png_indexed_image_loader.cpp

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#include "porytiles2/infra/services/png_indexed_image_loader.hpp"
 
#include <expected>
 
#include "fmt/format.h"
#include "png++/png.hpp"
 
#include "porytiles2/domain/models/index_pixel.hpp"
#include "porytiles2/templates/result.hpp"
 
namespace porytiles2 {
 
Result<std::unique_ptr<Image<IndexPixel>>>
PngIndexedImageLoader::load_from_file(const std::filesystem::path &path) const
{
    if (!exists(path)) {
        return std::unexpected{fmt::format("file does not exist: {}", path.string())};
    }
 
    try {
        // Do this here so if the source is not a PNG, we can catch and give a better error
        png::image<png::index_pixel> test{path};
    }
    catch (std::exception &) {
        return std::unexpected{fmt::format("file not a valid indexed PNG: {}", path.string())};
    }
 
    png::image<png::index_pixel> tilesheet_png{path};
    const auto tilesheet_width = tilesheet_png.get_width();
    const auto tilesheet_height = tilesheet_png.get_height();
    const auto tilesheet_size = tilesheet_width * tilesheet_height;
    auto image = std::make_unique<Image<IndexPixel>>(tilesheet_width, tilesheet_height);
    for (unsigned int pixel_index = 0; pixel_index < tilesheet_size; pixel_index++) {
        const auto row = pixel_index / tilesheet_width;
        const auto col = pixel_index % tilesheet_width;
        // TODO: make sure this sets 4-bit pixels only, even if input tiles.png is using true-color (8-bit)
        image->set(pixel_index, IndexPixel{tilesheet_png[row][col]});
    }
 
    return image;
}
 
} // namespace porytiles2