spreadsheetitem.cpp Example File

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  #include "spreadsheetitem.h"

  SpreadSheetItem::SpreadSheetItem()
          : QTableWidgetItem(), isResolving(false)
  {
  }

  SpreadSheetItem::SpreadSheetItem(const QString &text)
          : QTableWidgetItem(text), isResolving(false)
  {
  }

  QTableWidgetItem *SpreadSheetItem::clone() const
  {
      SpreadSheetItem *item = new SpreadSheetItem();
      *item = *this;
      return item;
  }

  QVariant SpreadSheetItem::data(int role) const
  {
      if (role == Qt::EditRole || role == Qt::StatusTipRole)
          return formula();

      if (role == Qt::DisplayRole)
          return display();

      QString t = display().toString();
      bool isNumber = false;
      int number = t.toInt(&isNumber);

      if (role == Qt::TextColorRole) {
          if (!isNumber)
              return QVariant::fromValue(QColor(Qt::black));
          else if (number < 0)
              return QVariant::fromValue(QColor(Qt::red));
          return QVariant::fromValue(QColor(Qt::blue));
      }

       if (role == Qt::TextAlignmentRole)
           if (!t.isEmpty() && (t.at(0).isNumber() || t.at(0) == '-'))
               return (int)(Qt::AlignRight | Qt::AlignVCenter);

       return QTableWidgetItem::data(role);
   }

  void SpreadSheetItem::setData(int role, const QVariant &value)
  {
      QTableWidgetItem::setData(role, value);
      if (tableWidget())
          tableWidget()->viewport()->update();
  }

  QVariant SpreadSheetItem::display() const
  {
      // avoid circular dependencies
      if (isResolving)
          return QVariant();

      isResolving = true;
      QVariant result = computeFormula(formula(), tableWidget(), this);
      isResolving = false;
      return result;
  }

  QVariant SpreadSheetItem::computeFormula(const QString &formula,
                                           const QTableWidget *widget,
                                           const QTableWidgetItem *self)
  {
      // check if the string is actually a formula or not
      QStringList list = formula.split(' ');
      if (list.isEmpty() || !widget)
          return formula; // it is a normal string

      QString op = list.value(0).toLower();

      int firstRow = -1;
      int firstCol = -1;
      int secondRow = -1;
      int secondCol = -1;

      if (list.count() > 1)
          decode_pos(list.value(1), &firstRow, &firstCol);

      if (list.count() > 2)
          decode_pos(list.value(2), &secondRow, &secondCol);

      const QTableWidgetItem *start = widget->item(firstRow, firstCol);
      const QTableWidgetItem *end = widget->item(secondRow, secondCol);

      int firstVal = start ? start->text().toInt() : 0;
      int secondVal = end ? end->text().toInt() : 0;

      QVariant result;
      if (op == "sum") {
          int sum = 0;
          for (int r = firstRow; r <= secondRow; ++r) {
              for (int c = firstCol; c <= secondCol; ++c) {
                  const QTableWidgetItem *tableItem = widget->item(r, c);
                  if (tableItem && tableItem != self)
                      sum += tableItem->text().toInt();
              }
          }

          result = sum;
      } else if (op == "+") {
          result = (firstVal + secondVal);
      } else if (op == "-") {
          result = (firstVal - secondVal);
      } else if (op == "*") {
          result = (firstVal * secondVal);
      } else if (op == "/") {
          if (secondVal == 0)
              result = QString("nan");
          else
              result = (firstVal / secondVal);
      } else if (op == "=") {
          if (start)
              result = start->text();
      } else {
          result = formula;
      }

      return result;
  }