cpdf_setgray_stroke
    (PHP 3>= 3.0.8, PHP 4 , PHP 5)
cpdf_setgray_stroke -- Sets drawing color to gray value
Description
bool 
cpdf_setgray_stroke ( int pdf_document, float gray_value )
     The cpdf_setgray_stroke() function sets the current
     drawing color to the given gray value. Returns TRUE on success or FALSE on failure.
    
     See also cpdf_setrgbcolor_stroke().