QGraphicsScene QPainterPath::arcTo: Adding arc where a parameter is NaN, results are undefined

kiepmad

Hello,

I just started out with QT and have a problem that I can't seem to solve.
I'm working on Nine Men's Morris and the everything works great, except for a strange bug that creeps up.

Sometimes, when I click on a Item the GraphicsView turns white and the following error is shown several times in the debug window:

QPainterPath::arcTo: Adding arc where a parameter is NaN, results are undefined

The GraphicsView cannot be recovered by resizing, etc., only by restarting the game.

I've created a MainWindow and with a QGraphicsView and a QGraphicsScene.

I created 3 seperate QGraphicsItems

A boardLayout which renders the background and does not handle click events.
A Token Item that handles click events, the color of the token, if it's selected, etc.
A BoardPosition Item that is invisible and handles the events when you click on an empty position on the board. Clicking this item causes the error described above.

MainWindow Code:
@
ui->setupUi(this);
this->setWindowIcon(QPixmap(QString(":/Images/icon2.jpeg")));

showWin = new WinDialog(this);
startWindow = new StartDialog(this);

view = new QGraphicsView(this);
this->setCentralWidget (view);

view->setVerticalScrollBarPolicy (Qt::ScrollBarAlwaysOff);
view->setHorizontalScrollBarPolicy (Qt::ScrollBarAlwaysOff);
view->setMinimumSize (1000, 800);
view->setViewportUpdateMode (QGraphicsView::FullViewportUpdate);
view->setCacheMode (QGraphicsView::CacheNone);
view->setRenderHints (QPainter::Antialiasing |  QPainter::TextAntialiasing);

scene = NULL;

//this->debugWidget = new DebugWidget(this);
//this->debugWidget->setMinimumWidth (200);

this->layout = NULL;
this->controller = NULL;

this->whiteTokensSet = 0;
this->blackTokensSet = 0;

}

void MainWindow::Initalize()
{
scene = new QGraphicsScene();
scene->setBackgroundBrush (QBrush(Qt::gray));
view->setScene (scene);
this->layout = new BoardLayout();
scene->addItem(layout);

float x = 0.081f;
float y = 0.025f;
for(int i = 0; i < 7; i++)
{
    text.append(scene->addText(QString('A'+i)));
    text.at(i)->setX(x+(i*0.13));
    text.at(i)->setY(y - 0.008);
    text.at(i)->setScale(0.003);
}
x = 0.072f;
for(int i = 7; i < 14; i++)
{
    text.append(scene->addText(QString('1'+(i-7))));
    text.at(i)->setX(y);
    text.at(i)->setY(x+((i-7)*0.13));
    text.at(i)->setScale(0.003);
}

this->controller = new GameController(this);

view->fitInView (layout, Qt::KeepAspectRatio);

points[0] = QPointF(0.085f, 0.085f);
points[1] = QPointF(0.475f, 0.085f);
points[2] = QPointF(0.865f, 0.085f);
points[3] = QPointF(0.215f, 0.215f);
points[4] = QPointF(0.475f, 0.215f);
points[5] = QPointF(0.735f, 0.215f);
points[6] = QPointF(0.345f, 0.345f);
points[7] = QPointF(0.475f, 0.345f);
points[8] = QPointF(0.605f, 0.345f);
points[9] = QPointF(0.085f, 0.475f);
points[10] = QPointF(0.215f, 0.475f);
points[11] = QPointF(0.345f, 0.475f);
points[12] = QPointF(0.605f, 0.475f);
points[13] = QPointF(0.735f, 0.475f);
points[14] = QPointF(0.865f, 0.475f);
points[15] = QPointF(0.345f, 0.605f);
points[16] = QPointF(0.475f, 0.605f);
points[17] = QPointF(0.605f, 0.605f);
points[18] = QPointF(0.215f, 0.735f);
points[19] = QPointF(0.475f, 0.735f);
points[20] = QPointF(0.735f, 0.735f);
points[21] = QPointF(0.085f, 0.865f);
points[22] = QPointF(0.475f, 0.865f);
points[23] = QPointF(0.865f, 0.865f);

for(int i = 0; i < 24; i++)
{
    boardPositions.append (new BoardPosition(i, points[i].x(), points[i].y(), this->controller));
    this->scene->addItem(boardPositions.at (i));
}

whiteTokensSet = 0;
blackTokensSet = 0;

for(int i = 0; i < 9; i++)
{
    whiteTokens.append(new GameToken(WHITE, this->controller));
    whiteTokens.at(i)->setVisible(false);
    this->scene->addItem(whiteTokens.at(i));
    blackTokens.append(new GameToken(BLACK, this->controller));
    blackTokens.at(i)->setVisible(false);
    this->scene->addItem(blackTokens.at(i));
}

this->startWindow->close ();
//this->debugWidget->appendText(QString("Welcome to Nine Men's Morris!"));
//this->addDockWidget(Qt::LeftDockWidgetArea, this->debugWidget);
this->show();
this->resize(QSize(1001, 801));

}
@
BoardPositions Code:
@
#include "boardposition.h"
#include "gamecontroller.h"

BoardPosition::BoardPosition(int pos, float coordx, float coordy, GameController *controller) :
QGraphicsItem()
{
boardPos = pos;
posx = coordx;
posy = coordy;
this->controller = controller;
}

QRectF BoardPosition::boundingRect() const
{
return QRectF(posx, posy, 0.05, 0.05);
}

void BoardPosition::paint(QPainter *painter, const QStyleOptionGraphicsItem *option,
QWidget *widget)
{
painter->setPen(Qt::NoPen);
painter->setBrush(Qt::transparent);

painter->drawRect(QRectF(posx, posy, 0.05, 0.05));

}

void BoardPosition::mousePressEvent(QGraphicsSceneMouseEvent *event)
{
controller->boardClicked(boardPos);

}
@

How could I debug this error, or did I do something entirely wrong?

Please let me know if you need any other information. (You can cownload the whole code here: https://www.dropbox.com/s/osc7l2tyxf63qp6/nine-mens-morris-ff306f393749.zip )

koahnig

welcome to devnet

What OS, compiler, IDE, etc are you using?
When you are running the application in the debugger, are you getting an exception?

kiepmad

Thanks!

I'm using Ubuntu 12.04 x64, Qt-Creator and the gcc that comes with latest ubuntu (4.6 I believe)

However the same occurs when using Windows7 with Qt-Creator and Visual C++ compiler.

I don't get any exceptions.

koahnig

Since you do not get exceptions, how do you know that you are introducing nan then?