Method loadFromStream

src/SFML/Graphics/Image.cpp:362–420

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bool Image::loadFromStream(InputStream& stream)
{
    // Make sure that the stream's reading position is at the beginning
    if (!stream.seek(0).has_value())
    {
        err() << "Failed to seek image stream" << std::endl;
        return false;
    }

    // Read a (possible) QOI magic number
    std::array<char, 4> qoiMagicNumber{};
    const auto          qoiMagicCount = stream.read(qoiMagicNumber.data(), qoiMagicNumber.size());

    const auto seekToStartResult = stream.seek(0);
    if (!seekToStartResult.has_value())
    {
        err() << "Failed to seek back the image stream" << std::endl;
        return false;
    }

    // Read the QOI file if it's valid
    if (qoiMagicCount.has_value() && isQoiMagicNumber(std::string_view(qoiMagicNumber.data(), *qoiMagicCount)))
    {
        if (const auto streamSize = stream.getSize(); streamSize.has_value())
        {
            // Read in the file contents since QOI doesn't support streams
            std::vector<char> buffer(*streamSize);
            const auto        readDataSize = stream.read(buffer.data(), *streamSize);

            qoi_desc formatDesc = {};
            if (const auto ptr = MallocPtr(qoi_decode(buffer.data(), static_cast<int>(*readDataSize), &formatDesc, 4)))
            {
                const Vector2u imageSize = {formatDesc.width, formatDesc.height};
                resize(imageSize, static_cast<const uint8_t*>(ptr.get()));
                return true;
            }
        }
    }

    // Setup the stb_image callbacks
    stbi_io_callbacks callbacks;
    callbacks.read = read;
    callbacks.skip = skip;
    callbacks.eof  = eof;

    // Load the image and get a pointer to the pixels in memory
    Vector2i imageSize;
    int      channels = 0;
    if (const auto ptr = StbPtr(
            stbi_load_from_callbacks(&callbacks, &stream, &imageSize.x, &imageSize.y, &channels, STBI_rgb_alpha)))
    {
        resize(Vector2u(imageSize), ptr.get());
        return true;
    }

    // Error, failed to load the image
    err() << "Failed to load image from stream. Reason: " << stbi_failure_reason() << std::endl;
    return false;