Display only superscript char mixed with regular char in a QTableWidget

canellas

Hi, everyone!

I need to display a superscript number followed by a letter in a QTableWidgetCell, and in the following cells, horizontally or vertically, display a simple char (requirement 1).

I do want the cell to be editable (requirement 2).

I need a arrow like cursor (requirement 3).

I created a subclass of QTextEdit so that I could use QTextEdit::setHtml(QString) like this textEdit->setHtml("<sup>39</sup>M");. I also used text->setReadOnly(true); to disable editing.

However, textEditor->setCursor(Qt::PointingHandCursor); does not work, as described here (issue 1).

Another problem happens when the following cell is below the one with the superscript number: I could not align them (issue 2). I mean, they look like:

I wonder if there is a better QWidget I could derive from to satisfy the requirements without the issues.

TIA!

Axel Spoerl

@canellas
Could you please share the code?

canellas

@Axel-Spoerl
The classes I created:

class Letter : public QTextEdit {
  Q_OBJECT
public:
  Letter() : QTextEdit(nullptr) {
    setFrameStyle(0);
    setReadOnly(true);
    setAlignment(Qt::AlignCenter);
    unsetCursor();
    setCursor(Qt::PointingHandCursor);
  }

  void highlight() { setTextColor(QColor(255, 255, 0)); }

  void lowlight() { setTextColor(QColor(255, 255, 255)); }
};

class NonFirstLetter : public Letter {
  Q_OBJECT
public:
  NonFirstLetter(QChar p_letter) : Letter() {
    QString _str{QString{"   "} + QString(p_letter).toUpper()};
    setHtml(_str);
  }
};

class FirstLetter : public Letter {
  Q_OBJECT
public:
  FirstLetter(int p_number, QChar p_letter) : Letter() {
    setMouseTracking(true);

    QString _str{"<sup>" + QString::number(p_number) + "</sup>" +
                 QString(p_letter).toUpper()};
    setHtml(_str);
  }

  void add_letter(NonFirstLetter *p_letter) {
    m_other_letters.push_back(p_letter);
  }

  void mousePressEvent(QMouseEvent * /*event*/) {
    for (auto _letter : m_other_letters) {
      _letter->highlight();
    }
  }

private:
  std::vector<NonFirstLetter *> m_other_letters;
};

A simple usage:

void MainWindow::on_pushButton_clicked() {
  ui->tableWidget->setSizeAdjustPolicy(QAbstractScrollArea::AdjustToContents);
  ui->tableWidget->setRowCount(2);
  ui->tableWidget->setColumnCount(1);
  ui->tableWidget->setColumnWidth(0, 1);

  auto _first_letter{new FirstLetter{39, 'M'}};
  auto _letter{new NonFirstLetter{'A'}};
  _first_letter->add_letter(_letter);

  ui->tableWidget->setCellWidget(0, 0, _first_letter);
  ui->tableWidget->setCellWidget(1, 0, _letter);
}

SGaist

Hi,

From the look of it, you should rather implement a custom QStyledItemDelegate. That way you can paint your text content the way you want it.

This RichTextDelegate class could serve as a base.

Axel Spoerl

Fully agree with @SGaist.
While the existing approach will actually work, its limits are Z-ordering and layouting. QStyleItemDelegate is a flexible tool and derives from the underlying data model. If the primary focus is on UI behaviour, you could also create a custom widget, that has a layout, a QLabel and a QLineEdit child. It could be used as a cell widget, if the underlying data can be handled manually.

canellas

@Axel-Spoerl and @SGaist ,

I am trying to avoid using [QAbstractItemDelegate](link https://doc.qt.io/qt-6/qabstractitemdelegate.html) in this [QTableWidget](link https://doc.qt.io/qt-6/qabstractitemdelegate.html), at least for now, because it would require some time for me to learn how to use it and I need a simple POC.

I got this so far:

With this code:

class Letter : public QLabel {
  Q_OBJECT
public:
  Letter() : QLabel(nullptr) {
    setAlignment(Qt::AlignCenter);
    unsetCursor();
    setCursor(Qt::PointingHandCursor);
    setTextFormat(Qt::RichText);
    setAlignment(Qt::AlignRight);
  }

  void highlight() { setStyleSheet("color: rgb(255, 0, 0);"); }

  void lowlight() { setStyleSheet("color: rgb(0, 0, 0);"); }
};

class NonFirstLetter : public Letter {
  Q_OBJECT
public:
  NonFirstLetter(QChar p_letter) : Letter() {
    QString _str{QString(p_letter).toUpper()};
    setText(_str);
    adjustSize();
  }
};

class FirstLetter : public Letter {
  Q_OBJECT
public:
  FirstLetter(int p_number, QChar p_letter) : Letter() {
    setMouseTracking(true);

    QString _str{"<sup>" + QString::number(p_number) + "</sup>" +
                 QString(p_letter).toUpper()};
    setText(_str);
    adjustSize();
  }

  void add_letter(NonFirstLetter *p_letter) {
    m_other_letters.push_back(p_letter);
  }

  void mousePressEvent(QMouseEvent * /*event*/) {
    highlight();
    for (auto _letter : m_other_letters) {
      _letter->highlight();
    }
  }

private:
  std::vector<NonFirstLetter *> m_other_letters;
};

and

void MainWindow::on_pushButton_clicked() {
  ui->verticalLayout->setSizeConstraint(QLayout::SetFixedSize);
  ui->tableWidget->setRowCount(2);
  ui->tableWidget->setColumnCount(1);
  ui->tableWidget->resizeColumnsToContents();

  auto _first_letter{new FirstLetter{39, 'M'}};
  auto _letter{new NonFirstLetter{'A'}};
  _first_letter->add_letter(_letter);

  ui->tableWidget->setCellWidget(0, 0, _first_letter);
  ui->tableWidget->setCellWidget(1, 0, _letter);
}

I would like to reduce the width of the label and column just enough to display the superscript number and the letter, but I failed to do it.

Is it possible?

Axel Spoerl

@canellas
If the simple POC needs proper formatting, then there's no way around the right tools IMHO.
In this case, the delegate the tool of choice. Trying to format cell content, mixed with cell widgets is drilling a wood screw into a screw nut. It will hold somehow, while looking ugly. Sorry for not being able to provide a better advice!