Qt 5.11 | Qt Widgets | Diagram Scene Example | diagramscene.cpp Example File

Qt 5.11.3 Reference Documentation

# diagramscene.cpp Example File

graphicsview/diagramscene/diagramscene.cpp

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      #include "diagramscene.h"
      #include "arrow.h"

      #include <QTextCursor>
      #include <QGraphicsSceneMouseEvent>

      DiagramScene::DiagramScene(QMenu *itemMenu, QObject *parent)
          : QGraphicsScene(parent)
      {
          myItemMenu = itemMenu;
          myMode = MoveItem;
          myItemType = DiagramItem::Step;
          line = 0;
          textItem = 0;
          myItemColor = Qt::white;
          myTextColor = Qt::black;
          myLineColor = Qt::black;
      }

      void DiagramScene::setLineColor(const QColor &color)
      {
          myLineColor = color;
          if (isItemChange(Arrow::Type)) {
              Arrow *item = qgraphicsitem_cast<Arrow *>(selectedItems().first());
              item->setColor(myLineColor);
              update();
          }
      }

      void DiagramScene::setTextColor(const QColor &color)
      {
          myTextColor = color;
          if (isItemChange(DiagramTextItem::Type)) {
              DiagramTextItem *item = qgraphicsitem_cast<DiagramTextItem *>(selectedItems().first());
              item->setDefaultTextColor(myTextColor);
          }
      }

      void DiagramScene::setItemColor(const QColor &color)
      {
          myItemColor = color;
          if (isItemChange(DiagramItem::Type)) {
              DiagramItem *item = qgraphicsitem_cast<DiagramItem *>(selectedItems().first());
              item->setBrush(myItemColor);
          }
      }

      void DiagramScene::setFont(const QFont &font)
      {
          myFont = font;

          if (isItemChange(DiagramTextItem::Type)) {
              QGraphicsTextItem *item = qgraphicsitem_cast<DiagramTextItem *>(selectedItems().first());
              //At this point the selection can change so the first selected item might not be a DiagramTextItem
              if (item)
                  item->setFont(myFont);
          }
      }

      void DiagramScene::setMode(Mode mode)
      {
          myMode = mode;
      }

      void DiagramScene::setItemType(DiagramItem::DiagramType type)
      {
          myItemType = type;
      }

      void DiagramScene::editorLostFocus(DiagramTextItem *item)
      {
          QTextCursor cursor = item->textCursor();
          cursor.clearSelection();
          item->setTextCursor(cursor);

          if (item->toPlainText().isEmpty()) {
              removeItem(item);
              item->deleteLater();
          }
      }

      void DiagramScene::mousePressEvent(QGraphicsSceneMouseEvent *mouseEvent)
      {
          if (mouseEvent->button() != Qt::LeftButton)
              return;

          DiagramItem *item;
          switch (myMode) {
              case InsertItem:
                  item = new DiagramItem(myItemType, myItemMenu);
                  item->setBrush(myItemColor);
                  addItem(item);
                  item->setPos(mouseEvent->scenePos());
                  emit itemInserted(item);
                  break;
              case InsertLine:
                  line = new QGraphicsLineItem(QLineF(mouseEvent->scenePos(),
                                              mouseEvent->scenePos()));
                  line->setPen(QPen(myLineColor, 2));
                  addItem(line);
                  break;
              case InsertText:
                  textItem = new DiagramTextItem();
                  textItem->setFont(myFont);
                  textItem->setTextInteractionFlags(Qt::TextEditorInteraction);
                  textItem->setZValue(1000.0);
                  connect(textItem, SIGNAL(lostFocus(DiagramTextItem*)),
                          this, SLOT(editorLostFocus(DiagramTextItem*)));
                  connect(textItem, SIGNAL(selectedChange(QGraphicsItem*)),
                          this, SIGNAL(itemSelected(QGraphicsItem*)));
                  addItem(textItem);
                  textItem->setDefaultTextColor(myTextColor);
                  textItem->setPos(mouseEvent->scenePos());
                  emit textInserted(textItem);
          default:
              ;
          }
          QGraphicsScene::mousePressEvent(mouseEvent);
      }

      void DiagramScene::mouseMoveEvent(QGraphicsSceneMouseEvent *mouseEvent)
      {
          if (myMode == InsertLine && line != 0) {
              QLineF newLine(line->line().p1(), mouseEvent->scenePos());
              line->setLine(newLine);
          } else if (myMode == MoveItem) {
              QGraphicsScene::mouseMoveEvent(mouseEvent);
          }
      }

      void DiagramScene::mouseReleaseEvent(QGraphicsSceneMouseEvent *mouseEvent)
      {
          if (line != 0 && myMode == InsertLine) {
              QList<QGraphicsItem *> startItems = items(line->line().p1());
              if (startItems.count() && startItems.first() == line)
                  startItems.removeFirst();
              QList<QGraphicsItem *> endItems = items(line->line().p2());
              if (endItems.count() && endItems.first() == line)
                  endItems.removeFirst();

              removeItem(line);
              delete line;

              if (startItems.count() > 0 && endItems.count() > 0 &&
                  startItems.first()->type() == DiagramItem::Type &&
                  endItems.first()->type() == DiagramItem::Type &&
                  startItems.first() != endItems.first()) {
                  DiagramItem *startItem = qgraphicsitem_cast<DiagramItem *>(startItems.first());
                  DiagramItem *endItem = qgraphicsitem_cast<DiagramItem *>(endItems.first());
                  Arrow *arrow = new Arrow(startItem, endItem);
                  arrow->setColor(myLineColor);
                  startItem->addArrow(arrow);
                  endItem->addArrow(arrow);
                  arrow->setZValue(-1000.0);
                  addItem(arrow);
                  arrow->updatePosition();
              }
          }
          line = 0;
          QGraphicsScene::mouseReleaseEvent(mouseEvent);
      }

      bool DiagramScene::isItemChange(int type)
      {
          foreach (QGraphicsItem *item, selectedItems()) {
              if (item->type() == type)
                  return true;
          }
          return false;
      }