Qt-4.8 has memory leak in QPainter::drawText(), the following code can reproduce this problem:

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

{ QImage img(512, 512, QImage::Format_ARGB32_Premultiplied); QPainter p(&img); p.drawText(0, 0, "Hello!"); }

#ifdef _MSC_VER
//////////////////////////////////////////////////////////////////////////
// memory leak detection
//////////////////////////////////////////////////////////////////////////

// get the current state of the flag
int nCrtDbgFlag = _CrtSetDbgFlag(_CRTDBG_REPORT_FLAG);
// set memory leak check flag
nCrtDbgFlag |= _CRTDBG_LEAK_CHECK_DF;
// set the new debug flag
_CrtSetDbgFlag(nCrtDbgFlag);
#endif

return 0;
}

To reproduce this problem you have to run this program by vistual studio in windows, start the program by pressing F5 and after the program exited you will see memory leaks report in the output window of visual studio.