Qt 5.11 | Qt Quick | Scene Graph - Graph | graph.cpp Example File

Qt 5.11.3 Reference Documentation

# graph.cpp Example File

scenegraph/graph/graph.cpp

      /****************************************************************************
      **
      ** Copyright (C) 2017 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 "graph.h"

      #include "noisynode.h"
      #include "gridnode.h"
      #include "linenode.h"

      Graph::Graph()
          : m_samplesChanged(false)
          , m_geometryChanged(false)
      {
          setFlag(ItemHasContents, true);
      }

      void Graph::appendSample(qreal value)
      {
          m_samples << value;
          m_samplesChanged = true;
          update();
      }

      void Graph::removeFirstSample()
      {
          m_samples.removeFirst();
          m_samplesChanged = true;
          update();
      }

      void Graph::geometryChanged(const QRectF &newGeometry, const QRectF &oldGeometry)
      {
          m_geometryChanged = true;
          update();
          QQuickItem::geometryChanged(newGeometry, oldGeometry);
      }

      class GraphNode : public QSGNode
      {
      public:
          NoisyNode *background;
          GridNode *grid;
          LineNode *line;
          LineNode *shadow;
      };

      QSGNode *Graph::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeData *)
      {
          GraphNode *n= static_cast<GraphNode *>(oldNode);

          QRectF rect = boundingRect();

          if (rect.isEmpty()) {
              delete n;
              return nullptr;
          }

          if (!n) {
              n = new GraphNode();

              n->background = new NoisyNode(window());
              n->grid = new GridNode();
              n->line = new LineNode(10, 0.5, QColor("steelblue"));
              n->shadow = new LineNode(20, 0.2f, QColor::fromRgbF(0.2, 0.2, 0.2, 0.4));

              n->appendChildNode(n->background);
              n->appendChildNode(n->grid);
              n->appendChildNode(n->shadow);
              n->appendChildNode(n->line);
          }

          if (m_geometryChanged) {
              n->background->setRect(rect);
              n->grid->setRect(rect);
          }

          if (m_geometryChanged || m_samplesChanged) {
              n->line->updateGeometry(rect, m_samples);
              // We don't need to calculate the geometry twice, so just steal it from the other one...
              n->shadow->setGeometry(n->line->geometry());
          }

          m_geometryChanged = false;
          m_samplesChanged = false;

          return n;
      }