paint with mouse

[Vincenzo]

I want paint some circle by press the mouse button.

void GraphArea::mousePressEvent1(QMouseEvent *event)
{
    if (event->button() == Qt::LeftButton) {
        show = true;  
    }
}
 
void GraphArea::paintEvent(QPaintEvent * /*event*/)
{
    QPainter painter(this);
    if (show)
        paintCircle1(painter);
}

void GraphArea::mousePressEvent1(QMouseEvent *event)
{
    if (event->button() == Qt::LeftButton) {
        show = true;  
    }
}

void GraphArea::paintEvent(QPaintEvent * /*event*/)
{
    QPainter painter(this);
    if (show)
        paintCircle1(painter);
}

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It works...
...but my plan/problem is: if i press mouse button 2nd time, then paint 2nd circle, to third press clear the whole widget - I don't know how to do it!

PS.: sorry for my english...

[wysota]

Store data about the circles and access it during next mousepress.

void xxx::mousePressEvent(QMouseEvent *me){
  // assuming QVector<QPair<QPoint, int> > circles is a member variable of the class
  switch(circles.count()){
    case 0:  case 1:  circles << qMakePair(me->pos(), 30); break;
    case 2: circles.clear();
  }
  update();
}
void xxx::paintEvent(QPaintEvent *pe){
  QPainter painter(this);
  for(int i=0;i<circles.count();i++){
    painter.drawEllipse(circles[i].first, circles[i].second, circles[i].second);
  }
}

void xxx::mousePressEvent(QMouseEvent *me){
  // assuming QVector<QPair<QPoint, int> > circles is a member variable of the class
  switch(circles.count()){
    case 0:  case 1:  circles << qMakePair(me->pos(), 30); break;
    case 2: circles.clear();
  }
  update();
}
void xxx::paintEvent(QPaintEvent *pe){
  QPainter painter(this);
  for(int i=0;i<circles.count();i++){
    painter.drawEllipse(circles[i].first, circles[i].second, circles[i].second);
  }
}

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[jacek]

You have three states: no circles, one circle, two circles.

So you need some variable that will hold the current state and then you have change this state accordingly in mousePressEvent() and paint the circles in paintEvent().