如何更改QCompleter弹出列表的位置？

Question

我正在开发一个基于Qt5的代码编辑器。当我尝试使用QCompleter向编辑器添加自动完成功能时，我发现弹出列表总是出现在编辑区域的底部。如何让它像真正的IDE一样弹出光标的位置？

下面是定义完成器的代码：

    QCompleter* HintList = new QCompleter(EditArea); 
    // EditArea is a QPlainTextEdit item

    HintList->setFilterMode(Qt::MatchStartsWith);
    HintList->setCompletionMode(QCompleter::PopupCompletion);   

    QStringListModel* KeyList = new QStringListModel(keywords, this); 
    // keywords is a QStringList item

    HintList->setModel(KeyList);
    EditArea->setCompleter(HintList);

Answer 1

你可以通过编辑器的子类化来实现它。下面是使用QLineEdit的示例

class ExtendedLineEdit : public QLineEdit
{
    Q_OBJECT
public:
    explicit ExtendedLineEdit(QWidget *parent = nullptr);

    void setWordCompleter(QCompleter* c);

protected:
    void keyPressEvent(QKeyEvent *e);

private slots:
    void insertCompletionWord(const QString& txtComp);

private:
    QCompleter* m_completerWord;

    void showCustomCompleter(QCompleter* completer);
};

void ExtendedLineEdit::setWordCompleter(QCompleter *c)
{
    m_completerWord = c;
    m_completerWord->setWidget(this);
    connect(m_completerWord, SIGNAL(activated(QString)),
            this, SLOT(insertCompletionWord(QString)));
}

void ExtendedLineEdit::keyPressEvent(QKeyEvent *e)
{
    QLineEdit::keyPressEvent(e);
    if (!m_completerWord)
        return;

    m_completerWord->setCompletionPrefix(this->text());
    showCustomCompleter(m_completerWord);
}

void ExtendedLineEdit::insertCompletionWord(const QString &txtComp)
{
    setText(txtComp);
}

void ExtendedLineEdit::showCustomCompleter(QCompleter *completer)
{
    if (completer->completionPrefix().length() < 1)
    {
        completer->popup()->hide();
        return;
    }
    //HERE is calculated geometry of completer popup
    QRect cr = cursorRect();
    cr.setWidth(completer->popup()->sizeHintForColumn(0) + completer->popup()->verticalScrollBar()->sizeHint().width());
    completer->complete(cr);
}