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https://github.com/leapmotion/leapcxx

Implementation of older C++ API using LeapC
https://github.com/leapmotion/leapcxx

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Implementation of older C++ API using LeapC

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README 

        
# LeapCxx

Implementation of LeapAPI (1.0-3.0) using LeapC



### Introduction

Leap SDK 4.0 deprecates the older LeapAPI, which was C++ natively. To help ease the transition, we are providing

this wrapper which implements the old API (with a few minor edits) and the various SWIG-based language bindings 

using LeapC. Users should be aware that the primary motivation for removing the C++ API was that it had 

architectural constraints that made it inherently slow and difficult to maintain, so this should **NOT** be taken

as an example of how to create a good language binding. For that, we recommend the referencing LeapCSharp binding 

in the UnityModules project that was designed from the ground up to take advantage of LeapC's performance.



### Migration from LeapAPI

LeapCxx is nearly identical to the old LeapAPI with a few notable exceptions:

 - The configuration API is signifigantly different

 - Several fields which had been deprecated have been removed, including gestures and the interaction box

 - Static linkage is now recommended for C++



Because this is a binding layer on top of LeapC, we recommend that users link with LeapCxx statically,

then ship only LeapC.dll with their application.



### Requirements

  * LeapSDK 4.0.0

  * CMake 3.10+

  * C++11 compliant compiler



  In addition, the Swig language bindings require

    * Swig 3.0.12+

    * Python 3.6+

    * JDK 8+



### Building LeapCxx

LeapCxx builds using CMake 3.10 or higher. See the [CMake documentation](https://cmake.org/cmake/help/latest/)

for more information on using CMake, and the LeapSDK Readme for information specific to using the SDK with 

CMake. CMake must know where to find the LeapSDK, so either set `CMAKE_PREFIX_PATH` to the directory containing

the LeapSDK, or set `LeapSDK_DIR` to `.../LeapSDK/lib/cmake/LeapSDK`. For just LeapCxx, no additional configuration is

needed.



### Building SWIG bindings

To build the SWIG bindings, set the cmake variables `BUILD_SHARED_LIBS` and `BUILD_SWIG` to `ON`, then regenerate

the solution files via CMake. The targets `LeapJava` and `LeapPython` should now be available, along with the

samples for each.



### Building Samples

All the samples have build steps defined as part of the cmake projects. If you'd like to build the swig

samples manually, follow the steps below.



Java

```

cd LeapCxx/samples

javac -cp .;/bin//LeapJava.jar Sample.java

java -Djava.library.path="/bin/" -cp .;/bin/LeapJava.jar Sample

```

Python

```

cp LeapCxx/samples/Sample.py /

cd 

python Sample.py

```



### Suggestions for future work

The current API, for the sake of compatibility, uses reference counting and a PIMPL idiom quite extensively. 

Neither of those are strictly necessary in a wrapper layer, and it should be possible to create a much faster,

lighterweight C++ and even SWIG binding layer which more directly maps to the LeapC idioms and allows a more

object oriented approach, for example allowing



```

auto connection = LeapCreateConnection(...);

connection.open();

LeapEvent event = connection.poll(...);

```

instead of

```

  LEAP_CONNECTION connection;

  LeapCreateConnection(cfg, &connection);

  LeapOpenConnection(connection);

```



Users wanting to implement such a wrapper should consult the LeapC documentation

for more information.