mrmBot-Matrix/natives/caption.cc

#include <Magick++.h>
#include <napi.h>

#include <list>

using namespace std;
using namespace Magick;

Napi::Value Caption(const Napi::CallbackInfo &info) {
  Napi::Env env = info.Env();

  Napi::Object obj = info[0].As<Napi::Object>();
  string path = obj.Get("path").As<Napi::String>().Utf8Value();
  string caption = obj.Get("caption").As<Napi::String>().Utf8Value();
  string type = obj.Get("type").As<Napi::String>().Utf8Value();
  int delay =
      obj.Has("delay") ? obj.Get("delay").As<Napi::Number>().Int32Value() : 0;

  Blob blob;

  list<Image> frames;
  list<Image> coalesced;
  list<Image> captioned;
  readImages(&frames, path);

  size_t width = frames.front().baseColumns();
  string query(to_string(width - ((width / 25) * 2)) + "x");
  Image caption_image(Geometry(query), Color("white"));
  caption_image.fillColor("black");
  caption_image.alpha(true);
  caption_image.font("Futura");
  caption_image.fontPointsize(width / 13);
  caption_image.textGravity(Magick::CenterGravity);
  caption_image.read("pango:" + caption);
  caption_image.extent(Geometry(width, caption_image.rows() + (width / 13)),
                       Magick::CenterGravity);

  coalesceImages(&coalesced, frames.begin(), frames.end());

  for (Image &image : coalesced) {
    Image appended;
    list<Image> images;
    image.backgroundColor("white");
    images.push_back(caption_image);
    images.push_back(image);
    appendImages(&appended, images.begin(), images.end(), true);
    appended.repage();
    appended.magick(type);
    appended.animationDelay(delay == 0 ? image.animationDelay() : delay);
    appended.gifDisposeMethod(Magick::BackgroundDispose);
    captioned.push_back(appended);
  }

  optimizeTransparency(captioned.begin(), captioned.end());

  if (type == "gif") {
    for (Image &image : captioned) {
      image.quantizeDither(false);
      image.quantize();
    }
  }

  writeImages(captioned.begin(), captioned.end(), &blob);

  Napi::Object result = Napi::Object::New(env);
  result.Set("data",
          Napi::Buffer<char>::Copy(env, (char *)blob.data(), blob.length()));
  result.Set("type", type);
  return result;
}