Detect if the FreeType PHP extension is installed on the server

Question

How do I test to see if the FreeType extension is installed on a server running PHP?

I wanted to make a simple CAPTCHA system on my site, so I used imagettftext() and it worked fine. But what if the server didn't have the FreeType library installed?

So is there a way to somehow detect FreeType library through code, and if it is not present, fall back to something like imagestring()?

If I can't use imagettftext() I may have to look at alternatives to draw big font text as the imagestring max size isn't good for something like a CAPTCHA.

Ignition

Answer 1

Use function_exists:

if (function_exists('imagettftext')) {
     imagettftext();
} else {
     // do other function
}

Hope that helps.

Pskov

+1 this does not a check if freetype is installed, but a check if a function imagettftext is available - but this should work in the given context – Collete

:) I was just hoping to point this person in a correct direction. – Pskov

Yes it does check for both GD and FreeType. imagettftext manual page – Syllabify

Answer 2

This will not be better in practice than the function_exists solutions already posted, but the technically correct way to check is by using extension_loaded.

Hovercraft

that's the easiest most effective way to check for the extension! – Collete

@downvoter: I would so love to hear what's wrong with this answer. Thanks. – Hovercraft

You can check for gd extension, but you cannot check for freetype simply because it's not PHP extension (see output of php -m). freetype is just linked to gd during compilation time. – Preachment

Answer 3

Assuming the GD library is installed, you can detect Freetype support using the gd_info() function.

$gdinfo = gd_info();
if($gdinfo['FreeType Support']) echo 'FreeType Support Enabled';

If you need to check whether or not GD library is installed first, use extension_loaded('gd');

Uno

Answer 4

This won't work for dynamic code (so not a true answer to the question) but for anyone who just want's to know if it's installed, from the command line on Linux:

php -i | grep -E "GD|FreeType"

Outputs:

GD Support => enabled
GD headers Version => 2.2.5
GD library Version => 2.2.5
FreeType Support => enabled
FreeType Linkage => with freetype
FreeType Version => 2.4.11

NOTE: On a system without it installed you'll get no output.

Buie

Answer 5

A first somewhat complicated approach:

call php_info() and search/parse the result for freetype

Collete

this might be complicated, but it will work (so why the downvote?) – Collete

Downvote wasn't mine, but 1) it will take effort to get it to work, 2) it's more brittle than any other solution (suppose the output of php_info changes in the future) and 3) it's the most computationally expensive way to do it by far. – Hovercraft

Answer 6

Try function_exists(), i.e.

if (!function_exists('imagettftext')) {
  // No freetype library
}

You'd probably be best asking for alternatives to imagettftext as a separate question.

Occlusive