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<h1 class="title">node.cpp Example File</h1>
<span class="subtitle">graphicsview/elasticnodes/node.cpp</span>
<!-- $$$graphicsview/elasticnodes/node.cpp-description -->
<div class="descr"> <a name="details"></a>
<pre class="cpp">

  <span class="comment">/****************************************************************************
  **
  ** 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:
  **
  ** &quot;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
  ** &quot;AS IS&quot; 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.&quot;
  **
  ** $QT_END_LICENSE$
  **
  ****************************************************************************/</span>

  <span class="preprocessor">#include &quot;edge.h&quot;</span>
  <span class="preprocessor">#include &quot;node.h&quot;</span>
  <span class="preprocessor">#include &quot;graphwidget.h&quot;</span>

  <span class="preprocessor">#include &lt;QGraphicsScene&gt;</span>
  <span class="preprocessor">#include &lt;QGraphicsSceneMouseEvent&gt;</span>
  <span class="preprocessor">#include &lt;QPainter&gt;</span>
  <span class="preprocessor">#include &lt;QStyleOption&gt;</span>

  Node<span class="operator">::</span>Node(GraphWidget <span class="operator">*</span>graphWidget)
      : graph(graphWidget)
  {
      setFlag(ItemIsMovable);
      setFlag(ItemSendsGeometryChanges);
      setCacheMode(DeviceCoordinateCache);
      setZValue(<span class="operator">-</span><span class="number">1</span>);
  }

  <span class="type">void</span> Node<span class="operator">::</span>addEdge(Edge <span class="operator">*</span>edge)
  {
      edgeList <span class="operator">&lt;</span><span class="operator">&lt;</span> edge;
      edge<span class="operator">-</span><span class="operator">&gt;</span>adjust();
  }

  <span class="type"><a href="../qtcore/qlist.html">QList</a></span><span class="operator">&lt;</span>Edge <span class="operator">*</span><span class="operator">&gt;</span> Node<span class="operator">::</span>edges() <span class="keyword">const</span>
  {
      <span class="keyword">return</span> edgeList;
  }

  <span class="type">void</span> Node<span class="operator">::</span>calculateForces()
  {
      <span class="keyword">if</span> (<span class="operator">!</span>scene() <span class="operator">|</span><span class="operator">|</span> scene()<span class="operator">-</span><span class="operator">&gt;</span>mouseGrabberItem() <span class="operator">=</span><span class="operator">=</span> <span class="keyword">this</span>) {
          newPos <span class="operator">=</span> pos();
          <span class="keyword">return</span>;
      }

      <span class="comment">// Sum up all forces pushing this item away</span>
      <span class="type"><a href="../qtcore/qtglobal.html#qreal-typedef">qreal</a></span> xvel <span class="operator">=</span> <span class="number">0</span>;
      <span class="type"><a href="../qtcore/qtglobal.html#qreal-typedef">qreal</a></span> yvel <span class="operator">=</span> <span class="number">0</span>;
      foreach (<span class="type"><a href="qgraphicsitem.html">QGraphicsItem</a></span> <span class="operator">*</span>item<span class="operator">,</span> scene()<span class="operator">-</span><span class="operator">&gt;</span>items()) {
          Node <span class="operator">*</span>node <span class="operator">=</span> qgraphicsitem_cast<span class="operator">&lt;</span>Node <span class="operator">*</span><span class="operator">&gt;</span>(item);
          <span class="keyword">if</span> (<span class="operator">!</span>node)
              <span class="keyword">continue</span>;

          <span class="type"><a href="../qtcore/qpointf.html">QPointF</a></span> vec <span class="operator">=</span> mapToItem(node<span class="operator">,</span> <span class="number">0</span><span class="operator">,</span> <span class="number">0</span>);
          <span class="type"><a href="../qtcore/qtglobal.html#qreal-typedef">qreal</a></span> dx <span class="operator">=</span> vec<span class="operator">.</span>x();
          <span class="type"><a href="../qtcore/qtglobal.html#qreal-typedef">qreal</a></span> dy <span class="operator">=</span> vec<span class="operator">.</span>y();
          <span class="type">double</span> l <span class="operator">=</span> <span class="number">2.0</span> <span class="operator">*</span> (dx <span class="operator">*</span> dx <span class="operator">+</span> dy <span class="operator">*</span> dy);
          <span class="keyword">if</span> (l <span class="operator">&gt;</span> <span class="number">0</span>) {
              xvel <span class="operator">+</span><span class="operator">=</span> (dx <span class="operator">*</span> <span class="number">150.0</span>) <span class="operator">/</span> l;
              yvel <span class="operator">+</span><span class="operator">=</span> (dy <span class="operator">*</span> <span class="number">150.0</span>) <span class="operator">/</span> l;
          }
      }

      <span class="comment">// Now subtract all forces pulling items together</span>
      <span class="type">double</span> weight <span class="operator">=</span> (edgeList<span class="operator">.</span>size() <span class="operator">+</span> <span class="number">1</span>) <span class="operator">*</span> <span class="number">10</span>;
      foreach (Edge <span class="operator">*</span>edge<span class="operator">,</span> edgeList) {
          <span class="type"><a href="../qtcore/qpointf.html">QPointF</a></span> vec;
          <span class="keyword">if</span> (edge<span class="operator">-</span><span class="operator">&gt;</span>sourceNode() <span class="operator">=</span><span class="operator">=</span> <span class="keyword">this</span>)
              vec <span class="operator">=</span> mapToItem(edge<span class="operator">-</span><span class="operator">&gt;</span>destNode()<span class="operator">,</span> <span class="number">0</span><span class="operator">,</span> <span class="number">0</span>);
          <span class="keyword">else</span>
              vec <span class="operator">=</span> mapToItem(edge<span class="operator">-</span><span class="operator">&gt;</span>sourceNode()<span class="operator">,</span> <span class="number">0</span><span class="operator">,</span> <span class="number">0</span>);
          xvel <span class="operator">-</span><span class="operator">=</span> vec<span class="operator">.</span>x() <span class="operator">/</span> weight;
          yvel <span class="operator">-</span><span class="operator">=</span> vec<span class="operator">.</span>y() <span class="operator">/</span> weight;
      }

      <span class="keyword">if</span> (<a href="../qtcore/qtglobal.html#qAbs">qAbs</a>(xvel) <span class="operator">&lt;</span> <span class="number">0.1</span> <span class="operator">&amp;</span><span class="operator">&amp;</span> <a href="../qtcore/qtglobal.html#qAbs">qAbs</a>(yvel) <span class="operator">&lt;</span> <span class="number">0.1</span>)
          xvel <span class="operator">=</span> yvel <span class="operator">=</span> <span class="number">0</span>;

      <span class="type"><a href="../qtcore/qrectf.html">QRectF</a></span> sceneRect <span class="operator">=</span> scene()<span class="operator">-</span><span class="operator">&gt;</span>sceneRect();
      newPos <span class="operator">=</span> pos() <span class="operator">+</span> <span class="type"><a href="../qtcore/qpointf.html">QPointF</a></span>(xvel<span class="operator">,</span> yvel);
      newPos<span class="operator">.</span>setX(<a href="../qtcore/qtglobal.html#qMin">qMin</a>(<a href="../qtcore/qtglobal.html#qMax">qMax</a>(newPos<span class="operator">.</span>x()<span class="operator">,</span> sceneRect<span class="operator">.</span>left() <span class="operator">+</span> <span class="number">10</span>)<span class="operator">,</span> sceneRect<span class="operator">.</span>right() <span class="operator">-</span> <span class="number">10</span>));
      newPos<span class="operator">.</span>setY(<a href="../qtcore/qtglobal.html#qMin">qMin</a>(<a href="../qtcore/qtglobal.html#qMax">qMax</a>(newPos<span class="operator">.</span>y()<span class="operator">,</span> sceneRect<span class="operator">.</span>top() <span class="operator">+</span> <span class="number">10</span>)<span class="operator">,</span> sceneRect<span class="operator">.</span>bottom() <span class="operator">-</span> <span class="number">10</span>));
  }

  bool Node<span class="operator">::</span>advance()
  {
      <span class="keyword">if</span> (newPos <span class="operator">=</span><span class="operator">=</span> pos())
          <span class="keyword">return</span> <span class="keyword">false</span>;

      setPos(newPos);
      <span class="keyword">return</span> <span class="keyword">true</span>;
  }

  <span class="type"><a href="../qtcore/qrectf.html">QRectF</a></span> Node<span class="operator">::</span>boundingRect() <span class="keyword">const</span>
  {
      <span class="type"><a href="../qtcore/qtglobal.html#qreal-typedef">qreal</a></span> adjust <span class="operator">=</span> <span class="number">2</span>;
      <span class="keyword">return</span> <span class="type"><a href="../qtcore/qrectf.html">QRectF</a></span>( <span class="operator">-</span><span class="number">10</span> <span class="operator">-</span> adjust<span class="operator">,</span> <span class="operator">-</span><span class="number">10</span> <span class="operator">-</span> adjust<span class="operator">,</span> <span class="number">23</span> <span class="operator">+</span> adjust<span class="operator">,</span> <span class="number">23</span> <span class="operator">+</span> adjust);
  }

  <span class="type"><a href="../qtgui/qpainterpath.html">QPainterPath</a></span> Node<span class="operator">::</span>shape() <span class="keyword">const</span>
  {
      <span class="type"><a href="../qtgui/qpainterpath.html">QPainterPath</a></span> path;
      path<span class="operator">.</span>addEllipse(<span class="operator">-</span><span class="number">10</span><span class="operator">,</span> <span class="operator">-</span><span class="number">10</span><span class="operator">,</span> <span class="number">20</span><span class="operator">,</span> <span class="number">20</span>);
      <span class="keyword">return</span> path;
  }

  <span class="type">void</span> Node<span class="operator">::</span>paint(<span class="type"><a href="../qtgui/qpainter.html">QPainter</a></span> <span class="operator">*</span>painter<span class="operator">,</span> <span class="keyword">const</span> <span class="type"><a href="qstyleoptiongraphicsitem.html">QStyleOptionGraphicsItem</a></span> <span class="operator">*</span>option<span class="operator">,</span> <span class="type"><a href="qwidget.html">QWidget</a></span> <span class="operator">*</span>)
  {
      painter<span class="operator">-</span><span class="operator">&gt;</span>setPen(<span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>NoPen);
      painter<span class="operator">-</span><span class="operator">&gt;</span>setBrush(<span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>darkGray);
      painter<span class="operator">-</span><span class="operator">&gt;</span>drawEllipse(<span class="operator">-</span><span class="number">7</span><span class="operator">,</span> <span class="operator">-</span><span class="number">7</span><span class="operator">,</span> <span class="number">20</span><span class="operator">,</span> <span class="number">20</span>);

      <span class="type"><a href="../qtgui/qradialgradient.html">QRadialGradient</a></span> gradient(<span class="operator">-</span><span class="number">3</span><span class="operator">,</span> <span class="operator">-</span><span class="number">3</span><span class="operator">,</span> <span class="number">10</span>);
      <span class="keyword">if</span> (option<span class="operator">-</span><span class="operator">&gt;</span>state <span class="operator">&amp;</span> <span class="type"><a href="qstyle.html">QStyle</a></span><span class="operator">::</span>State_Sunken) {
          gradient<span class="operator">.</span>setCenter(<span class="number">3</span><span class="operator">,</span> <span class="number">3</span>);
          gradient<span class="operator">.</span>setFocalPoint(<span class="number">3</span><span class="operator">,</span> <span class="number">3</span>);
          gradient<span class="operator">.</span>setColorAt(<span class="number">1</span><span class="operator">,</span> <span class="type"><a href="../qtgui/qcolor.html">QColor</a></span>(<span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>yellow)<span class="operator">.</span>light(<span class="number">120</span>));
          gradient<span class="operator">.</span>setColorAt(<span class="number">0</span><span class="operator">,</span> <span class="type"><a href="../qtgui/qcolor.html">QColor</a></span>(<span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>darkYellow)<span class="operator">.</span>light(<span class="number">120</span>));
      } <span class="keyword">else</span> {
          gradient<span class="operator">.</span>setColorAt(<span class="number">0</span><span class="operator">,</span> <span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>yellow);
          gradient<span class="operator">.</span>setColorAt(<span class="number">1</span><span class="operator">,</span> <span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>darkYellow);
      }
      painter<span class="operator">-</span><span class="operator">&gt;</span>setBrush(gradient);

      painter<span class="operator">-</span><span class="operator">&gt;</span>setPen(<span class="type"><a href="../qtgui/qpen.html">QPen</a></span>(<span class="type"><a href="../qtcore/qt.html">Qt</a></span><span class="operator">::</span>black<span class="operator">,</span> <span class="number">0</span>));
      painter<span class="operator">-</span><span class="operator">&gt;</span>drawEllipse(<span class="operator">-</span><span class="number">10</span><span class="operator">,</span> <span class="operator">-</span><span class="number">10</span><span class="operator">,</span> <span class="number">20</span><span class="operator">,</span> <span class="number">20</span>);
  }

  <span class="type"><a href="../qtcore/qvariant.html">QVariant</a></span> Node<span class="operator">::</span>itemChange(GraphicsItemChange change<span class="operator">,</span> <span class="keyword">const</span> <span class="type"><a href="../qtcore/qvariant.html">QVariant</a></span> <span class="operator">&amp;</span>value)
  {
      <span class="keyword">switch</span> (change) {
      <span class="keyword">case</span> ItemPositionHasChanged:
          foreach (Edge <span class="operator">*</span>edge<span class="operator">,</span> edgeList)
              edge<span class="operator">-</span><span class="operator">&gt;</span>adjust();
          graph<span class="operator">-</span><span class="operator">&gt;</span>itemMoved();
          <span class="keyword">break</span>;
      <span class="keyword">default</span>:
          <span class="keyword">break</span>;
      };

      <span class="keyword">return</span> <span class="type"><a href="qgraphicsitem.html">QGraphicsItem</a></span><span class="operator">::</span>itemChange(change<span class="operator">,</span> value);
  }

  <span class="type">void</span> Node<span class="operator">::</span>mousePressEvent(<span class="type"><a href="qgraphicsscenemouseevent.html">QGraphicsSceneMouseEvent</a></span> <span class="operator">*</span>event)
  {
      update();
      <span class="type"><a href="qgraphicsitem.html">QGraphicsItem</a></span><span class="operator">::</span>mousePressEvent(event);
  }

  <span class="type">void</span> Node<span class="operator">::</span>mouseReleaseEvent(<span class="type"><a href="qgraphicsscenemouseevent.html">QGraphicsSceneMouseEvent</a></span> <span class="operator">*</span>event)
  {
      update();
      <span class="type"><a href="qgraphicsitem.html">QGraphicsItem</a></span><span class="operator">::</span>mouseReleaseEvent(event);
  }

</pre>
</div>
<!-- @@@graphicsview/elasticnodes/node.cpp -->
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   their respective owners.<br>    The documentation provided herein is licensed under the terms of the    <a href="http://www.gnu.org/licenses/fdl.html">GNU Free Documentation    License version 1.3</a> as published by the Free Software Foundation.<br>    Qt and respective logos are trademarks of The Qt Company Ltd.     in Finland and/or other countries worldwide. All other trademarks are property
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