image_tileizer.hpp

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#pragma once
 
#include <cstddef>
#include <format>
#include <vector>
 
#include "porytiles/domain/models/image.hpp"
#include "porytiles/domain/models/pixel_tile.hpp"
#include "porytiles/utilities/result/chainable_result.hpp"
 
namespace porytiles {
 
template <typename T>
class ImageTileizer {
  public:
    [[nodiscard]] ChainableResult<std::vector<PixelTile<T>>> tileize(const Image<T> &img) const
    {
        // Validate that image dimensions are multiples of tile size
        if (img.width() % tile::side_length_pix != 0 || img.height() % tile::side_length_pix != 0) {
            return FormattableError{std::format(
                "image dimensions must be a multiple of {}, got {}x{}",
                tile::side_length_pix,
                img.width(),
                img.height())};
        }
 
        const std::size_t tiles_per_row = img.width() / tile::side_length_pix;
        const std::size_t tiles_per_col = img.height() / tile::side_length_pix;
        const std::size_t total_tiles = tiles_per_row * tiles_per_col;
 
        std::vector<PixelTile<T>> tiles;
        tiles.reserve(total_tiles);
 
        // Process each tile region
        for (std::size_t tile_row = 0; tile_row < tiles_per_col; ++tile_row) {
            for (std::size_t tile_col = 0; tile_col < tiles_per_row; ++tile_col) {
                PixelTile<T> tile;
 
                // Calculate pixel offsets for this tile
                const std::size_t pixel_row_offset = tile_row * tile::side_length_pix;
                const std::size_t pixel_col_offset = tile_col * tile::side_length_pix;
 
                // Copy pixels from source image to tile
                for (std::size_t pixel_row = 0; pixel_row < tile::side_length_pix; ++pixel_row) {
                    for (std::size_t pixel_col = 0; pixel_col < tile::side_length_pix; ++pixel_col) {
                        const std::size_t src_row = pixel_row_offset + pixel_row;
                        const std::size_t src_col = pixel_col_offset + pixel_col;
 
                        tile.set(pixel_row, pixel_col, img.at(src_row, src_col));
                    }
                }
 
                tiles.push_back(std::move(tile));
            }
        }
 
        return tiles;
    }
};
 
} // namespace porytiles