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;

}