My first program with QGraphicsView

[Morea]

I think I store all my questions about QGraphicsView in this thread.

First problem, I have a class Planet that is subclassedfrom GraphicsItem and I have this to draw it

void Planet::paint(QPainter* painter, QStyleOptionGraphicsItem* option,QWidget* widget)
{
	painter->setBrush(QColor(Qt::red));
	painter->drawEllipse(x,y,2*radius,2*radius);
}

void Planet::paint(QPainter* painter, QStyleOptionGraphicsItem* option,QWidget* widget)
{
	painter->setBrush(QColor(Qt::red));
	painter->drawEllipse(x,y,2*radius,2*radius);
}

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but all I get is a black circle on a white background. And the view isn't updated very much. How do I draw the ellipse and how do I update it more often?

[jpn]

There is QGraphicsEllipseItem which provides an GV ellipse item out of the box.
You may then use QAbstractGraphicsShapeItem::setBrush() and QAbstractGraphicsShapeItem::setPen() to set brush and pen, respectively.

[Morea]

There is QGraphicsEllipseItem which provides an GV ellipse item out of the box.
You may then use QAbstractGraphicsShapeItem::setBrush() and QAbstractGraphicsShapeItem::setPen() to set brush and pen, respectively.

So I tried:

Planet::Planet() 
{
	radius = 31;
	x=rand()%500;
	y=rand()%500;
	setRect(x,y,2*radius,2*radius);
	brush =QBrush(QColor(45,221,182));
	pen = QPen(QColor(200,100,100));
}
 
void Planet::paint(QPainter* painter, QStyleOptionGraphicsItem* option,QWidget* widget)
{
	setBrush(brush);
	setPen(pen);
	painter->drawEllipse(x,y,2*radius,2*radius);
}

Planet::Planet() 
{
	radius = 31;
	x=rand()%500;
	y=rand()%500;
	setRect(x,y,2*radius,2*radius);
	brush =QBrush(QColor(45,221,182));
	pen = QPen(QColor(200,100,100));
}

void Planet::paint(QPainter* painter, QStyleOptionGraphicsItem* option,QWidget* widget)
{
	setBrush(brush);
	setPen(pen);
	painter->drawEllipse(x,y,2*radius,2*radius);
}

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but with the same result.

[jpn]

I meant that for an ellipse you don't need to implement your own QGraphicsItem, you can simply use a QGrapgicsEllipseItem instead:

#include <QApplication>
#include <QGraphicsView>
#include <QGraphicsScene>
 
int main( int argc, char **argv )
{
	QApplication app(argc, argv);
 
	QGraphicsScene scene(QRectF(0,0,100,100));
	scene.addEllipse(QRectF(25,40,50,20), QPen(Qt::green), QBrush(Qt::red));
	QGraphicsView view(&scene);
	view.show();
 
	return app.exec();
}

#include <QApplication>
#include <QGraphicsView>
#include <QGraphicsScene>

int main( int argc, char **argv )
{
	QApplication app(argc, argv);

	QGraphicsScene scene(QRectF(0,0,100,100));
	scene.addEllipse(QRectF(25,40,50,20), QPen(Qt::green), QBrush(Qt::red));
	QGraphicsView view(&scene);
	view.show();

	return app.exec();
}

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[Morea]

With this constructor

Planet::Planet() //:QGraphicsEllipseItem(QRect(0,0,0,0))
{
	setBrush(QBrush(QColor(45,21,182)));
	setPen(QPen(QColor(200,10,10)));
}

Planet::Planet() //:QGraphicsEllipseItem(QRect(0,0,0,0))
{
	setBrush(QBrush(QColor(45,21,182)));
	setPen(QPen(QColor(200,10,10)));
}

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I get different colors, but it doesn't change the Brush if I add

setBrush(QBrush(QColor(rand()%255,rand()%255,rand()%255)));

setBrush(QBrush(QColor(rand()%255,rand()%255,rand()%255)));

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to the

void Planet::paint(QPainter* painter, QStyleOptionGraphicsItem* option,QWidget* widget)

void Planet::paint(QPainter* painter, QStyleOptionGraphicsItem* option,QWidget* widget)

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function.
Strange.