diagramscene.cpp Example File

  /****************************************************************************
  **
  ** Copyright (C) 2016 The Qt Company Ltd.
  ** Contact: https://www.qt.io/licensing/
  **
  ** This file is part of the examples of the Qt Toolkit.
  **
  ** $QT_BEGIN_LICENSE:BSD$
  ** Commercial License Usage
  ** Licensees holding valid commercial Qt licenses may use this file in
  ** accordance with the commercial license agreement provided with the
  ** Software or, alternatively, in accordance with the terms contained in
  ** a written agreement between you and The Qt Company. For licensing terms
  ** and conditions see https://www.qt.io/terms-conditions. For further
  ** information use the contact form at https://www.qt.io/contact-us.
  **
  ** BSD License Usage
  ** Alternatively, you may use this file under the terms of the BSD license
  ** as follows:
  **
  ** "Redistribution and use in source and binary forms, with or without
  ** modification, are permitted provided that the following conditions are
  ** met:
  **   * Redistributions of source code must retain the above copyright
  **     notice, this list of conditions and the following disclaimer.
  **   * Redistributions in binary form must reproduce the above copyright
  **     notice, this list of conditions and the following disclaimer in
  **     the documentation and/or other materials provided with the
  **     distribution.
  **   * Neither the name of The Qt Company Ltd nor the names of its
  **     contributors may be used to endorse or promote products derived
  **     from this software without specific prior written permission.
  **
  **
  ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  ** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
  **
  ** $QT_END_LICENSE$
  **
  ****************************************************************************/

  #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;
  }