How to draw shapes bellow a specific element using its position with QPainter and draw functions ?

DSpider

I have a QWT plot in the mainwindow and I am trying to draw some shapes just bellow. Here is what I am using:

void MainWindow::paintEvent(QPaintEvent *event)
{
    // unuse
    Q_UNUSED(event);

    // pass "this" pointer to painter
    QPainter painter(this);

    // setPen
    // QPen can take "Qt::black" directly as first arg (without QBrush() constructor)
    painter.setPen(QPen(Qt::black));

    // draw line
    painter.drawRect(10, 10, 10, 10);
}

I know we can play with the coordinates until I get to the desired position, but is there another way using the coordinate of the QWTPlot ?

mrjj

Hi
Well to get below the QWTPlot plot would
be QWTPlotptr->y() + QWTPlotptr->height()
However, a more solid approach could be to use a QLabel as
a canvas using a pixmap. That way, its very easy to position even if using layouts to make
GUI auto adjust to different screen sizes.

void PaintShapes() 
{
// take size of label
  int h = ui->label->height();
  int w = ui->label->width();
// make a pixmap of the wanted size
  QPixmap pix(w, h);
// assign painter to it so we can paint on it
  QPainter paint(&pix);
// fill it
  pix.fill( Qt::white );
// paint on canvas
  paint.setPen(QColor(0, 0, 0, 255));
 paint.drawRect(0, 0, w, h);
..other paint operations-..
 // set the pixmap to the label so its shown.
  ui->label->setPixmap(pix);
 }