Details
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Bug
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Resolution: Out of scope
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P3: Somewhat important
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None
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5.15.0
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None
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macOS
Description
Hi ,
Please see the attachment,
in function:
updatePaintNode()
if I initialize the QSGGeometry with 0 vertex, so in the first call of updatePaintNode, the vertex number is 0. Then in the rest of the calls when I allocate vertices according to the number of the samples. the geometrynode can not be drawn any more.
To fix this, I need to initialize the QSGGeometry with at least 1 vertex even through I don't have any points at this time.
Here is the content of updatePaintNode.
// code placeholder QSGNode * TGraph::updatePaintNode(QSGNode *oldNode, QQuickItem::UpdatePaintNodeData *updatePaintNodeData) { qDebug()<<"lenght of sample "<<m_samples.count(); QSGGeometryNode *node = nullptr; QSGGeometry *geometry = nullptr; if(!oldNode) { node = new QSGGeometryNode; geometry = new QSGGeometry(QSGGeometry::defaultAttributes_Point2D(), 1);//0 geometry->setLineWidth(2); geometry->setDrawingMode(QSGGeometry::DrawLines); node->setGeometry(geometry); node->setFlag(QSGNode::OwnsGeometry); //! [5] //! [6] QSGFlatColorMaterial *material = new QSGFlatColorMaterial; material->setColor(QColor(255, 0, 0)); node->setMaterial(material); node->setFlag(QSGNode::OwnsMaterial); } else { node = static_cast<QSGGeometryNode *>(oldNode); geometry = node->geometry(); geometry->allocate(m_samples.count()); } for(int i=0;i<m_samples.count();i++) { QSGGeometry::Point2D *v = geometry->vertexDataAsPoint2D(); for (int i=0; i<m_samples.size(); ++i) { v[i].set(m_samples.at(i).x(),m_samples.at(i).y()); } } node->markDirty(QSGNode::DirtyGeometry); return node; }