load_from_memory()

std::optional< ImageData > MayaFlux::IO::ImageReader::load_from_memory ( const void *  data, size_t  size  )

static

Load image from memory (static utility)

Parameters

data	Pointer to image data in memory
size	Size of the image data in bytes

Returns

Image data or nullopt on failure

Definition at line 563 of file ImageReader.cpp.

{
    if (!data || size == 0) {
        MF_ERROR(Journal::Component::IO, Journal::Context::FileIO,
            "Invalid memory buffer for image loading");
        return std::nullopt;
    }
 
    const auto* bytes = static_cast<const unsigned char*>(data);
 
    if (size >= 4
        && bytes[0] == 0x76 && bytes[1] == 0x2F
        && bytes[2] == 0x31 && bytes[3] == 0x01) {
        return load_exr_from_memory(bytes, size);
    }
 
    int width {}, height {}, channels {};
 
    stbi_info_from_memory(bytes, static_cast<int>(size),
        &width, &height, &channels);
 
    int load_as = (channels == 3) ? 4 : 0;
 
    unsigned char* pixels = stbi_load_from_memory(
        bytes,
        static_cast<int>(size),
        &width, &height, &channels,
        load_as);
 
    if (!pixels) {
        MF_ERROR(Journal::Component::IO, Journal::Context::FileIO,
            "Failed to decode image from memory: {}",
            stbi_failure_reason());
        return std::nullopt;
    }
 
    int result_channels = (load_as != 0) ? load_as : channels;
 
    MF_INFO(Journal::Component::IO, Journal::Context::FileIO,
        "Loaded image from memory ({}x{}, {} channels{})",
        width, height, result_channels,
        (channels == 3 && result_channels == 4) ? " [RGB→RGBA]" : "");
 
    ImageData result;
    auto& buf = result.pixels.emplace<std::vector<uint8_t>>();
    size_t data_size = static_cast<size_t>(width) * height * result_channels;
    buf.resize(data_size);
    std::memcpy(buf.data(), pixels, data_size);
 
    result.width = width;
    result.height = height;
    result.channels = result_channels;
 
    switch (result_channels) {
    case 1:
        result.format = Portal::Graphics::ImageFormat::R8;
        break;
    case 2:
        result.format = Portal::Graphics::ImageFormat::RG8;
        break;
    case 4:
        result.format = Portal::Graphics::ImageFormat::RGBA8;
        break;
    default:
        MF_ERROR(Journal::Component::IO, Journal::Context::FileIO,
            "Unsupported channel count: {}", result_channels);
        stbi_image_free(pixels);
        return std::nullopt;
    }
 
    stbi_image_free(pixels);
    return result;
}

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