Experimental Rust bindings for OpenCV 3 and 4.
The API is usable but unstable and not very battle-tested; use at your own risk.
API Documentation is, to varying success, translated from OpenCV's doxygen docs. Most likely you'll want to refer to the official OpenCV C++ documentation as well.
The following OpenCV versions are supported at the moment:
- 3.2
- 3.4
- 4.1
You can choose the target OpenCV version with the following Cargo features:
- opencv-32
- opencv-34 (default)
- opencv-41
Make sure the supported OpenCV version is installed in your system along with pkg_config
files or -dev
packages.
Update your Cargo.toml
opencv = "0.23"
Select OpenCV version if different from default in Cargo.toml:
opencv = {version = "0.23", default-features = false, features = ["opencv-41"]}
Import prelude
use opencv::prelude::*;
Generally you should use the latest stable rustc to compile this crate.
Currently development and testing of the crate is only performed on Linux, please feel free to submit support for other platforms.
Generally the crate tries to only wrap OpenCV API and provide some convenience functions to be able to use it in Rust easier. We try to avoid adding any functionality besides that.
Some API functions accept callbacks, e.g. set_mouse_callback. While currently
it's possible to successfully use those functions there are some limitations to
keep in mind. Current implementation of callback handling keeps hold of the
passed callback argument forever. That means that the closure used as a callback
will never be freed during the lifetime of a program and moreover Drop will
not be called for it (they are stored in global static Slab
).
There is a plan to implement possibility to be able to free at least some of the
closures.
Although crate tries to provide ergonomic Rust interface for OpenCV, don't expect
Rust safety guarantees at this stage. It's especially true for borrow checking and
shared mutable ownership. Notable example would be Mat
which is a reference counted
object in its essence. You can own a seemingly separate Mat
in Rust terms, but
it's going to be a mutable reference to the other Mat
under the hood. Treat safety
of the crate's API as you would treat one of C++, use clone()
when needed.
The following external dependencies are required:
- python3
- OpenCV 3.2.0, 3.4.7 or 4.1.1
OpenCV is a complicated dependency with a lot of different configurations that can break this crate since it relies on fragile header parsing. Try these strategies in order, continuing to the next if builds with this crate fail.
if OpenCV is installed, its version can be checked with:
opencv_version
Install supported version of OpenCV. Check your platform's package manager or see the upstream OpenCV installation guides.
When your OpenCV is installed in a location that's not being picked up by build script you can try setting one or both of the following environment vars prior to trying to build the crate:
export PKG_CONFIG_PATH=/custom/prefix/lib/pkgconfig/
export LD_LIBRARY_PATH=/custom/prefix/lib/
Path specified by PKG_CONFIG_PATH
must contain opencv.pc
or opencv4.pc
(for OpenCV 4.x).
Path specified by LD_LIBRARY_PATH
must contain libopencv_*.so
files.
During crate build it uses opencv headers supplied inside the crate for binding generation.
If you want to use your own (system) headers supply OPENCV_HEADER_DIR
environment variable.
The directory in that environment variable should contain opencv2
dir, e.g. /usr/include
for
OpenCV-3.4.x or /usr/include/opencv4
for OpenCV-4.x. Please be sure to match the supplied
header version with the crate version features (opencv-34, opencv-41, etc.).
In some cases you might want to override the pkgconfig package name, you can use OPENCV_PKGCONFIG_NAME
environment variable for that. If you set it pkgconfig will expect to find the file with that name
and .pc
extension in the package directory.
See the upstream guides for compiling OpenCV for your platform. Make sure to compile from the correct release tag! We recommend including opencv_contrib and configuring your build with the same flags the travis build uses:
The following modules require opencv_contrib
installed:
- aruco
- bgsegm
- bioinspired
- ccalib
- cvv
- dpm
- freetype
- fuzzy
- hdf
- img_hash
- line_descriptor
- phase_unwrapping
- plot
- sfm
- shape
- structured_light
- superres
- videostab
- viz
- xfeatures2d
- xobjdetect
- xphoto
If you can't use OpenCV 3.x or higher, the (no longer maintained) 0.2.4
version of this crate is known to work with OpenCV 2.4.7.13
(and probably other 2.4 versions).
This crate works following the model of python and java's OpenCV wrappers - it parses the OpenCV C++ headers, generates a C interface to the C++ api, and wraps the C interface in Rust.
All the major modules in the C++ API are merged together in a huge
cv::
namespace. We instead made one rust module for each major
OpenCV module. So, for example, C++ cv::Mat
is opencv::core::Mat
in this crate.
The methods and field names have been snake_cased. Methods arguments with default value lose these default values, but they are reported in the API documentation.
Overloaded methods have been — manually — given different names.
All methods return a Result to hack around C++ exception handling.
Most of the API is covered, but for various reasons several modules are not yet implemented. If a missing module is near and dear to you, file an issue (or better, open a pull request!)
The crate itself, as imported by users, consists of generated rust
code in src committed to the repo. This way, users don't have
to handle the code generation overhead in their builds. When
developing this crate, you can test changes to the binding generation
using cargo build -vv --features buildtime-bindgen
. When changing
the codegen, be sure to push changes to the generated code!
hdr_parser.py
comes from OpenCV python/java generator. We've tried
not to mess too much with this file, but had to make a few changes.
gen_rust.py
is initially a copy of gen_java, also from the OpenCV
generators, but it has drifted significantly from the original.
The license for the original work is MIT.
Special thanks to ttacon for yielding the crate name.