Adding MenuItem-level callbacks for MenuBackend

[kerinin]

The previous implementation allowed 3 callbacks to be defined on the root-level MenuBackend instance (menuUse, menuChange and itemChange). This commit introduces 8 callbacks for MenuItems:

• onChangeFrom / onChangeTo - called when the current menu is changed away from/to the base MenuItem
• onUp / onDown / onLeft / onRight - called when moveUp, etc is called with the base MenuItem as the current menu
• onUse - called when use is called with the base MenuItem as the current menu

These callbacks should simplify code organization in some cases by eliminating the need for a complex case statement to handle all menu events.

[AlexanderBrevig]

Thank you for this! I've actually intended to implement it for some time but you beat me to it! Thanks again.

[kerinin]

No problem! I also have a branch that splits the function implementations out into the *.cpp file if that's useful. I was did it trying to fix a problem that turned out to be unrelated.

-Ryan

On Tue, Jan 8, 2013 at 5:35 AM, Alexander Brevig notifications@github.comwrote:

Thank you for this! I've actually intended to implement it for some time but you beat me to it! Thanks again.

— Reply to this email directly or view it on GitHubhttps://github.com/WiringProject/Wiring/pull/30#issuecomment-11993919.