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@ -10,18 +10,18 @@
</refnamediv> </refnamediv>
There are full libvips bindings for quite a few environments now: C, C++, There are full libvips bindings for quite a few environments now: C, C++,
command-line, Ruby, PHP, Python and JavaScript (node). command-line, Ruby, PHP, Lua, Python and JavaScript (node).
This chapter runs through the four main styles that have been found to work This chapter runs through the four main styles that have been found to work
well. If you want to write a new binding, one of these should be close well. If you want to write a new binding, one of these should be close
to what you need. to what you need.
# C API # Don't bind the top-level C API
The libvips C API (vips_add() and so on) is very inconvenient to use from other The libvips C API (vips_add() and so on) is very inconvenient and dangerous
languages due to its heavy use of varargs. to use from other languages due to its heavy use of varargs.
It's much better to use the layer below. This lower layer is structured as: It's much better to use the layer below. This lower layer is structured as
create operator, set parameters, execute, extract results. For example, you can create operator, set parameters, execute, extract results. For example, you can
execute vips_invert() like this: execute vips_invert() like this:
@ -113,10 +113,10 @@ main( int argc, char **argv )
} }
``` ```
libvips has a couple of extra things to let you fetch the arguments and types libvips has a couple of extra things to let you examine the arguments and
of an operator. Use vips_lib.vips_argument_map() to loop over all the arguments types of an operator at runtime. Use vips_lib.vips_argument_map() to loop
of an operator, and vips_object_get_argument() to fetch the type and flags over all the arguments of an operator, and vips_object_get_argument()
of a specific argument. to fetch the type and flags of a specific argument.
Use vips_operation_get_flags() to get general information about an operator. Use vips_operation_get_flags() to get general information about an operator.
@ -124,7 +124,7 @@ Use vips_operation_get_flags() to get general information about an operator.
The C++ binding uses this lower layer to define a function called The C++ binding uses this lower layer to define a function called
`VImage::call()` which can call any libvips operator with a not-varargs set of `VImage::call()` which can call any libvips operator with a not-varargs set of
variable arguments. variable arguments.
A small Python program walks the set of all libvips operators and generates a A small Python program walks the set of all libvips operators and generates a
set of static bindings. For example: set of static bindings. For example:
@ -142,7 +142,7 @@ VImage VImage::invert( VOption *options )
} }
``` ```
So from C++ you can call any libvips operator, though without type-safety, with So from C++ you can call any libvips operator (though without type-safety) with
`VImage::call()`, or use the member functions on `VImage` to get type-safe `VImage::call()`, or use the member functions on `VImage` to get type-safe
calls for at least the required operator arguments. calls for at least the required operator arguments.
@ -158,7 +158,7 @@ but use FFI to call into libvips and run operations.
Since these languages are dynamic, they can add another trick: they intercept Since these languages are dynamic, they can add another trick: they intercept
the method-missing hook and attempt to run any method calls not implemented by the method-missing hook and attempt to run any method calls not implemented by
the `Image` class as libvips operators. This makes these bindings self-writing: the `Image` class as libvips operators. This makes these bindings self-writing:
they only contain a small amount of codeand just expose everything they find in they only contain a small amount of code and just expose everything they find in
the libvips class hierarchy. the libvips class hierarchy.
# Dynamic langauge without FFI # Dynamic langauge without FFI
@ -167,7 +167,7 @@ PHP does not have FFI, unfortunately, so for this language a small native
module implements the general `vips_call()` function for PHP language types, module implements the general `vips_call()` function for PHP language types,
and a larger pure PHP layer makes it convenient to use. and a larger pure PHP layer makes it convenient to use.
# `gobject-introspection` # gobject-introspection
The C source code to libvips has been marked up with special comments The C source code to libvips has been marked up with special comments
describing the interface in a standard way. These comments are read by describing the interface in a standard way. These comments are read by