在做用戶登錄、修改密碼的時候，往往會用到密碼框，其中一些功能要求與普通的輸入框不同。

例如：不能選中、復制、粘貼、無右鍵菜單等功能，當然設置密碼不可見是必須的！

一般的密碼框：(默認 可以選中，復制，粘貼，有右鍵菜單)

QLineEdit *pCommonLineEdit = new QLineEdit(this); pCommonLineEdit->setPlaceholderText(QStringLiteral("密碼由字母、數字、下劃線組成，長度8-16位")); pCommonLineEdit->setEchoMode(QLineEdit::Password);

下面進行一些設置：不可選擇，沒有右鍵菜單

1.可以進行事件重寫去完成

class PasswordLineEdit : public QLineEdit {Q_OBJECTpublic:explicit PasswordLineEdit(QWidget *parent = 0);~PasswordLineEdit();protected:virtual void keyPressEvent(QKeyEvent *event);virtual void mouseMoveEvent(QMouseEvent *event);virtual void mouseDoubleClickEvent(QMouseEvent *event); }; PasswordLineEdit::PasswordLineEdit(QWidget *parent): QLineEdit(parent) {//設置無右鍵菜單setContextMenuPolicy(Qt::NoContextMenu);//設置無輸入時密碼提示setPlaceholderText(QStringLiteral("請輸入密碼"));//設置密碼隱藏setEchoMode(QLineEdit::Password);//設置最大長度16位setMaxLength(16); }PasswordLineEdit::~PasswordLineEdit() { }//屏蔽輸入框全選、復制、粘貼功能 void PasswordLineEdit::keyPressEvent(QKeyEvent *event) {if(event->matches(QKeySequence::SelectAll)|| event->matches(QKeySequence::Copy)|| event->matches(QKeySequence::Paste)){return;}QLineEdit::keyPressEvent(event); }//鼠標位于密碼框中時不可移動 void PasswordLineEdit::mouseMoveEvent(QMouseEvent *event) {Q_UNUSED(event); }//鼠標位于密碼框中時不可移動 void PasswordLineEdit::mouseDoubleClickEvent(QMouseEvent *event) {Q_UNUSED(event); }

2.通過事件過濾器去實現上述的功能

QLineEdit *pFilterLineEdit = new QLineEdit(this); pFilterLineEdit->installEventFilter(new EventFilter(this)); pFilterLineEdit->setEchoMode(QLineEdit::Password); pFilterLineEdit->setPlaceholderText(QStringLiteral("密碼由字母、數字、下劃線組成，長度8-16位")); pFilterLineEdit->setContextMenuPolicy(Qt::NoContextMenu); pFilterLineEdit->setMaxLength(16);

class EventFilter : public QObject { public:explicit EventFilter(QObject *parent = 0);~EventFilter();protected:virtual bool eventFilter(QObject *obj, QEvent *event); }; EventFilter::EventFilter(QObject *parent): QObject(parent) {}EventFilter::~EventFilter() {}bool EventFilter::eventFilter(QObject *obj, QEvent *event) {QLineEdit *pLineEdit = qobject_cast<QLineEdit *>(obj);if (pLineEdit != NULL){switch (event->type()){case QEvent::MouseMove:case QEvent::MouseButtonDblClick:return true;case QEvent::KeyPress:{QKeyEvent *pKeyEvent = static_cast<QKeyEvent*>(event);if(pKeyEvent->matches(QKeySequence::SelectAll)|| pKeyEvent->matches(QKeySequence::Copy)|| pKeyEvent->matches(QKeySequence::Paste)){return true;}}}}return QObject::eventFilter(obj, event); }

上面就是三種關于密碼框的一些操作，基本也夠用了！

總結

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