192 lines
5.1 KiB
Markdown
192 lines
5.1 KiB
Markdown
# libdart_openmvg
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OpenMVG bindings for dart.
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[OpenMVG](https://openmvg.readthedocs.io/) is an AI graphics application that supports
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feature detection and surface-from-motion capabilities
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If you'd like to contribute, financially, please visit https://ko-fi.com/damngood and
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mention "libdart_openmvg" in your message.
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## Getting Started
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This project is a starting point for a Flutter
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[FFI plugin](https://docs.flutter.dev/development/platform-integration/c-interop),
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a specialized package that includes native code directly invoked with Dart FFI.
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## Building dependencies.
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My current project structure is as follows:
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```
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+- main_project
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+- libdart_openmvg (this project)
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+- libffmpeg
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+- cwalk (git clone https://github.com/likle/cwalk.git)
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+- openMVG (git clone https://github.com/openMVG/openMVG.git)
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```
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The install prefix for openMVG is expected to be `openMVG/build/_install`. I'll
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fix this at some point, but I hard-coded it to get the project built.
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To build libdart_openmvg...
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```
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$ mkdir build && cd build
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$ cmake -DCMAKE_INSTALL_PREFIX=_install ../src
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```
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## The C/C++ Bindings
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To run cunit tests...
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```
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$ cd build
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$ ./test_image
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```
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Or to auto-build & run cunit tests...
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```
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$ # in the libdart_openmvg project root
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$ ./scripts/watch_compilelib.sh # in one terminal
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$ ./scripts/watch_test.sh # in another terminal
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```
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Ensure you have the `entr` command installed.
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Now anytime you save a `.c/.cxx/.h/CMakeLists.txt` file, the program will be
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recompiled and retested.
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## The Dart Tests
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To run the dart tests ensure that the C bindings are built.
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```
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$ dart --define=CURRENT_EXEC_DIR="${ROOT_DIR}" test ${TEST_DIR}
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```
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Or if you want to rerun the tests every time the C or dart files are changed:
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```
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$ ./scripts/watch_darttest.sh
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```
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## Project structure
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This template uses the following structure:
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* `src`: Contains the native source code, and a CmakeFile.txt file for building
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that source code into a dynamic library.
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* `lib`: Contains the Dart code that defines the API of the plugin, and which
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calls into the native code using `dart:ffi`.
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* platform folders (`android`, `ios`, `windows`, etc.): Contains the build files
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for building and bundling the native code library with the platform application.
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## Building and bundling native code
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The `pubspec.yaml` specifies FFI plugins as follows:
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```yaml
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plugin:
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platforms:
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some_platform:
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ffiPlugin: true
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```
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This configuration invokes the native build for the various target platforms
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and bundles the binaries in Flutter applications using these FFI plugins.
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This can be combined with dartPluginClass, such as when FFI is used for the
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implementation of one platform in a federated plugin:
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```yaml
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plugin:
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implements: some_other_plugin
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platforms:
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some_platform:
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dartPluginClass: SomeClass
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ffiPlugin: true
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```
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A plugin can have both FFI and method channels:
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```yaml
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plugin:
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platforms:
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some_platform:
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pluginClass: SomeName
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ffiPlugin: true
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```
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The native build systems that are invoked by FFI (and method channel) plugins are:
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* For Android: Gradle, which invokes the Android NDK for native builds.
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* See the documentation in android/build.gradle.
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* For iOS and MacOS: Xcode, via CocoaPods.
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* See the documentation in ios/archimedes_mobile_lib.podspec.
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* See the documentation in macos/archimedes_mobile_lib.podspec.
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* For Linux and Windows: CMake.
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* See the documentation in linux/CMakeLists.txt.
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* See the documentation in windows/CMakeLists.txt.
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## Binding to native code
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To use the native code, bindings in Dart are needed.
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To avoid writing these by hand, they are generated from the header file
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(`src/archimedes_mobile_lib.h`) by `package:ffigen`.
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Regenerate the bindings by running `flutter pub run ffigen --config ffigen.yaml`.
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## Invoking native code
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Very short-running native functions can be directly invoked from any isolate.
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For example, see `sum` in `lib/archimedes_mobile_lib.dart`.
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Longer-running functions should be invoked on a helper isolate to avoid
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dropping frames in Flutter applications.
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For example, see `sumAsync` in `lib/archimedes_mobile_lib.dart`.
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## Flutter help
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For help getting started with Flutter, view our
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[online documentation](https://flutter.dev/docs), which offers tutorials,
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samples, guidance on mobile development, and a full API reference.
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# Developer Notes
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You'll get an error with Eiger, so watch out.
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```
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$ make
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finition.hpp:17:10: fatal error: Eigen/Dense: No such file or directory
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17 | #include <Eigen/Dense>
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| ^~~~~~~~~~~~~
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compilation terminated.
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```
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```shell
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$ sudo at install -y libeigen3-dev
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$ sudo ln -sf /usr/include/eigen3/Eigen /usr/include/Eigen
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```
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git clone --single-branch --branch n6.1 https://git.ffmpeg.org/ffmpeg.git
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Can I expose `FILE` in dart?
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Yea...no! https://github.com/dart-lang/sdk/issues/4160
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Instead, I'll have to load the data in directly.
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buliding open mvg needs to be done with the PIC flag
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```shell
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$ cmake ../src -DCMAKE_INSTALL_PREFIX="../../openMVG/build/_install" -DCMAKE_POSITION_INDEPENDENT_CODE=ON
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```
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A good SFM example (that I'm basically ripping from) can be found here:
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./openMVG/src/software/SfM/main_SfM.cpp |