Creating transparent QPixmap

Question

I am using QPainter on QPixmap as the painting framework. And QGraphicsScene is holding the QPixmap. The painting works well. But the problem is when I change the the background-color of the QGraphicsView it does not get reflected on the screen. I tried by QPixmap::fill(Qt::tranparent). But it didnt work.

How can I achieve this kind of transparent QPixmap? Thanx in advance?

int main(int argc, char **argv){

QApplication a(argc, argv);

QMainWindow *win = new QMainWindow();
win->resize(600,600);
win->move(80,80);
win->show();


QGraphicsScene *scene = new QGraphicsScene(win);
QGraphicsView view(scene,win);
view.resize(590,590);
view.setBackgroundBrush(QColor(rand()%255,rand()%255, rand()%255, 255));
view.show();

QPixmap *pix = new QPixmap(600,600);
pix->fill(&view,QPoint(0,0));
QGraphicsPixmapItem *item = scene->addPixmap(*pix);

QPainter *painter = new QPainter(pix);


int count=10;
while(count){

    painter->setPen((*new QColor(rand()%255,rand()%255, rand()%255, 255)));
    painter->setBrush(QColor(rand()%255,rand()%255, rand()%255, 255));
    painter->drawRect(rand()%300, rand()%300, rand()%300, rand()%300);


    item->setPixmap(*pix);
    a.processEvents(0x00);
    count--;

}


return a.exec();

}

Not quite sure why you've been down-voted, though your code has this line: pix->fill(&view,QPoint(0,0)); As far as I can see in the documentation, there is no such function in QPixmap that takes two parameters. This is the definition of fill: void fill(const QColor & color = Qt::white). Does your code actually compile? — TheDarkKnight, Jul 29 '13 at 08:26
@Merlin069 That is only true for Qt5. Qt4 contains the `QPixmap::fill ( const QWidget * widget, const QPoint & offset )` function. — thuga, Jul 29 '13 at 08:30
Do you want a transparent item (transparent towards other items), or a transparent graphicsview (whole widget)? — Frank Osterfeld, Jul 29 '13 at 09:24
This question appears to be off-topic because it's too localized. Oh, and the user has fixed his problem, doesn't care anymore, and won't share his solution. — Kuba hasn't forgotten Monica, Sep 24 '13 at 21:47
Here ( http://curtis.humphreyonline.us/code/qt-code/making-a-qpixmap-transparent-wrong-way-right-way ) it is shown how to do it. SO answer http://stackoverflow.com/a/18763634/356726 shows it for an image. — Horst Walter, Jan 16 '16 at 23:29

Creating transparent QPixmap

0 Answers0