graph.cpp Example File | Qt Quick 5.12.8

- Qt 5.12
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- graph.cpp Example File
- Qt 5.12.8 Reference Documentation

# graph.cpp Example File

scenegraph/graph/graph.cpp

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     #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;
     }