Method loadInputImage

tools/ktx/command_create.cpp:1905–1949

// -------------------------------------------------------------------------------------------------

std::unique_ptr<Image> CommandCreate::loadInputImage(ImageInput& inputImageFile) {
    std::unique_ptr<Image> image = nullptr;

    const auto& inputFormat = inputImageFile.spec().format();
    const auto width = inputImageFile.spec().width();
    const auto height = inputImageFile.spec().height();

    const auto inputBitLength = inputFormat.largestChannelBitLength();
    const auto requestBitLength = std::max(imageio::bit_ceil(inputBitLength), 8u);
    FormatDescriptor loadFormat;

    switch (inputImageFile.formatType()) {
    case ImageInputFormatType::exr_uint:
        image = std::make_unique<rgba32image>(width, height);
        loadFormat = createFormatDescriptor(VK_FORMAT_R32G32B32A32_UINT, *this);
        break;

    case ImageInputFormatType::exr_float:
        image = std::make_unique<rgba32fimage>(width, height);
        loadFormat = createFormatDescriptor(VK_FORMAT_R32G32B32A32_SFLOAT, *this);
        break;

    case ImageInputFormatType::npbm: [[fallthrough]];
    case ImageInputFormatType::jpg: [[fallthrough]];
    case ImageInputFormatType::png_l: [[fallthrough]];
    case ImageInputFormatType::png_la: [[fallthrough]];
    case ImageInputFormatType::png_rgb: [[fallthrough]];
    case ImageInputFormatType::png_rgba:
        if (requestBitLength == 8) {
            image = std::make_unique<rgba8image>(width, height);
            loadFormat = createFormatDescriptor(VK_FORMAT_R8G8B8A8_UNORM, *this);
            break;
        } else if (requestBitLength == 16) {
            image = std::make_unique<rgba16image>(width, height);
            loadFormat = createFormatDescriptor(VK_FORMAT_R16G16B16A16_UNORM, *this);
            break;
        } else {
            fatal(rc::INVALID_FILE, "Unsupported format with {}-bit channels.", requestBitLength);
        }
        break;
    }

    inputImageFile.readImage(static_cast<uint8_t*>(*image), image->getByteCount(), 0, 0, loadFormat);
    return image;
}

std::vector<uint8_t> convertUNORMPacked(const std::unique_ptr<Image>& image, uint32_t C0, uint32_t C1, uint32_t C2, uint32_t C3, std::string_view swizzle = "") {
    if (!swizzle.empty())