初学QT笔记: 多个QLineEdit之间的焦点设置、切换、获取

原文地址::https://blog.csdn.net/hzh_Beyond/article/details/50476430?utm_medium=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-4.nonecase&depth_1-utm_source=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-4.nonecase

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学习实现计算器中，点击一个lineEdit后，再点击数字按钮，可以将数据或符号显示在选定的lineEdit中。

bool eventFilter(QObject *, QEvent *);

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    m_iCalFlag = 0;
    m_editFlag = 0;
    ui->firstLineEdit->installEventFilter(this);
    ui->secondLineEdit->installEventFilter(this);
    ui->zeroButton->setFocusPolicy(Qt::NoFocus);
    ui->oneButton->setFocusPolicy(Qt::NoFocus);
    ui->twoButton->setFocusPolicy(Qt::NoFocus);
    //QWidget::setFocusPolicy(Qt::NoFocus);
    //QPushButton::setFocusPolicy(Qt::NoFocus);
    //this->setFocusPolicy(Qt::NoFocus);
}

/* 判断焦点位置 */
bool MainWindow::eventFilter(QObject *watched, QEvent *event)
{
    if(watched == ui->firstLineEdit)
    {
        if(event->type() == QEvent::FocusIn)
        {
            QPalette p = QPalette();
            p.setColor(QPalette::Base, Qt::green);
            ui->firstLineEdit->setPalette(p);
            printf("get first focusin \r\n");
            m_editFlag = 1;
        }
        else if(event->type() == QEvent::FocusOut)
        {
            QPalette p= QPalette();
            p.setColor(QPalette::Base, Qt::white);
            ui->firstLineEdit->setPalette(p);
            printf("get first focusout \r\n");
            m_editFlag = 0;
        }
    }
    else if(watched == ui->secondLineEdit)
    {
        if(event->type() == QEvent::FocusIn)
        {
            QPalette p= QPalette();
            p.setColor(QPalette::Base, Qt::green);
            ui->secondLineEdit->setPalette(p);
            printf("get two focusin \r\n");
            m_editFlag = 2;
        }
        else if(event->type() == QEvent::FocusOut)
        {
            QPalette p= QPalette();
            p.setColor(QPalette::Base, Qt::white);
            ui->secondLineEdit->setPalette(p);
            printf("get two focusout \r\n");
            m_editFlag = 0;
        }
    }
    return QWidget::eventFilter(watched, event);
}

单个控件分别设置焦点为无焦点即可。

Qt::TabFocus 0x1the widget accepts focus by tabbing.
Qt::ClickFocus 0x2the widget accepts focus by clicking.
Qt::StrongFocus TabFocus | ClickFocus | 0x8the widget accepts focus by both tabbing and clicking. On OS X this will also be indicate that the widget accepts tab focus when in 'Text/List focus mode'.
Qt::WheelFocus StrongFocus | 0x4like Qt::StrongFocus plus the widget accepts focus by using the mouse wheel.
Qt::NoFocus 0 the widget does not accept focus.

尝试了所有的pushbotton一个接口禁用，但是失败了。

在ui界面设置属性中直接设置更方便。

选中控件，在右侧属性栏中找到QWidget->focusPolicy->选择NoFocus，则此控件不产生焦点。
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原文链接：https://blog.csdn.net/hzh_Beyond/article/details/50476430