(PECL ps >= 1.1.0)
ps_setgray — Sets gray value
Sets the gray value for all following drawing operations.
Resource identifier of the postscript file as returned by ps_new().
The value must be between 0 (white) and 1 (black).
Возвращает TRUE в случае успешного завершения или FALSE в случае возникновения ошибки.