Qt 5.3.0 display Arabic text wrong :(

[aniasen]

I just used painter->drawText() to draw Arabic text(more than two lines)... but it display absolutely wrong! while i use QML to draw arabic text, it displays right....I am soooo confused, ive debuged the code, the glyph position( of course the positions are all wrong),,,, i thought it's the problem of new version harfbuzz-ng....but what confused me most that QML text and painter->drawtext() they are use the same harfbuzz ( i set a break point in harfbuzz-arabic.c) .... I am always thinking it's not hard for Qt itself to find out this bug,,,so how it happened like that? or i miss something? (i set the layout and wrapmode already,still same problem)....anyone could pls give me a hand?