How to do QPainter paint in the Widget?

[Macive Xiong]

Hey guys,

I would like to paint in the Qt Widget of dialog.ui or mainwindow.ui. How can I set my paint canvas as where I want it to be?? Should I create a new h and cpp file for Widget and promote to it?

[mrjj]

hi
the mainwindow class
do have a paintevent you can override
but it often easier to use a plain Widget
with a
void MyWidget::paintEvent(QPaintEvent *)
{
QPainter painter(this);
....
}
function.
and YES, you then place a plain widget and promote it - to your widget.

Other way is to use a QLabel and draw on a pixmap and then let it show that pixmap.

void MainForm::slot_buttonClick()
{
    QPixmap pixmap(100,100);
    pixmap.fill(QColor("transparent"));

    QPainter painter(&pixmap);
    painter.setBrush(QBrush(Qt::black));
    painter.drawRect(10, 10, 100, 100);

   ui->someQlabel->setPixmap(pixmap);
}