事件触发一个SIGNAL一些注册对象。

我的覆盖的keyPressEvent在QSGameBoard.cpp看起来像这样：

  void QSGameBoard :: keyPressEvent（QKeyEvent * event）{
 printf（板中的\\\
key事件：％i，event-> key 
 // emit keyCaught（event）; 
} 
  

当我改变QSGameBoard ::到QWidget ::它接收事件，我不能发出信号，因为编译器抱怨的范围。

这里有什么问题？

解决方案

编辑：
正如其他用户指出的，我最初概述的方法不是解决这个问题的正确方法。
由 Vasco Rinaldo 回答

使用将FocusPolicy设置为Qt :: ClickFocus以获取keybordfocus由
鼠标klick。 setFocusPolicy（Qt :: ClickFocus）;

我给出的上一个（虽然不完美）解决方案如下：

看起来您的小部件没有获得焦点。覆盖您的鼠标按下事件：

  void QSGameBoard :: mousePressEvent（QMouseEvent * event）{
 printf nMouse in Board）; 
 setFocus（）; 
} 
  

这是一个工作示例的源代码：

QSGameBoard.h

  #ifndef _QSGAMEBOARD_H 
 #define _QSGAMEBOARD_H 
 
 #include< QWidget> 
 #include< QGraphicsScene> 
 
 class QSGameBoard：public QWidget {
 Q_OBJECT 
 
 public：
 QSGameBoard（QWidget * p，int w，int h，QGraphicsScene * s）; 
 
信号：
 void keyCaught（QKeyEvent * e）; 
 
 protected：
 virtual void keyPressEvent（QKeyEvent * event）; 
 void mousePressEvent（QMouseEvent * event）; 
}; 
 
 
 #endif / * _QSGAMEBOARD_H * / 
  

QSGameBoard。 cpp

  #include< QKeyEvent> 
 #include< QLabel> 
 #include< QtGui / qgridlayout.h> 
 #include< QGridLayout> 
 
 #includeQSGameBoard.h
 
 
 QSGameBoard :: QSGameBoard（QWidget * p，int w，int h，QGraphicsScene * s）：
 QWidget（p）{
 
 QLabel * o = new QLabel（tr（Test Test Test））; 
 QGridLayout * g = new QGridLayout（this）; 
 g-> addWidget（o）; 
} 
 
 void QSGameBoard :: keyPressEvent（QKeyEvent * event）{
 printf（板中的\\\
key事件：％i，event-> key ; 
} 
 
 void QSGameBoard :: mousePressEvent（QMouseEvent * event）{
 printf（\\\
Mouse in board）; 
 setFocus（）; 
} 
  
 
 
 
 main.cpp 
  #include< QtGui / QApplication> 
 #include< QtGui / qmainwindow.h> 
 
 #includeQSGameBoard.h
 
 int main（int argc，char * argv []）{
 //如果需要，初始化资源
 // Q_INIT_RESOURCE（resfile）; 
 
 QApplication app（argc，argv）; 
 
 QMainWindow oM; 
 QGraphicsScene o; 
 QSGameBoard a（& oM，1，2，& o）; 
 oM.setCentralWidget（& a）; 
 a.show（）; 
 oM.show（）; 
 
 //创建并显示您的窗口小部件
 
 return app.exec（）; 
} 
  
 
I'm trying for half an eternity now overriding QWidgets keyPressEvent function in QT but it just won't work. I've to say i am new to CPP, but I know ObjC and standard C.

My problem looks like this:
class QSGameBoard : public QWidget {
Q_OBJECT

public:
  QSGameBoard(QWidget *p, int w, int h, QGraphicsScene *s);

signals:
  void keyCaught(QKeyEvent *e);

protected:
  virtual void  keyPressEvent(QKeyEvent *event);
};
QSGameBoard is my QWidget subclass and i need to override the keyPressEvent and fire a SIGNAL on each event to notify some registered objects.

My overridden keyPressEvent in QSGameBoard.cpp looks like this:
void QSGameBoard::keyPressEvent(QKeyEvent *event) {
  printf("\nkey event in board: %i", event->key());
  //emit keyCaught(event);
}
When i change QSGameBoard:: to QWidget:: it receives the events, but i cant emit the signal because the compiler complains about the scope. And if i write it like this the function doesn't get called at all.

What's the problem here?
解决方案
EDIT:
As pointed out by other users, the method I outlined originally is not the proper way to resolve this.
Answer by Vasco Rinaldo

  
Use Set the FocusPolicy to Qt::ClickFocus to get the keybordfocus by
  mouse klick. setFocusPolicy(Qt::ClickFocus);
The previous (albeit imperfect) solution I gave is given below:

Looks like your widget is not getting "focus". Override your mouse press event:
void QSGameBoard::mousePressEvent ( QMouseEvent * event ){
    printf("\nMouse in board");
    setFocus();
}
Here's the source code for a working example:

QSGameBoard.h
#ifndef _QSGAMEBOARD_H
#define _QSGAMEBOARD_H

#include <QWidget>
#include <QGraphicsScene>

class QSGameBoard : public QWidget {
Q_OBJECT

public:
  QSGameBoard(QWidget *p, int w, int h, QGraphicsScene *s);

signals:
  void keyCaught(QKeyEvent *e);

protected:
  virtual void  keyPressEvent(QKeyEvent *event);
  void  mousePressEvent ( QMouseEvent * event );
};


#endif  /* _QSGAMEBOARD_H */
QSGameBoard.cpp
#include <QKeyEvent>
#include <QLabel>
#include <QtGui/qgridlayout.h>
#include <QGridLayout>

#include "QSGameBoard.h"


QSGameBoard::QSGameBoard(QWidget* p, int w, int h, QGraphicsScene* s) :
    QWidget(p){

    QLabel* o = new QLabel(tr("Test Test Test"));
    QGridLayout* g  = new QGridLayout(this);
    g->addWidget(o);
}

void QSGameBoard::keyPressEvent(QKeyEvent* event){
    printf("\nkey event in board: %i", event->key());
}

void QSGameBoard::mousePressEvent ( QMouseEvent * event ){
    printf("\nMouse in board");
    setFocus();
}
main.cpp
#include <QtGui/QApplication>
#include <QtGui/qmainwindow.h>

#include "QSGameBoard.h"

int main(int argc, char *argv[]) {
    // initialize resources, if needed
    // Q_INIT_RESOURCE(resfile);

    QApplication app(argc, argv);

    QMainWindow oM;
    QGraphicsScene o;
    QSGameBoard a(&oM, 1, 2, &o);
    oM.setCentralWidget(&a);
    a.show();
    oM.show();

    // create and show your widgets here

    return app.exec();
}


                        
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