我有一个应用程序(与任何W / A / S / D键可能具有特殊导航意义的游戏无关),其中有一个QFrame.我重写了keyPressEvent()以通过键盘输入文本,同时专注于该QFrame.这是我的代码：
void MyFrame::keyPressEvent(QKeyEvent *event)
{
qDebug() << "At least came here" << endl;
QString text = event->text();
qDebug() << "Text: " << text << endl;
}
当我一次从键盘输入一个字符时,对于所有字符和数字,两个语句都会被正确记录.但是对于这四个键,都没有执行日志语句,即事件处理程序甚至没有触发.怎么了？
编辑：经过这些例子后,我试图形成我的bug的最小工作示例.这就是我所拥有的.这里也有同样的问题,通过事件过滤器来完成.仅对于这四个字符,它不会被记录.
bool MyWidget::eventFilter(QObject *obj,QEvent *event)
{
if (event->type() == QEvent::KeyPress)
{
//this never gets printed
qDebug() << "Phew!" << endl;
return true;
}
if (qobject_cast<ChildWidget *>(obj) != nullptr)
{
ChildWidget *option = qobject_cast<ChildWidget *>(obj);
if (event->type() == QEvent::Enter || event->type() == QEvent::MouseMove)
{
//do stuff
return true;
}
if (event->type() == QEvent::Leave)
{
//do stuff
return true;
}
return QWidget::eventFilter(obj,event);
}
else
{
// pass the event on to the parent class
return QWidget::eventFilter(obj,event);
}
}
MyWidget::MyWidget()
{
//do other initialization
this->installEventFilter(this);
}
void MyWidget::keyPressEvent(QKeyEvent *event)
{
qDebug("At least came here");
QString text = event->text();
//this prints out whenever I type any character,excpet W/A/S/D
qDebug() << text;
}
解决方法
不确定我是否误解了一些东西,但是下面的代码运行良好,我看到日志中的所有密钥(甚至大写)除了键“w”.
在这里你有：
编辑#1：在QApplication上安装了一个事件过滤器,以获取过滤事件的对象.
myframe.pro
TEMPLATE = app
QT += widgets
SOURCES += main.cpp \
myframe.cpp
HEADERS += myframe.h
main.cpp中
#include <QtWidgets/QApplication>
#include <QDebug>
#include "myframe.h"
class QApplicationFilter: public QObject
{
public:
QApplicationFilter(): QObject() {};
~QApplicationFilter() {};
bool eventFilter(QObject* obj,QEvent* event)
{
qDebug() << "QApplicationFilter: "
<< obj->objectName()
<< " - event type: "
<< event->type();
return QObject::eventFilter(obj,event);
};
};
int main(int argc,char *argv[])
{
QApplication a(argc,argv);
a.installEventFilter(new QApplicationFilter());
MyFrame mf;
mf.show();
return a.exec();
}
myframe.h
#ifndef MYFRAME_H
#define MYFRAME_H
#include <QtWidgets/QFrame>
class MyFrame : public QFrame
{
Q_OBJECT
public:
MyFrame();
bool eventFilter(QObject *object,QEvent *event);
protected:
void keyPressEvent(QKeyEvent *event);
};
#endif
myframe.cpp
#include <QDebug>
#include <QKeyEvent>
#include "myframe.h"
MyFrame::MyFrame()
{
this->installEventFilter(this);
}
bool MyFrame::eventFilter(QObject *object,QEvent *event)
{
if (object == this && event->type() == QEvent::KeyPress) {
QKeyEvent *keyEvent = static_cast<QKeyEvent *>(event);
if (keyEvent->key() == Qt::Key_W) {
return true;
} else {
return false;
}
}
return false;
}
void MyFrame::keyPressEvent(QKeyEvent *event)
{
qDebug("At least came here");
QString text = event->text();
qDebug() << text;
}
