Call to undefined function think\captcha\imagettftext()

        php install gd After the library , An error is reported when generating the verification code picture Call to undefined function think\captcha\imagettftext(), Access to information （ Reference material ：http://www.shangzh.com/1094.html） Probably because gd The library is missing freetype Support , Then look for download resources ：https://download.savannah.gnu.org/releases/freetype/, Download and install （ Location ：/usr/local/freetype）, Then reinstall gd,configure Specify additional parameters when adding --with-freetype-dir=/usr/local/freetype, Restart after installation php that will do , Verification code generation is normal .