netatmo-algo/src/pack.cpp

#include "pack.h"

#include <algorithm>
#include <cassert>
#include <cmath>
#include <cstring>
#include <iostream>

namespace freling {

void blit(const Frame& in_frame,
          const BoundingBox& in_box,
          Frame& out_frame,
          const BoundingBox& out_box) {
    assert(in_box.width() == out_box.width());
    assert(in_box.height() == out_box.height());

    const int data_width = in_box.width() * sizeof(Pixel);
    const int in_row_size = in_frame.width * sizeof(Pixel);
    const int out_row_size = out_frame.width * sizeof(Pixel);

    for (unsigned int i = 0; i < in_box.height(); ++i) {
        const int in_offset =
            in_box.left * sizeof(Pixel) + (i + in_box.top) * in_row_size;
        const int out_offset =
            out_box.left * sizeof(Pixel) + (i + out_box.top) * out_row_size;
        memcpy(out_frame.data + out_offset, in_frame.data + in_offset,
               data_width);
    }
}

std::optional<Frame> pack(const Frame& in_frame,
                          const std::vector<BoundingBox>& bboxes) {
    if (bboxes.size() == 0) {
        std::cerr << "No bounding box, cannot pack.\n";
        return {};
    }
    // We sort the bounding boxes by maximum area
    std::vector<BoundingBox> sorted_bboxes = bboxes;
    std::sort(sorted_bboxes.begin(), sorted_bboxes.end(),
              [](const auto& a, const auto& b) { return a.area() > b.area(); });

    // We keep a mapping between the sorted bounding boxes and the original
    // order
    std::vector<int> mapping(bboxes.size());
    for (int i = 0; i < sorted_bboxes.size(); ++i) {
        const auto& s_box = sorted_bboxes[i];
        for (int j = 0; j < bboxes.size(); ++j) {
            const auto& box = bboxes[j];
            if (box == s_box) {
                mapping[i] = j;
                continue;
            }
        }
    }

    int max_area = 0;
    for (const auto& box : sorted_bboxes) {
        int area = box.area();
        std::cout << "bounding box area: " << area << "\n";
        max_area += area;
    }
    std::cout << "max area: " << max_area << "\n";
    int min_dim = int(ceil(std::sqrt(max_area)));
    std::cout << "optimal image dimention: " << min_dim << " x " << min_dim
              << "\n";
    const int in_min_dim = std::min(in_frame.width, in_frame.height);
    std::cout << "maximum image dimention: " << in_min_dim << " x "
              << in_min_dim << "\n";

    const auto& largest = sorted_bboxes[0];
    BoundingBox out_largest = {0, 0, static_cast<uint32_t>(largest.width()),
                               static_cast<uint32_t>(largest.height())};
    Frame packed_frame(largest.width(), largest.height());
    blit(in_frame, largest, packed_frame, out_largest);
    return Frame(in_frame);
}

}  // namespace freling