Christmas snow with Qt?

Hey,

i want to let it sow with qt. The idea was to move three snowflakes (pictures) over a qwidget. Have anybody a tip for my how can i do that or know example that can do that?

It depends what exactly you want to achieve. If you want to "snow" over an existing widget, you have to install an event filter, intercept its paint event, use QWidget::render() to render the widget to a pixmap, paint the pixmap on the widget and then paint your flakes. If you don't need to interact with this widget, you can simplify things by setting a child widget on the window that will cover the whole window below, make it transparent and paint flakes on it.

Hi,

sorry my late answer, i don't have get a notification to your message. Now i have try to let it snow, but i cant paint a snowflake in my mainwindow. Can

anybody take a look to my attachment and help my please.

Thanks in advance

You need to do the painting inside a QWidget::paintEvent().
Call QWidget::update() when your timer fires (this in turn will trigger the repaint).
In paintEvent() paint the snowflakes according to your state (e.g. the time passed.)

HTH

Hi,

i have try like this:

Code:

---

QTimer *timer = new QTimer(this);
connect(timer, SIGNAL(timeout()), this, SLOT(update()));
timer->start(1000);
 
void MainWindow::paintEvent ( QPaintEvent * )
{
	QPixmap picture;
	qDebug() << picture.load(":flake_01.png");			// load picture (qDebug() == true)
 
	QPainter painter;
	painter.begin(this);								// paint in MainWindow
	painter.drawPixmap(150, 150, 100, 100, picture);	// draw the picture at (150,150)
	painter.end();										// painting done
}

---

but my picture was not paint. What is wrong?

a) for efficiency: do not load the image every time paint event gets called
b) add a drawLine and/or qDebug to make sure the function gets executed

Quote:

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a) for efficiency: do not load the image every time paint event gets called

---

OK, i can do that.

Quote:

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b) add a drawLine and/or qDebug to make sure the function gets executed

---

the function gets executed, but if i try this:

Code:

---

QPainter painter;
painter.begin(this);
painter.setPen(Qt::black);
painter.drawText(QRect(150, 150, 250, 250), Qt::TextWordWrap, tr("Let it snow"));
painter.end();

---

i cant see a result. Can you help me, please?

Theres something with QMainWindow...
convert QMainWindow to QWidget and try,,,

Code:

---

void MainWindow::paintEvent ( QPaintEvent * event)
{
 
	QPixmap picture;
    bool ret = picture.load(":flake_01.png");      // load picture (qDebug() == true)
    QPainter painter(this);
	painter.drawPixmap(0,0,QPixmap(":background.png") );
    painter.drawPixmap(110, 110, picture);    // draw the picture at (150,150)
}

---

i got it... though background is not covering whole area,,, but u can scale it anytime :)

or use..
painter.drawTiledPixmap(rect(),QPixmap(":backgroun d.png") ); instead of line 7

I have convert my QMainWindow to QWidget and all work's fine, but now i can't use my QMenuBar:

Code:

---

QMenu *fileMenu = menuBar()->addMenu(tr("&File"));
QAction *exitAction = fileMenu->addAction(tr("E&xit"));
exitAction->setShortcut(QKeySequence(tr("Ctrl+Q")));
connect(exitAction, SIGNAL(triggered()), qApp, SLOT(quit()));

---

What can i do?

so u made a widget,, and its working... good..
next step is to set this widget as central widget of QMainWindow :)

Thank you for your help, now it's all OK.

But notice you must setAutoFillBackground(true) to display the backgound from the widget.