XCEngine/new_editor/app/Host/InputModifierTracker.h

#pragma once

#ifndef NOMINMAX
#define NOMINMAX
#endif

#include <XCEngine/UI/Types.h>

#include <windows.h>

#include <cstddef>
#include <cstdint>

namespace XCEngine::UI::Editor::Host {

class InputModifierTracker {
public:
    void Reset() {
        m_leftShift = false;
        m_rightShift = false;
        m_leftControl = false;
        m_rightControl = false;
        m_leftAlt = false;
        m_rightAlt = false;
        m_leftSuper = false;
        m_rightSuper = false;
    }

    void SyncFromSystemState() {
        m_leftShift = (GetKeyState(VK_LSHIFT) & 0x8000) != 0;
        m_rightShift = (GetKeyState(VK_RSHIFT) & 0x8000) != 0;
        m_leftControl = (GetKeyState(VK_LCONTROL) & 0x8000) != 0;
        m_rightControl = (GetKeyState(VK_RCONTROL) & 0x8000) != 0;
        m_leftAlt = (GetKeyState(VK_LMENU) & 0x8000) != 0;
        m_rightAlt = (GetKeyState(VK_RMENU) & 0x8000) != 0;
        m_leftSuper = (GetKeyState(VK_LWIN) & 0x8000) != 0;
        m_rightSuper = (GetKeyState(VK_RWIN) & 0x8000) != 0;
    }

    ::XCEngine::UI::UIInputModifiers GetCurrentModifiers() const {
        return BuildModifiers();
    }

    ::XCEngine::UI::UIInputModifiers BuildPointerModifiers(std::size_t wParam) const {
        ::XCEngine::UI::UIInputModifiers modifiers = BuildModifiers();
        modifiers.shift = modifiers.shift || (wParam & MK_SHIFT) != 0;
        modifiers.control = modifiers.control || (wParam & MK_CONTROL) != 0;
        return modifiers;
    }

    ::XCEngine::UI::UIInputModifiers ApplyKeyMessage(
        ::XCEngine::UI::UIInputEventType type,
        WPARAM wParam,
        LPARAM lParam) {
        if (type == ::XCEngine::UI::UIInputEventType::KeyDown) {
            SetModifierState(ResolveModifierKey(wParam, lParam), true);
        } else if (type == ::XCEngine::UI::UIInputEventType::KeyUp) {
            SetModifierState(ResolveModifierKey(wParam, lParam), false);
        }

        return BuildModifiers();
    }

private:
    enum class ModifierKey : std::uint8_t {
        None = 0,
        LeftShift,
        RightShift,
        LeftControl,
        RightControl,
        LeftAlt,
        RightAlt,
        LeftSuper,
        RightSuper
    };

    static bool IsExtendedKey(LPARAM lParam) {
        return (static_cast<std::uint32_t>(lParam) & 0x01000000u) != 0u;
    }

    static std::uint32_t ExtractScanCode(LPARAM lParam) {
        return (static_cast<std::uint32_t>(lParam) >> 16u) & 0xffu;
    }

    static ModifierKey ResolveModifierKey(WPARAM wParam, LPARAM lParam) {
        switch (static_cast<std::uint32_t>(wParam)) {
        case VK_SHIFT: {
            const UINT shiftVirtualKey = MapVirtualKeyW(ExtractScanCode(lParam), MAPVK_VSC_TO_VK_EX);
            return shiftVirtualKey == VK_RSHIFT
                ? ModifierKey::RightShift
                : ModifierKey::LeftShift;
        }
        case VK_LSHIFT:
            return ModifierKey::LeftShift;
        case VK_RSHIFT:
            return ModifierKey::RightShift;
        case VK_CONTROL:
            return IsExtendedKey(lParam)
                ? ModifierKey::RightControl
                : ModifierKey::LeftControl;
        case VK_LCONTROL:
            return ModifierKey::LeftControl;
        case VK_RCONTROL:
            return ModifierKey::RightControl;
        case VK_MENU:
            return IsExtendedKey(lParam)
                ? ModifierKey::RightAlt
                : ModifierKey::LeftAlt;
        case VK_LMENU:
            return ModifierKey::LeftAlt;
        case VK_RMENU:
            return ModifierKey::RightAlt;
        case VK_LWIN:
            return ModifierKey::LeftSuper;
        case VK_RWIN:
            return ModifierKey::RightSuper;
        default:
            return ModifierKey::None;
        }
    }

    void SetModifierState(ModifierKey key, bool pressed) {
        switch (key) {
        case ModifierKey::LeftShift:
            m_leftShift = pressed;
            break;
        case ModifierKey::RightShift:
            m_rightShift = pressed;
            break;
        case ModifierKey::LeftControl:
            m_leftControl = pressed;
            break;
        case ModifierKey::RightControl:
            m_rightControl = pressed;
            break;
        case ModifierKey::LeftAlt:
            m_leftAlt = pressed;
            break;
        case ModifierKey::RightAlt:
            m_rightAlt = pressed;
            break;
        case ModifierKey::LeftSuper:
            m_leftSuper = pressed;
            break;
        case ModifierKey::RightSuper:
            m_rightSuper = pressed;
            break;
        case ModifierKey::None:
        default:
            break;
        }
    }

    ::XCEngine::UI::UIInputModifiers BuildModifiers() const {
        ::XCEngine::UI::UIInputModifiers modifiers = {};
        modifiers.shift = m_leftShift || m_rightShift;
        modifiers.control = m_leftControl || m_rightControl;
        modifiers.alt = m_leftAlt || m_rightAlt;
        modifiers.super = m_leftSuper || m_rightSuper;
        return modifiers;
    }

    bool m_leftShift = false;
    bool m_rightShift = false;
    bool m_leftControl = false;
    bool m_rightControl = false;
    bool m_leftAlt = false;
    bool m_rightAlt = false;
    bool m_leftSuper = false;
    bool m_rightSuper = false;
};

} // namespace XCEngine::UI::Editor::Host