QT事件系统_lineEdit输入信息触发事件方法

应用程序输出：

"MyLineEdit类的keypress事件已触发，键盘按下"

"2022-09-09 22:04:33.810" "主窗口的键盘事件触发，键盘按下"

"主窗口的事件过滤器触发"

"mylineEdit的event函数已经触发"

"MyLineEdit类的keypress事件已触发，键盘按下"

"2022-09-09 22:05:29.685" "主窗口的键盘事件触发，键盘按下"

"主窗口的事件过滤器触发"

"mylineEdit的event函数已经触发"

"MyLineEdit类的keypress事件已触发，键盘按下"

"2022-09-09 22:05:33.897" "主窗口的键盘事件触发，键盘按下"

"主窗口的事件过滤器触发"

"mylineEdit的event函数已经触发"

"MyLineEdit类的keypress事件已触发，键盘按下"

"2022-09-09 22:05:34.483" "主窗口的键盘事件触发，键盘按下"

"主窗口的事件过滤器触发"

"mylineEdit的event函数已经触发"

"MyLineEdit类的keypress事件已触发，键盘按下"

"2022-09-09 22:05:35.553" "主窗口的键盘事件触发，键盘按下"

新建一个mylineedit类

#ifndef MYLINEEDIT_H
#define MYLINEEDIT_H
#include 
 
 
class MyLineEdit : public QLineEdit
{
    Q_OBJECT
public:
    explicit MyLineEdit(QWidget *parent=0);
    bool event(QEvent *event);//src6_2
protected:
    void keyPressEvent(QKeyEvent *event);
};
 
#endif // MYLINEEDIT_H

#include "mylineedit.h"
#include 
#include 
 
 
 
MyLineEdit::MyLineEdit(QWidget *parent):QLineEdit(parent)
{
 
}
 
bool MyLineEdit::event(QEvent *event)//src6_2
{
    if(event->type()==QEvent::KeyPress)
    {
        qDebug()<<tr("mylineEdit的event函数已经触发");
    }
    return QLineEdit::event(event);//执行QlineEdit类的event函数的默认操作
}
 
void MyLineEdit::keyPressEvent(QKeyEvent *event)
{
    qDebug()<<tr("MyLineEdit类的keypress事件已触发，键盘按下");
    QLineEdit::keyPressEvent(event);//执行
    event->ignore();//输出后，才将继续执行主窗口的keypressEvent事件
}

主窗口事件：

#ifndef MAINWINDOW_6_1_H
#define MAINWINDOW_6_1_H
 
#include 
class MyLineEdit;//类的前置声明
 
QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow_6_1; }
QT_END_NAMESPACE
 
class MainWindow_6_1 : public QWidget
{
    Q_OBJECT
 
public:
    MainWindow_6_1(QWidget *parent = nullptr);
    ~MainWindow_6_1();
    bool eventFilter(QObject *obj,QEvent *event);
 
private:
    Ui::MainWindow_6_1 *ui;
    MyLineEdit *line_edit;
protected:
    void keyPressEvent(QKeyEvent *event);
};
#endif // MAINWINDOW_6_1_H

#include "mainwindow_6_1.h"
#include "ui_mainwindow_6_1.h"
#include "mylineedit.h"
#include 
#include 
#include 
 
MainWindow_6_1::MainWindow_6_1(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::MainWindow_6_1)
{
    ui->setupUi(this);
    line_edit=new MyLineEdit(this);
    line_edit->move(100,100);
    line_edit->installEventFilter(this);//在主窗口的lineedit控件安装事件过滤器，src6_2
 
}
 
MainWindow_6_1::~MainWindow_6_1()
{
    delete ui;
}
 
bool MainWindow_6_1::eventFilter(QObject *obj, QEvent *event)//src_6_2事件过滤器
{
   if(obj==line_edit)
   {
       if(event->type()==QEvent::KeyPress)
       {
           qDebug()<<tr("主窗口的事件过滤器触发");
       }
   }
   return QWidget::eventFilter(obj,event);
}
 
void MainWindow_6_1::keyPressEvent(QKeyEvent *event)
{
    qDebug()<currentDateTime().toString("yyyy-MM-dd HH:mm:ss.zzz")<<tr("主窗口的键盘事件触发，键盘按下");
}