Yes, got your idea of checking the height. And the binary search would be very cool! For time being this code does the job for me:

void TrimQTFTextEllipsis(String& qtf, int width, const String& ellipsis) {
	String str = qtf;
	while(ParseQTF(qtf).GetWidth() > width) {
		str.TrimLast();
		qtf = str + ellipsis;
	}
}

It's not really elegant, will trim ending ']' from QTF if it's there, so that should be added after trimming. However with the width given correctly it works pretty good. Uploading image of output.



Will try to implement the way you suggested when I can do some optimisation.