Paint Event does not correspond to coordinates!

[wysota]

But what is the purpose of all that code? You can get the label width and height by calling width() and height(), you don't need any "windowSize" for that. ev->rect().width() is going to return the width of the exposed rect which can be anything ranging from 1 to the width of your label. Hence your code makes no sense. Your drawing code needs to draw within QRect(0,0, width(), height()).

[ebsaith]

Please give me a simple example on how to resize my paintEvent
So when a user clicks a point it displays a point(working)
& when window is resized that point is adjusted accordingly

I'm stuck, tried many plausible theories to no avail though
Assistance please

example code appreciated

[wysota]

I have no idea what you mean by "resize my paintEvent".

Resizing the window should not influence your drawing code in any way. Your canvas is simply larger. If you mean that you wish to scale the contents then use QPainter::setWindow(), QPainter::setViewport() and QPainter::worldTransform() (the latter can be used to map mouse event coordinates to what you specify by setWindow()).

The most trivial approach would be something along:

void X::mousePressEvent(QMouseEvent *me) {
  QPointF meF = me->pos();
  m_points << QPointF(100*meF.x()/(qreal)width(), 100*meF.y()/(qreal)height());
  update();
}
 
void X::paintEvent(QPaintEvent *pe) {
  QPainter p(this);
  p.setViewport(rect());
  p.setWindow(QRect(0,0,100,100));
  foreach(QPointF pt, m_points) p.drawPoint(pt);
}
 
void X::resizeEvent(QResizeEvent*) { update(); }

void X::mousePressEvent(QMouseEvent *me) {
  QPointF meF = me->pos();
  m_points << QPointF(100*meF.x()/(qreal)width(), 100*meF.y()/(qreal)height());
  update();
}

void X::paintEvent(QPaintEvent *pe) {
  QPainter p(this);
  p.setViewport(rect());
  p.setWindow(QRect(0,0,100,100));
  foreach(QPointF pt, m_points) p.drawPoint(pt);
}

void X::resizeEvent(QResizeEvent*) { update(); }

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[ebsaith]

Thanks will try it out

My apologies, What I meant by "resize my paintEvent".
Is If I draw a point(p1) at lets say (x=50, y=50)
& I resize my window to lets say double the initial size of the window
that The p1 should now move to (x=100, y=100)
The painted point needs to move with the resize!

further Ideas welcome
Kind Regards

[wysota]

What I gave you earlier should work fine. Another approach, one that doesn't use setWindow would be:

void X::mousePressEvent(QMouseEvent *me) {
  m_pts << QPointF(me->pos().x()/(qreal)width(), me->pos().y()/(qreal)height());
}
 
void X::paintEvent(QPaintEvent *) {
  QPainter p(this):
  foreach(QPointF pt, m_pts) p.drawPoint(pt.x()*width(), pt.y()*height());
}

void X::mousePressEvent(QMouseEvent *me) {
  m_pts << QPointF(me->pos().x()/(qreal)width(), me->pos().y()/(qreal)height());
}

void X::paintEvent(QPaintEvent *) {
  QPainter p(this):
  foreach(QPointF pt, m_pts) p.drawPoint(pt.x()*width(), pt.y()*height());
}

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