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;
 }