C

SWFFilter 
newGradientGlowFilter(SWFGradient gradient /* gradient */, 
                      SWFBlur blur /* blur */, 
                      SWFShadow shadow /* shadow */,
                      int flags /* FILTER_MODE_INNER,  FILTER_MODE_KO, FILTER_MODE_ONTOP */)

Example

see also GlowFilter

PHP

$f = new SWFFilter(SWFFILTER_TYPE_GRADIENTGLOW, $gradient, $blur, $shadow, $flags);

see also GlowFilter