roro9stack/lib/input/src/key_mapper.h

#pragma once

#include <cstdint>
#include <vector>

#include "key_event.h"

namespace roro {

// The physical keyboard state as reported by the keyboard driver: every character key currently
// held (already shifted) plus the modifier and special keys.
struct RawKeys {
    std::vector<char> chars;
    bool fn = false;
    bool opt = false;
    bool ctrl = false;
    bool alt = false;
    bool shift = false;
    bool enter = false;
    bool del = false;
    bool tab = false;
};

// Turns keyboard state changes into logical KeyEvents: only newly pressed keys produce events;
// Fn + ; . , / are arrows, and so are ; . , / alone when no text is being entered; ` is Back and
// Fn + ` is Home; Fn + h is Help anywhere, and so is ? when no text is being entered; the Compose Key (opt) followed by an accent and a letter types the accented
// letter (opt ' e -> é).
class KeyMapper {
   public:
    std::vector<KeyEvent> update(const RawKeys& keys);

    // Whether the foreground App is editing text (default). Outside text entry, the arrow keys
    // don't need Fn.
    void setTextEntry(bool active) { textEntry_ = active; }

    // Is this key down right now, as of the last update()? Events only say when a key goes down:
    // a Game that moves something for as long as a key is held asks this (issue #101). The arrows
    // are ; . , / as for events: alone outside Text Entry, with Fn anywhere.
    bool held(Key key) const;
    bool heldChar(char c) const;  // a character key, as it types

    // 0 when idle, '*' when opt was pressed, or the accent character waiting for its letter.
    char pendingCompose() const { return compose_; }

   private:
    void onChar(char c, const RawKeys& keys, std::vector<KeyEvent>& out);

    RawKeys previous_;
    char compose_ = 0;
    bool textEntry_ = true;
};

}  // namespace roro