Ghost lines and incorrect colors while using a QPrinter with OutputFormat set to PdfFormat

Hi.

I have been trying to print to pdf with incorrect results.

Expected behavior

Using the combination of a PdfFormat on a QPrinter, a linear gradient and a scale to draw a rectangle (NoPen) should draw a gradient only, using the right colors.

What happens

Without anti-aliasing, lines appear on the top and left corners of the rectangle.
Activating anti-aliasing seems to fix the lines problem but creates a new one where colors becomes dirty in adobe reader (but fine with any other pdf reader). I suspect to bug to be linked to the first one, but may be a separate one.

Minimal code reproducing the problem

(try false/true for setRenderHints(QPainter::Antialiasing, ...) to get different results)

#include <QPainter>
#include <QPrinter>
#include <QtCore/QCoreApplication>

int main(int argc, char *argv[])
{
	QCoreApplication a(argc, argv);

	QPrinter* printer = new QPrinter();
	printer->setOutputFileName("print.pdf");
	printer->setOutputFormat(QPrinter::PdfFormat);

	QPainter painter(printer);
	painter.setRenderHints(QPainter::Antialiasing, false);
	painter.setPen(Qt::NoPen);

	QLinearGradient grad(0.0f, 0.0f, 0.0f, 90.0f);
	grad.setColorAt(0.0f, Qt::blue);
	grad.setColorAt(1.0f, Qt::white);

	painter.setBrush(grad);
	painter.scale(1.337, 1.337);
	painter.drawRect(QRect(10, 10, 100, 100));
	painter.end();

	return 0;
}

Attachment

Screenshot showing on the:

• left-top: Adobe Reader with Antialiasing to false
• left-right: Adobe Reader with Antialiasing to true
• bottom: Foxit Reader with Antialiasing to true
  Lines still appear on Foxit Reader with Antialiasing to false.