react-native-vision-camera/package/android/src/main/cpp/frameprocessor/FrameHostObject.cpp

//
// Created by Marc on 19/06/2021.
//

#include "FrameHostObject.h"

#include <fbjni/fbjni.h>
#include <jni.h>

#include "JSITypedArray.h"

#include <string>
#include <vector>

#include <android/hardware_buffer.h>
#include <android/hardware_buffer_jni.h>

namespace vision {

using namespace facebook;

FrameHostObject::FrameHostObject(const jni::alias_ref<JFrame::javaobject>& frame) : frame(make_global(frame)) {}

FrameHostObject::~FrameHostObject() {
  // Hermes' Garbage Collector (Hades GC) calls destructors on a separate Thread
  // which might not be attached to JNI. Ensure that we use the JNI class loader when
  // deallocating the `frame` HybridClass, because otherwise JNI cannot call the Java
  // destroy() function.
  jni::ThreadScope::WithClassLoader([&] { frame.reset(); });
}

std::vector<jsi::PropNameID> FrameHostObject::getPropertyNames(jsi::Runtime& rt) {
  std::vector<jsi::PropNameID> result;
  // Ref Management
  result.push_back(jsi::PropNameID::forUtf8(rt, std::string("isValid")));
  result.push_back(jsi::PropNameID::forUtf8(rt, std::string("incrementRefCount")));
  result.push_back(jsi::PropNameID::forUtf8(rt, std::string("decrementRefCount")));

  if (frame != nullptr && frame->getIsValid()) {
    // Frame Properties
    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")));
    result.push_back(jsi::PropNameID::forUtf8(rt, std::string("orientation")));
    result.push_back(jsi::PropNameID::forUtf8(rt, std::string("isMirrored")));
    result.push_back(jsi::PropNameID::forUtf8(rt, std::string("timestamp")));
    result.push_back(jsi::PropNameID::forUtf8(rt, std::string("pixelFormat")));
    // Conversion
    result.push_back(jsi::PropNameID::forUtf8(rt, std::string("toString")));
    result.push_back(jsi::PropNameID::forUtf8(rt, std::string("toArrayBuffer")));
  }

  return result;
}

#define JSI_FUNC [=](jsi::Runtime & runtime, const jsi::Value& thisValue, const jsi::Value* arguments, size_t count) -> jsi::Value

jsi::Value FrameHostObject::get(jsi::Runtime& runtime, const jsi::PropNameID& propName) {
  auto name = propName.utf8(runtime);

  if (name == "incrementRefCount") {
    jsi::HostFunctionType incrementRefCount = JSI_FUNC {
      // Increment retain count by one.
      this->frame->incrementRefCount();
      return jsi::Value::undefined();
    };
    return jsi::Function::createFromHostFunction(runtime, jsi::PropNameID::forUtf8(runtime, "incrementRefCount"), 0, incrementRefCount);
  }
  if (name == "decrementRefCount") {
    auto decrementRefCount = JSI_FUNC {
      // Decrement retain count by one. If the retain count is zero, the Frame gets closed.
      this->frame->decrementRefCount();
      return jsi::Value::undefined();
    };
    return jsi::Function::createFromHostFunction(runtime, jsi::PropNameID::forUtf8(runtime, "decrementRefCount"), 0, decrementRefCount);
  }
  if (name == "toString") {
    jsi::HostFunctionType toString = JSI_FUNC {
      if (!this->frame) {
        return jsi::String::createFromUtf8(runtime, "[closed frame]");
      }
      auto width = this->frame->getWidth();
      auto height = this->frame->getHeight();
      auto format = this->frame->getPixelFormat();
      auto formatString = format->getUnionValue();
      auto str = std::to_string(width) + " x " + std::to_string(height) + " " + formatString->toString() + " Frame";
      return jsi::String::createFromUtf8(runtime, str);
    };
    return jsi::Function::createFromHostFunction(runtime, jsi::PropNameID::forUtf8(runtime, "toString"), 0, toString);
  }
  if (name == "toArrayBuffer") {
    jsi::HostFunctionType toArrayBuffer = JSI_FUNC {
#if __ANDROID_API__ >= 26
      AHardwareBuffer* hardwareBuffer = this->frame->getHardwareBuffer();

      AHardwareBuffer_Desc bufferDescription;
      AHardwareBuffer_describe(hardwareBuffer, &bufferDescription);
      __android_log_print(ANDROID_LOG_INFO, "Frame", "Buffer %i x %i @ %i", bufferDescription.width, bufferDescription.height,
                          bufferDescription.stride);
      size_t size = bufferDescription.height * bufferDescription.stride;

      static constexpr auto ARRAYBUFFER_CACHE_PROP_NAME = "__frameArrayBufferCache";
      if (!runtime.global().hasProperty(runtime, ARRAYBUFFER_CACHE_PROP_NAME)) {
        vision::TypedArray<vision::TypedArrayKind::Uint8ClampedArray> arrayBuffer(runtime, size);
        runtime.global().setProperty(runtime, ARRAYBUFFER_CACHE_PROP_NAME, arrayBuffer);
      }

      // Get from global JS cache
      auto arrayBufferCache = runtime.global().getPropertyAsObject(runtime, ARRAYBUFFER_CACHE_PROP_NAME);
      auto arrayBuffer = vision::getTypedArray(runtime, arrayBufferCache).get<vision::TypedArrayKind::Uint8ClampedArray>(runtime);
      if (arrayBuffer.size(runtime) != size) {
        arrayBuffer = vision::TypedArray<vision::TypedArrayKind::Uint8ClampedArray>(runtime, size);
        runtime.global().setProperty(runtime, ARRAYBUFFER_CACHE_PROP_NAME, arrayBuffer);
      }

      // Get CPU access to the HardwareBuffer (&buffer is a virtual temporary address)
      void* buffer;
      AHardwareBuffer_lock(hardwareBuffer, AHARDWAREBUFFER_USAGE_CPU_READ_MASK, -1, nullptr, &buffer);

      // directly write to C++ JSI ArrayBuffer
      auto destinationBuffer = arrayBuffer.data(runtime);
      memcpy(destinationBuffer, buffer, sizeof(uint8_t) * size);

      // Release HardwareBuffer again
      AHardwareBuffer_unlock(hardwareBuffer, nullptr);
      AHardwareBuffer_release(hardwareBuffer);

      return arrayBuffer;
#else
      throw jsi::JSError(runtime, "Frame.toArrayBuffer() is only available if minSdkVersion is set to 26 or higher!");
#endif
    };
    return jsi::Function::createFromHostFunction(runtime, jsi::PropNameID::forUtf8(runtime, "toArrayBuffer"), 0, toArrayBuffer);
  }

  if (name == "isValid") {
    return jsi::Value(this->frame && this->frame->getIsValid());
  }
  if (name == "width") {
    return jsi::Value(this->frame->getWidth());
  }
  if (name == "height") {
    return jsi::Value(this->frame->getHeight());
  }
  if (name == "isMirrored") {
    return jsi::Value(this->frame->getIsMirrored());
  }
  if (name == "orientation") {
    auto orientation = this->frame->getOrientation();
    auto string = orientation->getUnionValue();
    return jsi::String::createFromUtf8(runtime, string->toStdString());
  }
  if (name == "pixelFormat") {
    auto pixelFormat = this->frame->getPixelFormat();
    auto string = pixelFormat->getUnionValue();
    return jsi::String::createFromUtf8(runtime, string->toStdString());
  }
  if (name == "timestamp") {
    return jsi::Value(static_cast<double>(this->frame->getTimestamp()));
  }
  if (name == "bytesPerRow") {
    return jsi::Value(this->frame->getBytesPerRow());
  }
  if (name == "planesCount") {
    return jsi::Value(this->frame->getPlanesCount());
  }

  // fallback to base implementation
  return HostObject::get(runtime, propName);
}

} // namespace vision