Qt键盘事件

Qt键盘事件

1. 主要函数

主要重写如下两个函数：键盘按下事件和键盘释放事件

[virtual protected] void QWindow::keyPressEvent(QKeyEvent *event)
[virtual protected] void QWindow::keyReleaseEvent(QKeyEvent *event)

2. QKeyEvent常用函数

Qt::KeyboardModifiers QKeyEvent::modifiers() const
int QKeyEvent::key() const

Qt::KeyboardModifiers QKeyEvent::modifiers() const
Returns the keyboard modifier flags that existed immediately after the event occurred.
Warning: This function cannot always be trusted. The user can confuse it by pressing both Shift keys simultaneously and releasing one of them, for example.
返回事件发生后立即存在的键盘修饰符标志。
警告： 此功能并不总是可信的。例如，用户可以通过同时按下两个 Shift 键并释放其中一个来混淆它。

常见修饰键列表：

枚举名称	枚举值	键名称解释
Qt::NoModifier	0x00000000	No modifier key is pressed.
Qt::ShiftModifier	0x02000000	A Shift key on the keyboard is pressed.
Qt::ControlModifier	0x04000000	A Ctrl key on the keyboard is pressed.
Qt::AltModifier	0x08000000	An Alt key on the keyboard is pressed.

int QKeyEvent::key() const
Returns the code of the key that was pressed or released.
返回按下或释放键的键名

3. 示例

键盘方向键按下时显示按键名称

// .h文件
#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

protected:
    void keyPressEvent(QKeyEvent* event) override;
    void keyReleaseEvent(QKeyEvent* event) override;


private:
    Ui::MainWindow *ui;
};
#endif // MAINWINDOW_H

// .cpp文件
#include "MainWindow.h"
#include "ui_MainWindow.h"
#include <QKeyEvent>


MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
}

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

void MainWindow::keyPressEvent(QKeyEvent *event)
{
    if (Qt::Key_Left == event->key())
    {
        ui->labelKeyInfo->setText(QString::fromLocal8Bit("左"));
    }

    if (Qt::Key_Right == event->key())
    {
        ui->labelKeyInfo->setText(QString::fromLocal8Bit("右"));
    }

    if (Qt::Key_Up == event->key())
    {
        ui->labelKeyInfo->setText(QString::fromLocal8Bit("上"));
    }

    if (Qt::Key_Down == event->key())
    {
        ui->labelKeyInfo->setText(QString::fromLocal8Bit("下"));
    }
}

void MainWindow::keyReleaseEvent(QKeyEvent *event)
{

}