Function ensureMapping

src/SFML/Window/Unix/KeyboardImpl.cpp:457–517

///////////////////////////////////////////////////////

////////////////////////////////////////////////////////////
void ensureMapping()
{
    static bool isMappingInitialized = false;

    if (isMappingInitialized)
        return;

    // Phase 1: Initialize mappings with default values
    scancodeToKeycode.fill(nullKeyCode);
    keycodeToScancode.fill(sf::Keyboard::Scan::Unknown);

    // Phase 2: Get XKB names with key code
    const auto display = sf::priv::openDisplay();

    std::array<char, XkbKeyNameLength + 1> name{};
    XkbDescPtr                             descriptor = XkbGetMap(display.get(), 0, XkbUseCoreKbd);
    XkbGetNames(display.get(), XkbKeyNamesMask, descriptor);

    std::unordered_map<std::string, sf::Keyboard::Scancode> nameScancodeMap = getNameScancodeMap();

    for (int keycode = descriptor->min_key_code; keycode <= descriptor->max_key_code; ++keycode)
    {
        if (!isValidKeycode(static_cast<KeyCode>(keycode)))
        {
            continue;
        }

        std::memcpy(name.data(), descriptor->names->keys[keycode].name, XkbKeyNameLength);
        name[XkbKeyNameLength] = '\0';

        const auto mappedScancode = nameScancodeMap.find(std::string(name.data()));
        auto       scancode       = sf::Keyboard::Scan::Unknown;

        if (mappedScancode != nameScancodeMap.end())
            scancode = mappedScancode->second;

        if (scancode != sf::Keyboard::Scan::Unknown)
            scancodeToKeycode[scancode] = static_cast<KeyCode>(keycode);

        keycodeToScancode[static_cast<KeyCode>(keycode)] = scancode;
    }

    XkbFreeNames(descriptor, XkbKeyNamesMask, True);
    XkbFreeKeyboard(descriptor, 0, True);

    // Phase 3: Translate un-translated keycodes using traditional X11 KeySym lookups
    for (int keycode = 8; keycode < maxKeyCode; ++keycode)
    {
        if (keycodeToScancode[static_cast<KeyCode>(keycode)] == sf::Keyboard::Scan::Unknown)
        {
            const auto scancode = translateKeyCode(display.get(), static_cast<KeyCode>(keycode));

            if (scancode != sf::Keyboard::Scan::Unknown && scancodeToKeycode[scancode] == nullKeyCode)
                scancodeToKeycode[scancode] = static_cast<KeyCode>(keycode);

            keycodeToScancode[static_cast<KeyCode>(keycode)] = scancode;
        }
    }