ruby-vips8

Ruby binding for the vips8 API. This is still not quite done.

The older vips7-based ruby-vips gem might be more robust.

This binding is based on the gobject-introspection gem. Try gir_ffi-vips for one based on gir_ffi.

To try it out

Make sure you have vips-8.2 or later installed and that Vips-8.0.typelib is on your GI_TYPELIB_PATH. Then install with:

$ rake install

And take a look in examples/. There is full rdoc documentation, take a look there too.

Example

im = Vips::Image.new_from_file filename

# put im at position (100, 100) in a 3000 x 3000 pixel image, 
# make the other pixels in the image by mirroring im up / down / 
# left / right, see
# http://www.vips.ecs.soton.ac.uk/supported/current/doc/html/libvips/libvips-conversion.html#vips-embed
im = im.embed 100, 100, 3000, 3000, :extend => :mirror
im.write_to_file output_filename

# multiply the green (middle) band by 2, leave the other two alone
im *= [1, 2, 1]

# make an image from an array constant, convolve with it
mask = Vips::Image.new_from_array [
    [-1, -1, -1],
    [-1, 16, -1],
    [-1, -1, -1]], 8
im = im.conv mask

What's wrong with ruby-vips?

There's an existing Ruby binding for vips here. It was written by a Ruby expert, it works well, it includes a test-suite, and has pretty full documentation. Why do another?

ruby-vips is based on the old vips7 API. There's now vips8, which adds several very useful new features:

GObject-based API with full introspection. You can discover the vips8 API at runtime. This means that if libvips gets a new operator, any binding that goes via vips8 will get the new thing immediately. With vips7, whenever libvips was changed, all the bindings needed to be changed too.
No C required. Thanks to gobject-introspection you can write the binding in Ruby itself, there's no need for any C. This makes it a lot smaller and more portable.
vips7 probably won't get new features. vips7 doesn't really exist any more: the API is still there, but now just a thin compatibility layer over vips8. New features may well not get added to the vips7 API.

There are some more minor pluses as well:

Named and optional arguments. vips8 lets you have optional and required arguments, both input and output, and optional arguments can have default values.
Operation cache. vips8 keeps track of the last 1,000 or so operations and will automatically reuse results when it can. This can give a huge speedup in some cases.
vips8 is much simpler and more regular. For example, ruby-vips had to work hard to offer a nice loader system, but that's all built into vips8. It can do things like load and save formatted images to and from memory buffers as well, which just wasn't possible before.

This binding adds some extra useful features over the old ruby-vips binding.

Full set of arithmetic operator overloads.
Automatic constant expansion. You can write things like image.bandjoin(255) and the 255 will be automatically expanded to an image and attached as an extra band. You can mix int, float, scalar, vector and image constants freely.