QOpenGLWidget and QPainter ,Can't render 2D and 3D at the same time

[sdaujiaojiao]

I don't know why .I do as Qt Assistant：put opengl code in @QPainter::beginNativePainting ();/QPainter::endNativePainting ();@ .But I only get the 3D.
my code:
@
class Render : public QOpenGLWidget
{
public:
Render();
~Render();
protected:
void initializeGL();
void paintGL();
void resizeGL(int w ,int h);
QOpenGLFunctions_3_3_Core * f;
QOpenGLBuffer * triangle;
QOpenGLVertexArrayObject * vao;
QOpenGLShaderProgram * program;
QMatrix4x4 mv,p;
QTimer * time;
float rota;
QPainter * painter;
bool needInit;
//void paintEvent(QPaintEvent *e);

};
@

@
#include "render.h"
GLfloat tri[] =
{
0.0f,1.0f,-1.0f,1.0f,
1.0f,1.0f,-1.0f,1.0f,
1.0f,0.0f,-1.0f,1.0f,

};
Render::Render()
{
QSurfaceFormat format;
format.setDepthBufferSize(24);
format.setStencilBufferSize(8);
// format.setVersion(3,3);
//format.setProfile(QSurfaceFormat::CoreProfile);

setFormat( format);
rota = 1.5;
needInit = true;
//setAutoFillBackground(false);
time =  new QTimer;
connect(time,SIGNAL(timeout()),this,SLOT(update()));
time->start(50);

}

Render::~Render()
{

}
void Render::initializeGL()
{
f = QOpenGLContext::currentContext()->versionFunctions<QOpenGLFunctions_3_3_Core>();
f->initializeOpenGLFunctions();

//f = context()->functions();

}
void Render::resizeGL(int w ,int h)
{

p.setToIdentity();
p.perspective(35.0f,float(w)/float(h),1.0f,30.0f);

}

void Render::paintGL()
{
QPainter pntr(this);
// painter->setViewport(50,50,100,100);
pntr.beginNativePainting();
QOpenGLShaderProgram programs ;
programs.addShaderFromSourceCode(QOpenGLShader::Vertex,
"#version 330 core \n
layout(location = 0) in vec4 vertex;
uniform mat4 mvp;
void main()
{
gl_Position = mvp * vertex;
}");

programs.addShaderFromSourceCode(QOpenGLShader::Fragment,
                                 "#version 330 core \n\
                                 out vec4 fragColor;\
        void main() \
{ \
    fragColor = vec4(0.0f,1.0f,0.0f,1.0f);\
}");
programs.link();

QOpenGLVertexArrayObject vaos;
vaos.create();
f->glBindVertexArray(vaos.objectId());
QOpenGLBuffer triangles(QOpenGLBuffer::VertexBuffer);
triangles.create();
f->glBindBuffer(GL_ARRAY_BUFFER,triangles.bufferId());
triangles.setUsagePattern(QOpenGLBuffer::DynamicDraw);
triangles.allocate(tri,sizeof(tri));
programs.enableAttributeArray(0);
programs.setAttributeBuffer(0,GL_FLOAT,0,4,0);

f->glEnable(GL_DEPTH_TEST);

needInit = false;

// this->makeCurrent();
f->glViewport(0,0,width(),height());
f->glClearColor(1.0f,0.5f,0.5f,1.0f);
f->glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT|GL_STENCIL_BUFFER_BIT);

programs.bind();
mv.setToIdentity();

mv.lookAt(QVector3D(0.0f,0.0f,5.0f),QVector3D(0.0f,0.0f,0.0f),QVector3D(0.0f,1.0f,0.0f));
mv.rotate(0.5+rota,0,1,0);
programs.setUniformValue("mvp",p*mv);
f->glBindVertexArray(vaos.objectId());
f->glDrawArrays(GL_TRIANGLES,0,3);
rota=rota+1.5;

pntr.endNativePainting();

pntr.drawText(50,100,"Look This!");

}
@