C++ 无法在Qt 4中的eventFilter中检测到多个按键
我试图理解Qt中的事件过滤机制。为此,我将QLineEdit子类化,并尝试在实际的QLineEdit之前捕获任何按键。我所写的代码(大部分是从Qt文档中粘贴的)部分有效:如果我按任意一个键,QLineEdit会正确地显示“Ate按键字母” 如果我按下选项键(我在Mac电脑上)并按下,说“S”,我正确地得到“Ate按键”∫"; 但是,如果我在按住Option键的同时再次按下“S”,QLineEdit将显示“Ate键按下”∫∫,我无法解释。看起来第二次(以及随后)按“S”键不是QKeyEvent或QShortcutEvent,而是直接传递到实际的小部件,但它是什么类型的事件 更复杂的是,如果在按住Option键的同时按下“S”以外的键,则结果会因键的不同而不同。例如,对于键序列Option+{S,D,F,G,H},QLineEdit会显示“Ate key press”∫∂ƒ™。但是,如果我继续按“J”,则QLineEdit仅显示“Ate按键” 有人可以复制这种行为,更好的是,解释它吗?提前谢谢大家 main.cpp:C++ 无法在Qt 4中的eventFilter中检测到多个按键,c++,qt,event-handling,C++,Qt,Event Handling,我试图理解Qt中的事件过滤机制。为此,我将QLineEdit子类化,并尝试在实际的QLineEdit之前捕获任何按键。我所写的代码(大部分是从Qt文档中粘贴的)部分有效:如果我按任意一个键,QLineEdit会正确地显示“Ate按键字母” 如果我按下选项键(我在Mac电脑上)并按下,说“S”,我正确地得到“Ate按键”∫"; 但是,如果我在按住Option键的同时再次按下“S”,QLineEdit将显示“Ate键按下”∫∫,我无法解释。看起来第二次(以及随后)按“S”键不是QKeyEvent或Q
#include <QApplication>
#include "customlineedit.h"
int main(int argc, char *argv[]) {
QApplication a(argc, argv);
CustomLineEdit w;
w.show();
return a.exec();
}
#包括
#包括“customlineedit.h”
int main(int argc,char*argv[]){
质量保证申请a(argc、argv);
自定义行编辑w;
w、 show();
返回a.exec();
}
customlineedit.h
#ifndef CUSTOMLINEEDIT_H
#define CUSTOMLINEEDIT_H
#include <QLineEdit>
class CustomLineEdit : public QLineEdit
{
Q_OBJECT
public:
explicit CustomLineEdit(QWidget *parent = 0);
virtual bool eventFilter(QObject *watched, QEvent *event);
};
#endif // CUSTOMLINEEDIT_H
#ifndef CUSTOMLINEEDIT_H
#define CUSTOMLINEEDIT_H
#include <QLineEdit>
class CustomLineEdit : public QLineEdit
{
Q_OBJECT
public:
explicit CustomLineEdit(QWidget *parent = 0);
virtual bool eventFilter(QObject *watched, QEvent *event);
};
#endif // CUSTOMLINEEDIT_H
\ifndef CUSTOMLINEEDIT\u H
#定义CUSTOMLINEEDIT_H
#包括
类CustomLineEdit:公共QLineEdit
{
Q_对象
公众:
显式CustomLineEdit(QWidget*parent=0);
虚拟布尔事件过滤器(QObject*监视,QEvent*事件);
};
#endif//CUSTOMLINEEDIT\u H
customlineedit.cpp
#include "customlineedit.h"
#include <QKeyEvent>
CustomLineEdit::CustomLineEdit(QWidget *parent) :
QLineEdit(parent)
{
this->installEventFilter (this);
}
bool CustomLineEdit::eventFilter (QObject *watched, QEvent *event)
{
if (event->type () == QEvent::KeyPress
|| event->type () == QEvent::ShortcutOverride) {
QKeyEvent *keyEvent = static_cast<QKeyEvent*>(event);
this->setText("Ate key press " + keyEvent->text());
return true;
} else if (event->type () == QEvent::Shortcut) {
this->setText ("Shortcut event");
return true;
} else {
return false;
}
}
#include <QtGui/QApplication>
#include "customlineedit.h"
#include <QWidget>
#include <QLineEdit>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QWidget w;
QLineEdit *le1 = new QLineEdit( &w );
le1->move( 4, 4 );
le1->setMinimumWidth( 200 );
CustomLineEdit *le2 = new CustomLineEdit( &w );
le2->move( 4, 35 );
le2->setMinimumWidth( 200 );
le1->installEventFilter (le2);
w.setMinimumWidth( 260);
w.show();
return a.exec();
}
#include "customlineedit.h"
#include<QShortcutEvent>
CustomLineEdit::CustomLineEdit(QWidget *parent) :
QLineEdit(parent)
{
}
bool CustomLineEdit::eventFilter (QObject *watched, QEvent *event)
{
if (event->type() == QEvent::KeyPress) {
QKeyEvent *keyEvent = static_cast<QKeyEvent*>(event);
this->setText("QKeyEvent: " + QString::number(keyEvent->modifiers() ) +" / "+ QString::number(keyEvent->key()) );
return false;
} else if (event->type () == QEvent::Shortcut) { //you shouldn't see these here...
QShortcutEvent *shrtcutEvent = static_cast<QShortcutEvent*>(event);
this->setText ("Shortcut event: " + shrtcutEvent->key().toString() );
return false;
} else {
return false;
}
}
#包括“customlineedit.h”
#包括
CustomLineEdit::CustomLineEdit(QWidget*父项):
QLineEdit(父级)
{
此->installEventFilter(此);
}
bool CustomLineEdit::eventFilter(QObject*监视,QEvent*事件)
{
如果(事件->类型()==QEvent::按键
||事件->类型()==QEvent::ShortcutOverride){
QKeyEvent*keyEvent=静态广播(事件);
此->设置文本(“Ate按键”+keyEvent->文本());
返回true;
}else if(事件->类型()==QEvent::快捷方式){
此->设置文本(“快捷方式事件”);
返回true;
}否则{
返回false;
}
}
那里发生了很多不寻常的事情
首先,事件筛选器用于允许QoObject接收并选择性地对另一个QoObject的事件做出反应。您正在做的事情,尤其是这一行:
this->installEventFilter (this);
基本上是将小部件的事件重定向到自身。这与功能设计的工作方式不一致,也不能真正反映您将如何在实际项目中使用事件过滤。当这与您非常强烈的事件吞噬相结合时,您基本上破坏了小部件。例如,按修改器键会导致这是一个QKeyEvent,因此在eventfilter函数中使用它们很可能会导致快捷方式处理失败
您可能无法获取QShortcut事件的几个原因。我看不到任何QShortcut对象被附加。在您获取QShortcutEvent事件之前,我不希望获取任何QShortcutEvent事件。此外,我相信它们是用于QMenus的,而不是作为在所有小部件中获取修饰符+键序列的通用方法。您通常会使用QKeyEvent::modifiers()这样做
此外,还不清楚通过过滤shortcutoverride事件并将其转换为keyevents,您试图做什么
根据文档,修改键的keyEvent->text()将为空,这可能解释了它在窗口上显示为空的字符
不过,事件过滤器非常方便,非常适合保持松散耦合和高度可重用性。下面的示例可能是您学习的更好起点:
main.cpp
#include "customlineedit.h"
#include <QKeyEvent>
CustomLineEdit::CustomLineEdit(QWidget *parent) :
QLineEdit(parent)
{
this->installEventFilter (this);
}
bool CustomLineEdit::eventFilter (QObject *watched, QEvent *event)
{
if (event->type () == QEvent::KeyPress
|| event->type () == QEvent::ShortcutOverride) {
QKeyEvent *keyEvent = static_cast<QKeyEvent*>(event);
this->setText("Ate key press " + keyEvent->text());
return true;
} else if (event->type () == QEvent::Shortcut) {
this->setText ("Shortcut event");
return true;
} else {
return false;
}
}
#include <QtGui/QApplication>
#include "customlineedit.h"
#include <QWidget>
#include <QLineEdit>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QWidget w;
QLineEdit *le1 = new QLineEdit( &w );
le1->move( 4, 4 );
le1->setMinimumWidth( 200 );
CustomLineEdit *le2 = new CustomLineEdit( &w );
le2->move( 4, 35 );
le2->setMinimumWidth( 200 );
le1->installEventFilter (le2);
w.setMinimumWidth( 260);
w.show();
return a.exec();
}
#include "customlineedit.h"
#include<QShortcutEvent>
CustomLineEdit::CustomLineEdit(QWidget *parent) :
QLineEdit(parent)
{
}
bool CustomLineEdit::eventFilter (QObject *watched, QEvent *event)
{
if (event->type() == QEvent::KeyPress) {
QKeyEvent *keyEvent = static_cast<QKeyEvent*>(event);
this->setText("QKeyEvent: " + QString::number(keyEvent->modifiers() ) +" / "+ QString::number(keyEvent->key()) );
return false;
} else if (event->type () == QEvent::Shortcut) { //you shouldn't see these here...
QShortcutEvent *shrtcutEvent = static_cast<QShortcutEvent*>(event);
this->setText ("Shortcut event: " + shrtcutEvent->key().toString() );
return false;
} else {
return false;
}
}
#包括
#包括“customlineedit.h”
#包括
#包括
int main(int argc,char*argv[])
{
质量保证申请a(argc、argv);
qw;
QLineEdit*le1=新的QLineEdit(&w);
le1->移动(4,4);
le1->设置最小宽度(200);
CustomLineEdit*le2=新的CustomLineEdit(&w);
le2->move(4,35);
le2->设置最小宽度(200);
le1->installEventFilter(le2);
w、 设置最小宽度(260);
w、 show();
返回a.exec();
}
customlineedit.h
#ifndef CUSTOMLINEEDIT_H
#define CUSTOMLINEEDIT_H
#include <QLineEdit>
class CustomLineEdit : public QLineEdit
{
Q_OBJECT
public:
explicit CustomLineEdit(QWidget *parent = 0);
virtual bool eventFilter(QObject *watched, QEvent *event);
};
#endif // CUSTOMLINEEDIT_H
#ifndef CUSTOMLINEEDIT_H
#define CUSTOMLINEEDIT_H
#include <QLineEdit>
class CustomLineEdit : public QLineEdit
{
Q_OBJECT
public:
explicit CustomLineEdit(QWidget *parent = 0);
virtual bool eventFilter(QObject *watched, QEvent *event);
};
#endif // CUSTOMLINEEDIT_H
\ifndef CUSTOMLINEEDIT\u H
#定义CUSTOMLINEEDIT_H
#包括
类CustomLineEdit:公共QLineEdit
{
Q_对象
公众:
显式CustomLineEdit(QWidget*parent=0);
虚拟布尔事件过滤器(QObject*监视,QEvent*事件);
};
#endif//CUSTOMLINEEDIT\u H
customlineedit.cpp
#include "customlineedit.h"
#include <QKeyEvent>
CustomLineEdit::CustomLineEdit(QWidget *parent) :
QLineEdit(parent)
{
this->installEventFilter (this);
}
bool CustomLineEdit::eventFilter (QObject *watched, QEvent *event)
{
if (event->type () == QEvent::KeyPress
|| event->type () == QEvent::ShortcutOverride) {
QKeyEvent *keyEvent = static_cast<QKeyEvent*>(event);
this->setText("Ate key press " + keyEvent->text());
return true;
} else if (event->type () == QEvent::Shortcut) {
this->setText ("Shortcut event");
return true;
} else {
return false;
}
}
#include <QtGui/QApplication>
#include "customlineedit.h"
#include <QWidget>
#include <QLineEdit>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QWidget w;
QLineEdit *le1 = new QLineEdit( &w );
le1->move( 4, 4 );
le1->setMinimumWidth( 200 );
CustomLineEdit *le2 = new CustomLineEdit( &w );
le2->move( 4, 35 );
le2->setMinimumWidth( 200 );
le1->installEventFilter (le2);
w.setMinimumWidth( 260);
w.show();
return a.exec();
}
#include "customlineedit.h"
#include<QShortcutEvent>
CustomLineEdit::CustomLineEdit(QWidget *parent) :
QLineEdit(parent)
{
}
bool CustomLineEdit::eventFilter (QObject *watched, QEvent *event)
{
if (event->type() == QEvent::KeyPress) {
QKeyEvent *keyEvent = static_cast<QKeyEvent*>(event);
this->setText("QKeyEvent: " + QString::number(keyEvent->modifiers() ) +" / "+ QString::number(keyEvent->key()) );
return false;
} else if (event->type () == QEvent::Shortcut) { //you shouldn't see these here...
QShortcutEvent *shrtcutEvent = static_cast<QShortcutEvent*>(event);
this->setText ("Shortcut event: " + shrtcutEvent->key().toString() );
return false;
} else {
return false;
}
}
#包括“customlineedit.h”
#包括
CustomLineEdit::CustomLineEdit(QWidget*父项):
QLineEdit(父级)
{
}
bool CustomLineEdit::eventFilter(QObject*监视,QEvent*事件)
{
如果(事件->类型()==QEvent::按键){
QKeyEvent*keyEvent=静态广播(事件);
这->setText(“QKeyEvent:+QString::number(keyEvent->modifiers())+”/“+QString::number(keyEvent->key());
返回false;
}否则如果(event->type()==QEvent::Shortcut){//您不应该在这里看到这些。。。
QShortcutEvent*shrtcutEvent=static_cast(事件);
此->设置文本(“快捷方式事件:+shrtcutEvent->key().toString());
返回false;
}否则{
返回false;
}
}
编辑:因此,我从评论中看到,您正在尝试添加Emacs样式的自定义快捷方式。这是一个好主意!以下是我在不使用事件筛选的情况下的做法:
#include <QtGui/QApplication>
#include <QLineEdit>
#include <QKeyEvent>
#include <QDebug>
class LineEditEmacs : public QLineEdit
{
void keyPressEvent( QKeyEvent* event )
{
//qDebug()<< QString::number( event->key(), 16 ).toUpper();
switch ( event->key() )
{
case Qt::Key_Up:
{ undo(); return; }
case Qt::Key_Down:
{ redo(); return; }
case Qt::Key_Minus: //shift+underscore
if( (event->modifiers() & Qt::ShiftModifier) == Qt::ShiftModifier ) { undo(); return; }
case Qt::Key_U:
if( (event->modifiers() & Qt::ControlModifier) == Qt::ControlModifier ) {
SetSelectionToCase( true );
return;
}
case Qt::Key_L:
if( (event->modifiers() & Qt::ControlModifier) == Qt::ControlModifier ) {
SetSelectionToCase( false );
return;
}
default:
break;
}
QLineEdit::keyPressEvent( event );
}
void SetSelectionToCase( bool Upper )
{
if( !hasSelectedText() )
return;
QString s = selectedText();
int iPreviousCursorPos = cursorPosition();
del();
QString su = Upper? s.toUpper() : s.toLower();
insert( su );
int iNewCursorPos = cursorPosition();
//restore selection
if( iPreviousCursorPos < iNewCursorPos )
cursorBackward( true, su.length() );
else if( iPreviousCursorPos == iNewCursorPos )
setSelection( iPreviousCursorPos-su.length(), su.length() );
}
};
int main( int argc, char *argv[] )
{
QApplication a( argc, argv );
LineEditEmacs w;
w.show();
return a.exec();
}
#包括
#包括
#包括
#包括
类LineEditEmacs:公共QLineEdit
{
无效按键事件(QKeyEvent*事件)
{
//qDebug()键(),16).toUpper();
开关(事件->键())
{
案例Qt::键向上: