Keyboard Input Handling: Row Editor (FamiTrackerView.cpp)

Keyboard input is handled by class CFamiTrackerView.

Keyboard input comes from OnKeyDown and OnChar.

• Keycode is int64_t (TODO change types), since it helps catch function signature errors.
  • Keycodes encompass A-Z, 0-9, and a series of Win32/MFC VK_... constants, and do not match ASCII/Unicode in general.
  • This was the only method of input in FamiTracker and 0CC.
• Character is a strong_typedef of int, which does not support arithmetic operations.
  • Characters are CP1252 (eventually Unicode?) and match ASCII.
• Input is a std::variant<Keycode, Character>.

All keys with associated characters trigger both OnKeyDown and OnChar. OnKeyDown handles alphanumeric keys and special mappings. OnChar handles non-alphanumeric characters (effect names only, at the moment). If you add special mappings (Clear, Repeat, Echo Buffer...) on top of non-alphanumeric effects (=00), OnKeyDown (mapping) triggers, then OnChar (=00).

• OnKeyDown handles keycodes, and passes HandleKeyboardInput a Keycode.

  • HandleKeyboardInput's children process alphanumeric keycodes and special mappings.
  • Children ignore non-alphanumeric keys, if they're not special keys.

• OnChar handles characters, and passes HandleKeyboardInput a non-alphanumeric Character.

  • OnChar drops all alphanumeric characters.
  • OnChar drops key repeats (if desired).

• HandleKeyboardInput takes an Input (Keycode or Character). If input is Keycode, HandleKeyboardInput drops key repeats (if desired).

  • Most child functions are never called on Character inputs, and only get passed Keycodes.
  • Character inputs are ignored unless the cursor is in the effect name column.
  • If the cursor is in the effect name column, EditEffNumberColumn gets called.

• EditEffNumberColumn takes an Input, unlike other functions.

  • Effect names are expressed in ASCII, so EditEffNumberColumn aborts on non-alphanumeric Keycodes (which don't match ASCII).

Lessons learned: std::variant is a pain to work with. https://github.com/solodon4/Mach7 supports pattern-matching, but only on boost::variant. I can't tell if it's a precompiler or a library.

Docs:

• https://foonathan.net/blog/2016/10/19/strong-typedefs.html