Strange behaviour of QPainter...

[oscar]

I'm missing something:
In the following code, I must display a QMessageBox to get a correct QPixmap (with a chart in it).
Do you know what's the problem?

Thanks.
Regards,
Oscar

QPixmap MyExport::drawPie(int size, QList<int> valueList, QList<QString> colorList) {
 
	QPixmap qPixmap(size,size);
	QPainter *myQPainter = new QPainter(&qPixmap);
 
	myQPainter->setBrush(QBrush(QColor(245,245,245)));
	myQPainter->drawRect(0,0,size,size);
 
	double startAngle = 0.0;
	double totalValue; foreach(int value, valueList) totalValue += value;
 
	for (int i=0; i<valueList.size(); i++) {
		 if (valueList[i] > 0.0) {
			double angle = 360*valueList[i]/totalValue;
			QColor color = QColor(colorList[i]);
			myQPainter->setBrush(QBrush(color));
			myQPainter->drawPie(0, 0, size-2, size-2, int(startAngle*16), int(angle*16));
			startAngle += angle;
		 }
	}
	delete myQPainter;
 
		QMessageBox::information(NULL, QString::fromUtf8("Warn"),
					  QString::fromUtf8("This messagebox must be called to make this example function"),
							  QString::fromUtf8("Quitter"));
	return qPixmap;
}

QPixmap MyExport::drawPie(int size, QList<int> valueList, QList<QString> colorList) {

	QPixmap qPixmap(size,size);
	QPainter *myQPainter = new QPainter(&qPixmap);

	myQPainter->setBrush(QBrush(QColor(245,245,245)));
	myQPainter->drawRect(0,0,size,size);

	double startAngle = 0.0;
	double totalValue; foreach(int value, valueList) totalValue += value;

	for (int i=0; i<valueList.size(); i++) {
		 if (valueList[i] > 0.0) {
			double angle = 360*valueList[i]/totalValue;
			QColor color = QColor(colorList[i]);
			myQPainter->setBrush(QBrush(color));
			myQPainter->drawPie(0, 0, size-2, size-2, int(startAngle*16), int(angle*16));
			startAngle += angle;
		 }
	}
	delete myQPainter;
	
		QMessageBox::information(NULL, QString::fromUtf8("Warn"),
					  QString::fromUtf8("This messagebox must be called to make this example function"),
							  QString::fromUtf8("Quitter"));
	return qPixmap;
}

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[oscar]

This code works fine on Linux but generates an empty pixmap on windows (unless I display a messagebox at the end of processing!)

It sounds like a bug...

Regards,
Oscar

[oscar]

Well, now it's working when I create a class Pie subclassing
a QWidget and draw the pie in the paintEvent(QPaintEvent *event) method.

The Pie class is used like this:

Pie *pie = new Pie(valueList, colorList, 150);
QImage image; image = QPixmap::grabWidget(pie).toImage();^M
                image = image.copy(1,1,image.width()-1,image.height()-1);^M
                qPainter->drawImage(xPos, yPos, image);

Pie *pie = new Pie(valueList, colorList, 150);
QImage image; image = QPixmap::grabWidget(pie).toImage();^M
                image = image.copy(1,1,image.width()-1,image.height()-1);^M
                qPainter->drawImage(xPos, yPos, image);

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I still think there's a problem in Windows release of Qt when using QPainter...

Regards,
Oscar