Method crop

mllm/preprocessor/visual/Image.cpp:109–151

int Image::c() { return c_; }

Image Image::crop(int left, int upper, int right, int lower) {
  // Validate input dimensions and ensure source image is loaded
  MLLM_RT_ASSERT(image_ptr_ != nullptr);
  MLLM_RT_ASSERT(right > left && lower > upper);

  const int crop_w = right - left;
  const int crop_h = lower - upper;

  Image new_img;
  new_img.w_ = crop_w;
  new_img.h_ = crop_h;
  new_img.c_ = 3;  // Force RGB, consistent with Image::open

  // Allocate output buffer; stbi_image_free uses free, so malloc is compatible
  unsigned char* output = static_cast<unsigned char*>(malloc(static_cast<size_t>(crop_w) * crop_h * new_img.c_));
  MLLM_RT_ASSERT(output != nullptr);

  const unsigned char* src = static_cast<const unsigned char*>(image_ptr_->ptr_);

  // PIL-style crop: pad out-of-bounds with zeros
  for (int y = 0; y < crop_h; ++y) {
    const int sy = upper + y;
    for (int x = 0; x < crop_w; ++x) {
      const int sx = left + x;
      unsigned char* dst_px = output + (static_cast<size_t>(y) * crop_w + x) * new_img.c_;
      if (sx >= 0 && sx < w_ && sy >= 0 && sy < h_) {
        const unsigned char* src_px = src + (static_cast<size_t>(sy) * w_ + sx) * c_;
        dst_px[0] = src_px[0];
        dst_px[1] = src_px[1];
        dst_px[2] = src_px[2];
      } else {
        dst_px[0] = 0;
        dst_px[1] = 0;
        dst_px[2] = 0;
      }
    }
  }

  new_img.image_ptr_ = std::make_shared<_ImagePtr>();
  new_img.image_ptr_->ptr_ = output;

  return new_img;
}

// Pad the image to target size with given RGB color.
// Semantics mirror PIL ImageOps.pad: resize to fit within target (keeping aspect ratio)