check ImagickDraw::SetTextAlignment notes for examples and constants values
http://php.net/manual/en/function.imagickdraw-settextalignment.php
(PECL imagick 2, PECL imagick 3)
ImagickDraw::getTextAlignment — Returns the text alignment
本函数还未编写文档，仅有参数列表。
Returns the alignment applied when annotating with text.
Returns a ALIGN constant
(imagick::ALIGN_*), and 0 if no align is set.
check ImagickDraw::SetTextAlignment notes for examples and constants values
http://php.net/manual/en/function.imagickdraw-settextalignment.php