qt事件过滤----eventFilter应用

 

文章目录

 

qt事件过滤

第一步：

子控件注册过滤器

ui->lineEdit->installEventFilter(this);
ui->lineEdit_2->installEventFilter(this);
ui->lineEdit_3->installEventFilter(this);

第二步：

添加事件过滤

virtual bool eventFilter(QObject *watched, QEvent *event);      // 添加事件过滤器声明

Demo示例程序–通过事件过滤实现文本框回车焦点下移

新建一个 Widget 项目，往UI界面拖三个 LineEdit 空间

widget.h

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>

QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACE

class Widget : public QWidget
{
    Q_OBJECT

public:
    Widget(QWidget *parent = nullptr);
    ~Widget();
    virtual bool eventFilter(QObject *watched, QEvent *event);      // 添加事件过滤器声明
private:
    Ui::Widget *ui;
};
#endif // WIDGET_H

widget.cpp

#include "widget.h"
#include "ui_widget.h"
#include <QKeyEvent>
#include <qDebug>

Widget::Widget(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::Widget)
{
    ui->setupUi(this);
    ui->lineEdit->installEventFilter(this);
    ui->lineEdit_2->installEventFilter(this);
    ui->lineEdit_3->installEventFilter(this);
}

Widget::~Widget()
{
    delete ui;
}

bool Widget::eventFilter(QObject *watched, QEvent *event)
{
    if(watched == ui->lineEdit)
    {
        if(event->type() == QEvent::KeyPress)
        {
            QKeyEvent* keyEvent = (QKeyEvent *)event;
            /*Qt中，Qt::Key_Enter是小键盘的回车，而大键盘的回车是Qt::Key_Return*/
            if(keyEvent->key() == Qt::Key_Return){
                ui->lineEdit_2->setFocus();
                qDebug()<<"lineEdit Enter"<< endl;
            }
        }
    }
    else if(watched == ui->lineEdit_2)
    {
        if(event->type() == QEvent::KeyPress)
        {
            QKeyEvent* keyEvent = (QKeyEvent *)event;
            if(keyEvent->key() == Qt::Key_Return){
                ui->lineEdit_3->setFocus();
                qDebug()<<"lineEdit_2 Enter"<< endl;
            }
        }
    }
    else if(watched == ui->lineEdit_3)
    {
        if(event->type() == QEvent::KeyPress)
        {
            QKeyEvent* keyEvent = (QKeyEvent *)event;
            if(keyEvent->key() == Qt::Key_Return){
                ui->lineEdit->setFocus();
                qDebug()<<"lineEdit_3 Enter"<< endl;
            }
        }
    }
    return QWidget::eventFilter(watched, event);
}