(PECL ps >= 1.1.0)
ps_open_file — Opens a file for output
Creates a new file on disk and writes the PostScript document into it. The file will be closed when ps_close() is called.
Resource identifier of the postscript file as returned by ps_new().
The name of the postscript file. If filename is not passed the document will be created in memory and all output will go straight to the browser.
如果成功则返回 TRUE,失败则返回 FALSE。