This extension lets you use the libvips image processing library from PHP. It is intentionally very low-level. Modules such as https://github.com/jcupitt/php-vips try to layer a nice API on top of this.
libvips is fast and it can work without needing to have the entire image loaded into memory. Programs that use libvips don't manipulate images directly, instead they create pipelines of image processing operations starting from a source image. When the end of the pipe is connected to a destination, the whole pipeline executes at once, streaming the image in parallel from source to destination in a set of small fragments.
See the benchmarks at the official libvips website. There's a handy blog post explaining how libvips opens files which gives some more background.
#!/usr/bin/env php
<?php
if (!extension_loaded("vips")) {
dl('vips.' . PHP_SHLIB_SUFFIX);
}
$x = vips_image_new_from_file($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://www.vips.ecs.soton.ac.uk/supported/current/doc/html/libvips/
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 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
You'll need libvips 8.0 or later, including all the headers for
development. On linux, install with your package manager. On OS X,
install with brew or MacPorts. For Windows, download a zip from the
libvips website, or build your own.
$ pear install vips-0.1.2.tgz
to install.
Add:
extension=vips.so
to your php.ini, perhaps in ~/vips/lib/php.ini, if you configured php as
above.
Try:
#!/usr/bin/env php
<?php
if (!extension_loaded("vips")) {
dl('vips.' . PHP_SHLIB_SUFFIX);
}
$x = vips_image_new_from_file($argv[1])["out"];
$x = vips_call("invert", $x)["out"];
vips_image_write_to_file($x, $argv[2]);
?>And run with:
$ ./try1.php ~/pics/k2.jpg x.tif
See examples/.
$ pear package
to make vips-0.1.2.tgz.
To install by hand:
$ phpize
To scan config.m4 and your php install and regenerate the build system.
Run
$ ./configure
Check the output carefully for errors, and obviously check that it found your libvips.
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
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/