首先，我们来看看
Scene Graph的官方例子，在qt的示例里查找Scene Graph下载customgeometry项目它的h文件是下面的：
/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the demonstration applications 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."
**
** $QT_END_LICENSE$
**
****************************************************************************/
#ifndef BEZIERCURVE_H
#define BEZIERCURVE_H
//! [1]
#include <QtQuick/QQuickItem>
class BezierCurve : public QQuickItem
{
Q_OBJECT
Q_PROPERTY(QPointF p1 READ p1 WRITE setP1 NOTIFY p1Changed)
Q_PROPERTY(QPointF p2 READ p2 WRITE setP2 NOTIFY p2Changed)
Q_PROPERTY(QPointF p3 READ p3 WRITE setP3 NOTIFY p3Changed)
Q_PROPERTY(QPointF p4 READ p4 WRITE setP4 NOTIFY p4Changed)
Q_PROPERTY(int segmentCount READ segmentCount WRITE setSegmentCount NOTIFY segmentCountChanged)
public:
BezierCurve(QQuickItem *parent = 0);
~BezierCurve();
//! [2]
QSGNode *updatePaintNode(QSGNode *, UpdatePaintNodeData *);
//! [2]
QPointF p1() const { return m_p1; }
QPointF p2() const { return m_p2; }
QPointF p3() const { return m_p3; }
QPointF p4() const { return m_p4; }
int segmentCount() const { return m_segmentCount; }
void setP1(const QPointF &p);
void setP2(const QPointF &p);
void setP3(const QPointF &p);
void setP4(const QPointF &p);
void setSegmentCount(int count);
signals:
void p1Changed(const QPointF &p);
void p2Changed(const QPointF &p);
void p3Changed(const QPointF &p);
void p4Changed(const QPointF &p);
void segmentCountChanged(int count);
private:
QPointF m_p1;
QPointF m_p2;
QPointF m_p3;
QPointF m_p4;
int m_segmentCount;
};
//! [1]
#endif
/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the demonstration applications 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 "beziercurve.h"
#include <QtQuick/qsgnode.h>
#include <QtQuick/qsgflatcolormaterial.h>
//! [1]
BezierCurve::BezierCurve(QQuickItem *parent)
: QQuickItem(parent)
, m_p1(0, 0)
, m_p2(1, 0)
, m_p3(0, 1)
, m_p4(1, 1)
, m_segmentCount(6)
{
setFlag(ItemHasContents, true);
}
//! [1]
//! [2]
BezierCurve::~BezierCurve()
{
}
//! [2]
//! [3]
void BezierCurve::setP1(const QPointF &p)
{
if (p == m_p1)
return;
m_p1 = p;
emit p1Changed(p);
update();
}
//! [3]
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();
}
//! [4]
QSGNode *BezierCurve::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeData *)
{
QSGGeometryNode *node = 0;
QSGGeometry *geometry = 0;
if (!oldNode) {
node = new QSGGeometryNode;
//! [4] //! [5]
geometry = new QSGGeometry(QSGGeometry::defaultAttributes_Point2D(), m_segmentCount);
geometry->setLineWidth(2);
geometry->setDrawingMode(GL_LINE_STRIP);
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);
//! [6] //! [7]
} else {
node = static_cast<QSGGeometryNode *>(oldNode);
geometry = node->geometry();
geometry->allocate(m_segmentCount);
}
//! [7]
//! [8]
QRectF bounds = boundingRect();
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 = bounds.x() + pos.x() * bounds.width();
float y = bounds.y() + pos.y() * bounds.height();
vertices[i].set(x, y);
}
node->markDirty(QSGNode::DirtyGeometry);
//! [8]
//! [9]
return node;
}
//! [9]
qml文件
/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the demonstration applications 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."
**
** $QT_END_LICENSE$
**
****************************************************************************/
//! [1]
import QtQuick 2.0
import CustomGeometry 1.0
//! [1] //! [2]
Item {
width: 300
height: 200
BezierCurve {
id: line
anchors.fill: parent
anchors.margins: 20
//! [2] //! [3]
property real t
SequentialAnimation on t {
NumberAnimation { to: 1; duration: 2000; easing.type: Easing.InOutQuad }
NumberAnimation { to: 0; duration: 2000; easing.type: Easing.InOutQuad }
loops: Animation.Infinite
}
//p2: Qt.point(t, 1 - t)//绑定p2
p3: Qt.point(1 - t, t)
}
//! [3] //! [4]
}
//! [4]
main.cpp
/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the demonstration applications 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 <QtGui>
#include <QtQuick>
#include "beziercurve.h"
//! [1]
int main(int argc, char **argv)
{
QGuiApplication app(argc, argv);
qmlRegisterType<BezierCurve>("CustomGeometry", 1, 0, "BezierCurve");//注册
QQuickView view;
QSurfaceFormat format = view.format();
format.setSamples(16);
view.setFormat(format);
view.setSource(QUrl("qrc:///scenegraph/customgeometry/main.qml"));
view.show();
app.exec();
}
//! [1]