load() [1/2]

std::optional< ImageData > MayaFlux::IO::ImageReader::load ( const std::filesystem::path &  path, int  desired_channels = 4  )

static

Load image from file (static utility)

Parameters

path	Image file path
desired_channels	Force channel count (0 = keep original, 4 = RGBA)

Returns

Image data or nullopt on failure

Definition at line 229 of file ImageReader.cpp.

{
    if (!std::filesystem::exists(path)) {
        MF_ERROR(Journal::Component::IO, Journal::Context::FileIO,
            "Image file not found: {}", path.string());
        return std::nullopt;
    }
 
    std::ifstream file(path, std::ios::binary | std::ios::ate);
    if (!file.is_open()) {
        MF_ERROR(Journal::Component::IO, Journal::Context::FileIO,
            "Failed to open image file: {}", path.string());
        return std::nullopt;
    }
 
    std::streamsize file_size = file.tellg();
    file.seekg(0, std::ios::beg);
 
    std::vector<unsigned char> file_buffer(file_size);
    if (!file.read(reinterpret_cast<char*>(file_buffer.data()), file_size)) {
        MF_ERROR(Journal::Component::IO, Journal::Context::FileIO,
            "Failed to read image file: {}", path.string());
        return std::nullopt;
    }
    file.close();
 
    int width {}, height {}, channels {};
    unsigned char* pixels = stbi_load_from_memory(
        file_buffer.data(),
        static_cast<int>(file_buffer.size()),
        &width, &height, &channels,
        desired_channels);
 
    if (!pixels) {
        MF_ERROR(Journal::Component::IO, Journal::Context::FileIO,
            "Failed to decode image: {} - {}",
            path.string(), stbi_failure_reason());
        return std::nullopt;
    }
 
    Portal::Graphics::ImageFormat format {};
    switch (channels) {
    case 1:
        format = Portal::Graphics::ImageFormat::R8;
        break;
    case 2:
        format = Portal::Graphics::ImageFormat::RG8;
        break;
    case 3:
        format = Portal::Graphics::ImageFormat::RGB8;
        break;
    case 4:
        format = Portal::Graphics::ImageFormat::RGBA8;
        break;
    default:
        MF_ERROR(Journal::Component::IO, Journal::Context::FileIO,
            "Unsupported channel count: {}", channels);
        stbi_image_free(pixels);
        return std::nullopt;
    }
 
    ImageData result;
 
    size_t data_size = static_cast<long>(width * height) * channels;
    result.pixels.resize(data_size);
    std::memcpy(result.pixels.data(), pixels, data_size);
 
    result.width = width;
    result.height = height;
    result.format = format;
 
    stbi_image_free(pixels);
 
    MF_INFO(Journal::Component::IO, Journal::Context::FileIO,
        "Loaded image: {} ({}x{}, {} channels)",
        path.filename().string(), width, height, channels);
 
    return result;
}

References MayaFlux::Journal::FileIO, MayaFlux::IO::ImageData::format, MayaFlux::IO::ImageData::height, MayaFlux::Journal::IO, MF_ERROR, MF_INFO, MayaFlux::IO::ImageData::pixels, MayaFlux::Portal::Graphics::R8, MayaFlux::Portal::Graphics::RG8, MayaFlux::Portal::Graphics::RGB8, MayaFlux::Portal::Graphics::RGBA8, and MayaFlux::IO::ImageData::width.