mrmBot-Matrix/natives/uncaption.cc

#include "common.h"

#include <map>
#include <vips/vips8>

using namespace std;
using namespace vips;

char *Uncaption(string type, char *BufferData, size_t BufferLength,
                ArgumentMap Arguments, size_t *DataSize) {

  float tolerance = GetArgumentWithFallback<float>(Arguments, "tolerance", 0.5);

  VOption *options = VImage::option();

  VImage in =
      VImage::new_from_buffer(
          BufferData, BufferLength, "",
          type == "gif" ? options->set("n", -1)->set("access", "sequential")
                        : options)
          .colourspace(VIPS_INTERPRETATION_sRGB);
  if (!in.has_alpha())
    in = in.bandjoin(255);

  int width = in.width();
  int pageHeight = vips_image_get_page_height(in.get_image());
  int nPages = vips_image_get_n_pages(in.get_image());

  VImage first =
      in.crop(0, 0, 3, pageHeight).colourspace(VIPS_INTERPRETATION_B_W) >
      (255 * tolerance);
  int top, captionWidth, captionHeight;
  first.find_trim(&top, &captionWidth, &captionHeight);

  vector<VImage> img;
  int newHeight = pageHeight - top;
  if (top == pageHeight) {
    newHeight = pageHeight;
    top = 0;
  }
  for (int i = 0; i < nPages; i++) {
    VImage img_frame = in.crop(0, (i * pageHeight) + top, width, newHeight);
    img.push_back(img_frame);
  }
  VImage final = VImage::arrayjoin(img, VImage::option()->set("across", 1));
  final.set(VIPS_META_PAGE_HEIGHT, newHeight);

  void *buf;
  final.write_to_buffer(
      ("." + type).c_str(), &buf, DataSize,
      type == "gif" ? VImage::option()->set("dither", 0)->set("reoptimise", 1)
                    : 0);

  vips_error_clear();
  vips_thread_shutdown();
  return (char *)buf;
}