QGraphicsItem::shape

[A Former User]

hi sigrid.

i finally managed to change your code to show the same problem.

@#include <QtGui>

class GraphicsItemParent :public QGraphicsItem {
public:
GraphicsItemParent() {
setFlag(ItemClipsChildrenToShape);
}

QRectF boundingRect() const {
    return QRectF(0, 0, 200, 200);
}

void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) {
    painter->setPen(Qt::black);
    painter->drawRect(boundingRect());
}

};

class GraphicsItem : public QGraphicsItem
{

public:
GraphicsItem(QColor c, QGraphicsItem* parent = 0):QGraphicsItem(parent)
{
setFlags(flags() | QGraphicsItem::ItemClipsToShape);
setFlag(ItemIsMovable);
color = c;
}

QRectF boundingRect() const {
return QRectF(0,0, 100, 100);
}
void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) {
painter->setRenderHint(QPainter::Antialiasing);
painter->fillPath(shape(), color);
}

QPainterPath shape () const
{
QPainterPath p;
p.addEllipse(50, 50, 50, 50);
return p;
}
QColor color;
};
class GraphicsView : public QGraphicsView
{
Q_OBJECT
public:
GraphicsView()
{
QGraphicsScene myScene = new QGraphicsScene(this);
setScene(myScene);
GraphicsItemParent parent = new GraphicsItemParent();
myScene->addItem(parent);
GraphicsItem *myItem1 = new GraphicsItem(Qt::red, parent);
GraphicsItem *myItem2 = new GraphicsItem(Qt::green, parent);
myItem1->setPos(50, 50);
myItem2->setRotation(15);
setSceneRect(0, 0, 100, 100);
scale(3, 3);
setRenderHint(QPainter::Antialiasing);

}

};

#include "main.moc"

int main(int argc, char** argv)
{
QApplication app(argc, argv);
GraphicsView window;
window.show();
return app.exec();

}@

as you can see, i only changed to draw a colored circle instead of an image (same behavior with image). as well as i added a parent item.

now the both circles are jagged, as well as the green circle is clipped to the parents shape with jags because of its rotation.

What is the best work around to get it painted probably?

thanks

Nazgul

[A Former User]

oh i forgot to say, that I'm also scaling the view. but imo that shouldn't make the difference.

[A Former User]

I do not see that problem here when running your example on Windows using Qt 4.7.3. Which Qt version are you using? Do you only see this problem on Mac? Can you send a screenshot of what you see when running the example you sent?

[A Former User]

I'm using Qt 4.7.4 on Mac. I currently don't have a windows machine to test it there.

Here is the screen:

!http://www.image-load.net/users/public/images/IzBG3bbCdy.png(screenshot)!

[A Former User]

as you can see, it becomes also jagged, when it clips to the rectangle

[A Former User]

ok, i now tried with Qt 4.7.3 on Mac and got the same results as with qt 4.7.4.

then i tried on a windows machine (Windows Vista) also with qt 4.7.3 .

On windows there was a regular clipping like intended. no jags at all, like you experienced too.

is it a Qt Bug?

[A Former User]

This sounds like a Qt bug, I suggest you report it in "Jira":https://bugreports.qt.nokia.com//secure/Dashboard.jspa and include the example that reproduces the problem and the screenshots as well.

[A Former User]

ok i created one.

[A Former User]

well i reported this bug on jura on the 22nd September, but theres still no reply to it? is this normal?

[A Former User]

i now found out, that i did not change to raster paint engine ( called it after qapp ctor) i changed that and it works fine now with raster engine. But I'm still wondering why QCoreGraphicsPaintEngine messes up with the shapes.