feat: Frame Processors for Android (#196)

* Create android gradle build setup

* Fix `prefab` config

* Add `pickFirst **/*.so` to example build.gradle

* fix REA path

* cache gradle builds

* Update validate-android.yml

* Create Native Proxy

* Copy REA header

* implement ctor

* Rename CameraViewModule -> FrameProcessorRuntimeManager

* init FrameProcessorRuntimeManager

* fix name

* Update FrameProcessorRuntimeManager.h

* format

* Create AndroidErrorHandler.h

* Initialize runtime and install JSI funcs

* Update FrameProcessorRuntimeManager.cpp

* Update CameraViewModule.kt

* Make CameraView hybrid C++ class to find view & set frame processor

* Update FrameProcessorRuntimeManager.cpp

* pass function by rvalue

* pass by const &&

* extract hermes and JSC REA

* pass `FOR_HERMES`

* correctly prepare JSC and Hermes

* Update CMakeLists.txt

* add missing hermes include

* clean up imports

* Create JImageProxy.h

* pass ImageProxy to JNI as `jobject`

* try use `JImageProxy` C++ wrapper type

* Use `local_ref<JImageProxy>`

* Create `JImageProxyHostObject` for JSI interop

* debug call to frame processor

* Unset frame processor

* Fix CameraView native part not being registered

* close image

* use `jobject` instead of `JImageProxy` for now :(

* fix hermes build error

* Set enable FP callback

* fix JNI call

* Update CameraView.cpp

* Get Format

* Create plugin abstract

* Make `FrameProcessorPlugin` a hybrid object

* Register plugin CXX

* Call `registerPlugin`

* Catch

* remove JSI

* Create sample QR code plugin

* register plugins

* Fix missing JNI binding

* Add `mHybridData`

* prefix name with two underscores (`__`)

* Update CameraPage.tsx

* wrap `ImageProxy` in host object

* Use `jobject` for HO box

* Update JImageProxy.h

* reinterpret jobject

* Try using `JImageProxy` instead of `jobject`

* Update JImageProxy.h

* get bytes per row and plane count

* Update CameraView.cpp

* Return base

* add some docs and JNI JSI conversion

* indent

* Convert JSI value to JNI jobject

* using namespace facebook

* Try using class

* Use plain old Object[]

* Try convert JNI -> JSI

* fix decl

* fix bool init

* Correctly link folly

* Update CMakeLists.txt

* Convert Map to Object

* Use folly for Map and Array

* Return `alias_ref<jobject>` instead of raw `jobject`

* fix JNI <-> JSI conversion

* Update JSIJNIConversion.cpp

* Log parameters

* fix params index offset

* add more test cases

* Update FRAME_PROCESSORS_CREATE_OVERVIEW.mdx

* fix types

* Rename to example plugin

* remove support for hashmap

* Try use HashMap iterable fbjni binding

* try using JReadableArray/JReadableMap

* Fix list return values

* Update JSIJNIConversion.cpp

* Update JSIJNIConversion.cpp

* (iOS) Rename ObjC QR Code Plugin to Example Plugin

* Rename Swift plugin QR -> Example

* Update ExamplePluginSwift.swift

* Fix Map/Dictionary logging format

* Update ExampleFrameProcessorPlugin.m

* Reconfigure session if frame processor changed

* Handle use-cases via `maxUseCasesCount`

* Don't crash app on `configureSession` error

* Document "use-cases"

* Update DEVICES.mdx

* fix merge

* Make `const &`

* iOS: Automatically enable `video` if a `frameProcessor` is set

* Update CameraView.cpp

* fix docs

* Automatically fallback to snapshot capture if `supportsParallelVideoProcessing` is false.

* Fix lookup

* Update CameraView.kt

* Implement `frameProcessorFps`

* Finalize Frame Processor Plugin Hybrid

* Update CameraViewModule.kt

* Support `flash` on `takeSnapshot()`

* Update docs

* Add docs

* Update CameraPage.tsx

* Attribute NonNull

* remove unused imports

* Add Android docs for Frame Processors

* Make JNI HashMap <-> JSI Object conversion faster

directly access `toHashMap` instead of going through java

* add todo

* Always run `prepareJSC` and `prepareHermes`

* switch jsc and hermes

* Specify ndkVersion `21.4.7075529`

* Update gradle.properties

* Update gradle.properties

* Create .aar

* Correctly prepare android package

* Update package.json

* Update package.json

* remove `prefab` build feature

* split

* Add docs for registering the FP plugin

* Add step for dep

* Update CaptureButton.tsx

* Move to `reanimated-headers/`

* Exclude reanimated-headers from cpplint

* disable `build/include_order` rule

* cpplint fixes

* perf: Make `JSIJNIConversion` a `namespace` instead of `class`

* Ignore runtime/references for `convert` funcs

* Build Android .aar in CI

* Run android build script only on `prepack`

* Update package.json

* Update package.json

* Update build-android-npm-package.sh

* Move to `yarn build`

* Also install node_modules in example step

* Update validate-android.yml

* sort imports

* fix torch

* Run ImageAnalysis on `FrameProcessorThread`

* Update Errors.kt

* Add clean android script

* Upgrade reanimated to 2.3.0-alpha.1

* Revert "Upgrade reanimated to 2.3.0-alpha.1"

This reverts commit c1d3bed5e03728d0b5e335a359524ff4f56f5035.

* ⚠️ TEMP FIX: hotfix reanimated build.gradle

* Update CameraView+TakeSnapshot.kt

* ⚠️ TEMP FIX: Disable ktlint action for now

* Update clean.sh

* Set max heap size to 4g

* rebuild lockfiles

* Update Podfile.lock

* rename

* Build lib .aar before example/

android/src/main/cpp/CameraView.cpp

@@ -0,0 +1,69 @@
+//
+// Created by Marc Rousavy on 14.06.21.
+//
+
+#include "CameraView.h"
+
+#include <jni.h>
+#include <fbjni/fbjni.h>
+
+#include <memory>
+#include <string>
+
+namespace vision {
+
+using namespace facebook;
+using namespace jni;
+
+using TSelf = local_ref<HybridClass<vision::CameraView>::jhybriddata>;
+
+TSelf CameraView::initHybrid(alias_ref<HybridClass::jhybridobject> jThis) {
+    return makeCxxInstance(jThis);
+}
+
+void CameraView::registerNatives() {
+    registerHybrid({
+        makeNativeMethod("initHybrid", CameraView::initHybrid),
+        makeNativeMethod("frameProcessorCallback", CameraView::frameProcessorCallback),
+    });
+}
+
+void CameraView::frameProcessorCallback(const alias_ref<JImageProxy::javaobject>& frame) {
+  if (frameProcessor_ == nullptr) {
+    __android_log_write(ANDROID_LOG_WARN, TAG, "Frame Processor is null!");
+    setEnableFrameProcessor(false);
+    return;
+  }
+
+  auto frameStrong = make_local(frame);
+  try {
+    __android_log_write(ANDROID_LOG_INFO, TAG, "Calling Frame Processor...");
+    frameProcessor_(frameStrong);
+  } catch (const std::exception& exception) {
+    // TODO: jsi::JSErrors cannot be caught on Hermes. They crash the entire app.
+    auto message = "Frame Processor threw an error! " + std::string(exception.what());
+    __android_log_write(ANDROID_LOG_ERROR, TAG, message.c_str());
+  }
+}
+
+void CameraView::setEnableFrameProcessor(bool enable) {
+  if (enable) {
+    __android_log_write(ANDROID_LOG_INFO, TAG, "Enabling Frame Processor Callback...");
+  } else {
+    __android_log_write(ANDROID_LOG_INFO, TAG, "Disabling Frame Processor Callback...");
+  }
+  static const auto javaMethod = javaPart_->getClass()->getMethod<void(bool)>("setEnableFrameProcessor");
+  javaMethod(javaPart_.get(), enable);
+}
+
+void CameraView::setFrameProcessor(const FrameProcessor&& frameProcessor) {
+  frameProcessor_ = frameProcessor;
+  setEnableFrameProcessor(true);
+}
+
+void vision::CameraView::unsetFrameProcessor() {
+  frameProcessor_ = nullptr;
+  setEnableFrameProcessor(false);
+}
+
+} // namespace vision

android/src/main/cpp/CameraView.h

@@ -0,0 +1,44 @@
+//
+// Created by Marc Rousavy on 14.06.21.
+//
+
+#pragma once
+
+#include <jni.h>
+#include <fbjni/fbjni.h>
+
+#include <memory>
+
+#include "JImageProxy.h"
+
+namespace vision {
+
+using namespace facebook;
+using FrameProcessor = std::function<void(jni::local_ref<JImageProxy::javaobject>)>;
+
+class CameraView : public jni::HybridClass<CameraView> {
+ public:
+  static auto constexpr kJavaDescriptor = "Lcom/mrousavy/camera/CameraView;";
+  static auto constexpr TAG = "VisionCamera";
+  static jni::local_ref<jhybriddata> initHybrid(jni::alias_ref<jhybridobject> jThis);
+  static void registerNatives();
+
+  // TODO: Use template<> to avoid heap allocation for std::function<>
+  void setFrameProcessor(const FrameProcessor&& frameProcessor);
+  void unsetFrameProcessor();
+  void setEnableFrameProcessor(bool enable);
+
+ private:
+  friend HybridBase;
+  jni::global_ref<CameraView::javaobject> javaPart_;
+  FrameProcessor frameProcessor_;
+
+  void frameProcessorCallback(const jni::alias_ref<JImageProxy::javaobject>& frame);
+
+  explicit CameraView(jni::alias_ref<CameraView::jhybridobject> jThis) :
+    javaPart_(jni::make_global(jThis)),
+    frameProcessor_(nullptr)
+  {}
+};
+
+} // namespace vision

android/src/main/cpp/FrameProcessorPlugin.cpp

@@ -0,0 +1,37 @@
+//
+// Created by Marc Rousavy on 22.06.21.
+//
+
+#include "FrameProcessorPlugin.h"
+#include <string>
+
+namespace vision {
+
+using namespace facebook;
+using namespace jni;
+
+using TSelf = local_ref<HybridClass<FrameProcessorPlugin>::jhybriddata>;
+using TFrameProcessorPlugin = jobject(alias_ref<JImageProxy::javaobject>, alias_ref<JArrayClass<jobject>>);
+
+TSelf vision::FrameProcessorPlugin::initHybrid(alias_ref<HybridClass::jhybridobject> jThis, const std::string& name) {
+  return makeCxxInstance(jThis, name);
+}
+
+void FrameProcessorPlugin::registerNatives() {
+  registerHybrid({
+    makeNativeMethod("initHybrid",
+                     FrameProcessorPlugin::initHybrid),
+  });
+}
+
+local_ref<jobject> FrameProcessorPlugin::callback(alias_ref<JImageProxy::javaobject> image, alias_ref<JArrayClass<jobject>> params) {
+  static const auto func = javaPart_->getClass()->getMethod<TFrameProcessorPlugin>("callback");
+  auto result = func(javaPart_.get(), image, params);
+  return make_local(result);
+}
+
+std::string FrameProcessorPlugin::getName() {
+  return name;
+}
+
+} // namespace vision

android/src/main/cpp/FrameProcessorPlugin.h

@@ -0,0 +1,39 @@
+//
+// Created by Marc Rousavy on 22.06.21.
+//
+
+#pragma once
+
+#include <jni.h>
+#include <fbjni/fbjni.h>
+#include <string>
+
+#include "JImageProxy.h"
+
+namespace vision {
+
+using namespace facebook;
+using namespace jni;
+
+class FrameProcessorPlugin: public HybridClass<FrameProcessorPlugin> {
+ public:
+  static auto constexpr kJavaDescriptor = "Lcom/mrousavy/camera/frameprocessor/FrameProcessorPlugin;";
+  static jni::local_ref<jhybriddata> initHybrid(jni::alias_ref<jhybridobject> jThis,
+                                                const std::string& name);
+  static void registerNatives();
+
+  local_ref<jobject> callback(alias_ref<JImageProxy::javaobject> image, alias_ref<JArrayClass<jobject>> params);
+  std::string getName();
+
+ private:
+  friend HybridBase;
+  jni::global_ref<FrameProcessorPlugin::javaobject> javaPart_;
+  std::string name;
+
+  FrameProcessorPlugin(alias_ref<FrameProcessorPlugin::jhybridobject> jThis,
+                       std::string name): javaPart_(make_global(jThis)),
+                       name(name)
+  {}
+};
+
+} // namespace vision

android/src/main/cpp/FrameProcessorRuntimeManager.cpp

@@ -0,0 +1,234 @@
+//
+// Created by Marc Rousavy on 11.06.21.
+//
+
+#include "FrameProcessorRuntimeManager.h"
+#include <android/log.h>
+#include <jni.h>
+#include <utility>
+
+#include "RuntimeDecorator.h"
+#include "RuntimeManager.h"
+#include "reanimated-headers/AndroidScheduler.h"
+#include "reanimated-headers/AndroidErrorHandler.h"
+
+#include "MakeJSIRuntime.h"
+#include "CameraView.h"
+#include "JImageProxy.h"
+#include "JImageProxyHostObject.h"
+#include "JSIJNIConversion.h"
+
+namespace vision {
+
+// type aliases
+using TSelf = local_ref<HybridClass<vision::FrameProcessorRuntimeManager>::jhybriddata>;
+using JSCallInvokerHolder = jni::alias_ref<facebook::react::CallInvokerHolder::javaobject>;
+using AndroidScheduler = jni::alias_ref<reanimated::AndroidScheduler::javaobject>;
+
+// JNI binding
+void vision::FrameProcessorRuntimeManager::registerNatives() {
+  registerHybrid({
+    makeNativeMethod("initHybrid",
+                     FrameProcessorRuntimeManager::initHybrid),
+    makeNativeMethod("installJSIBindings",
+                     FrameProcessorRuntimeManager::installJSIBindings),
+    makeNativeMethod("initializeRuntime",
+                     FrameProcessorRuntimeManager::initializeRuntime),
+    makeNativeMethod("registerPlugin",
+                     FrameProcessorRuntimeManager::registerPlugin),
+  });
+}
+
+// JNI init
+TSelf vision::FrameProcessorRuntimeManager::initHybrid(
+    alias_ref<jhybridobject> jThis,
+    jlong jsContext,
+    JSCallInvokerHolder jsCallInvokerHolder,
+    AndroidScheduler androidScheduler) {
+  __android_log_write(ANDROID_LOG_INFO, TAG,
+                      "Initializing FrameProcessorRuntimeManager...");
+
+  // cast from JNI hybrid objects to C++ instances
+  auto jsCallInvoker = jsCallInvokerHolder->cthis()->getCallInvoker();
+  auto scheduler = androidScheduler->cthis()->getScheduler();
+  scheduler->setJSCallInvoker(jsCallInvoker);
+
+  return makeCxxInstance(jThis, reinterpret_cast<jsi::Runtime *>(jsContext), jsCallInvoker, scheduler);
+}
+
+void vision::FrameProcessorRuntimeManager::initializeRuntime() {
+  __android_log_write(ANDROID_LOG_INFO, TAG,
+                      "Initializing Vision JS-Runtime...");
+
+  // create JSI runtime and decorate it
+  auto runtime = makeJSIRuntime();
+  reanimated::RuntimeDecorator::decorateRuntime(*runtime, "FRAME_PROCESSOR");
+  runtime->global().setProperty(*runtime, "_FRAME_PROCESSOR",
+                                jsi::Value(true));
+
+  // create REA runtime manager
+  auto errorHandler = std::make_shared<reanimated::AndroidErrorHandler>(scheduler_);
+  _runtimeManager = std::make_unique<reanimated::RuntimeManager>(std::move(runtime),
+                                                                 errorHandler,
+                                                                 scheduler_);
+
+  __android_log_write(ANDROID_LOG_INFO, TAG,
+                      "Initialized Vision JS-Runtime!");
+}
+
+CameraView* FrameProcessorRuntimeManager::findCameraViewById(int viewId) {
+  static const auto func = javaPart_->getClass()->getMethod<CameraView*(jint)>("findCameraViewById");
+  auto result = func(javaPart_.get(), viewId);
+  return result->cthis();
+}
+
+// actual JSI installer
+void FrameProcessorRuntimeManager::installJSIBindings() {
+  __android_log_write(ANDROID_LOG_INFO, TAG, "Installing JSI bindings...");
+
+  if (runtime_ == nullptr) {
+    __android_log_write(ANDROID_LOG_ERROR, TAG,
+                        "JS-Runtime was null, Frame Processor JSI bindings could not be installed!");
+    return;
+  }
+
+  auto &jsiRuntime = *runtime_;
+
+  auto setFrameProcessor = [this](jsi::Runtime &runtime,
+                                  const jsi::Value &thisValue,
+                                  const jsi::Value *arguments,
+                                  size_t count) -> jsi::Value {
+    __android_log_write(ANDROID_LOG_INFO, TAG,
+                        "Setting new Frame Processor...");
+
+    if (!arguments[0].isNumber()) {
+      throw jsi::JSError(runtime,
+                         "Camera::setFrameProcessor: First argument ('viewTag') must be a number!");
+    }
+    if (!arguments[1].isObject()) {
+      throw jsi::JSError(runtime,
+                         "Camera::setFrameProcessor: Second argument ('frameProcessor') must be a function!");
+    }
+    if (!_runtimeManager || !_runtimeManager->runtime) {
+      throw jsi::JSError(runtime,
+                         "Camera::setFrameProcessor: The RuntimeManager is not yet initialized!");
+    }
+
+    // find camera view
+    auto viewTag = arguments[0].asNumber();
+    auto cameraView = findCameraViewById(static_cast<int>(viewTag));
+    __android_log_write(ANDROID_LOG_INFO, TAG, "Found CameraView!");
+
+    // TODO: does this have to be called on the separate VisionCamera Frame Processor Thread?
+
+    // convert jsi::Function to a ShareableValue (can be shared across runtimes)
+    __android_log_write(ANDROID_LOG_INFO, TAG, "Adapting Shareable value from function (conversion to worklet)...");
+    auto worklet = reanimated::ShareableValue::adapt(runtime, arguments[1],
+                                                     _runtimeManager.get());
+    __android_log_write(ANDROID_LOG_INFO, TAG, "Successfully created worklet!");
+
+    // cast worklet to a jsi::Function for the new runtime
+    auto &rt = *this->_runtimeManager->runtime;
+    auto function = std::make_shared<jsi::Function>(worklet->getValue(rt).asObject(rt).asFunction(rt));
+
+    // assign lambda to frame processor
+    cameraView->setFrameProcessor([&rt, function](jni::local_ref<JImageProxy::javaobject> frame) {
+      __android_log_write(ANDROID_LOG_INFO, TAG, "Frame Processor called!");
+
+      // create HostObject which holds the Frame (JImageProxy)
+      auto hostObject = std::make_shared<JImageProxyHostObject>(frame);
+      function->call(rt, jsi::Object::createFromHostObject(rt, hostObject));
+    });
+
+    __android_log_write(ANDROID_LOG_INFO, TAG, "Frame Processor set!");
+
+    return jsi::Value::undefined();
+  };
+  jsiRuntime.global().setProperty(jsiRuntime,
+                                  "setFrameProcessor",
+                                  jsi::Function::createFromHostFunction(
+                                      jsiRuntime,
+                                      jsi::PropNameID::forAscii(jsiRuntime,
+                                                                "setFrameProcessor"),
+                                      2,  // viewTag, frameProcessor
+                                      setFrameProcessor));
+
+
+  auto unsetFrameProcessor = [this](jsi::Runtime &runtime,
+                                    const jsi::Value &thisValue,
+                                    const jsi::Value *arguments,
+                                    size_t count) -> jsi::Value {
+    __android_log_write(ANDROID_LOG_INFO, TAG, "Removing Frame Processor...");
+    if (!arguments[0].isNumber()) {
+      throw jsi::JSError(runtime,
+                         "Camera::unsetFrameProcessor: First argument ('viewTag') must be a number!");
+    }
+
+    // find camera view
+    auto viewTag = arguments[0].asNumber();
+    auto cameraView = findCameraViewById(static_cast<int>(viewTag));
+
+    // call Java method to unset frame processor
+    cameraView->unsetFrameProcessor();
+
+    __android_log_write(ANDROID_LOG_INFO, TAG, "Frame Processor removed!");
+
+    return jsi::Value::undefined();
+  };
+  jsiRuntime.global().setProperty(jsiRuntime,
+                                  "unsetFrameProcessor",
+                                  jsi::Function::createFromHostFunction(
+                                      jsiRuntime,
+                                      jsi::PropNameID::forAscii(jsiRuntime,
+                                                                "unsetFrameProcessor"),
+                                      1, // viewTag
+                                      unsetFrameProcessor));
+
+  __android_log_write(ANDROID_LOG_INFO, TAG, "Finished installing JSI bindings!");
+}
+
+void FrameProcessorRuntimeManager::registerPlugin(alias_ref<FrameProcessorPlugin::javaobject> plugin) {
+  // _runtimeManager might never be null, but we can never be too sure.
+  if (!_runtimeManager || !_runtimeManager->runtime) {
+    throw std::runtime_error("Tried to register plugin before initializing JS runtime! Call `initializeRuntime()` first.");
+  }
+
+  auto& runtime = *_runtimeManager->runtime;
+
+  // we need a strong reference on the plugin, make_global does that.
+  auto pluginGlobal = make_global(plugin);
+  auto pluginCxx = pluginGlobal->cthis();
+  // name is always prefixed with two underscores (__)
+  auto name = "__" + pluginCxx->getName();
+
+  auto message = "Installing Frame Processor Plugin \"" + name + "\"...";
+  __android_log_write(ANDROID_LOG_INFO, TAG, message.c_str());
+
+  auto callback = [pluginCxx](jsi::Runtime& runtime,
+                              const jsi::Value& thisValue,
+                              const jsi::Value* arguments,
+                              size_t count) -> jsi::Value {
+    // Unbox object and get typed HostObject
+    auto boxedHostObject = arguments[0].asObject(runtime).asHostObject(runtime);
+    auto frameHostObject = dynamic_cast<JImageProxyHostObject*>(boxedHostObject.get());
+
+    // parse params - we are offset by `1` because the frame is the first parameter.
+    auto params = JArrayClass<jobject>::newArray(count - 1);
+    for (size_t i = 1; i < count; i++) {
+      params->setElement(i - 1, JSIJNIConversion::convertJSIValueToJNIObject(runtime, arguments[i]));
+    }
+
+    // call implemented virtual method
+    auto result = pluginCxx->callback(frameHostObject->frame, params);
+
+    // convert result from JNI to JSI value
+    return JSIJNIConversion::convertJNIObjectToJSIValue(runtime, result);
+  };
+
+  runtime.global().setProperty(runtime, name.c_str(), jsi::Function::createFromHostFunction(runtime,
+                                                                                            jsi::PropNameID::forAscii(runtime, name),
+                                                                                            1, // frame
+                                                                                            callback));
+}
+
+} // namespace vision

android/src/main/cpp/FrameProcessorRuntimeManager.h

@@ -0,0 +1,58 @@
+//
+// Created by Marc Rousavy on 11.06.21.
+//
+
+#pragma once
+
+#include <fbjni/fbjni.h>
+#include <jsi/jsi.h>
+#include <ReactCommon/CallInvokerHolder.h>
+#include <memory>
+
+#include "Scheduler.h"
+#include "RuntimeManager.h"
+#include "reanimated-headers/AndroidScheduler.h"
+
+#include "CameraView.h"
+#include "FrameProcessorPlugin.h"
+
+namespace vision {
+
+using namespace facebook;
+
+class FrameProcessorRuntimeManager : public jni::HybridClass<FrameProcessorRuntimeManager> {
+ public:
+  static auto constexpr kJavaDescriptor = "Lcom/mrousavy/camera/frameprocessor/FrameProcessorRuntimeManager;";
+  static auto constexpr TAG = "VisionCamera";
+  static jni::local_ref<jhybriddata> initHybrid(jni::alias_ref<jhybridobject> jThis,
+                                                jlong jsContext,
+                                                jni::alias_ref<facebook::react::CallInvokerHolder::javaobject> jsCallInvokerHolder,
+                                                jni::alias_ref<reanimated::AndroidScheduler::javaobject> androidScheduler);
+  static void registerNatives();
+
+  FrameProcessorRuntimeManager() {}
+  explicit FrameProcessorRuntimeManager(jni::alias_ref<FrameProcessorRuntimeManager::jhybridobject> jThis,
+                                        jsi::Runtime* runtime,
+                                        std::shared_ptr<facebook::react::CallInvoker> jsCallInvoker,
+                                        std::shared_ptr<reanimated::Scheduler> scheduler) :
+      javaPart_(jni::make_global(jThis)),
+      runtime_(runtime),
+      jsCallInvoker_(jsCallInvoker),
+      scheduler_(scheduler)
+  {}
+
+ private:
+  friend HybridBase;
+  jni::global_ref<FrameProcessorRuntimeManager::javaobject> javaPart_;
+  jsi::Runtime* runtime_;
+  std::shared_ptr<facebook::react::CallInvoker> jsCallInvoker_;
+  std::shared_ptr<reanimated::RuntimeManager> _runtimeManager;
+  std::shared_ptr<reanimated::Scheduler> scheduler_;
+
+  CameraView* findCameraViewById(int viewId);
+  void initializeRuntime();
+  void installJSIBindings();
+  void registerPlugin(alias_ref<FrameProcessorPlugin::javaobject> plugin);
+};
+
+} // namespace vision

android/src/main/cpp/JArrayList.h

@@ -0,0 +1,20 @@
+//
+// Created by Marc Rousavy on 24.06.21.
+//
+
+#pragma once
+
+#include <jni.h>
+#include <fbjni/fbjni.h>
+
+namespace vision {
+
+using namespace facebook;
+using namespace jni;
+
+// TODO: Remove when fbjni 0.2.3 releases.
+struct JArrayList : public JavaClass<JArrayList> {
+  static constexpr auto kJavaDescriptor = "Ljava/util/ArrayList;";
+};
+
+} // namespace vision

android/src/main/cpp/JHashMap.cpp

@@ -0,0 +1,20 @@
+//
+// Created by Marc Rousavy on 25.06.21.
+//
+
+#include "JHashMap.h"
+
+#include <jni.h>
+#include <fbjni/fbjni.h>
+
+
+namespace facebook {
+namespace jni {
+
+template <typename K, typename V>
+local_ref<JHashMap<K, V>> JHashMap<K, V>::create() {
+  return JHashMap<K, V>::newInstance();
+}
+
+} // namespace jni
+} // namespace facebook

android/src/main/cpp/JHashMap.h

@@ -0,0 +1,23 @@
+//
+// Created by Marc Rousavy on 25.06.21.
+//
+
+#pragma once
+
+#include <jni.h>
+#include <fbjni/fbjni.h>
+
+
+namespace facebook {
+namespace jni {
+
+// TODO: Remove when fbjni 0.2.3 releases.
+template <typename K = jobject, typename V = jobject>
+struct JHashMap : JavaClass<JHashMap<K, V>, JMap<K, V>> {
+  constexpr static auto kJavaDescriptor = "Ljava/util/HashMap;";
+
+  static local_ref<JHashMap<K, V>> create();
+};
+
+} // namespace jni
+} // namespace facebook

android/src/main/cpp/JImageProxy.cpp

@@ -0,0 +1,54 @@
+//
+// Created by Marc Rousavy on 22.06.21.
+//
+
+#include "JImageProxy.h"
+
+#include <jni.h>
+#include <fbjni/fbjni.h>
+
+namespace vision {
+
+using namespace facebook;
+using namespace jni;
+
+int JImageProxy::getWidth() {
+  static const auto getWidthMethod = getClass()->getMethod<jint()>("getWidth");
+  return getWidthMethod(javaClassLocal());
+}
+
+int JImageProxy::getHeight() {
+  static const auto getWidthMethod = getClass()->getMethod<jint()>("getHeight");
+  return getWidthMethod(javaClassLocal());
+}
+
+bool JImageProxy::getIsValid() {
+  static const auto getImageMethod = getClass()->getMethod<JImageProxy::javaobject()>("getImage");
+  auto image = getImageMethod(javaClassLocal());
+
+  static const auto getHardwareBufferMethod = findClassLocal("android/media/Image")->getMethod<jobject()>("getHardwareBuffer");
+  try {
+    getHardwareBufferMethod(image.get());
+    return true;
+  } catch (...) {
+    // function throws if the image is not active anymore
+    return false;
+  }
+}
+
+int JImageProxy::getPlaneCount() {
+  static const auto getPlanesMethod = getClass()->getMethod<JArrayClass<jobject>()>("getPlanes");
+  auto planes = getPlanesMethod(javaClassLocal());
+  return planes->size();
+}
+
+int JImageProxy::getBytesPerRow() {
+  static const auto getPlanesMethod = getClass()->getMethod<JArrayClass<jobject>()>("getPlanes");
+  auto planes = getPlanesMethod(javaClassLocal());
+  auto firstPlane = planes->getElement(0);
+
+  static const auto getRowStrideMethod = findClassLocal("android/media/Image$PlaneProxy")->getMethod<int()>("getRowStride");
+  return getRowStrideMethod(firstPlane.get());
+}
+
+} // namespace vision

android/src/main/cpp/JImageProxy.h

@@ -0,0 +1,23 @@
+//
+// Created by Marc on 19/06/2021.
+//
+
+#pragma once
+
+#include <jni.h>
+#include <fbjni/fbjni.h>
+
+namespace vision {
+
+struct JImageProxy : public facebook::jni::JavaClass<JImageProxy> {
+  static constexpr auto kJavaDescriptor = "Landroidx/camera/core/ImageProxy;";
+
+ public:
+  int getWidth();
+  int getHeight();
+  bool getIsValid();
+  int getPlaneCount();
+  int getBytesPerRow();
+};
+
+} // namespace vision

android/src/main/cpp/JImageProxyHostObject.cpp

@@ -0,0 +1,65 @@
+//
+// Created by Marc on 19/06/2021.
+//
+
+#include "JImageProxyHostObject.h"
+#include <android/log.h>
+#include <vector>
+#include <string>
+
+namespace vision {
+
+std::vector<jsi::PropNameID> JImageProxyHostObject::getPropertyNames(jsi::Runtime& rt) {
+  std::vector<jsi::PropNameID> result;
+  result.push_back(jsi::PropNameID::forUtf8(rt, std::string("toString")));
+  result.push_back(jsi::PropNameID::forUtf8(rt, std::string("isValid")));
+  result.push_back(jsi::PropNameID::forUtf8(rt, std::string("isReady")));
+  result.push_back(jsi::PropNameID::forUtf8(rt, std::string("width")));
+  result.push_back(jsi::PropNameID::forUtf8(rt, std::string("height")));
+  result.push_back(jsi::PropNameID::forUtf8(rt, std::string("bytesPerRow")));
+  result.push_back(jsi::PropNameID::forUtf8(rt, std::string("planesCount")));
+  return result;
+}
+
+jsi::Value JImageProxyHostObject::get(jsi::Runtime& runtime, const jsi::PropNameID& propNameId) {
+  auto name = propNameId.utf8(runtime);
+  __android_log_write(ANDROID_LOG_INFO, TAG, ("Getting prop \"" + name + "\"...").c_str());
+
+  if (name == "toString") {
+    auto toString = [this] (jsi::Runtime& runtime, const jsi::Value& thisValue, const jsi::Value* arguments, size_t count) -> jsi::Value {
+      auto width = this->frame->getWidth();
+      auto height = this->frame->getHeight();
+      auto str = std::to_string(width) + " x " + std::to_string(height) + " Frame";
+      return jsi::String::createFromUtf8(runtime, str);
+    };
+    return jsi::Function::createFromHostFunction(runtime, jsi::PropNameID::forUtf8(runtime, "toString"), 0, toString);
+  }
+
+  if (name == "isValid") {
+    return jsi::Value(this->frame->getIsValid());
+  }
+  if (name == "isReady") {
+    return jsi::Value(this->frame->getIsValid());
+  }
+  if (name == "width") {
+    return jsi::Value(this->frame->getWidth());
+  }
+  if (name == "height") {
+    return jsi::Value(this->frame->getHeight());
+  }
+  if (name == "bytesPerRow") {
+    return jsi::Value(this->frame->getBytesPerRow());
+  }
+  if (name == "planesCount") {
+    return jsi::Value(this->frame->getPlaneCount());
+  }
+
+  return jsi::Value::undefined();
+}
+
+
+JImageProxyHostObject::~JImageProxyHostObject() {
+  __android_log_write(ANDROID_LOG_INFO, TAG, "Destroying JImageProxyHostObject...");
+}
+
+} // namespace vision

android/src/main/cpp/JImageProxyHostObject.h

@@ -0,0 +1,35 @@
+//
+// Created by Marc on 19/06/2021.
+//
+
+#pragma once
+
+#include <jsi/jsi.h>
+#include <jni.h>
+#include <fbjni/fbjni.h>
+#include <vector>
+
+#include "JImageProxy.h"
+
+namespace vision {
+
+using namespace facebook;
+
+class JSI_EXPORT JImageProxyHostObject : public jsi::HostObject {
+ public:
+  explicit JImageProxyHostObject(jni::local_ref<JImageProxy::javaobject> image): frame(image) {}
+  ~JImageProxyHostObject();
+
+ public:
+  jsi::Value get(jsi::Runtime &, const jsi::PropNameID &name) override;
+
+  std::vector<jsi::PropNameID> getPropertyNames(jsi::Runtime &rt) override;
+
+ public:
+  jni::local_ref<JImageProxy> frame;
+
+ private:
+  static auto constexpr TAG = "VisionCamera";
+};
+
+} // namespace vision

android/src/main/cpp/JReadableArray.h

@@ -0,0 +1,19 @@
+//
+// Created by Marc Rousavy on 24.06.21.
+//
+
+#pragma once
+
+#include <jni.h>
+#include <fbjni/fbjni.h>
+
+namespace vision {
+
+using namespace facebook;
+using namespace jni;
+
+struct JReadableArray : public JavaClass<JReadableArray> {
+  static constexpr auto kJavaDescriptor = "Lcom/facebook/react/bridge/ReadableArray;";
+};
+
+} // namespace vision

android/src/main/cpp/JReadableMap.h

@@ -0,0 +1,19 @@
+//
+// Created by Marc Rousavy on 24.06.21.
+//
+
+#pragma once
+
+#include <jni.h>
+#include <fbjni/fbjni.h>
+
+namespace vision {
+
+using namespace facebook;
+using namespace jni;
+
+struct JReadableMap : public JavaClass<JReadableMap> {
+  static constexpr auto kJavaDescriptor = "Lcom/facebook/react/bridge/ReadableMap;";
+};
+
+} // namespace vision

android/src/main/cpp/JSIJNIConversion.cpp

@@ -0,0 +1,186 @@
+//
+// Created by Marc Rousavy on 22.06.21.
+//
+
+#include "JSIJNIConversion.h"
+
+#include <jsi/jsi.h>
+#include <jni.h>
+#include <fbjni/fbjni.h>
+#include <android/log.h>
+
+#include <string>
+#include <utility>
+
+#include <react/jni/NativeMap.h>
+#include <react/jni/ReadableNativeMap.h>
+#include <react/jni/WritableNativeMap.h>
+
+#include <jsi/JSIDynamic.h>
+#include <folly/dynamic.h>
+
+#include "JImageProxyHostObject.h"
+#include "JImageProxy.h"
+#include "JReadableArray.h"
+#include "JReadableMap.h"
+#include "JArrayList.h"
+#include "JHashMap.h"
+
+namespace vision {
+
+using namespace facebook;
+
+jobject JSIJNIConversion::convertJSIValueToJNIObject(jsi::Runtime &runtime, const jsi::Value &value) {
+  if (value.isBool()) {
+    // jsi::Bool
+
+    auto boolean = jni::JBoolean::valueOf(value.getBool());
+    return boolean.release();
+
+  } else if (value.isNumber()) {
+    // jsi::Number
+
+    auto number = jni::JDouble::valueOf(value.getNumber());
+    return number.release();
+
+  } else if (value.isNull() || value.isUndefined()) {
+    // jsi::undefined
+
+    return nullptr;
+
+  } else if (value.isString()) {
+    // jsi::String
+
+    auto string = jni::make_jstring(value.getString(runtime).utf8(runtime));
+    return string.release();
+
+  } else if (value.isObject()) {
+    // jsi::Object
+
+    auto object = value.asObject(runtime);
+
+    if (object.isArray(runtime)) {
+      // jsi::Array
+
+      auto dynamic = jsi::dynamicFromValue(runtime, value);
+      auto nativeArray = react::ReadableNativeArray::newObjectCxxArgs(std::move(dynamic));
+      return nativeArray.release();
+
+    } else if (object.isHostObject(runtime)) {
+      // jsi::HostObject
+
+      auto boxedHostObject = object.getHostObject(runtime);
+      auto hostObject = dynamic_cast<JImageProxyHostObject*>(boxedHostObject.get());
+      if (hostObject != nullptr) {
+        // return jni local_ref to the JImageProxy
+        return hostObject->frame.get();
+      } else {
+        // it's different kind of HostObject. We don't support it.
+        return nullptr;
+      }
+
+    } else if (object.isFunction(runtime)) {
+      // jsi::Function
+
+      // TODO: Convert Function to Callback
+      return nullptr;
+
+    } else {
+      // jsi::Object
+
+      auto dynamic = jsi::dynamicFromValue(runtime, value);
+      auto map = react::ReadableNativeMap::createWithContents(std::move(dynamic));
+      return map.release();
+    }
+  } else {
+    // unknown jsi type!
+    auto stringRepresentation = value.toString(runtime).utf8(runtime);
+    auto message = "Received unknown JSI value! (" + stringRepresentation + ") Cannot convert to JNI Object.";
+    __android_log_write(ANDROID_LOG_ERROR, "VisionCamera", message.c_str());
+    return nullptr;
+  }
+}
+
+jsi::Value JSIJNIConversion::convertJNIObjectToJSIValue(jsi::Runtime &runtime, const jni::local_ref<jobject>& object) {
+  if (object->isInstanceOf(jni::JBoolean::javaClassStatic())) {
+    // Boolean
+
+    static const auto getBooleanFunc = jni::findClassLocal("java/lang/Boolean")->getMethod<jboolean()>("booleanValue");
+    auto boolean = getBooleanFunc(object.get());
+    return jsi::Value(boolean == true);
+
+  } else if (object->isInstanceOf(jni::JDouble::javaClassStatic())) {
+    // Double
+
+    static const auto getDoubleFunc = jni::findClassLocal("java/lang/Double")->getMethod<jdouble()>("doubleValue");
+    auto d = getDoubleFunc(object.get());
+    return jsi::Value(d);
+
+  } else if (object->isInstanceOf(jni::JInteger::javaClassStatic())) {
+    // Integer
+
+    static const auto getIntegerFunc = jni::findClassLocal("java/lang/Integer")->getMethod<jint()>("integerValue");
+    auto i = getIntegerFunc(object.get());
+    return jsi::Value(i);
+
+  } else if (object->isInstanceOf(jni::JString::javaClassStatic())) {
+    // String
+
+    return jsi::String::createFromUtf8(runtime, object->toString());
+
+  } else if (object->isInstanceOf(JReadableArray::javaClassStatic())) {
+    // ReadableArray
+
+    static const auto toArrayListFunc = JReadableArray::javaClassLocal()->getMethod<jni::JArrayClass<jobject>()>("toArrayList");
+
+    auto array = toArrayListFunc(object.get());
+    auto size = array->size();
+
+    auto result = jsi::Array(runtime, size);
+    for (size_t i = 0; i < size; i++) {
+      result.setValueAtIndex(runtime, i, convertJNIObjectToJSIValue(runtime, (*array)[i]));
+    }
+    return result;
+
+  } else if (object->isInstanceOf(JArrayList::javaClassStatic())) {
+    // ArrayList
+
+    static const auto iteratorFunc = JArrayList::javaClassLocal()->getMethod<jni::JIterator<jobject>()>("iterator");
+    static const auto sizeFunc = JArrayList::javaClassLocal()->getMethod<jint()>("size");
+
+    auto iterator = iteratorFunc(object.get());
+    auto size = sizeFunc(object.get());
+
+    auto result = jsi::Array(runtime, size);
+    size_t i = 0;
+    for (auto& item : *iterator) {
+      result.setValueAtIndex(runtime, i, convertJNIObjectToJSIValue(runtime, item));
+      i++;
+    }
+    return result;
+
+  } else if (object->isInstanceOf(JReadableMap::javaClassStatic())) {
+    // ReadableMap
+
+    static const auto toHashMapFunc = JReadableMap::javaClassLocal()->getMethod<jni::JHashMap<jstring, jobject>()>("toHashMap");
+    auto hashMap = toHashMapFunc(object.get());
+
+    auto result = jsi::Object(runtime);
+
+    for (const auto& entry : *hashMap) {
+      auto key = entry.first->toString();
+      auto value = entry.second;
+      auto jsiValue = convertJNIObjectToJSIValue(runtime, value);
+      result.setProperty(runtime, key.c_str(), jsiValue);
+    }
+
+    return result;
+  }
+
+  auto type = object->getClass()->toString();
+  auto message = "Received unknown JNI type \"" + type + "\"! Cannot convert to jsi::Value.";
+  __android_log_write(ANDROID_LOG_ERROR, "VisionCamera", message.c_str());
+  return jsi::Value::undefined();
+}
+
+} // namespace vision

android/src/main/cpp/JSIJNIConversion.h

@@ -0,0 +1,21 @@
+//
+// Created by Marc Rousavy on 22.06.21.
+//
+
+#pragma once
+
+#include <jsi/jsi.h>
+#include <jni.h>
+#include <fbjni/fbjni.h>
+
+namespace vision {
+
+using namespace facebook;
+
+namespace JSIJNIConversion {
+  jobject convertJSIValueToJNIObject(jsi::Runtime& runtime, const jsi::Value& value); // NOLINT(runtime/references)
+
+  jsi::Value convertJNIObjectToJSIValue(jsi::Runtime& runtime, const jni::local_ref<jobject>& object); // NOLINT(runtime/references)
+};
+
+} // namespace vision

android/src/main/cpp/VisionCamera.cpp

@@ -0,0 +1,13 @@
+#include <jni.h>
+#include <fbjni/fbjni.h>
+#include "FrameProcessorRuntimeManager.h"
+#include "FrameProcessorPlugin.h"
+#include "CameraView.h"
+
+JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *vm, void *) {
+  return facebook::jni::initialize(vm, [] {
+    vision::FrameProcessorRuntimeManager::registerNatives();
+    vision::FrameProcessorPlugin::registerNatives();
+    vision::CameraView::registerNatives();
+  });
+}

android/src/main/cpp/reanimated-headers/AndroidErrorHandler.h

@@ -0,0 +1,30 @@
+// copied from https://github.com/software-mansion/react-native-reanimated/blob/master/android/src/main/cpp/headers/AndroidErrorHandler.h
+
+#pragma once
+
+#include "ErrorHandler.h"
+#include "AndroidScheduler.h"
+#include "Scheduler.h"
+#include <jni.h>
+#include <memory>
+#include <fbjni/fbjni.h>
+#include "Logger.h"
+
+namespace reanimated
+{
+
+  class AndroidErrorHandler : public JavaClass<AndroidErrorHandler>, public ErrorHandler {
+    std::shared_ptr<ErrorWrapper> error;
+    std::shared_ptr<Scheduler> scheduler;
+    void raiseSpec() override;
+  public:
+    static auto constexpr kJavaDescriptor = "Lcom/swmansion/reanimated/AndroidErrorHandler;";
+    AndroidErrorHandler(
+        std::shared_ptr<Scheduler> scheduler);
+    std::shared_ptr<Scheduler> getScheduler() override;
+    std::shared_ptr<ErrorWrapper> getError() override;
+    void setError(std::string message) override;
+    virtual ~AndroidErrorHandler() {}
+  };
+
+}

android/src/main/cpp/reanimated-headers/AndroidScheduler.h

@@ -0,0 +1,37 @@
+// copied from https://github.com/software-mansion/react-native-reanimated/blob/master/android/src/main/cpp/headers/AndroidScheduler.h
+
+#pragma once
+
+#include <jni.h>
+#include <fbjni/fbjni.h>
+#include <jsi/jsi.h>
+#include <react/jni/CxxModuleWrapper.h>
+#include <react/jni/JMessageQueueThread.h>
+#include "Scheduler.h"
+
+namespace reanimated {
+
+  using namespace facebook;
+
+  class AndroidScheduler : public jni::HybridClass<AndroidScheduler> {
+  public:
+    static auto constexpr kJavaDescriptor = "Lcom/swmansion/reanimated/Scheduler;";
+    static jni::local_ref<jhybriddata> initHybrid(jni::alias_ref<jhybridobject> jThis);
+    static void registerNatives();
+
+    std::shared_ptr<Scheduler> getScheduler() { return scheduler_; }
+
+    void scheduleOnUI();
+
+  private:
+    friend HybridBase;
+
+    void triggerUI();
+
+    jni::global_ref<AndroidScheduler::javaobject> javaPart_;
+    std::shared_ptr<Scheduler> scheduler_;
+
+    explicit AndroidScheduler(jni::alias_ref<AndroidScheduler::jhybridobject> jThis);
+  };
+
+}

android/src/main/java/com/mrousavy/camera/CameraView+TakePhoto.kt

@@ -17,8 +17,13 @@ import kotlin.system.measureTimeMillis
 
 @SuppressLint("UnsafeOptInUsageError")
 suspend fun CameraView.takePhoto(options: ReadableMap): WritableMap = coroutineScope {
+  if (fallbackToSnapshot) {
+    Log.i(CameraView.TAG, "takePhoto() called, but falling back to Snapshot because 1 use-case is already occupied.")
+    return@coroutineScope takeSnapshot(options)
+  }
+
   val startFunc = System.nanoTime()
-  Log.d(CameraView.TAG, "takePhoto() called")
+  Log.i(CameraView.TAG, "takePhoto() called")
   if (imageCapture == null) {
     if (photo == true) {
       throw CameraNotReadyError()

android/src/main/java/com/mrousavy/camera/CameraView+TakeSnapshot.kt

@@ -11,32 +11,48 @@ import kotlinx.coroutines.coroutineScope
 import kotlinx.coroutines.withContext
 import java.io.File
 import java.io.FileOutputStream
+import kotlinx.coroutines.guava.await
 
 suspend fun CameraView.takeSnapshot(options: ReadableMap): WritableMap = coroutineScope {
-  val bitmap = this@takeSnapshot.previewView.bitmap ?: throw CameraNotReadyError()
+  val camera = camera ?: throw com.mrousavy.camera.CameraNotReadyError()
+  val enableFlash = options.getString("flash") == "on"
 
-  val quality = if (options.hasKey("quality")) options.getInt("quality") else 100
-
-  val file: File
-  val exif: ExifInterface
-  @Suppress("BlockingMethodInNonBlockingContext")
-  withContext(Dispatchers.IO) {
-    file = File.createTempFile("mrousavy", ".jpg", context.cacheDir).apply { deleteOnExit() }
-    FileOutputStream(file).use { stream ->
-      bitmap.compress(Bitmap.CompressFormat.JPEG, quality, stream)
+  try {
+    if (enableFlash) {
+      camera.cameraControl.enableTorch(true).await()
+    }
+
+    val bitmap = this@takeSnapshot.previewView.bitmap ?: throw CameraNotReadyError()
+
+    val quality = if (options.hasKey("quality")) options.getInt("quality") else 100
+
+    val file: File
+    val exif: ExifInterface
+    @Suppress("BlockingMethodInNonBlockingContext")
+    withContext(Dispatchers.IO) {
+      file = File.createTempFile("mrousavy", ".jpg", context.cacheDir).apply { deleteOnExit() }
+      FileOutputStream(file).use { stream ->
+        bitmap.compress(Bitmap.CompressFormat.JPEG, quality, stream)
+      }
+      exif = ExifInterface(file)
+    }
+
+    val map = Arguments.createMap()
+    map.putString("path", file.absolutePath)
+    map.putInt("width", bitmap.width)
+    map.putInt("height", bitmap.height)
+    map.putBoolean("isRawPhoto", false)
+
+    val skipMetadata =
+      if (options.hasKey("skipMetadata")) options.getBoolean("skipMetadata") else false
+    val metadata = if (skipMetadata) null else exif.buildMetadataMap()
+    map.putMap("metadata", metadata)
+
+    return@coroutineScope map
+  } finally {
+    if (enableFlash) {
+      // reset to `torch` property
+      camera.cameraControl.enableTorch(this@takeSnapshot.torch == "on")
     }
-    exif = ExifInterface(file)
   }
-
-  val map = Arguments.createMap()
-  map.putString("path", file.absolutePath)
-  map.putInt("width", bitmap.width)
-  map.putInt("height", bitmap.height)
-  map.putBoolean("isRawPhoto", false)
-
-  val skipMetadata = if (options.hasKey("skipMetadata")) options.getBoolean("skipMetadata") else false
-  val metadata = if (skipMetadata) null else exif.buildMetadataMap()
-  map.putMap("metadata", metadata)
-
-  return@coroutineScope map
 }

android/src/main/java/com/mrousavy/camera/CameraView.kt

@@ -21,6 +21,8 @@ import androidx.camera.lifecycle.ProcessCameraProvider
 import androidx.camera.view.PreviewView
 import androidx.core.content.ContextCompat
 import androidx.lifecycle.*
+import com.facebook.jni.HybridData
+import com.facebook.proguard.annotations.DoNotStrip
 import com.facebook.react.bridge.*
 import com.facebook.react.uimanager.events.RCTEventEmitter
 import com.mrousavy.camera.utils.*
@@ -82,11 +84,14 @@ class CameraView(context: Context) : FrameLayout(context), LifecycleOwner {
   var torch = "off"
   var zoom = 0.0 // in percent
   var enableZoomGesture = false
+  var frameProcessorFps = 1.0
 
   // private properties
   private val reactContext: ReactContext
     get() = context as ReactContext
 
+  private var enableFrameProcessor = false
+
   @Suppress("JoinDeclarationAndAssignment")
   internal val previewView: PreviewView
   private val cameraExecutor = Executors.newSingleThreadExecutor()
@@ -96,6 +101,7 @@ class CameraView(context: Context) : FrameLayout(context), LifecycleOwner {
   internal var camera: Camera? = null
   internal var imageCapture: ImageCapture? = null
   internal var videoCapture: VideoCapture? = null
+  internal var imageAnalysis: ImageAnalysis? = null
 
   private val scaleGestureListener: ScaleGestureDetector.SimpleOnScaleGestureListener
   private val scaleGestureDetector: ScaleGestureDetector
@@ -107,7 +113,42 @@ class CameraView(context: Context) : FrameLayout(context), LifecycleOwner {
   private var minZoom: Float = 1f
   private var maxZoom: Float = 1f
 
+  @DoNotStrip
+  private var mHybridData: HybridData?
+
+  @Suppress("LiftReturnOrAssignment", "RedundantIf")
+  internal val fallbackToSnapshot: Boolean
+    @SuppressLint("UnsafeOptInUsageError")
+    get() {
+      if (video != true && !enableFrameProcessor) {
+        // Both use-cases are disabled, so `photo` is the only use-case anyways. Don't need to fallback here.
+        return false
+      }
+      cameraId?.let { cameraId ->
+        val cameraManger = reactContext.getSystemService(Context.CAMERA_SERVICE) as? CameraManager
+        cameraManger?.let {
+          val characteristics = cameraManger.getCameraCharacteristics(cameraId)
+          val hardwareLevel = characteristics.get(CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL)
+          if (hardwareLevel == CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL_LEGACY) {
+            // Camera only supports a single use-case at a time
+            return true
+          } else {
+            if (video == true && enableFrameProcessor) {
+              // Camera supports max. 2 use-cases, but both are occupied by `frameProcessor` and `video`
+              return true
+            } else {
+              // Camera supports max. 2 use-cases and only one is occupied (either `frameProcessor` or `video`), so we can add `photo`
+              return false
+            }
+          }
+        }
+      }
+      return false
+    }
+
   init {
+    mHybridData = initHybrid()
+
     previewView = PreviewView(context)
     previewView.layoutParams = LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT)
     previewView.installHierarchyFitter() // If this is not called correctly, view finder will be black/blank
@@ -144,6 +185,28 @@ class CameraView(context: Context) : FrameLayout(context), LifecycleOwner {
     })
   }
 
+  fun finalize() {
+    mHybridData?.resetNative()
+  }
+
+  private external fun initHybrid(): HybridData
+  private external fun frameProcessorCallback(frame: ImageProxy)
+
+  @Suppress("unused")
+  @DoNotStrip
+  fun setEnableFrameProcessor(enable: Boolean) {
+    Log.d(TAG, "Set enable frame processor: $enable")
+    val before = enableFrameProcessor
+    enableFrameProcessor = enable
+
+    if (before != enable) {
+      // reconfigure session if frame processor was added/removed to adjust use-cases.
+      GlobalScope.launch(Dispatchers.Main) {
+        configureSession()
+      }
+    }
+  }
+
   override fun getLifecycle(): Lifecycle {
     return lifecycleRegistry
   }
@@ -245,6 +308,10 @@ class CameraView(context: Context) : FrameLayout(context), LifecycleOwner {
         .setCaptureMode(ImageCapture.CAPTURE_MODE_MINIMIZE_LATENCY)
       val videoCaptureBuilder = VideoCapture.Builder()
         .setTargetRotation(rotation)
+      val imageAnalysisBuilder = ImageAnalysis.Builder()
+        .setBackpressureStrategy(ImageAnalysis.STRATEGY_KEEP_ONLY_LATEST)
+        .setTargetRotation(rotation)
+        .setBackgroundExecutor(CameraViewModule.FrameProcessorThread)
 
       if (format == null) {
         // let CameraX automatically find best resolution for the target aspect ratio
@@ -311,11 +378,10 @@ class CameraView(context: Context) : FrameLayout(context), LifecycleOwner {
         }
       }
 
-      val preview = previewBuilder.build()
-
       // Unbind use cases before rebinding
       videoCapture = null
       imageCapture = null
+      imageAnalysis = null
       cameraProvider.unbindAll()
 
       // Bind use cases to camera
@@ -325,9 +391,32 @@ class CameraView(context: Context) : FrameLayout(context), LifecycleOwner {
         useCases.add(videoCapture!!)
       }
       if (photo == true) {
-        imageCapture = imageCaptureBuilder.build()
-        useCases.add(imageCapture!!)
+        if (fallbackToSnapshot) {
+          Log.i(TAG, "Tried to add photo use-case (`photo={true}`) but the Camera device only supports " +
+            "a single use-case at a time. Falling back to Snapshot capture.")
+        } else {
+          imageCapture = imageCaptureBuilder.build()
+          useCases.add(imageCapture!!)
+        }
       }
+      if (enableFrameProcessor) {
+        var lastCall = System.currentTimeMillis() - 1000
+        val intervalMs = (1.0 / frameProcessorFps) * 1000.0
+        imageAnalysis = imageAnalysisBuilder.build().apply {
+          setAnalyzer(cameraExecutor, { image ->
+            val now = System.currentTimeMillis()
+            if (now - lastCall > intervalMs) {
+              lastCall = now
+              Log.d(TAG, "Calling Frame Processor...")
+              frameProcessorCallback(image)
+            }
+            image.close()
+          })
+        }
+        useCases.add(imageAnalysis!!)
+      }
+
+      val preview = previewBuilder.build()
       camera = cameraProvider.bindToLifecycle(this, cameraSelector, preview, *useCases.toTypedArray())
       preview.setSurfaceProvider(previewView.surfaceProvider)
 
@@ -338,11 +427,18 @@ class CameraView(context: Context) : FrameLayout(context), LifecycleOwner {
       Log.i(TAG_PERF, "Session configured in $duration ms! Camera: ${camera!!}")
       invokeOnInitialized()
     } catch (exc: Throwable) {
-      throw when (exc) {
+      val error = when (exc) {
         is CameraError -> exc
-        is IllegalArgumentException -> InvalidCameraDeviceError(exc)
+        is IllegalArgumentException -> {
+          if (exc.message?.contains("too many use cases") == true) {
+            ParallelVideoProcessingNotSupportedError(exc)
+          } else {
+            InvalidCameraDeviceError(exc)
+          }
+        }
         else -> UnknownCameraError(exc)
       }
+      invokeOnError(error)
     }
   }
 
@@ -381,7 +477,7 @@ class CameraView(context: Context) : FrameLayout(context), LifecycleOwner {
     const val TAG = "CameraView"
     const val TAG_PERF = "CameraView.performance"
 
-    private val propsThatRequireSessionReconfiguration = arrayListOf("cameraId", "format", "fps", "hdr", "lowLightBoost", "photo", "video")
+    private val propsThatRequireSessionReconfiguration = arrayListOf("cameraId", "format", "fps", "hdr", "lowLightBoost", "photo", "video", "frameProcessorFps")
 
     private val arrayListOfZoom = arrayListOf("zoom")
   }

android/src/main/java/com/mrousavy/camera/CameraViewManager.kt

@@ -1,7 +1,6 @@
 package com.mrousavy.camera
 
 import android.util.Log
-import com.facebook.react.bridge.ReadableArray
 import com.facebook.react.bridge.ReadableMap
 import com.facebook.react.common.MapBuilder
 import com.facebook.react.uimanager.SimpleViewManager
@@ -81,6 +80,13 @@ class CameraViewManager : SimpleViewManager<CameraView>() {
     view.fps = if (fps > 0) fps else null
   }
 
+  @ReactProp(name = "frameProcessorFps", defaultDouble = 1.0)
+  fun setFrameProcessorFps(view: CameraView, frameProcessorFps: Double) {
+    if (view.frameProcessorFps != frameProcessorFps)
+      addChangedPropToTransaction(view, "frameProcessorFps")
+    view.frameProcessorFps = frameProcessorFps
+  }
+
   @ReactProp(name = "hdr")
   fun setHdr(view: CameraView, hdr: Boolean?) {
     if (view.hdr != hdr)

android/src/main/java/com/mrousavy/camera/CameraViewModule.kt

@@ -17,8 +17,11 @@ import androidx.core.content.ContextCompat
 import com.facebook.react.bridge.*
 import com.facebook.react.modules.core.PermissionAwareActivity
 import com.facebook.react.modules.core.PermissionListener
+import com.mrousavy.camera.frameprocessor.FrameProcessorRuntimeManager
 import com.mrousavy.camera.parsers.*
 import com.mrousavy.camera.utils.*
+import java.util.concurrent.ExecutorService
+import java.util.concurrent.Executors
 import kotlinx.coroutines.*
 import kotlinx.coroutines.guava.await
 
@@ -26,6 +29,7 @@ class CameraViewModule(reactContext: ReactApplicationContext) : ReactContextBase
   companion object {
     const val REACT_CLASS = "CameraView"
     var RequestCode = 10
+    val FrameProcessorThread: ExecutorService = Executors.newSingleThreadExecutor()
 
     fun parsePermissionStatus(status: Int): String {
       return when (status) {
@@ -36,6 +40,23 @@ class CameraViewModule(reactContext: ReactApplicationContext) : ReactContextBase
     }
   }
 
+  private var frameProcessorManager: FrameProcessorRuntimeManager? = null
+
+  override fun initialize() {
+    super.initialize()
+    FrameProcessorThread.execute {
+      frameProcessorManager = FrameProcessorRuntimeManager(reactApplicationContext)
+      reactApplicationContext.runOnJSQueueThread {
+        frameProcessorManager!!.installJSIBindings()
+      }
+    }
+  }
+
+  override fun onCatalystInstanceDestroy() {
+    super.onCatalystInstanceDestroy()
+    frameProcessorManager?.destroy()
+  }
+
   override fun getName(): String {
     return REACT_CLASS
   }
@@ -73,7 +94,7 @@ class CameraViewModule(reactContext: ReactApplicationContext) : ReactContextBase
         val map = makeErrorMap("${error.domain}/${error.id}", error.message, error)
         onRecordCallback(null, map)
       } catch (error: Throwable) {
-        val map = makeErrorMap("capture/unknown", "An unknown error occured while trying to start a video recording!", error)
+        val map = makeErrorMap("capture/unknown", "An unknown error occurred while trying to start a video recording!", error)
         onRecordCallback(null, map)
       }
     }
@@ -149,6 +170,8 @@ class CameraViewModule(reactContext: ReactApplicationContext) : ReactContextBase
           val supportsHdr = hdrExtension.isExtensionAvailable(cameraSelector)
           val nightExtension = NightImageCaptureExtender.create(imageCaptureBuilder)
           val supportsLowLightBoost = nightExtension.isExtensionAvailable(cameraSelector)
+          // see https://developer.android.com/reference/android/hardware/camera2/CameraDevice#regular-capture
+          val supportsParallelVideoProcessing = hardwareLevel != CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL_LEGACY && hardwareLevel != CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL_LIMITED
 
           val fieldOfView = characteristics.getFieldOfView()
 
@@ -160,7 +183,7 @@ class CameraViewModule(reactContext: ReactApplicationContext) : ReactContextBase
           map.putBoolean("hasFlash", hasFlash)
           map.putBoolean("hasTorch", hasFlash)
           map.putBoolean("isMultiCam", isMultiCam)
-          map.putBoolean("supportsPhotoAndVideoCapture", hardwareLevel != CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL_LEGACY)
+          map.putBoolean("supportsParallelVideoProcessing", supportsParallelVideoProcessing)
           map.putBoolean("supportsRawCapture", supportsRawCapture)
           map.putBoolean("supportsDepthCapture", supportsDepthCapture)
           map.putBoolean("supportsLowLightBoost", supportsLowLightBoost)

android/src/main/java/com/mrousavy/camera/Errors.kt

@@ -37,6 +37,9 @@ class InvalidTypeScriptUnionError(unionName: String, unionValue: String) : Camer
 
 class NoCameraDeviceError : CameraError("device", "no-device", "No device was set! Use `getAvailableCameraDevices()` to select a suitable Camera device.")
 class InvalidCameraDeviceError(cause: Throwable) : CameraError("device", "invalid-device", "The given Camera device could not be found for use-case binding!", cause)
+class ParallelVideoProcessingNotSupportedError(cause: Throwable) : CameraError("device", "parallel-video-processing-not-supported", "The given LEGACY Camera device does not support parallel " +
+  "video processing (`video={true}` + `frameProcessor={...}`). Disable either `video` or `frameProcessor`. To find out if a device supports parallel video processing, check the `supportsParallelVideoProcessing` property on the CameraDevice. " +
+  "See https://mrousavy.github.io/react-native-vision-camera/docs/guides/lifecycle#the-supportsparallelvideoprocessing-prop for more information.", cause)
 
 class FpsNotContainedInFormatError(fps: Int) : CameraError("format", "invalid-fps", "The given FPS were not valid for the currently selected format. Make sure you select a format which `frameRateRanges` includes $fps FPS!")
 class HdrNotContainedInFormatError() : CameraError(

android/src/main/java/com/mrousavy/camera/frameprocessor/FrameProcessorPlugin.java

@@ -0,0 +1,54 @@
+package com.mrousavy.camera.frameprocessor;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.camera.core.ImageProxy;
+import com.facebook.jni.HybridData;
+
+/**
+ * Declares a Frame Processor Plugin.
+ */
+public abstract class FrameProcessorPlugin {
+    static {
+        System.loadLibrary("VisionCamera");
+    }
+
+    @SuppressWarnings({"FieldCanBeLocal", "unused"})
+    private final HybridData mHybridData;
+
+    /**
+     * The actual Frame Processor plugin callback. Called for every frame the ImageAnalyzer receives.
+     * @param image The CameraX ImageProxy. Don't call .close() on this, as VisionCamera handles that.
+     * @return You can return any primitive, map or array you want. See the
+     * <a href="https://mrousavy.github.io/react-native-vision-camera/docs/guides/frame-processors-plugins-overview#types">Types</a>
+     * table for a list of supported types.
+     */
+    public abstract @Nullable Object callback(@NonNull ImageProxy image, @NonNull Object[] params);
+
+    /**
+     * Initializes the native plugin part.
+     * @param name Specifies the Frame Processor Plugin's name in the Runtime.
+     *             The actual name in the JS Runtime will be prefixed with two underscores (`__`)
+     */
+    protected FrameProcessorPlugin(@NonNull String name) {
+        mHybridData = initHybrid(name);
+    }
+
+    @Override
+    protected void finalize() throws Throwable {
+        super.finalize();
+        if (mHybridData != null) {
+            mHybridData.resetNative();
+        }
+    }
+
+    private native @NonNull HybridData initHybrid(@NonNull String name);
+
+    /**
+     * Registers the given plugin in the Frame Processor Runtime.
+     * @param plugin An instance of a plugin.
+     */
+    public static void register(@NonNull FrameProcessorPlugin plugin) {
+        FrameProcessorRuntimeManager.Companion.getPlugins().add(plugin);
+    }
+}

android/src/main/java/com/mrousavy/camera/frameprocessor/FrameProcessorRuntimeManager.kt

@@ -0,0 +1,75 @@
+package com.mrousavy.camera.frameprocessor
+
+import android.util.Log
+import com.facebook.jni.HybridData
+import com.facebook.proguard.annotations.DoNotStrip
+import com.facebook.react.bridge.ReactApplicationContext
+import com.facebook.react.turbomodule.core.CallInvokerHolderImpl
+import com.mrousavy.camera.CameraView
+import com.mrousavy.camera.ViewNotFoundError
+import com.swmansion.reanimated.Scheduler
+import java.lang.ref.WeakReference
+
+class FrameProcessorRuntimeManager(context: ReactApplicationContext) {
+  companion object {
+    const val TAG = "FrameProcessorRuntime"
+    private var HasRegisteredPlugins = false
+    val Plugins: ArrayList<FrameProcessorPlugin> = ArrayList()
+      get() {
+        if (HasRegisteredPlugins) {
+          throw Error("Tried to access Frame Processor Plugin list, " +
+            "but plugins have already been registered (list is frozen now!).")
+        }
+        return field
+      }
+
+    init {
+      System.loadLibrary("reanimated")
+      System.loadLibrary("VisionCamera")
+    }
+  }
+
+  @DoNotStrip
+  private var mHybridData: HybridData?
+  private var mContext: WeakReference<ReactApplicationContext>?
+  private var mScheduler: Scheduler?
+
+  init {
+    val holder = context.catalystInstance.jsCallInvokerHolder as CallInvokerHolderImpl
+    mScheduler = Scheduler(context)
+    mContext = WeakReference(context)
+    mHybridData = initHybrid(context.javaScriptContextHolder.get(), holder, mScheduler!!)
+    initializeRuntime()
+
+    Log.i(TAG, "Installing Frame Processor Plugins...")
+    Plugins.forEach { plugin ->
+      registerPlugin(plugin)
+    }
+    Log.i(TAG, "Successfully installed ${Plugins.count()} Frame Processor Plugins!")
+    HasRegisteredPlugins = true
+  }
+
+  fun destroy() {
+    mScheduler?.deactivate()
+    mHybridData?.resetNative()
+  }
+
+  fun findCameraViewById(viewId: Int): CameraView {
+    Log.d(TAG, "finding view $viewId...")
+    val view = mContext?.get()?.currentActivity?.findViewById<CameraView>(viewId)
+    Log.d(TAG, "found view $viewId! is null: ${view == null}")
+    return view ?: throw ViewNotFoundError(viewId)
+  }
+
+  // private C++ funcs
+  private external fun initHybrid(
+    jsContext: Long,
+    jsCallInvokerHolder: CallInvokerHolderImpl,
+    scheduler: Scheduler
+  ): HybridData?
+  private external fun initializeRuntime()
+  private external fun registerPlugin(plugin: FrameProcessorPlugin)
+
+  // public C++ funcs
+  external fun installJSIBindings()
+}

android/src/main/java/com/mrousavy/camera/utils/ImageProxy.save.kt

@@ -14,7 +14,6 @@ import java.io.FileOutputStream
 import java.nio.ByteBuffer
 import kotlin.system.measureTimeMillis
 
-
 // TODO: Fix this flip() function (this outputs a black image)
 fun flip(imageBytes: ByteArray, imageWidth: Int): ByteArray {
   // separate out the sub arrays