problem QGLwidget responding clicking

[gch0214]

I added a VerticalLayout(600px*600px) in UI ,

adding it via these code:

MainWindow::MainWindow(QWidget *parent) :  QMainWindow(parent),  ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    w = new RenjuWidget();
    QRect r(0,0,600,600);
    ui->verticalLayout->setGeometry(r);
    ui->verticalLayout->addWidget(w);   //this adds the widget
    this->move(0,0);
}

MainWindow::MainWindow(QWidget *parent) :  QMainWindow(parent),  ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    w = new RenjuWidget();
    QRect r(0,0,600,600);
    ui->verticalLayout->setGeometry(r);
    ui->verticalLayout->addWidget(w);   //this adds the widget
    this->move(0,0);
}

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my widget code is :

class RenjuWidget : public QGLWidget
{
 
 
    Q_OBJECT
 
 
public:
 
 
    RenjuWidget( QWidget * parent = 0 );
    ~RenjuWidget();
 
 
protected:
 
 
  int posx, posy;
 
 
  void initializeGL();
  void paintGL();
  void resizeGL(int width, int height);
 
 
  void keyPressEvent( QKeyEvent *e );
  void mousePressEvent(QMouseEvent *e);
};

class RenjuWidget : public QGLWidget
{


    Q_OBJECT


public:


    RenjuWidget( QWidget * parent = 0 );
    ~RenjuWidget();


protected:


  int posx, posy;


  void initializeGL();
  void paintGL();
  void resizeGL(int width, int height);


  void keyPressEvent( QKeyEvent *e );
  void mousePressEvent(QMouseEvent *e);
};

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my mouse click responding function is:

void RenjuWidget::mousePressEvent(QMouseEvent *e)
{
    if(e->button() == Qt::LeftButton)
    {
        posx = e->x();
        posy = e->y();
        cout<<posx<<"\t"<<posy<<endl;
        paintGL();
       //QMessageBox::information(NULL,QString("%1").arg(posx),QString("%1").arg(posy),QMessageBox::Ok,QMessageBox::NoButton);
       //if I use messagebox , the problem doesn't appear
        return ;
    }
}

void RenjuWidget::mousePressEvent(QMouseEvent *e)
{
    if(e->button() == Qt::LeftButton)
    {
        posx = e->x();
        posy = e->y();
        cout<<posx<<"\t"<<posy<<endl;
        paintGL();
       //QMessageBox::information(NULL,QString("%1").arg(posx),QString("%1").arg(posy),QMessageBox::Ok,QMessageBox::NoButton);
       //if I use messagebox , the problem doesn't appear
        return ;
    }
}

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draw function is to draw a triangle on the left side if you click on the left half or a square on the right side if you clicked on the right half.

void RenjuWidget::paintGL()
{
    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
    glLoadIdentity();
 
 
    if(posx < 300)
    {
        glTranslatef( -1.5,  0.0, -10.0 );
 
 
        glBegin( GL_TRIANGLES );
          glColor3f( 1.0, 0.0, 0.0 );
          glVertex3f(  0.0,  1.0,  0.0 );
          glColor3f( 0.0, 1.0, 0.0 );
          glVertex3f( -1.0, -1.0,  0.0 );
          glColor3f( 0.0, 0.0, 1.0 );
          glVertex3f(  1.0, -1.0,  0.0 );
        glEnd();
    }
 
 
    if(posx > 300)
    {
        glTranslatef(  1.5,  0.0,  -10.0 );
 
 
        glBegin( GL_QUADS );
          glColor3f(1.0 , 0.0 , 0.0);
          glVertex3f( -1.0,  1.0,  0.0 );
          glColor3f(0.0 , 1.0 , 0.0);
          glVertex3f(  1.0,  1.0,  0.0 );
          glColor3f(0.0 , 0.0 , 1.0);
          glVertex3f(  1.0, -1.0,  0.0 );
          glColor3f(1.0 , 1.0 , 1.0);
          glVertex3f( -1.0, -1.0,  0.0 );
        glEnd();
    }
 
 
    glLoadIdentity();
}

void RenjuWidget::paintGL()
{
    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
    glLoadIdentity();


    if(posx < 300)
    {
        glTranslatef( -1.5,  0.0, -10.0 );


        glBegin( GL_TRIANGLES );
          glColor3f( 1.0, 0.0, 0.0 );
          glVertex3f(  0.0,  1.0,  0.0 );
          glColor3f( 0.0, 1.0, 0.0 );
          glVertex3f( -1.0, -1.0,  0.0 );
          glColor3f( 0.0, 0.0, 1.0 );
          glVertex3f(  1.0, -1.0,  0.0 );
        glEnd();
    }


    if(posx > 300)
    {
        glTranslatef(  1.5,  0.0,  -10.0 );


        glBegin( GL_QUADS );
          glColor3f(1.0 , 0.0 , 0.0);
          glVertex3f( -1.0,  1.0,  0.0 );
          glColor3f(0.0 , 1.0 , 0.0);
          glVertex3f(  1.0,  1.0,  0.0 );
          glColor3f(0.0 , 0.0 , 1.0);
          glVertex3f(  1.0, -1.0,  0.0 );
          glColor3f(1.0 , 1.0 , 1.0);
          glVertex3f( -1.0, -1.0,  0.0 );
        glEnd();
    }


    glLoadIdentity();
}

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but here comes the problem :

the picture didn't change after i clicked on it , it has to lost focus and get foucus again to redraw the picture

for example : I clicked on the left part of the widget , but it doesn't change , if i click on the desktop(or another window) , it changes immediately.

so why?

---

Added after 12 minutes:

OKAY……I get it solved....

I have to add "update();" in the mouse clicking function.