QValueAxis how to set label fixsize with blank space

[jinming]

Hi, I'm doing a project with multi y-axis, we need to align the y-axis in vertical,but I can not set the y-axis label fix size,and I used the code " axisY->setLabelFormat(" %10.2f ");" to insert blank char,but it does't work.I do not know how to solve it.Please help me.