pieview.cpp Example File

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  #include <QtWidgets>
  #include <cmath>

  #ifndef M_PI
  #define M_PI 3.1415927
  #endif

  #include "pieview.h"

  PieView::PieView(QWidget *parent)
      : QAbstractItemView(parent)
  {
      horizontalScrollBar()->setRange(0, 0);
      verticalScrollBar()->setRange(0, 0);

      margin = 8;
      totalSize = 300;
      pieSize = totalSize - 2 * margin;
      validItems = 0;
      totalValue = 0.0;
      rubberBand = 0;
  }

  void PieView::dataChanged(const QModelIndex &topLeft,
                            const QModelIndex &bottomRight,
                            const QVector<int> &)
  {
      QAbstractItemView::dataChanged(topLeft, bottomRight);

      validItems = 0;
      totalValue = 0.0;

      for (int row = 0; row < model()->rowCount(rootIndex()); ++row) {

          QModelIndex index = model()->index(row, 1, rootIndex());
          double value = model()->data(index).toDouble();

          if (value > 0.0) {
              totalValue += value;
              validItems++;
          }
      }
      viewport()->update();
  }

  bool PieView::edit(const QModelIndex &index, EditTrigger trigger, QEvent *event)
  {
      if (index.column() == 0)
          return QAbstractItemView::edit(index, trigger, event);
      else
          return false;
  }

  /*
      Returns the item that covers the coordinate given in the view.
  */

  QModelIndex PieView::indexAt(const QPoint &point) const
  {
      if (validItems == 0)
          return QModelIndex();

      // Transform the view coordinates into contents widget coordinates.
      int wx = point.x() + horizontalScrollBar()->value();
      int wy = point.y() + verticalScrollBar()->value();

      if (wx < totalSize) {
          double cx = wx - totalSize / 2;
          double cy = totalSize / 2 - wy; // positive cy for items above the center

          // Determine the distance from the center point of the pie chart.
          double d = std::sqrt(std::pow(cx, 2) + std::pow(cy, 2));

          if (d == 0 || d > pieSize / 2)
              return QModelIndex();

          // Determine the angle of the point.
          double angle = (180 / M_PI) * std::acos(cx / d);
          if (cy < 0)
              angle = 360 - angle;

          // Find the relevant slice of the pie.
          double startAngle = 0.0;

          for (int row = 0; row < model()->rowCount(rootIndex()); ++row) {

              QModelIndex index = model()->index(row, 1, rootIndex());
              double value = model()->data(index).toDouble();

              if (value > 0.0) {
                  double sliceAngle = 360 * value / totalValue;

                  if (angle >= startAngle && angle < (startAngle + sliceAngle))
                      return model()->index(row, 1, rootIndex());

                  startAngle += sliceAngle;
              }
          }
      } else {
          double itemHeight = QFontMetrics(viewOptions().font).height();
          int listItem = int((wy - margin) / itemHeight);
          int validRow = 0;

          for (int row = 0; row < model()->rowCount(rootIndex()); ++row) {

              QModelIndex index = model()->index(row, 1, rootIndex());
              if (model()->data(index).toDouble() > 0.0) {

                  if (listItem == validRow)
                      return model()->index(row, 0, rootIndex());

                  // Update the list index that corresponds to the next valid row.
                  ++validRow;
              }
          }
      }

      return QModelIndex();
  }

  bool PieView::isIndexHidden(const QModelIndex & /*index*/) const
  {
      return false;
  }

  /*
      Returns the rectangle of the item at position \a index in the
      model. The rectangle is in contents coordinates.
  */

  QRect PieView::itemRect(const QModelIndex &index) const
  {
      if (!index.isValid())
          return QRect();

      // Check whether the index's row is in the list of rows represented
      // by slices.
      QModelIndex valueIndex;

      if (index.column() != 1)
          valueIndex = model()->index(index.row(), 1, rootIndex());
      else
          valueIndex = index;

      if (model()->data(valueIndex).toDouble() <= 0.0)
          return QRect();

      int listItem = 0;
      for (int row = index.row()-1; row >= 0; --row) {
          if (model()->data(model()->index(row, 1, rootIndex())).toDouble() > 0.0)
              listItem++;
      }

      double itemHeight;

      switch (index.column()) {
      case 0:
          itemHeight = QFontMetrics(viewOptions().font).height();

          return QRect(totalSize,
                       int(margin + listItem*itemHeight),
                       totalSize - margin, int(itemHeight));
      case 1:
          return viewport()->rect();
      }
      return QRect();
  }

  QRegion PieView::itemRegion(const QModelIndex &index) const
  {
      if (!index.isValid())
          return QRegion();

      if (index.column() != 1)
          return itemRect(index);

      if (model()->data(index).toDouble() <= 0.0)
          return QRegion();

      double startAngle = 0.0;
      for (int row = 0; row < model()->rowCount(rootIndex()); ++row) {

          QModelIndex sliceIndex = model()->index(row, 1, rootIndex());
          double value = model()->data(sliceIndex).toDouble();

          if (value > 0.0) {
              double angle = 360 * value / totalValue;

              if (sliceIndex == index) {
                  QPainterPath slicePath;
                  slicePath.moveTo(totalSize / 2, totalSize / 2);
                  slicePath.arcTo(margin, margin, margin+pieSize, margin+pieSize,
                                  startAngle, angle);
                  slicePath.closeSubpath();

                  return QRegion(slicePath.toFillPolygon().toPolygon());
              }

              startAngle += angle;
          }
      }

      return QRegion();
  }

  int PieView::horizontalOffset() const
  {
      return horizontalScrollBar()->value();
  }

  void PieView::mousePressEvent(QMouseEvent *event)
  {
      QAbstractItemView::mousePressEvent(event);
      origin = event->pos();
      if (!rubberBand)
          rubberBand = new QRubberBand(QRubberBand::Rectangle, viewport());
      rubberBand->setGeometry(QRect(origin, QSize()));
      rubberBand->show();
  }

  void PieView::mouseMoveEvent(QMouseEvent *event)
  {
      if (rubberBand)
          rubberBand->setGeometry(QRect(origin, event->pos()).normalized());
      QAbstractItemView::mouseMoveEvent(event);
  }

  void PieView::mouseReleaseEvent(QMouseEvent *event)
  {
      QAbstractItemView::mouseReleaseEvent(event);
      if (rubberBand)
          rubberBand->hide();
      viewport()->update();
  }

  QModelIndex PieView::moveCursor(QAbstractItemView::CursorAction cursorAction,
                                  Qt::KeyboardModifiers /*modifiers*/)
  {
      QModelIndex current = currentIndex();

      switch (cursorAction) {
          case MoveLeft:
          case MoveUp:
              if (current.row() > 0)
                  current = model()->index(current.row() - 1, current.column(),
                                           rootIndex());
              else
                  current = model()->index(0, current.column(), rootIndex());
              break;
          case MoveRight:
          case MoveDown:
              if (current.row() < rows(current) - 1)
                  current = model()->index(current.row() + 1, current.column(),
                                           rootIndex());
              else
                  current = model()->index(rows(current) - 1, current.column(),
                                           rootIndex());
              break;
          default:
              break;
      }

      viewport()->update();
      return current;
  }

  void PieView::paintEvent(QPaintEvent *event)
  {
      QItemSelectionModel *selections = selectionModel();
      QStyleOptionViewItem option = viewOptions();

      QBrush background = option.palette.base();
      QPen foreground(option.palette.color(QPalette::WindowText));

      QPainter painter(viewport());
      painter.setRenderHint(QPainter::Antialiasing);

      painter.fillRect(event->rect(), background);
      painter.setPen(foreground);

      // Viewport rectangles
      QRect pieRect = QRect(margin, margin, pieSize, pieSize);

      if (validItems <= 0)
          return;

      painter.save();
      painter.translate(pieRect.x() - horizontalScrollBar()->value(),
                        pieRect.y() - verticalScrollBar()->value());
      painter.drawEllipse(0, 0, pieSize, pieSize);
      double startAngle = 0.0;
      int row;

      for (row = 0; row < model()->rowCount(rootIndex()); ++row) {
          QModelIndex index = model()->index(row, 1, rootIndex());
          double value = model()->data(index).toDouble();

          if (value > 0.0) {
              double angle = 360*value/totalValue;

              QModelIndex colorIndex = model()->index(row, 0, rootIndex());
              QColor color = QColor(model()->data(colorIndex, Qt::DecorationRole).toString());

              if (currentIndex() == index)
                  painter.setBrush(QBrush(color, Qt::Dense4Pattern));
              else if (selections->isSelected(index))
                  painter.setBrush(QBrush(color, Qt::Dense3Pattern));
              else
                  painter.setBrush(QBrush(color));

              painter.drawPie(0, 0, pieSize, pieSize, int(startAngle*16), int(angle*16));

              startAngle += angle;
          }
      }
      painter.restore();

      int keyNumber = 0;

      for (row = 0; row < model()->rowCount(rootIndex()); ++row) {
          QModelIndex index = model()->index(row, 1, rootIndex());
          double value = model()->data(index).toDouble();

          if (value > 0.0) {
              QModelIndex labelIndex = model()->index(row, 0, rootIndex());

              QStyleOptionViewItem option = viewOptions();
              option.rect = visualRect(labelIndex);
              if (selections->isSelected(labelIndex))
                  option.state |= QStyle::State_Selected;
              if (currentIndex() == labelIndex)
                  option.state |= QStyle::State_HasFocus;
              itemDelegate()->paint(&painter, option, labelIndex);

              ++keyNumber;
          }
      }
  }

  void PieView::resizeEvent(QResizeEvent * /* event */)
  {
      updateGeometries();
  }

  int PieView::rows(const QModelIndex &index) const
  {
      return model()->rowCount(model()->parent(index));
  }

  void PieView::rowsInserted(const QModelIndex &parent, int start, int end)
  {
      for (int row = start; row <= end; ++row) {
          QModelIndex index = model()->index(row, 1, rootIndex());
          double value = model()->data(index).toDouble();

          if (value > 0.0) {
              totalValue += value;
              ++validItems;
          }
      }

      QAbstractItemView::rowsInserted(parent, start, end);
  }

  void PieView::rowsAboutToBeRemoved(const QModelIndex &parent, int start, int end)
  {
      for (int row = start; row <= end; ++row) {
          QModelIndex index = model()->index(row, 1, rootIndex());
          double value = model()->data(index).toDouble();
          if (value > 0.0) {
              totalValue -= value;
              --validItems;
          }
      }

      QAbstractItemView::rowsAboutToBeRemoved(parent, start, end);
  }

  void PieView::scrollContentsBy(int dx, int dy)
  {
      viewport()->scroll(dx, dy);
  }

  void PieView::scrollTo(const QModelIndex &index, ScrollHint)
  {
      QRect area = viewport()->rect();
      QRect rect = visualRect(index);

      if (rect.left() < area.left()) {
          horizontalScrollBar()->setValue(
              horizontalScrollBar()->value() + rect.left() - area.left());
      } else if (rect.right() > area.right()) {
          horizontalScrollBar()->setValue(
              horizontalScrollBar()->value() + qMin(
                  rect.right() - area.right(), rect.left() - area.left()));
      }

      if (rect.top() < area.top()) {
          verticalScrollBar()->setValue(
              verticalScrollBar()->value() + rect.top() - area.top());
      } else if (rect.bottom() > area.bottom()) {
          verticalScrollBar()->setValue(
              verticalScrollBar()->value() + qMin(
                  rect.bottom() - area.bottom(), rect.top() - area.top()));
      }

      update();
  }

  /*
      Find the indices corresponding to the extent of the selection.
  */

  void PieView::setSelection(const QRect &rect, QItemSelectionModel::SelectionFlags command)
  {
      // Use content widget coordinates because we will use the itemRegion()
      // function to check for intersections.

      QRect contentsRect = rect.translated(
                              horizontalScrollBar()->value(),
                              verticalScrollBar()->value()).normalized();

      int rows = model()->rowCount(rootIndex());
      int columns = model()->columnCount(rootIndex());
      QModelIndexList indexes;

      for (int row = 0; row < rows; ++row) {
          for (int column = 0; column < columns; ++column) {
              QModelIndex index = model()->index(row, column, rootIndex());
              QRegion region = itemRegion(index);
              if (region.intersects(contentsRect))
                  indexes.append(index);
          }
      }

      if (indexes.size() > 0) {
          int firstRow = indexes[0].row();
          int lastRow = indexes[0].row();
          int firstColumn = indexes[0].column();
          int lastColumn = indexes[0].column();

          for (int i = 1; i < indexes.size(); ++i) {
              firstRow = qMin(firstRow, indexes[i].row());
              lastRow = qMax(lastRow, indexes[i].row());
              firstColumn = qMin(firstColumn, indexes[i].column());
              lastColumn = qMax(lastColumn, indexes[i].column());
          }

          QItemSelection selection(
              model()->index(firstRow, firstColumn, rootIndex()),
              model()->index(lastRow, lastColumn, rootIndex()));
          selectionModel()->select(selection, command);
      } else {
          QModelIndex noIndex;
          QItemSelection selection(noIndex, noIndex);
          selectionModel()->select(selection, command);
      }

      update();
  }

  void PieView::updateGeometries()
  {
      horizontalScrollBar()->setPageStep(viewport()->width());
      horizontalScrollBar()->setRange(0, qMax(0, 2*totalSize - viewport()->width()));
      verticalScrollBar()->setPageStep(viewport()->height());
      verticalScrollBar()->setRange(0, qMax(0, totalSize - viewport()->height()));
  }

  int PieView::verticalOffset() const
  {
      return verticalScrollBar()->value();
  }

  /*
      Returns the position of the item in viewport coordinates.
  */

  QRect PieView::visualRect(const QModelIndex &index) const
  {
      QRect rect = itemRect(index);
      if (!rect.isValid())
          return rect;

      return QRect(rect.left() - horizontalScrollBar()->value(),
                   rect.top() - verticalScrollBar()->value(),
                   rect.width(), rect.height());
  }

  /*
      Returns a region corresponding to the selection in viewport coordinates.
  */

  QRegion PieView::visualRegionForSelection(const QItemSelection &selection) const
  {
      int ranges = selection.count();

      if (ranges == 0)
          return QRect();

      QRegion region;
      for (int i = 0; i < ranges; ++i) {
          QItemSelectionRange range = selection.at(i);
          for (int row = range.top(); row <= range.bottom(); ++row) {
              for (int col = range.left(); col <= range.right(); ++col) {
                  QModelIndex index = model()->index(row, col, rootIndex());
                  region += visualRect(index);
              }
          }
      }
      return region;
  }