Low-level PHP binding for libvips

This extension is deprecated php-vips 2.0+ has switched to FFI for calls
into the libvips binary, so this extension is no longer necessary. It will not
be updated again (though it might still be useful if for some reason you don't
/ can't update to php-vips 2.0).

This extension lets you use the libvips image processing library
from PHP 7 and PHP 8.

This is not supposed to be used directly! Install this, then use
php-vips 1.x to layer a nice (and
documented!) API on top of this extension.

libvips is fast and needs little memory. The vips-php-bench repository tests
php-vips against imagick and gd: on that test, and on my laptop,
php-vips is around four times faster than imagick and needs 10 times less
memory.

Example

#!/usr/bin/env php
<?php

# never use this extension directly! this is just an example
$x = vips_image_new_from_file($argv[1])["out"];
$x = vips_call("invert", $x)["out"];
vips_image_write_to_file($x, $argv[2]);

Almost all operations return an array of result values. Usually there is a
single result called "out".

Use vips_call() to call any operation in the vips library. There are around
around 300 operations available, see the vips docs for an introduction:

http://libvips.github.io/libvips/API/current/

Arguments can be long, double, image, array of long, array of double or array
of image. The final argument to vips_call() is an array of operation options.

php-vips layers a nice API, including full docs, on top of this extension,
see:

https://github.com/libvips/php-vips

Installing

First install the libvips library. It will be in your package manager on linux,
it's in brew and MacPorts on macOS, or the vips website has Windows binaries.

Next, install this extension:

$ pecl install vips

And add:

extension=vips.so

to your php.ini.

Finally, add vips to your composer.json to pull in the high-level PHP API.

    "require": {
            "jcupitt/vips" : "1.0.0"
    }

The high-level API has all the documentation, see:

https://github.com/libvips/php-vips

Development: preparation

PHP is normally built for speed and is missing a lot of debugging support you
need for extension development. For testing and dev, build your own php.
I used 7.0.11 and configured with:

$ ./configure --prefix=/home/john/vips --enable-debug --enable-maintainer-zts \
    --enable-cgi --enable-cli --with-readline --with-openssl --with-zlib \
    --with-gd --with-jpeg-dir=/usr --with-libxml-dir=/usr --enable-mbstring 

You'll need libvips 8.2 or later, including all the headers for
development. On linux, install with your package manager. On macOS,
install with brew or MacPorts. For Windows, download a zip from the
libvips website, or build your own.

Development: regenerate build system

$ pear package

To make vips-1.0.13.tgz.

To install by hand:

$ phpize

To scan config.m4 and your php install and regenerate the build system.

Development: configure

Run

$ ./configure 

Check the output carefully for errors, and obviously check that it found your
libvips.

Development: make, test and install

Run:

$ make

To build the module to the modules/ directory in this repository.

Don't post php-vips test results to php.net! Stop this with:

$ export NO_INTERACTION=1

Test with:

$ make test

Finally, install to your php extensions area with:

$ make install

Add extension=vips.so to php.ini, perhaps in ~/vips/lib/php.ini,
if you configured php as above.

Development: regenerate vips_arginfo.h

Run:

$ curl -LO https://github.com/php/php-src/raw/ffacda14b88be797a466f472359f306d626e698f/build/gen_stub.php
$ php gen_stub.php

Links

http://php.net/manual/en/internals2.php

https://devzone.zend.com/303/extension-writing-part-i-introduction-to-php-and-zend/

https://devzone.zend.com/317/extension-writing-part-ii-parameters-arrays-and-zvals/

https://devzone.zend.com/446/extension-writing-part-iii-resources/