beziercurve.cpp Example File

scenegraph/customgeometry/beziercurve.cpp
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#include "beziercurve.h" #include <QtQuick/qsgnode.h> #include <QtQuick/qsgflatcolormaterial.h> BezierCurve::BezierCurve(QQuickItem *parent) : QQuickItem(parent) , m_p1(0, 0) , m_p2(1, 0) , m_p3(0, 1) , m_p4(1, 1) , m_segmentCount(32) { setFlag(ItemHasContents, true); } BezierCurve::~BezierCurve() { } void BezierCurve::setP1(const QPointF &p) { if (p == m_p1) return; m_p1 = p; emit p1Changed(p); update(); } void BezierCurve::setP2(const QPointF &p) { if (p == m_p2) return; m_p2 = p; emit p2Changed(p); update(); } void BezierCurve::setP3(const QPointF &p) { if (p == m_p3) return; m_p3 = p; emit p3Changed(p); update(); } void BezierCurve::setP4(const QPointF &p) { if (p == m_p4) return; m_p4 = p; emit p4Changed(p); update(); } void BezierCurve::setSegmentCount(int count) { if (m_segmentCount == count) return; m_segmentCount = count; emit segmentCountChanged(count); update(); } QSGNode *BezierCurve::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeData *) { QSGGeometryNode *node = nullptr; QSGGeometry *geometry = nullptr; if (!oldNode) { node = new QSGGeometryNode; geometry = new QSGGeometry(QSGGeometry::defaultAttributes_Point2D(), m_segmentCount); geometry->setLineWidth(2); geometry->setDrawingMode(QSGGeometry::DrawLineStrip); node->setGeometry(geometry); node->setFlag(QSGNode::OwnsGeometry); 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_segmentCount); } QSizeF itemSize = size(); QSGGeometry::Point2D *vertices = geometry->vertexDataAsPoint2D(); for (int i = 0; i < m_segmentCount; ++i) { qreal t = i / qreal(m_segmentCount - 1); qreal invt = 1 - t; QPointF pos = invt * invt * invt * m_p1 + 3 * invt * invt * t * m_p2 + 3 * invt * t * t * m_p3 + t * t * t * m_p4; float x = pos.x() * itemSize.width(); float y = pos.y() * itemSize.height(); vertices[i].set(x, y); } node->markDirty(QSGNode::DirtyGeometry); return node; }