qt qml opengl QPainter画笔实例

最近 需要 用qt 做手写输入法的界面，所以调研了 一些东西，与大家分享 源码

1.用qt+qml+QPainter 来实现，如下图，pc机还好，但是上到手机上就会卡顿。（从网上借鉴来的）

源码下载地址：http://download.csdn.net/detail/zzjzmdx/9058731

部分代码：

void PaintedItem::paint(QPainter *painter)
{  

    painter->setRenderHint(QPainter::Antialiasing,true);

    int size = m_elements.size();

    ElementGroup *element;

    for(int i = 0; i < size ; ++i)

    {

        element = m_elements.at(i);

        element->m_pen.setCapStyle(Qt::RoundCap);

        element->m_pen.setJoinStyle(Qt::MiterJoin);

        element->m_pen.setWidth(20);

        element->m_pen.setStyle(Qt::SolidLine);

       int flag = 0;

       float p = 0;

       float q = 0;

       QVector<QLineF>::iterator i;

       float variable = 0;

       float average = 0;

       float sum = 0;

       int flag1 = 0;

       for (i = element->m_lines.begin(); i != element->m_lines.end(); ++i) {

           if((flag1>5&&flag1<element->m_lines.size()-5)&&(i->length()<5)){

           }else{

               sum = sum + i->length();

           }

           flag1 ++;

       }

       average = sum / element->m_lines.size();

       if(element->m_lines.size()>3){

            variable = 10.0/(element->m_lines.size()/2);

       }

       for (i = element->m_lines.begin(); i != element->m_lines.end(); ++i) {

           if(average>4){

               if(flag==0){

                   q = q + variable;

                   if(20-q>9){

                       if(20-q>10){

                            element->m_pen.setWidthF(20-q);

                       }else{

                            element->m_pen.setWidthF(10);

                       }

                   }else{

                       flag=1;

                   }

               }else{

                   q = q - variable;

                   if(20-q<=20){

                       element->m_pen.setWidthF(20-q);

                   }else{

                       flag=0;

                   }

               }

           }else{

                element->m_pen.setWidthF(18);

           }

           painter->setPen(element->m_pen);

           painter->drawLine(*i);

       }

}

2 用qt+qml+纯opengl 来实现，如下图，pc机可以运行。效果自行优化

源码下载地址：http://download.csdn.net/detail/zzjzmdx/9058741

部分代码：

void Test::paint()

{

        qreal ratio = window()->devicePixelRatio();

        int w = int(ratio * window()->width());

        int h = int(ratio * window()->height());

        if(flag==2){

            glViewport(0, 0, w, h);

            glDisable(GL_DEPTH_TEST);

            glClearColor(1.0f, 1.0f, 1.0f, 1);

            glClear(GL_COLOR_BUFFER_BIT);

            glTranslatef(-1.0f,1.0f,0.0f);

        }

        flag++;

        glColor3f(0.2f,0.2f,1.0f);

        glLineWidth(5.0f);

        int size = m_elements.size();

        ElementGroup *element;

        for(int k = 0; k < size ; ++k)

        {

            element = m_elements.at(k);

            QVector<QLineF>::iterator i;

            for (i = element->m_lines.begin(); i != element->m_lines.end(); ++i) {

                if(k == size -1){

                    glBegin(GL_LINES);  

                        glVertex3f(i->p1().rx()/250, -(i->p1().ry()/250), 0.0f);   

                        glVertex3f(i->p2().rx()/250, -(i->p2().ry()/250), 0.0f);  

                    glEnd();

                }

            }

        }

}

3 用qt+qml+qt封装的opengl 来实现，如下图，pc机可以运行，手机也可运行。效果自行优化

源码下载地址：http://download.csdn.net/detail/zzjzmdx/9058761

部分代码：

QSGNode *OpenGLTest::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeData *)

{

    flag++;

    QSGNode *nodeP = 0;

    if(!oldNode){

        nodeP = new QSGNode;

    }else{

        nodeP = static_cast<QSGNode *>(oldNode);

    }

    QSGGeometryNode *node = 0;

    QSGGeometry *geometry = 0;

    node = new QSGGeometryNode;

    geometry = new QSGGeometry(QSGGeometry::defaultAttributes_Point2D(), 2);

    geometry->setLineWidth(5);

    geometry->setDrawingMode(GL_LINE_STRIP);

    node->setGeometry(geometry);

    node->setFlag(QSGNode::OwnsGeometry);

    QSGFlatColorMaterial *material = new QSGFlatColorMaterial;

    material->setColor(QColor(255, 0, 0));

    node->setMaterial(material);

    QSGGeometry::Point2D *vertices ;

    vertices = geometry->vertexDataAsPoint2D();

    int size = m_elements.size();

    ElementGroup *element;

    for(int k = 0; k < size ; ++k)

    {

        element = m_elements.at(k);

        int currentIndex = 0;

        if(k == size -1){

            QVector<QLineF>::iterator i;

            for (i = element->m_lines.begin(); i != element->m_lines.end(); ++i) {

                currentIndex++;

                if(element->m_lines.size()>1){

                    if(currentIndex == lastlenth){

                        vertices[0].set(i->p1().rx(),i->p1().ry());

                    }

                    if(currentIndex == element->m_lines.size()){

                        vertices[1].set(i->p1().rx(),i->p1().ry());

                    }

                }else{

                    vertices[0].set(i->p1().rx(),i->p1().ry());

                    vertices[1].set(i->p2().rx(),i->p2().ry());

                }

            }

            lastlenth = element->m_lines.size();

        }

    }

    node->markDirty(QSGNode::DirtyGeometry);

    nodeP->appendChildNode(node);

    return nodeP;

}