本函数是实验性的。本函数的行为，包括函数名称以及其它任何关于本函数的文档可能会在没有通知的情况下随 PHP 以后的发布而改变。使用本函数风险自担。
If filename is the name of an FDB file (i.e., it ends in ".fdb"), load the font definition found in said file. Otherwise, create a browser-defined font reference.
FDB ("font definition block") is a very simple wrapper for the SWF DefineFont2 block which contains a full description of a font. One may create FDB files from SWT Generator template files with the included makefdb utility- look in the util directory off the main ming distribution directory.
Browser-defined fonts don't contain any information about the font other than its name. It is assumed that the font definition will be provided by the movie player. The fonts _serif, _sans, and _typewriter should always be available. For example:
$f = newSWFFont("_sans");
will give you the standard sans-serif font, probably the same as what you'd get
<font name="sans-serif"> in HTML.
swffont() returns a reference to the font definition, for use in the swftext->setfont() and the swftextfield->setfont() methods.
SWFFont has the following methods : swffont->getwidth().