我有一个QLineEdit,与之关联的QCompleter对象.如果用户输入至少一个字符,则显示QCompleter中的弹出菜单,但是当用户删除最后一个字符(从而使该字段为空)时,弹出窗口消失.即使QLineEdit的文本为空,有没有办法让它显示？
解决方法
使用
QCompliter::complete插槽删除行编辑文本后,您应该可以强制完成弹出窗口的显示：
lineEdit->completer()->complete();
这是你如何做到的：
>为你的lineedit定义textChanged插槽;
>覆盖窗口的customEvent方法;
>在textChanged插槽中将用户事件发送到窗口
lineedit的文字长度为零;
>在customEvent方法中,只要收到用户事件,就会显示完成;
以下是一个例子：
mainwindow.h：
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
protected:
void customEvent(QEvent * event);
private:
Ui::MainWindow *ui;
private slots:
void on_lineEdit_textChanged(QString );
};
mainwindow.cpp：
class CompleteEvent : public QEvent
{
public:
CompleteEvent(QLineEdit *lineEdit) : QEvent(QEvent::User),m_lineEdit(lineEdit) { }
void complete()
{
m_lineEdit->completer()->complete();
}
private:
QLineEdit *m_lineEdit;
};
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),ui(new Ui::MainWindow)
{
ui->setupUi(this);
QStringList wordList;
wordList << "one" << "two" << "three" << "four";
QLineEdit *lineEdit = new QLineEdit(this);
lineEdit->setGeometry(20,20,200,30);
connect(lineEdit,SIGNAL(textChanged(QString)),SLOT(on_lineEdit_textChanged(QString )));
QCompleter *completer = new QCompleter(wordList,this);
completer->setCaseSensitivity(Qt::CaseInsensitive);
completer->setCompletionMode(QCompleter::UnfilteredPopupCompletion);
lineEdit->setCompleter(completer);
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::customEvent(QEvent * event)
{
QMainWindow::customEvent(event);
if (event->type()==QEvent::User)
((CompleteEvent*)event)->complete();
}
void MainWindow::on_lineEdit_textChanged(QString text)
{
if (text.length()==0)
QApplication::postEvent(this,new CompleteEvent((QLineEdit*)sender()));
}
希望这有帮助,问候
