align right-to-left text with QPainter::drawText - c++

Question

I am trying to paint a right-to-left text with QPainter. It however still aligns the text to left despite the fact that it should be right-aligned. Or at least it is right-aligned when displayed in QTextEdit. That am I doing wrong? See the example:
QTextOption option;
option.setTextDirection(Qt::LayoutDirectionAuto);
painter->drawText(rect, "خامل\nخاملخامل", option); // this is just testing text, I have no idea what it means, hopefully it is not something offensive :)
This is what I get. The red arrow shows where it should be aligned.
Of course I cannot use fixed right alignment because I do not whether the text in question is left-to-right or right-to-left text. So it must work for both directions automatically depending on the text.
UPDATE: I want to emphasize that I need a solution which automatically recognizes the language/writing system of the text (left-to-right, such as English, versus right-to-left, such as Arabic) and aligns the text automatically.

Answer 1

you should check your text with isRightToLeft() function.
QString isRightToLeft():
Returns true if the string is read right to left.
This will help you to understand your text language.
I checked the QTextEdit source and understand it uses this function.
void MainWindow::paintEvent(QPaintEvent *event)
{
QPainter painter(this);
painter.setRenderHint(QPainter::Antialiasing);
QRect rect = QRect(0, 0, width(), height());
QString txt = tr("خامل\nخاملخامل");
// QString txt = tr("ABCD\nABCD");
QTextOption option;
if (txt.isRightToLeft())
{
option.setTextDirection(Qt::RightToLeft);
}
else
{
option.setTextDirection(Qt::LeftToRight);
}
painter.drawText(rect, txt, option);
}