Qt 5.9 | Qt Widgets | Chart Example | pieview.cpp Example File

Qt 5.9.9 Reference Documentation

# pieview.cpp Example File

itemviews/chart/pieview.cpp

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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;
      }